1 |
3 |
xianfeng |
/*
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2 |
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* linux/mm/filemap.c
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3 |
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*
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* Copyright (C) 1994-1999 Linus Torvalds
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*/
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/*
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* This file handles the generic file mmap semantics used by
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* most "normal" filesystems (but you don't /have/ to use this:
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* the NFS filesystem used to do this differently, for example)
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/uaccess.h>
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#include <linux/aio.h>
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#include <linux/capability.h>
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#include <linux/kernel_stat.h>
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#include <linux/mm.h>
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#include <linux/swap.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/file.h>
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#include <linux/uio.h>
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#include <linux/hash.h>
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#include <linux/writeback.h>
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#include <linux/backing-dev.h>
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#include <linux/pagevec.h>
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#include <linux/blkdev.h>
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#include <linux/backing-dev.h>
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#include <linux/security.h>
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#include <linux/syscalls.h>
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#include <linux/cpuset.h>
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#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
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#include "internal.h"
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/*
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* FIXME: remove all knowledge of the buffer layer from the core VM
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*/
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#include <linux/buffer_head.h> /* for generic_osync_inode */
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#include <asm/mman.h>
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static ssize_t
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generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
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loff_t offset, unsigned long nr_segs);
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/*
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* Shared mappings implemented 30.11.1994. It's not fully working yet,
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* though.
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*
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* Shared mappings now work. 15.8.1995 Bruno.
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*
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* finished 'unifying' the page and buffer cache and SMP-threaded the
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* page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
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*
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* SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
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*/
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/*
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* Lock ordering:
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*
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* ->i_mmap_lock (vmtruncate)
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* ->private_lock (__free_pte->__set_page_dirty_buffers)
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* ->swap_lock (exclusive_swap_page, others)
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* ->mapping->tree_lock
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* ->zone.lock
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*
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* ->i_mutex
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* ->i_mmap_lock (truncate->unmap_mapping_range)
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*
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* ->mmap_sem
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* ->i_mmap_lock
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* ->page_table_lock or pte_lock (various, mainly in memory.c)
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* ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
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*
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* ->mmap_sem
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* ->lock_page (access_process_vm)
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*
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* ->i_mutex (generic_file_buffered_write)
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* ->mmap_sem (fault_in_pages_readable->do_page_fault)
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*
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* ->i_mutex
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* ->i_alloc_sem (various)
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*
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* ->inode_lock
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* ->sb_lock (fs/fs-writeback.c)
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* ->mapping->tree_lock (__sync_single_inode)
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*
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* ->i_mmap_lock
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* ->anon_vma.lock (vma_adjust)
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*
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* ->anon_vma.lock
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* ->page_table_lock or pte_lock (anon_vma_prepare and various)
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*
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* ->page_table_lock or pte_lock
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* ->swap_lock (try_to_unmap_one)
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* ->private_lock (try_to_unmap_one)
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* ->tree_lock (try_to_unmap_one)
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* ->zone.lru_lock (follow_page->mark_page_accessed)
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* ->zone.lru_lock (check_pte_range->isolate_lru_page)
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* ->private_lock (page_remove_rmap->set_page_dirty)
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* ->tree_lock (page_remove_rmap->set_page_dirty)
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* ->inode_lock (page_remove_rmap->set_page_dirty)
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* ->inode_lock (zap_pte_range->set_page_dirty)
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* ->private_lock (zap_pte_range->__set_page_dirty_buffers)
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*
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* ->task->proc_lock
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* ->dcache_lock (proc_pid_lookup)
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*/
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/*
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* Remove a page from the page cache and free it. Caller has to make
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* sure the page is locked and that nobody else uses it - or that usage
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* is safe. The caller must hold a write_lock on the mapping's tree_lock.
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*/
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void __remove_from_page_cache(struct page *page)
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{
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struct address_space *mapping = page->mapping;
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radix_tree_delete(&mapping->page_tree, page->index);
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page->mapping = NULL;
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mapping->nrpages--;
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__dec_zone_page_state(page, NR_FILE_PAGES);
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BUG_ON(page_mapped(page));
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/*
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* Some filesystems seem to re-dirty the page even after
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* the VM has canceled the dirty bit (eg ext3 journaling).
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*
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* Fix it up by doing a final dirty accounting check after
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* having removed the page entirely.
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*/
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if (PageDirty(page) && mapping_cap_account_dirty(mapping)) {
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dec_zone_page_state(page, NR_FILE_DIRTY);
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dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
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138 |
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}
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139 |
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}
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void remove_from_page_cache(struct page *page)
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{
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143 |
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struct address_space *mapping = page->mapping;
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BUG_ON(!PageLocked(page));
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write_lock_irq(&mapping->tree_lock);
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__remove_from_page_cache(page);
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write_unlock_irq(&mapping->tree_lock);
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}
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static int sync_page(void *word)
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{
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struct address_space *mapping;
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struct page *page;
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page = container_of((unsigned long *)word, struct page, flags);
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/*
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* page_mapping() is being called without PG_locked held.
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* Some knowledge of the state and use of the page is used to
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* reduce the requirements down to a memory barrier.
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* The danger here is of a stale page_mapping() return value
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* indicating a struct address_space different from the one it's
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* associated with when it is associated with one.
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* After smp_mb(), it's either the correct page_mapping() for
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* the page, or an old page_mapping() and the page's own
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* page_mapping() has gone NULL.
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* The ->sync_page() address_space operation must tolerate
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* page_mapping() going NULL. By an amazing coincidence,
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* this comes about because none of the users of the page
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* in the ->sync_page() methods make essential use of the
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* page_mapping(), merely passing the page down to the backing
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* device's unplug functions when it's non-NULL, which in turn
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* ignore it for all cases but swap, where only page_private(page) is
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* of interest. When page_mapping() does go NULL, the entire
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* call stack gracefully ignores the page and returns.
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* -- wli
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*/
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smp_mb();
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mapping = page_mapping(page);
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if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
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mapping->a_ops->sync_page(page);
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io_schedule();
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return 0;
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}
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187 |
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/**
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189 |
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* __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
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* @mapping: address space structure to write
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191 |
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* @start: offset in bytes where the range starts
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192 |
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* @end: offset in bytes where the range ends (inclusive)
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193 |
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* @sync_mode: enable synchronous operation
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*
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* Start writeback against all of a mapping's dirty pages that lie
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196 |
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* within the byte offsets <start, end> inclusive.
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*
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198 |
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* If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
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* opposed to a regular memory cleansing writeback. The difference between
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200 |
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* these two operations is that if a dirty page/buffer is encountered, it must
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* be waited upon, and not just skipped over.
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202 |
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*/
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203 |
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int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
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204 |
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loff_t end, int sync_mode)
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205 |
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{
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206 |
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int ret;
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207 |
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struct writeback_control wbc = {
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208 |
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.sync_mode = sync_mode,
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209 |
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.nr_to_write = mapping->nrpages * 2,
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210 |
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.range_start = start,
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211 |
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.range_end = end,
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212 |
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};
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213 |
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214 |
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if (!mapping_cap_writeback_dirty(mapping))
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return 0;
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216 |
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217 |
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ret = do_writepages(mapping, &wbc);
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218 |
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return ret;
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219 |
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}
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220 |
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221 |
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static inline int __filemap_fdatawrite(struct address_space *mapping,
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222 |
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int sync_mode)
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223 |
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{
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224 |
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return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
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225 |
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}
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226 |
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227 |
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int filemap_fdatawrite(struct address_space *mapping)
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228 |
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{
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229 |
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return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
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230 |
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}
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231 |
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EXPORT_SYMBOL(filemap_fdatawrite);
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232 |
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233 |
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static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
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234 |
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loff_t end)
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235 |
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{
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236 |
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return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
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237 |
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}
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238 |
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|
239 |
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/**
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240 |
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* filemap_flush - mostly a non-blocking flush
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241 |
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* @mapping: target address_space
|
242 |
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*
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243 |
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* This is a mostly non-blocking flush. Not suitable for data-integrity
|
244 |
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* purposes - I/O may not be started against all dirty pages.
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245 |
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*/
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246 |
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int filemap_flush(struct address_space *mapping)
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247 |
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{
|
248 |
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return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
|
249 |
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}
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250 |
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EXPORT_SYMBOL(filemap_flush);
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251 |
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252 |
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/**
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253 |
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* wait_on_page_writeback_range - wait for writeback to complete
|
254 |
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* @mapping: target address_space
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255 |
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* @start: beginning page index
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256 |
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* @end: ending page index
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257 |
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*
|
258 |
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* Wait for writeback to complete against pages indexed by start->end
|
259 |
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* inclusive
|
260 |
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*/
|
261 |
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int wait_on_page_writeback_range(struct address_space *mapping,
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262 |
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pgoff_t start, pgoff_t end)
|
263 |
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{
|
264 |
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struct pagevec pvec;
|
265 |
|
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int nr_pages;
|
266 |
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int ret = 0;
|
267 |
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pgoff_t index;
|
268 |
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|
269 |
|
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if (end < start)
|
270 |
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return 0;
|
271 |
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|
272 |
|
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pagevec_init(&pvec, 0);
|
273 |
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index = start;
|
274 |
|
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while ((index <= end) &&
|
275 |
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(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
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276 |
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PAGECACHE_TAG_WRITEBACK,
|
277 |
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min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
|
278 |
|
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unsigned i;
|
279 |
|
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|
280 |
|
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for (i = 0; i < nr_pages; i++) {
|
281 |
|
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struct page *page = pvec.pages[i];
|
282 |
|
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|
283 |
|
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/* until radix tree lookup accepts end_index */
|
284 |
|
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if (page->index > end)
|
285 |
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continue;
|
286 |
|
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|
287 |
|
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wait_on_page_writeback(page);
|
288 |
|
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if (PageError(page))
|
289 |
|
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ret = -EIO;
|
290 |
|
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}
|
291 |
|
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pagevec_release(&pvec);
|
292 |
|
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cond_resched();
|
293 |
|
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}
|
294 |
|
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|
295 |
|
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/* Check for outstanding write errors */
|
296 |
|
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if (test_and_clear_bit(AS_ENOSPC, &mapping->flags))
|
297 |
|
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ret = -ENOSPC;
|
298 |
|
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if (test_and_clear_bit(AS_EIO, &mapping->flags))
|
299 |
|
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ret = -EIO;
|
300 |
|
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|
301 |
|
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return ret;
|
302 |
|
|
}
|
303 |
|
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|
304 |
|
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/**
|
305 |
|
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* sync_page_range - write and wait on all pages in the passed range
|
306 |
|
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* @inode: target inode
|
307 |
|
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* @mapping: target address_space
|
308 |
|
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* @pos: beginning offset in pages to write
|
309 |
|
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* @count: number of bytes to write
|
310 |
|
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*
|
311 |
|
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* Write and wait upon all the pages in the passed range. This is a "data
|
312 |
|
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* integrity" operation. It waits upon in-flight writeout before starting and
|
313 |
|
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* waiting upon new writeout. If there was an IO error, return it.
|
314 |
|
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*
|
315 |
|
|
* We need to re-take i_mutex during the generic_osync_inode list walk because
|
316 |
|
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* it is otherwise livelockable.
|
317 |
|
|
*/
|
318 |
|
|
int sync_page_range(struct inode *inode, struct address_space *mapping,
|
319 |
|
|
loff_t pos, loff_t count)
|
320 |
|
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{
|
321 |
|
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pgoff_t start = pos >> PAGE_CACHE_SHIFT;
|
322 |
|
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pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
|
323 |
|
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int ret;
|
324 |
|
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|
325 |
|
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if (!mapping_cap_writeback_dirty(mapping) || !count)
|
326 |
|
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return 0;
|
327 |
|
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ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
|
328 |
|
|
if (ret == 0) {
|
329 |
|
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mutex_lock(&inode->i_mutex);
|
330 |
|
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ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
|
331 |
|
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mutex_unlock(&inode->i_mutex);
|
332 |
|
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}
|
333 |
|
|
if (ret == 0)
|
334 |
|
|
ret = wait_on_page_writeback_range(mapping, start, end);
|
335 |
|
|
return ret;
|
336 |
|
|
}
|
337 |
|
|
EXPORT_SYMBOL(sync_page_range);
|
338 |
|
|
|
339 |
|
|
/**
|
340 |
|
|
* sync_page_range_nolock
|
341 |
|
|
* @inode: target inode
|
342 |
|
|
* @mapping: target address_space
|
343 |
|
|
* @pos: beginning offset in pages to write
|
344 |
|
|
* @count: number of bytes to write
|
345 |
|
|
*
|
346 |
|
|
* Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
|
347 |
|
|
* as it forces O_SYNC writers to different parts of the same file
|
348 |
|
|
* to be serialised right until io completion.
|
349 |
|
|
*/
|
350 |
|
|
int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
|
351 |
|
|
loff_t pos, loff_t count)
|
352 |
|
|
{
|
353 |
|
|
pgoff_t start = pos >> PAGE_CACHE_SHIFT;
|
354 |
|
|
pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
|
355 |
|
|
int ret;
|
356 |
|
|
|
357 |
|
|
if (!mapping_cap_writeback_dirty(mapping) || !count)
|
358 |
|
|
return 0;
|
359 |
|
|
ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
|
360 |
|
|
if (ret == 0)
|
361 |
|
|
ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
|
362 |
|
|
if (ret == 0)
|
363 |
|
|
ret = wait_on_page_writeback_range(mapping, start, end);
|
364 |
|
|
return ret;
|
365 |
|
|
}
|
366 |
|
|
EXPORT_SYMBOL(sync_page_range_nolock);
|
367 |
|
|
|
368 |
|
|
/**
|
369 |
|
|
* filemap_fdatawait - wait for all under-writeback pages to complete
|
370 |
|
|
* @mapping: address space structure to wait for
|
371 |
|
|
*
|
372 |
|
|
* Walk the list of under-writeback pages of the given address space
|
373 |
|
|
* and wait for all of them.
|
374 |
|
|
*/
|
375 |
|
|
int filemap_fdatawait(struct address_space *mapping)
|
376 |
|
|
{
|
377 |
|
|
loff_t i_size = i_size_read(mapping->host);
|
378 |
|
|
|
379 |
|
|
if (i_size == 0)
|
380 |
|
|
return 0;
|
381 |
|
|
|
382 |
|
|
return wait_on_page_writeback_range(mapping, 0,
|
383 |
|
|
(i_size - 1) >> PAGE_CACHE_SHIFT);
|
384 |
|
|
}
|
385 |
|
|
EXPORT_SYMBOL(filemap_fdatawait);
|
386 |
|
|
|
387 |
|
|
int filemap_write_and_wait(struct address_space *mapping)
|
388 |
|
|
{
|
389 |
|
|
int err = 0;
|
390 |
|
|
|
391 |
|
|
if (mapping->nrpages) {
|
392 |
|
|
err = filemap_fdatawrite(mapping);
|
393 |
|
|
/*
|
394 |
|
|
* Even if the above returned error, the pages may be
|
395 |
|
|
* written partially (e.g. -ENOSPC), so we wait for it.
|
396 |
|
|
* But the -EIO is special case, it may indicate the worst
|
397 |
|
|
* thing (e.g. bug) happened, so we avoid waiting for it.
|
398 |
|
|
*/
|
399 |
|
|
if (err != -EIO) {
|
400 |
|
|
int err2 = filemap_fdatawait(mapping);
|
401 |
|
|
if (!err)
|
402 |
|
|
err = err2;
|
403 |
|
|
}
|
404 |
|
|
}
|
405 |
|
|
return err;
|
406 |
|
|
}
|
407 |
|
|
EXPORT_SYMBOL(filemap_write_and_wait);
|
408 |
|
|
|
409 |
|
|
/**
|
410 |
|
|
* filemap_write_and_wait_range - write out & wait on a file range
|
411 |
|
|
* @mapping: the address_space for the pages
|
412 |
|
|
* @lstart: offset in bytes where the range starts
|
413 |
|
|
* @lend: offset in bytes where the range ends (inclusive)
|
414 |
|
|
*
|
415 |
|
|
* Write out and wait upon file offsets lstart->lend, inclusive.
|
416 |
|
|
*
|
417 |
|
|
* Note that `lend' is inclusive (describes the last byte to be written) so
|
418 |
|
|
* that this function can be used to write to the very end-of-file (end = -1).
|
419 |
|
|
*/
|
420 |
|
|
int filemap_write_and_wait_range(struct address_space *mapping,
|
421 |
|
|
loff_t lstart, loff_t lend)
|
422 |
|
|
{
|
423 |
|
|
int err = 0;
|
424 |
|
|
|
425 |
|
|
if (mapping->nrpages) {
|
426 |
|
|
err = __filemap_fdatawrite_range(mapping, lstart, lend,
|
427 |
|
|
WB_SYNC_ALL);
|
428 |
|
|
/* See comment of filemap_write_and_wait() */
|
429 |
|
|
if (err != -EIO) {
|
430 |
|
|
int err2 = wait_on_page_writeback_range(mapping,
|
431 |
|
|
lstart >> PAGE_CACHE_SHIFT,
|
432 |
|
|
lend >> PAGE_CACHE_SHIFT);
|
433 |
|
|
if (!err)
|
434 |
|
|
err = err2;
|
435 |
|
|
}
|
436 |
|
|
}
|
437 |
|
|
return err;
|
438 |
|
|
}
|
439 |
|
|
|
440 |
|
|
/**
|
441 |
|
|
* add_to_page_cache - add newly allocated pagecache pages
|
442 |
|
|
* @page: page to add
|
443 |
|
|
* @mapping: the page's address_space
|
444 |
|
|
* @offset: page index
|
445 |
|
|
* @gfp_mask: page allocation mode
|
446 |
|
|
*
|
447 |
|
|
* This function is used to add newly allocated pagecache pages;
|
448 |
|
|
* the page is new, so we can just run SetPageLocked() against it.
|
449 |
|
|
* The other page state flags were set by rmqueue().
|
450 |
|
|
*
|
451 |
|
|
* This function does not add the page to the LRU. The caller must do that.
|
452 |
|
|
*/
|
453 |
|
|
int add_to_page_cache(struct page *page, struct address_space *mapping,
|
454 |
|
|
pgoff_t offset, gfp_t gfp_mask)
|
455 |
|
|
{
|
456 |
|
|
int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
|
457 |
|
|
|
458 |
|
|
if (error == 0) {
|
459 |
|
|
write_lock_irq(&mapping->tree_lock);
|
460 |
|
|
error = radix_tree_insert(&mapping->page_tree, offset, page);
|
461 |
|
|
if (!error) {
|
462 |
|
|
page_cache_get(page);
|
463 |
|
|
SetPageLocked(page);
|
464 |
|
|
page->mapping = mapping;
|
465 |
|
|
page->index = offset;
|
466 |
|
|
mapping->nrpages++;
|
467 |
|
|
__inc_zone_page_state(page, NR_FILE_PAGES);
|
468 |
|
|
}
|
469 |
|
|
write_unlock_irq(&mapping->tree_lock);
|
470 |
|
|
radix_tree_preload_end();
|
471 |
|
|
}
|
472 |
|
|
return error;
|
473 |
|
|
}
|
474 |
|
|
EXPORT_SYMBOL(add_to_page_cache);
|
475 |
|
|
|
476 |
|
|
int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
|
477 |
|
|
pgoff_t offset, gfp_t gfp_mask)
|
478 |
|
|
{
|
479 |
|
|
int ret = add_to_page_cache(page, mapping, offset, gfp_mask);
|
480 |
|
|
if (ret == 0)
|
481 |
|
|
lru_cache_add(page);
|
482 |
|
|
return ret;
|
483 |
|
|
}
|
484 |
|
|
|
485 |
|
|
#ifdef CONFIG_NUMA
|
486 |
|
|
struct page *__page_cache_alloc(gfp_t gfp)
|
487 |
|
|
{
|
488 |
|
|
if (cpuset_do_page_mem_spread()) {
|
489 |
|
|
int n = cpuset_mem_spread_node();
|
490 |
|
|
return alloc_pages_node(n, gfp, 0);
|
491 |
|
|
}
|
492 |
|
|
return alloc_pages(gfp, 0);
|
493 |
|
|
}
|
494 |
|
|
EXPORT_SYMBOL(__page_cache_alloc);
|
495 |
|
|
#endif
|
496 |
|
|
|
497 |
|
|
static int __sleep_on_page_lock(void *word)
|
498 |
|
|
{
|
499 |
|
|
io_schedule();
|
500 |
|
|
return 0;
|
501 |
|
|
}
|
502 |
|
|
|
503 |
|
|
/*
|
504 |
|
|
* In order to wait for pages to become available there must be
|
505 |
|
|
* waitqueues associated with pages. By using a hash table of
|
506 |
|
|
* waitqueues where the bucket discipline is to maintain all
|
507 |
|
|
* waiters on the same queue and wake all when any of the pages
|
508 |
|
|
* become available, and for the woken contexts to check to be
|
509 |
|
|
* sure the appropriate page became available, this saves space
|
510 |
|
|
* at a cost of "thundering herd" phenomena during rare hash
|
511 |
|
|
* collisions.
|
512 |
|
|
*/
|
513 |
|
|
static wait_queue_head_t *page_waitqueue(struct page *page)
|
514 |
|
|
{
|
515 |
|
|
const struct zone *zone = page_zone(page);
|
516 |
|
|
|
517 |
|
|
return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
|
518 |
|
|
}
|
519 |
|
|
|
520 |
|
|
static inline void wake_up_page(struct page *page, int bit)
|
521 |
|
|
{
|
522 |
|
|
__wake_up_bit(page_waitqueue(page), &page->flags, bit);
|
523 |
|
|
}
|
524 |
|
|
|
525 |
|
|
void fastcall wait_on_page_bit(struct page *page, int bit_nr)
|
526 |
|
|
{
|
527 |
|
|
DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
|
528 |
|
|
|
529 |
|
|
if (test_bit(bit_nr, &page->flags))
|
530 |
|
|
__wait_on_bit(page_waitqueue(page), &wait, sync_page,
|
531 |
|
|
TASK_UNINTERRUPTIBLE);
|
532 |
|
|
}
|
533 |
|
|
EXPORT_SYMBOL(wait_on_page_bit);
|
534 |
|
|
|
535 |
|
|
/**
|
536 |
|
|
* unlock_page - unlock a locked page
|
537 |
|
|
* @page: the page
|
538 |
|
|
*
|
539 |
|
|
* Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
|
540 |
|
|
* Also wakes sleepers in wait_on_page_writeback() because the wakeup
|
541 |
|
|
* mechananism between PageLocked pages and PageWriteback pages is shared.
|
542 |
|
|
* But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
|
543 |
|
|
*
|
544 |
|
|
* The first mb is necessary to safely close the critical section opened by the
|
545 |
|
|
* TestSetPageLocked(), the second mb is necessary to enforce ordering between
|
546 |
|
|
* the clear_bit and the read of the waitqueue (to avoid SMP races with a
|
547 |
|
|
* parallel wait_on_page_locked()).
|
548 |
|
|
*/
|
549 |
|
|
void fastcall unlock_page(struct page *page)
|
550 |
|
|
{
|
551 |
|
|
smp_mb__before_clear_bit();
|
552 |
|
|
if (!TestClearPageLocked(page))
|
553 |
|
|
BUG();
|
554 |
|
|
smp_mb__after_clear_bit();
|
555 |
|
|
wake_up_page(page, PG_locked);
|
556 |
|
|
}
|
557 |
|
|
EXPORT_SYMBOL(unlock_page);
|
558 |
|
|
|
559 |
|
|
/**
|
560 |
|
|
* end_page_writeback - end writeback against a page
|
561 |
|
|
* @page: the page
|
562 |
|
|
*/
|
563 |
|
|
void end_page_writeback(struct page *page)
|
564 |
|
|
{
|
565 |
|
|
if (!TestClearPageReclaim(page) || rotate_reclaimable_page(page)) {
|
566 |
|
|
if (!test_clear_page_writeback(page))
|
567 |
|
|
BUG();
|
568 |
|
|
}
|
569 |
|
|
smp_mb__after_clear_bit();
|
570 |
|
|
wake_up_page(page, PG_writeback);
|
571 |
|
|
}
|
572 |
|
|
EXPORT_SYMBOL(end_page_writeback);
|
573 |
|
|
|
574 |
|
|
/**
|
575 |
|
|
* __lock_page - get a lock on the page, assuming we need to sleep to get it
|
576 |
|
|
* @page: the page to lock
|
577 |
|
|
*
|
578 |
|
|
* Ugly. Running sync_page() in state TASK_UNINTERRUPTIBLE is scary. If some
|
579 |
|
|
* random driver's requestfn sets TASK_RUNNING, we could busywait. However
|
580 |
|
|
* chances are that on the second loop, the block layer's plug list is empty,
|
581 |
|
|
* so sync_page() will then return in state TASK_UNINTERRUPTIBLE.
|
582 |
|
|
*/
|
583 |
|
|
void fastcall __lock_page(struct page *page)
|
584 |
|
|
{
|
585 |
|
|
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
|
586 |
|
|
|
587 |
|
|
__wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
|
588 |
|
|
TASK_UNINTERRUPTIBLE);
|
589 |
|
|
}
|
590 |
|
|
EXPORT_SYMBOL(__lock_page);
|
591 |
|
|
|
592 |
|
|
/*
|
593 |
|
|
* Variant of lock_page that does not require the caller to hold a reference
|
594 |
|
|
* on the page's mapping.
|
595 |
|
|
*/
|
596 |
|
|
void fastcall __lock_page_nosync(struct page *page)
|
597 |
|
|
{
|
598 |
|
|
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
|
599 |
|
|
__wait_on_bit_lock(page_waitqueue(page), &wait, __sleep_on_page_lock,
|
600 |
|
|
TASK_UNINTERRUPTIBLE);
|
601 |
|
|
}
|
602 |
|
|
|
603 |
|
|
/**
|
604 |
|
|
* find_get_page - find and get a page reference
|
605 |
|
|
* @mapping: the address_space to search
|
606 |
|
|
* @offset: the page index
|
607 |
|
|
*
|
608 |
|
|
* Is there a pagecache struct page at the given (mapping, offset) tuple?
|
609 |
|
|
* If yes, increment its refcount and return it; if no, return NULL.
|
610 |
|
|
*/
|
611 |
|
|
struct page * find_get_page(struct address_space *mapping, pgoff_t offset)
|
612 |
|
|
{
|
613 |
|
|
struct page *page;
|
614 |
|
|
|
615 |
|
|
read_lock_irq(&mapping->tree_lock);
|
616 |
|
|
page = radix_tree_lookup(&mapping->page_tree, offset);
|
617 |
|
|
if (page)
|
618 |
|
|
page_cache_get(page);
|
619 |
|
|
read_unlock_irq(&mapping->tree_lock);
|
620 |
|
|
return page;
|
621 |
|
|
}
|
622 |
|
|
EXPORT_SYMBOL(find_get_page);
|
623 |
|
|
|
624 |
|
|
/**
|
625 |
|
|
* find_lock_page - locate, pin and lock a pagecache page
|
626 |
|
|
* @mapping: the address_space to search
|
627 |
|
|
* @offset: the page index
|
628 |
|
|
*
|
629 |
|
|
* Locates the desired pagecache page, locks it, increments its reference
|
630 |
|
|
* count and returns its address.
|
631 |
|
|
*
|
632 |
|
|
* Returns zero if the page was not present. find_lock_page() may sleep.
|
633 |
|
|
*/
|
634 |
|
|
struct page *find_lock_page(struct address_space *mapping,
|
635 |
|
|
pgoff_t offset)
|
636 |
|
|
{
|
637 |
|
|
struct page *page;
|
638 |
|
|
|
639 |
|
|
repeat:
|
640 |
|
|
read_lock_irq(&mapping->tree_lock);
|
641 |
|
|
page = radix_tree_lookup(&mapping->page_tree, offset);
|
642 |
|
|
if (page) {
|
643 |
|
|
page_cache_get(page);
|
644 |
|
|
if (TestSetPageLocked(page)) {
|
645 |
|
|
read_unlock_irq(&mapping->tree_lock);
|
646 |
|
|
__lock_page(page);
|
647 |
|
|
|
648 |
|
|
/* Has the page been truncated while we slept? */
|
649 |
|
|
if (unlikely(page->mapping != mapping)) {
|
650 |
|
|
unlock_page(page);
|
651 |
|
|
page_cache_release(page);
|
652 |
|
|
goto repeat;
|
653 |
|
|
}
|
654 |
|
|
VM_BUG_ON(page->index != offset);
|
655 |
|
|
goto out;
|
656 |
|
|
}
|
657 |
|
|
}
|
658 |
|
|
read_unlock_irq(&mapping->tree_lock);
|
659 |
|
|
out:
|
660 |
|
|
return page;
|
661 |
|
|
}
|
662 |
|
|
EXPORT_SYMBOL(find_lock_page);
|
663 |
|
|
|
664 |
|
|
/**
|
665 |
|
|
* find_or_create_page - locate or add a pagecache page
|
666 |
|
|
* @mapping: the page's address_space
|
667 |
|
|
* @index: the page's index into the mapping
|
668 |
|
|
* @gfp_mask: page allocation mode
|
669 |
|
|
*
|
670 |
|
|
* Locates a page in the pagecache. If the page is not present, a new page
|
671 |
|
|
* is allocated using @gfp_mask and is added to the pagecache and to the VM's
|
672 |
|
|
* LRU list. The returned page is locked and has its reference count
|
673 |
|
|
* incremented.
|
674 |
|
|
*
|
675 |
|
|
* find_or_create_page() may sleep, even if @gfp_flags specifies an atomic
|
676 |
|
|
* allocation!
|
677 |
|
|
*
|
678 |
|
|
* find_or_create_page() returns the desired page's address, or zero on
|
679 |
|
|
* memory exhaustion.
|
680 |
|
|
*/
|
681 |
|
|
struct page *find_or_create_page(struct address_space *mapping,
|
682 |
|
|
pgoff_t index, gfp_t gfp_mask)
|
683 |
|
|
{
|
684 |
|
|
struct page *page;
|
685 |
|
|
int err;
|
686 |
|
|
repeat:
|
687 |
|
|
page = find_lock_page(mapping, index);
|
688 |
|
|
if (!page) {
|
689 |
|
|
page = __page_cache_alloc(gfp_mask);
|
690 |
|
|
if (!page)
|
691 |
|
|
return NULL;
|
692 |
|
|
err = add_to_page_cache_lru(page, mapping, index, gfp_mask);
|
693 |
|
|
if (unlikely(err)) {
|
694 |
|
|
page_cache_release(page);
|
695 |
|
|
page = NULL;
|
696 |
|
|
if (err == -EEXIST)
|
697 |
|
|
goto repeat;
|
698 |
|
|
}
|
699 |
|
|
}
|
700 |
|
|
return page;
|
701 |
|
|
}
|
702 |
|
|
EXPORT_SYMBOL(find_or_create_page);
|
703 |
|
|
|
704 |
|
|
/**
|
705 |
|
|
* find_get_pages - gang pagecache lookup
|
706 |
|
|
* @mapping: The address_space to search
|
707 |
|
|
* @start: The starting page index
|
708 |
|
|
* @nr_pages: The maximum number of pages
|
709 |
|
|
* @pages: Where the resulting pages are placed
|
710 |
|
|
*
|
711 |
|
|
* find_get_pages() will search for and return a group of up to
|
712 |
|
|
* @nr_pages pages in the mapping. The pages are placed at @pages.
|
713 |
|
|
* find_get_pages() takes a reference against the returned pages.
|
714 |
|
|
*
|
715 |
|
|
* The search returns a group of mapping-contiguous pages with ascending
|
716 |
|
|
* indexes. There may be holes in the indices due to not-present pages.
|
717 |
|
|
*
|
718 |
|
|
* find_get_pages() returns the number of pages which were found.
|
719 |
|
|
*/
|
720 |
|
|
unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
|
721 |
|
|
unsigned int nr_pages, struct page **pages)
|
722 |
|
|
{
|
723 |
|
|
unsigned int i;
|
724 |
|
|
unsigned int ret;
|
725 |
|
|
|
726 |
|
|
read_lock_irq(&mapping->tree_lock);
|
727 |
|
|
ret = radix_tree_gang_lookup(&mapping->page_tree,
|
728 |
|
|
(void **)pages, start, nr_pages);
|
729 |
|
|
for (i = 0; i < ret; i++)
|
730 |
|
|
page_cache_get(pages[i]);
|
731 |
|
|
read_unlock_irq(&mapping->tree_lock);
|
732 |
|
|
return ret;
|
733 |
|
|
}
|
734 |
|
|
|
735 |
|
|
/**
|
736 |
|
|
* find_get_pages_contig - gang contiguous pagecache lookup
|
737 |
|
|
* @mapping: The address_space to search
|
738 |
|
|
* @index: The starting page index
|
739 |
|
|
* @nr_pages: The maximum number of pages
|
740 |
|
|
* @pages: Where the resulting pages are placed
|
741 |
|
|
*
|
742 |
|
|
* find_get_pages_contig() works exactly like find_get_pages(), except
|
743 |
|
|
* that the returned number of pages are guaranteed to be contiguous.
|
744 |
|
|
*
|
745 |
|
|
* find_get_pages_contig() returns the number of pages which were found.
|
746 |
|
|
*/
|
747 |
|
|
unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
|
748 |
|
|
unsigned int nr_pages, struct page **pages)
|
749 |
|
|
{
|
750 |
|
|
unsigned int i;
|
751 |
|
|
unsigned int ret;
|
752 |
|
|
|
753 |
|
|
read_lock_irq(&mapping->tree_lock);
|
754 |
|
|
ret = radix_tree_gang_lookup(&mapping->page_tree,
|
755 |
|
|
(void **)pages, index, nr_pages);
|
756 |
|
|
for (i = 0; i < ret; i++) {
|
757 |
|
|
if (pages[i]->mapping == NULL || pages[i]->index != index)
|
758 |
|
|
break;
|
759 |
|
|
|
760 |
|
|
page_cache_get(pages[i]);
|
761 |
|
|
index++;
|
762 |
|
|
}
|
763 |
|
|
read_unlock_irq(&mapping->tree_lock);
|
764 |
|
|
return i;
|
765 |
|
|
}
|
766 |
|
|
EXPORT_SYMBOL(find_get_pages_contig);
|
767 |
|
|
|
768 |
|
|
/**
|
769 |
|
|
* find_get_pages_tag - find and return pages that match @tag
|
770 |
|
|
* @mapping: the address_space to search
|
771 |
|
|
* @index: the starting page index
|
772 |
|
|
* @tag: the tag index
|
773 |
|
|
* @nr_pages: the maximum number of pages
|
774 |
|
|
* @pages: where the resulting pages are placed
|
775 |
|
|
*
|
776 |
|
|
* Like find_get_pages, except we only return pages which are tagged with
|
777 |
|
|
* @tag. We update @index to index the next page for the traversal.
|
778 |
|
|
*/
|
779 |
|
|
unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
|
780 |
|
|
int tag, unsigned int nr_pages, struct page **pages)
|
781 |
|
|
{
|
782 |
|
|
unsigned int i;
|
783 |
|
|
unsigned int ret;
|
784 |
|
|
|
785 |
|
|
read_lock_irq(&mapping->tree_lock);
|
786 |
|
|
ret = radix_tree_gang_lookup_tag(&mapping->page_tree,
|
787 |
|
|
(void **)pages, *index, nr_pages, tag);
|
788 |
|
|
for (i = 0; i < ret; i++)
|
789 |
|
|
page_cache_get(pages[i]);
|
790 |
|
|
if (ret)
|
791 |
|
|
*index = pages[ret - 1]->index + 1;
|
792 |
|
|
read_unlock_irq(&mapping->tree_lock);
|
793 |
|
|
return ret;
|
794 |
|
|
}
|
795 |
|
|
EXPORT_SYMBOL(find_get_pages_tag);
|
796 |
|
|
|
797 |
|
|
/**
|
798 |
|
|
* grab_cache_page_nowait - returns locked page at given index in given cache
|
799 |
|
|
* @mapping: target address_space
|
800 |
|
|
* @index: the page index
|
801 |
|
|
*
|
802 |
|
|
* Same as grab_cache_page(), but do not wait if the page is unavailable.
|
803 |
|
|
* This is intended for speculative data generators, where the data can
|
804 |
|
|
* be regenerated if the page couldn't be grabbed. This routine should
|
805 |
|
|
* be safe to call while holding the lock for another page.
|
806 |
|
|
*
|
807 |
|
|
* Clear __GFP_FS when allocating the page to avoid recursion into the fs
|
808 |
|
|
* and deadlock against the caller's locked page.
|
809 |
|
|
*/
|
810 |
|
|
struct page *
|
811 |
|
|
grab_cache_page_nowait(struct address_space *mapping, pgoff_t index)
|
812 |
|
|
{
|
813 |
|
|
struct page *page = find_get_page(mapping, index);
|
814 |
|
|
|
815 |
|
|
if (page) {
|
816 |
|
|
if (!TestSetPageLocked(page))
|
817 |
|
|
return page;
|
818 |
|
|
page_cache_release(page);
|
819 |
|
|
return NULL;
|
820 |
|
|
}
|
821 |
|
|
page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
|
822 |
|
|
if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
|
823 |
|
|
page_cache_release(page);
|
824 |
|
|
page = NULL;
|
825 |
|
|
}
|
826 |
|
|
return page;
|
827 |
|
|
}
|
828 |
|
|
EXPORT_SYMBOL(grab_cache_page_nowait);
|
829 |
|
|
|
830 |
|
|
/*
|
831 |
|
|
* CD/DVDs are error prone. When a medium error occurs, the driver may fail
|
832 |
|
|
* a _large_ part of the i/o request. Imagine the worst scenario:
|
833 |
|
|
*
|
834 |
|
|
* ---R__________________________________________B__________
|
835 |
|
|
* ^ reading here ^ bad block(assume 4k)
|
836 |
|
|
*
|
837 |
|
|
* read(R) => miss => readahead(R...B) => media error => frustrating retries
|
838 |
|
|
* => failing the whole request => read(R) => read(R+1) =>
|
839 |
|
|
* readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
|
840 |
|
|
* readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
|
841 |
|
|
* readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
|
842 |
|
|
*
|
843 |
|
|
* It is going insane. Fix it by quickly scaling down the readahead size.
|
844 |
|
|
*/
|
845 |
|
|
static void shrink_readahead_size_eio(struct file *filp,
|
846 |
|
|
struct file_ra_state *ra)
|
847 |
|
|
{
|
848 |
|
|
if (!ra->ra_pages)
|
849 |
|
|
return;
|
850 |
|
|
|
851 |
|
|
ra->ra_pages /= 4;
|
852 |
|
|
}
|
853 |
|
|
|
854 |
|
|
/**
|
855 |
|
|
* do_generic_mapping_read - generic file read routine
|
856 |
|
|
* @mapping: address_space to be read
|
857 |
|
|
* @ra: file's readahead state
|
858 |
|
|
* @filp: the file to read
|
859 |
|
|
* @ppos: current file position
|
860 |
|
|
* @desc: read_descriptor
|
861 |
|
|
* @actor: read method
|
862 |
|
|
*
|
863 |
|
|
* This is a generic file read routine, and uses the
|
864 |
|
|
* mapping->a_ops->readpage() function for the actual low-level stuff.
|
865 |
|
|
*
|
866 |
|
|
* This is really ugly. But the goto's actually try to clarify some
|
867 |
|
|
* of the logic when it comes to error handling etc.
|
868 |
|
|
*
|
869 |
|
|
* Note the struct file* is only passed for the use of readpage.
|
870 |
|
|
* It may be NULL.
|
871 |
|
|
*/
|
872 |
|
|
void do_generic_mapping_read(struct address_space *mapping,
|
873 |
|
|
struct file_ra_state *ra,
|
874 |
|
|
struct file *filp,
|
875 |
|
|
loff_t *ppos,
|
876 |
|
|
read_descriptor_t *desc,
|
877 |
|
|
read_actor_t actor)
|
878 |
|
|
{
|
879 |
|
|
struct inode *inode = mapping->host;
|
880 |
|
|
pgoff_t index;
|
881 |
|
|
pgoff_t last_index;
|
882 |
|
|
pgoff_t prev_index;
|
883 |
|
|
unsigned long offset; /* offset into pagecache page */
|
884 |
|
|
unsigned int prev_offset;
|
885 |
|
|
int error;
|
886 |
|
|
|
887 |
|
|
index = *ppos >> PAGE_CACHE_SHIFT;
|
888 |
|
|
prev_index = ra->prev_pos >> PAGE_CACHE_SHIFT;
|
889 |
|
|
prev_offset = ra->prev_pos & (PAGE_CACHE_SIZE-1);
|
890 |
|
|
last_index = (*ppos + desc->count + PAGE_CACHE_SIZE-1) >> PAGE_CACHE_SHIFT;
|
891 |
|
|
offset = *ppos & ~PAGE_CACHE_MASK;
|
892 |
|
|
|
893 |
|
|
for (;;) {
|
894 |
|
|
struct page *page;
|
895 |
|
|
pgoff_t end_index;
|
896 |
|
|
loff_t isize;
|
897 |
|
|
unsigned long nr, ret;
|
898 |
|
|
|
899 |
|
|
cond_resched();
|
900 |
|
|
find_page:
|
901 |
|
|
page = find_get_page(mapping, index);
|
902 |
|
|
if (!page) {
|
903 |
|
|
page_cache_sync_readahead(mapping,
|
904 |
|
|
ra, filp,
|
905 |
|
|
index, last_index - index);
|
906 |
|
|
page = find_get_page(mapping, index);
|
907 |
|
|
if (unlikely(page == NULL))
|
908 |
|
|
goto no_cached_page;
|
909 |
|
|
}
|
910 |
|
|
if (PageReadahead(page)) {
|
911 |
|
|
page_cache_async_readahead(mapping,
|
912 |
|
|
ra, filp, page,
|
913 |
|
|
index, last_index - index);
|
914 |
|
|
}
|
915 |
|
|
if (!PageUptodate(page))
|
916 |
|
|
goto page_not_up_to_date;
|
917 |
|
|
page_ok:
|
918 |
|
|
/*
|
919 |
|
|
* i_size must be checked after we know the page is Uptodate.
|
920 |
|
|
*
|
921 |
|
|
* Checking i_size after the check allows us to calculate
|
922 |
|
|
* the correct value for "nr", which means the zero-filled
|
923 |
|
|
* part of the page is not copied back to userspace (unless
|
924 |
|
|
* another truncate extends the file - this is desired though).
|
925 |
|
|
*/
|
926 |
|
|
|
927 |
|
|
isize = i_size_read(inode);
|
928 |
|
|
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
|
929 |
|
|
if (unlikely(!isize || index > end_index)) {
|
930 |
|
|
page_cache_release(page);
|
931 |
|
|
goto out;
|
932 |
|
|
}
|
933 |
|
|
|
934 |
|
|
/* nr is the maximum number of bytes to copy from this page */
|
935 |
|
|
nr = PAGE_CACHE_SIZE;
|
936 |
|
|
if (index == end_index) {
|
937 |
|
|
nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
|
938 |
|
|
if (nr <= offset) {
|
939 |
|
|
page_cache_release(page);
|
940 |
|
|
goto out;
|
941 |
|
|
}
|
942 |
|
|
}
|
943 |
|
|
nr = nr - offset;
|
944 |
|
|
|
945 |
|
|
/* If users can be writing to this page using arbitrary
|
946 |
|
|
* virtual addresses, take care about potential aliasing
|
947 |
|
|
* before reading the page on the kernel side.
|
948 |
|
|
*/
|
949 |
|
|
if (mapping_writably_mapped(mapping))
|
950 |
|
|
flush_dcache_page(page);
|
951 |
|
|
|
952 |
|
|
/*
|
953 |
|
|
* When a sequential read accesses a page several times,
|
954 |
|
|
* only mark it as accessed the first time.
|
955 |
|
|
*/
|
956 |
|
|
if (prev_index != index || offset != prev_offset)
|
957 |
|
|
mark_page_accessed(page);
|
958 |
|
|
prev_index = index;
|
959 |
|
|
|
960 |
|
|
/*
|
961 |
|
|
* Ok, we have the page, and it's up-to-date, so
|
962 |
|
|
* now we can copy it to user space...
|
963 |
|
|
*
|
964 |
|
|
* The actor routine returns how many bytes were actually used..
|
965 |
|
|
* NOTE! This may not be the same as how much of a user buffer
|
966 |
|
|
* we filled up (we may be padding etc), so we can only update
|
967 |
|
|
* "pos" here (the actor routine has to update the user buffer
|
968 |
|
|
* pointers and the remaining count).
|
969 |
|
|
*/
|
970 |
|
|
ret = actor(desc, page, offset, nr);
|
971 |
|
|
offset += ret;
|
972 |
|
|
index += offset >> PAGE_CACHE_SHIFT;
|
973 |
|
|
offset &= ~PAGE_CACHE_MASK;
|
974 |
|
|
prev_offset = offset;
|
975 |
|
|
|
976 |
|
|
page_cache_release(page);
|
977 |
|
|
if (ret == nr && desc->count)
|
978 |
|
|
continue;
|
979 |
|
|
goto out;
|
980 |
|
|
|
981 |
|
|
page_not_up_to_date:
|
982 |
|
|
/* Get exclusive access to the page ... */
|
983 |
|
|
lock_page(page);
|
984 |
|
|
|
985 |
|
|
/* Did it get truncated before we got the lock? */
|
986 |
|
|
if (!page->mapping) {
|
987 |
|
|
unlock_page(page);
|
988 |
|
|
page_cache_release(page);
|
989 |
|
|
continue;
|
990 |
|
|
}
|
991 |
|
|
|
992 |
|
|
/* Did somebody else fill it already? */
|
993 |
|
|
if (PageUptodate(page)) {
|
994 |
|
|
unlock_page(page);
|
995 |
|
|
goto page_ok;
|
996 |
|
|
}
|
997 |
|
|
|
998 |
|
|
readpage:
|
999 |
|
|
/* Start the actual read. The read will unlock the page. */
|
1000 |
|
|
error = mapping->a_ops->readpage(filp, page);
|
1001 |
|
|
|
1002 |
|
|
if (unlikely(error)) {
|
1003 |
|
|
if (error == AOP_TRUNCATED_PAGE) {
|
1004 |
|
|
page_cache_release(page);
|
1005 |
|
|
goto find_page;
|
1006 |
|
|
}
|
1007 |
|
|
goto readpage_error;
|
1008 |
|
|
}
|
1009 |
|
|
|
1010 |
|
|
if (!PageUptodate(page)) {
|
1011 |
|
|
lock_page(page);
|
1012 |
|
|
if (!PageUptodate(page)) {
|
1013 |
|
|
if (page->mapping == NULL) {
|
1014 |
|
|
/*
|
1015 |
|
|
* invalidate_inode_pages got it
|
1016 |
|
|
*/
|
1017 |
|
|
unlock_page(page);
|
1018 |
|
|
page_cache_release(page);
|
1019 |
|
|
goto find_page;
|
1020 |
|
|
}
|
1021 |
|
|
unlock_page(page);
|
1022 |
|
|
error = -EIO;
|
1023 |
|
|
shrink_readahead_size_eio(filp, ra);
|
1024 |
|
|
goto readpage_error;
|
1025 |
|
|
}
|
1026 |
|
|
unlock_page(page);
|
1027 |
|
|
}
|
1028 |
|
|
|
1029 |
|
|
goto page_ok;
|
1030 |
|
|
|
1031 |
|
|
readpage_error:
|
1032 |
|
|
/* UHHUH! A synchronous read error occurred. Report it */
|
1033 |
|
|
desc->error = error;
|
1034 |
|
|
page_cache_release(page);
|
1035 |
|
|
goto out;
|
1036 |
|
|
|
1037 |
|
|
no_cached_page:
|
1038 |
|
|
/*
|
1039 |
|
|
* Ok, it wasn't cached, so we need to create a new
|
1040 |
|
|
* page..
|
1041 |
|
|
*/
|
1042 |
|
|
page = page_cache_alloc_cold(mapping);
|
1043 |
|
|
if (!page) {
|
1044 |
|
|
desc->error = -ENOMEM;
|
1045 |
|
|
goto out;
|
1046 |
|
|
}
|
1047 |
|
|
error = add_to_page_cache_lru(page, mapping,
|
1048 |
|
|
index, GFP_KERNEL);
|
1049 |
|
|
if (error) {
|
1050 |
|
|
page_cache_release(page);
|
1051 |
|
|
if (error == -EEXIST)
|
1052 |
|
|
goto find_page;
|
1053 |
|
|
desc->error = error;
|
1054 |
|
|
goto out;
|
1055 |
|
|
}
|
1056 |
|
|
goto readpage;
|
1057 |
|
|
}
|
1058 |
|
|
|
1059 |
|
|
out:
|
1060 |
|
|
ra->prev_pos = prev_index;
|
1061 |
|
|
ra->prev_pos <<= PAGE_CACHE_SHIFT;
|
1062 |
|
|
ra->prev_pos |= prev_offset;
|
1063 |
|
|
|
1064 |
|
|
*ppos = ((loff_t)index << PAGE_CACHE_SHIFT) + offset;
|
1065 |
|
|
if (filp)
|
1066 |
|
|
file_accessed(filp);
|
1067 |
|
|
}
|
1068 |
|
|
EXPORT_SYMBOL(do_generic_mapping_read);
|
1069 |
|
|
|
1070 |
|
|
int file_read_actor(read_descriptor_t *desc, struct page *page,
|
1071 |
|
|
unsigned long offset, unsigned long size)
|
1072 |
|
|
{
|
1073 |
|
|
char *kaddr;
|
1074 |
|
|
unsigned long left, count = desc->count;
|
1075 |
|
|
|
1076 |
|
|
if (size > count)
|
1077 |
|
|
size = count;
|
1078 |
|
|
|
1079 |
|
|
/*
|
1080 |
|
|
* Faults on the destination of a read are common, so do it before
|
1081 |
|
|
* taking the kmap.
|
1082 |
|
|
*/
|
1083 |
|
|
if (!fault_in_pages_writeable(desc->arg.buf, size)) {
|
1084 |
|
|
kaddr = kmap_atomic(page, KM_USER0);
|
1085 |
|
|
left = __copy_to_user_inatomic(desc->arg.buf,
|
1086 |
|
|
kaddr + offset, size);
|
1087 |
|
|
kunmap_atomic(kaddr, KM_USER0);
|
1088 |
|
|
if (left == 0)
|
1089 |
|
|
goto success;
|
1090 |
|
|
}
|
1091 |
|
|
|
1092 |
|
|
/* Do it the slow way */
|
1093 |
|
|
kaddr = kmap(page);
|
1094 |
|
|
left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
|
1095 |
|
|
kunmap(page);
|
1096 |
|
|
|
1097 |
|
|
if (left) {
|
1098 |
|
|
size -= left;
|
1099 |
|
|
desc->error = -EFAULT;
|
1100 |
|
|
}
|
1101 |
|
|
success:
|
1102 |
|
|
desc->count = count - size;
|
1103 |
|
|
desc->written += size;
|
1104 |
|
|
desc->arg.buf += size;
|
1105 |
|
|
return size;
|
1106 |
|
|
}
|
1107 |
|
|
|
1108 |
|
|
/*
|
1109 |
|
|
* Performs necessary checks before doing a write
|
1110 |
|
|
* @iov: io vector request
|
1111 |
|
|
* @nr_segs: number of segments in the iovec
|
1112 |
|
|
* @count: number of bytes to write
|
1113 |
|
|
* @access_flags: type of access: %VERIFY_READ or %VERIFY_WRITE
|
1114 |
|
|
*
|
1115 |
|
|
* Adjust number of segments and amount of bytes to write (nr_segs should be
|
1116 |
|
|
* properly initialized first). Returns appropriate error code that caller
|
1117 |
|
|
* should return or zero in case that write should be allowed.
|
1118 |
|
|
*/
|
1119 |
|
|
int generic_segment_checks(const struct iovec *iov,
|
1120 |
|
|
unsigned long *nr_segs, size_t *count, int access_flags)
|
1121 |
|
|
{
|
1122 |
|
|
unsigned long seg;
|
1123 |
|
|
size_t cnt = 0;
|
1124 |
|
|
for (seg = 0; seg < *nr_segs; seg++) {
|
1125 |
|
|
const struct iovec *iv = &iov[seg];
|
1126 |
|
|
|
1127 |
|
|
/*
|
1128 |
|
|
* If any segment has a negative length, or the cumulative
|
1129 |
|
|
* length ever wraps negative then return -EINVAL.
|
1130 |
|
|
*/
|
1131 |
|
|
cnt += iv->iov_len;
|
1132 |
|
|
if (unlikely((ssize_t)(cnt|iv->iov_len) < 0))
|
1133 |
|
|
return -EINVAL;
|
1134 |
|
|
if (access_ok(access_flags, iv->iov_base, iv->iov_len))
|
1135 |
|
|
continue;
|
1136 |
|
|
if (seg == 0)
|
1137 |
|
|
return -EFAULT;
|
1138 |
|
|
*nr_segs = seg;
|
1139 |
|
|
cnt -= iv->iov_len; /* This segment is no good */
|
1140 |
|
|
break;
|
1141 |
|
|
}
|
1142 |
|
|
*count = cnt;
|
1143 |
|
|
return 0;
|
1144 |
|
|
}
|
1145 |
|
|
EXPORT_SYMBOL(generic_segment_checks);
|
1146 |
|
|
|
1147 |
|
|
/**
|
1148 |
|
|
* generic_file_aio_read - generic filesystem read routine
|
1149 |
|
|
* @iocb: kernel I/O control block
|
1150 |
|
|
* @iov: io vector request
|
1151 |
|
|
* @nr_segs: number of segments in the iovec
|
1152 |
|
|
* @pos: current file position
|
1153 |
|
|
*
|
1154 |
|
|
* This is the "read()" routine for all filesystems
|
1155 |
|
|
* that can use the page cache directly.
|
1156 |
|
|
*/
|
1157 |
|
|
ssize_t
|
1158 |
|
|
generic_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
|
1159 |
|
|
unsigned long nr_segs, loff_t pos)
|
1160 |
|
|
{
|
1161 |
|
|
struct file *filp = iocb->ki_filp;
|
1162 |
|
|
ssize_t retval;
|
1163 |
|
|
unsigned long seg;
|
1164 |
|
|
size_t count;
|
1165 |
|
|
loff_t *ppos = &iocb->ki_pos;
|
1166 |
|
|
|
1167 |
|
|
count = 0;
|
1168 |
|
|
retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
|
1169 |
|
|
if (retval)
|
1170 |
|
|
return retval;
|
1171 |
|
|
|
1172 |
|
|
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
|
1173 |
|
|
if (filp->f_flags & O_DIRECT) {
|
1174 |
|
|
loff_t size;
|
1175 |
|
|
struct address_space *mapping;
|
1176 |
|
|
struct inode *inode;
|
1177 |
|
|
|
1178 |
|
|
mapping = filp->f_mapping;
|
1179 |
|
|
inode = mapping->host;
|
1180 |
|
|
retval = 0;
|
1181 |
|
|
if (!count)
|
1182 |
|
|
goto out; /* skip atime */
|
1183 |
|
|
size = i_size_read(inode);
|
1184 |
|
|
if (pos < size) {
|
1185 |
|
|
retval = generic_file_direct_IO(READ, iocb,
|
1186 |
|
|
iov, pos, nr_segs);
|
1187 |
|
|
if (retval > 0)
|
1188 |
|
|
*ppos = pos + retval;
|
1189 |
|
|
}
|
1190 |
|
|
if (likely(retval != 0)) {
|
1191 |
|
|
file_accessed(filp);
|
1192 |
|
|
goto out;
|
1193 |
|
|
}
|
1194 |
|
|
}
|
1195 |
|
|
|
1196 |
|
|
retval = 0;
|
1197 |
|
|
if (count) {
|
1198 |
|
|
for (seg = 0; seg < nr_segs; seg++) {
|
1199 |
|
|
read_descriptor_t desc;
|
1200 |
|
|
|
1201 |
|
|
desc.written = 0;
|
1202 |
|
|
desc.arg.buf = iov[seg].iov_base;
|
1203 |
|
|
desc.count = iov[seg].iov_len;
|
1204 |
|
|
if (desc.count == 0)
|
1205 |
|
|
continue;
|
1206 |
|
|
desc.error = 0;
|
1207 |
|
|
do_generic_file_read(filp,ppos,&desc,file_read_actor);
|
1208 |
|
|
retval += desc.written;
|
1209 |
|
|
if (desc.error) {
|
1210 |
|
|
retval = retval ?: desc.error;
|
1211 |
|
|
break;
|
1212 |
|
|
}
|
1213 |
|
|
if (desc.count > 0)
|
1214 |
|
|
break;
|
1215 |
|
|
}
|
1216 |
|
|
}
|
1217 |
|
|
out:
|
1218 |
|
|
return retval;
|
1219 |
|
|
}
|
1220 |
|
|
EXPORT_SYMBOL(generic_file_aio_read);
|
1221 |
|
|
|
1222 |
|
|
static ssize_t
|
1223 |
|
|
do_readahead(struct address_space *mapping, struct file *filp,
|
1224 |
|
|
pgoff_t index, unsigned long nr)
|
1225 |
|
|
{
|
1226 |
|
|
if (!mapping || !mapping->a_ops || !mapping->a_ops->readpage)
|
1227 |
|
|
return -EINVAL;
|
1228 |
|
|
|
1229 |
|
|
force_page_cache_readahead(mapping, filp, index,
|
1230 |
|
|
max_sane_readahead(nr));
|
1231 |
|
|
return 0;
|
1232 |
|
|
}
|
1233 |
|
|
|
1234 |
|
|
asmlinkage ssize_t sys_readahead(int fd, loff_t offset, size_t count)
|
1235 |
|
|
{
|
1236 |
|
|
ssize_t ret;
|
1237 |
|
|
struct file *file;
|
1238 |
|
|
|
1239 |
|
|
ret = -EBADF;
|
1240 |
|
|
file = fget(fd);
|
1241 |
|
|
if (file) {
|
1242 |
|
|
if (file->f_mode & FMODE_READ) {
|
1243 |
|
|
struct address_space *mapping = file->f_mapping;
|
1244 |
|
|
pgoff_t start = offset >> PAGE_CACHE_SHIFT;
|
1245 |
|
|
pgoff_t end = (offset + count - 1) >> PAGE_CACHE_SHIFT;
|
1246 |
|
|
unsigned long len = end - start + 1;
|
1247 |
|
|
ret = do_readahead(mapping, file, start, len);
|
1248 |
|
|
}
|
1249 |
|
|
fput(file);
|
1250 |
|
|
}
|
1251 |
|
|
return ret;
|
1252 |
|
|
}
|
1253 |
|
|
|
1254 |
|
|
#ifdef CONFIG_MMU
|
1255 |
|
|
/**
|
1256 |
|
|
* page_cache_read - adds requested page to the page cache if not already there
|
1257 |
|
|
* @file: file to read
|
1258 |
|
|
* @offset: page index
|
1259 |
|
|
*
|
1260 |
|
|
* This adds the requested page to the page cache if it isn't already there,
|
1261 |
|
|
* and schedules an I/O to read in its contents from disk.
|
1262 |
|
|
*/
|
1263 |
|
|
static int fastcall page_cache_read(struct file * file, pgoff_t offset)
|
1264 |
|
|
{
|
1265 |
|
|
struct address_space *mapping = file->f_mapping;
|
1266 |
|
|
struct page *page;
|
1267 |
|
|
int ret;
|
1268 |
|
|
|
1269 |
|
|
do {
|
1270 |
|
|
page = page_cache_alloc_cold(mapping);
|
1271 |
|
|
if (!page)
|
1272 |
|
|
return -ENOMEM;
|
1273 |
|
|
|
1274 |
|
|
ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
|
1275 |
|
|
if (ret == 0)
|
1276 |
|
|
ret = mapping->a_ops->readpage(file, page);
|
1277 |
|
|
else if (ret == -EEXIST)
|
1278 |
|
|
ret = 0; /* losing race to add is OK */
|
1279 |
|
|
|
1280 |
|
|
page_cache_release(page);
|
1281 |
|
|
|
1282 |
|
|
} while (ret == AOP_TRUNCATED_PAGE);
|
1283 |
|
|
|
1284 |
|
|
return ret;
|
1285 |
|
|
}
|
1286 |
|
|
|
1287 |
|
|
#define MMAP_LOTSAMISS (100)
|
1288 |
|
|
|
1289 |
|
|
/**
|
1290 |
|
|
* filemap_fault - read in file data for page fault handling
|
1291 |
|
|
* @vma: vma in which the fault was taken
|
1292 |
|
|
* @vmf: struct vm_fault containing details of the fault
|
1293 |
|
|
*
|
1294 |
|
|
* filemap_fault() is invoked via the vma operations vector for a
|
1295 |
|
|
* mapped memory region to read in file data during a page fault.
|
1296 |
|
|
*
|
1297 |
|
|
* The goto's are kind of ugly, but this streamlines the normal case of having
|
1298 |
|
|
* it in the page cache, and handles the special cases reasonably without
|
1299 |
|
|
* having a lot of duplicated code.
|
1300 |
|
|
*/
|
1301 |
|
|
int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
|
1302 |
|
|
{
|
1303 |
|
|
int error;
|
1304 |
|
|
struct file *file = vma->vm_file;
|
1305 |
|
|
struct address_space *mapping = file->f_mapping;
|
1306 |
|
|
struct file_ra_state *ra = &file->f_ra;
|
1307 |
|
|
struct inode *inode = mapping->host;
|
1308 |
|
|
struct page *page;
|
1309 |
|
|
unsigned long size;
|
1310 |
|
|
int did_readaround = 0;
|
1311 |
|
|
int ret = 0;
|
1312 |
|
|
|
1313 |
|
|
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
1314 |
|
|
if (vmf->pgoff >= size)
|
1315 |
|
|
return VM_FAULT_SIGBUS;
|
1316 |
|
|
|
1317 |
|
|
/* If we don't want any read-ahead, don't bother */
|
1318 |
|
|
if (VM_RandomReadHint(vma))
|
1319 |
|
|
goto no_cached_page;
|
1320 |
|
|
|
1321 |
|
|
/*
|
1322 |
|
|
* Do we have something in the page cache already?
|
1323 |
|
|
*/
|
1324 |
|
|
retry_find:
|
1325 |
|
|
page = find_lock_page(mapping, vmf->pgoff);
|
1326 |
|
|
/*
|
1327 |
|
|
* For sequential accesses, we use the generic readahead logic.
|
1328 |
|
|
*/
|
1329 |
|
|
if (VM_SequentialReadHint(vma)) {
|
1330 |
|
|
if (!page) {
|
1331 |
|
|
page_cache_sync_readahead(mapping, ra, file,
|
1332 |
|
|
vmf->pgoff, 1);
|
1333 |
|
|
page = find_lock_page(mapping, vmf->pgoff);
|
1334 |
|
|
if (!page)
|
1335 |
|
|
goto no_cached_page;
|
1336 |
|
|
}
|
1337 |
|
|
if (PageReadahead(page)) {
|
1338 |
|
|
page_cache_async_readahead(mapping, ra, file, page,
|
1339 |
|
|
vmf->pgoff, 1);
|
1340 |
|
|
}
|
1341 |
|
|
}
|
1342 |
|
|
|
1343 |
|
|
if (!page) {
|
1344 |
|
|
unsigned long ra_pages;
|
1345 |
|
|
|
1346 |
|
|
ra->mmap_miss++;
|
1347 |
|
|
|
1348 |
|
|
/*
|
1349 |
|
|
* Do we miss much more than hit in this file? If so,
|
1350 |
|
|
* stop bothering with read-ahead. It will only hurt.
|
1351 |
|
|
*/
|
1352 |
|
|
if (ra->mmap_miss > MMAP_LOTSAMISS)
|
1353 |
|
|
goto no_cached_page;
|
1354 |
|
|
|
1355 |
|
|
/*
|
1356 |
|
|
* To keep the pgmajfault counter straight, we need to
|
1357 |
|
|
* check did_readaround, as this is an inner loop.
|
1358 |
|
|
*/
|
1359 |
|
|
if (!did_readaround) {
|
1360 |
|
|
ret = VM_FAULT_MAJOR;
|
1361 |
|
|
count_vm_event(PGMAJFAULT);
|
1362 |
|
|
}
|
1363 |
|
|
did_readaround = 1;
|
1364 |
|
|
ra_pages = max_sane_readahead(file->f_ra.ra_pages);
|
1365 |
|
|
if (ra_pages) {
|
1366 |
|
|
pgoff_t start = 0;
|
1367 |
|
|
|
1368 |
|
|
if (vmf->pgoff > ra_pages / 2)
|
1369 |
|
|
start = vmf->pgoff - ra_pages / 2;
|
1370 |
|
|
do_page_cache_readahead(mapping, file, start, ra_pages);
|
1371 |
|
|
}
|
1372 |
|
|
page = find_lock_page(mapping, vmf->pgoff);
|
1373 |
|
|
if (!page)
|
1374 |
|
|
goto no_cached_page;
|
1375 |
|
|
}
|
1376 |
|
|
|
1377 |
|
|
if (!did_readaround)
|
1378 |
|
|
ra->mmap_miss--;
|
1379 |
|
|
|
1380 |
|
|
/*
|
1381 |
|
|
* We have a locked page in the page cache, now we need to check
|
1382 |
|
|
* that it's up-to-date. If not, it is going to be due to an error.
|
1383 |
|
|
*/
|
1384 |
|
|
if (unlikely(!PageUptodate(page)))
|
1385 |
|
|
goto page_not_uptodate;
|
1386 |
|
|
|
1387 |
|
|
/* Must recheck i_size under page lock */
|
1388 |
|
|
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
|
1389 |
|
|
if (unlikely(vmf->pgoff >= size)) {
|
1390 |
|
|
unlock_page(page);
|
1391 |
|
|
page_cache_release(page);
|
1392 |
|
|
return VM_FAULT_SIGBUS;
|
1393 |
|
|
}
|
1394 |
|
|
|
1395 |
|
|
/*
|
1396 |
|
|
* Found the page and have a reference on it.
|
1397 |
|
|
*/
|
1398 |
|
|
mark_page_accessed(page);
|
1399 |
|
|
ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
|
1400 |
|
|
vmf->page = page;
|
1401 |
|
|
return ret | VM_FAULT_LOCKED;
|
1402 |
|
|
|
1403 |
|
|
no_cached_page:
|
1404 |
|
|
/*
|
1405 |
|
|
* We're only likely to ever get here if MADV_RANDOM is in
|
1406 |
|
|
* effect.
|
1407 |
|
|
*/
|
1408 |
|
|
error = page_cache_read(file, vmf->pgoff);
|
1409 |
|
|
|
1410 |
|
|
/*
|
1411 |
|
|
* The page we want has now been added to the page cache.
|
1412 |
|
|
* In the unlikely event that someone removed it in the
|
1413 |
|
|
* meantime, we'll just come back here and read it again.
|
1414 |
|
|
*/
|
1415 |
|
|
if (error >= 0)
|
1416 |
|
|
goto retry_find;
|
1417 |
|
|
|
1418 |
|
|
/*
|
1419 |
|
|
* An error return from page_cache_read can result if the
|
1420 |
|
|
* system is low on memory, or a problem occurs while trying
|
1421 |
|
|
* to schedule I/O.
|
1422 |
|
|
*/
|
1423 |
|
|
if (error == -ENOMEM)
|
1424 |
|
|
return VM_FAULT_OOM;
|
1425 |
|
|
return VM_FAULT_SIGBUS;
|
1426 |
|
|
|
1427 |
|
|
page_not_uptodate:
|
1428 |
|
|
/* IO error path */
|
1429 |
|
|
if (!did_readaround) {
|
1430 |
|
|
ret = VM_FAULT_MAJOR;
|
1431 |
|
|
count_vm_event(PGMAJFAULT);
|
1432 |
|
|
}
|
1433 |
|
|
|
1434 |
|
|
/*
|
1435 |
|
|
* Umm, take care of errors if the page isn't up-to-date.
|
1436 |
|
|
* Try to re-read it _once_. We do this synchronously,
|
1437 |
|
|
* because there really aren't any performance issues here
|
1438 |
|
|
* and we need to check for errors.
|
1439 |
|
|
*/
|
1440 |
|
|
ClearPageError(page);
|
1441 |
|
|
error = mapping->a_ops->readpage(file, page);
|
1442 |
|
|
page_cache_release(page);
|
1443 |
|
|
|
1444 |
|
|
if (!error || error == AOP_TRUNCATED_PAGE)
|
1445 |
|
|
goto retry_find;
|
1446 |
|
|
|
1447 |
|
|
/* Things didn't work out. Return zero to tell the mm layer so. */
|
1448 |
|
|
shrink_readahead_size_eio(file, ra);
|
1449 |
|
|
return VM_FAULT_SIGBUS;
|
1450 |
|
|
}
|
1451 |
|
|
EXPORT_SYMBOL(filemap_fault);
|
1452 |
|
|
|
1453 |
|
|
struct vm_operations_struct generic_file_vm_ops = {
|
1454 |
|
|
.fault = filemap_fault,
|
1455 |
|
|
};
|
1456 |
|
|
|
1457 |
|
|
/* This is used for a general mmap of a disk file */
|
1458 |
|
|
|
1459 |
|
|
int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
|
1460 |
|
|
{
|
1461 |
|
|
struct address_space *mapping = file->f_mapping;
|
1462 |
|
|
|
1463 |
|
|
if (!mapping->a_ops->readpage)
|
1464 |
|
|
return -ENOEXEC;
|
1465 |
|
|
file_accessed(file);
|
1466 |
|
|
vma->vm_ops = &generic_file_vm_ops;
|
1467 |
|
|
vma->vm_flags |= VM_CAN_NONLINEAR;
|
1468 |
|
|
return 0;
|
1469 |
|
|
}
|
1470 |
|
|
|
1471 |
|
|
/*
|
1472 |
|
|
* This is for filesystems which do not implement ->writepage.
|
1473 |
|
|
*/
|
1474 |
|
|
int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
|
1475 |
|
|
{
|
1476 |
|
|
if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
|
1477 |
|
|
return -EINVAL;
|
1478 |
|
|
return generic_file_mmap(file, vma);
|
1479 |
|
|
}
|
1480 |
|
|
#else
|
1481 |
|
|
int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
|
1482 |
|
|
{
|
1483 |
|
|
return -ENOSYS;
|
1484 |
|
|
}
|
1485 |
|
|
int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
|
1486 |
|
|
{
|
1487 |
|
|
return -ENOSYS;
|
1488 |
|
|
}
|
1489 |
|
|
#endif /* CONFIG_MMU */
|
1490 |
|
|
|
1491 |
|
|
EXPORT_SYMBOL(generic_file_mmap);
|
1492 |
|
|
EXPORT_SYMBOL(generic_file_readonly_mmap);
|
1493 |
|
|
|
1494 |
|
|
static struct page *__read_cache_page(struct address_space *mapping,
|
1495 |
|
|
pgoff_t index,
|
1496 |
|
|
int (*filler)(void *,struct page*),
|
1497 |
|
|
void *data)
|
1498 |
|
|
{
|
1499 |
|
|
struct page *page;
|
1500 |
|
|
int err;
|
1501 |
|
|
repeat:
|
1502 |
|
|
page = find_get_page(mapping, index);
|
1503 |
|
|
if (!page) {
|
1504 |
|
|
page = page_cache_alloc_cold(mapping);
|
1505 |
|
|
if (!page)
|
1506 |
|
|
return ERR_PTR(-ENOMEM);
|
1507 |
|
|
err = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
|
1508 |
|
|
if (unlikely(err)) {
|
1509 |
|
|
page_cache_release(page);
|
1510 |
|
|
if (err == -EEXIST)
|
1511 |
|
|
goto repeat;
|
1512 |
|
|
/* Presumably ENOMEM for radix tree node */
|
1513 |
|
|
return ERR_PTR(err);
|
1514 |
|
|
}
|
1515 |
|
|
err = filler(data, page);
|
1516 |
|
|
if (err < 0) {
|
1517 |
|
|
page_cache_release(page);
|
1518 |
|
|
page = ERR_PTR(err);
|
1519 |
|
|
}
|
1520 |
|
|
}
|
1521 |
|
|
return page;
|
1522 |
|
|
}
|
1523 |
|
|
|
1524 |
|
|
/*
|
1525 |
|
|
* Same as read_cache_page, but don't wait for page to become unlocked
|
1526 |
|
|
* after submitting it to the filler.
|
1527 |
|
|
*/
|
1528 |
|
|
struct page *read_cache_page_async(struct address_space *mapping,
|
1529 |
|
|
pgoff_t index,
|
1530 |
|
|
int (*filler)(void *,struct page*),
|
1531 |
|
|
void *data)
|
1532 |
|
|
{
|
1533 |
|
|
struct page *page;
|
1534 |
|
|
int err;
|
1535 |
|
|
|
1536 |
|
|
retry:
|
1537 |
|
|
page = __read_cache_page(mapping, index, filler, data);
|
1538 |
|
|
if (IS_ERR(page))
|
1539 |
|
|
return page;
|
1540 |
|
|
if (PageUptodate(page))
|
1541 |
|
|
goto out;
|
1542 |
|
|
|
1543 |
|
|
lock_page(page);
|
1544 |
|
|
if (!page->mapping) {
|
1545 |
|
|
unlock_page(page);
|
1546 |
|
|
page_cache_release(page);
|
1547 |
|
|
goto retry;
|
1548 |
|
|
}
|
1549 |
|
|
if (PageUptodate(page)) {
|
1550 |
|
|
unlock_page(page);
|
1551 |
|
|
goto out;
|
1552 |
|
|
}
|
1553 |
|
|
err = filler(data, page);
|
1554 |
|
|
if (err < 0) {
|
1555 |
|
|
page_cache_release(page);
|
1556 |
|
|
return ERR_PTR(err);
|
1557 |
|
|
}
|
1558 |
|
|
out:
|
1559 |
|
|
mark_page_accessed(page);
|
1560 |
|
|
return page;
|
1561 |
|
|
}
|
1562 |
|
|
EXPORT_SYMBOL(read_cache_page_async);
|
1563 |
|
|
|
1564 |
|
|
/**
|
1565 |
|
|
* read_cache_page - read into page cache, fill it if needed
|
1566 |
|
|
* @mapping: the page's address_space
|
1567 |
|
|
* @index: the page index
|
1568 |
|
|
* @filler: function to perform the read
|
1569 |
|
|
* @data: destination for read data
|
1570 |
|
|
*
|
1571 |
|
|
* Read into the page cache. If a page already exists, and PageUptodate() is
|
1572 |
|
|
* not set, try to fill the page then wait for it to become unlocked.
|
1573 |
|
|
*
|
1574 |
|
|
* If the page does not get brought uptodate, return -EIO.
|
1575 |
|
|
*/
|
1576 |
|
|
struct page *read_cache_page(struct address_space *mapping,
|
1577 |
|
|
pgoff_t index,
|
1578 |
|
|
int (*filler)(void *,struct page*),
|
1579 |
|
|
void *data)
|
1580 |
|
|
{
|
1581 |
|
|
struct page *page;
|
1582 |
|
|
|
1583 |
|
|
page = read_cache_page_async(mapping, index, filler, data);
|
1584 |
|
|
if (IS_ERR(page))
|
1585 |
|
|
goto out;
|
1586 |
|
|
wait_on_page_locked(page);
|
1587 |
|
|
if (!PageUptodate(page)) {
|
1588 |
|
|
page_cache_release(page);
|
1589 |
|
|
page = ERR_PTR(-EIO);
|
1590 |
|
|
}
|
1591 |
|
|
out:
|
1592 |
|
|
return page;
|
1593 |
|
|
}
|
1594 |
|
|
EXPORT_SYMBOL(read_cache_page);
|
1595 |
|
|
|
1596 |
|
|
/*
|
1597 |
|
|
* The logic we want is
|
1598 |
|
|
*
|
1599 |
|
|
* if suid or (sgid and xgrp)
|
1600 |
|
|
* remove privs
|
1601 |
|
|
*/
|
1602 |
|
|
int should_remove_suid(struct dentry *dentry)
|
1603 |
|
|
{
|
1604 |
|
|
mode_t mode = dentry->d_inode->i_mode;
|
1605 |
|
|
int kill = 0;
|
1606 |
|
|
|
1607 |
|
|
/* suid always must be killed */
|
1608 |
|
|
if (unlikely(mode & S_ISUID))
|
1609 |
|
|
kill = ATTR_KILL_SUID;
|
1610 |
|
|
|
1611 |
|
|
/*
|
1612 |
|
|
* sgid without any exec bits is just a mandatory locking mark; leave
|
1613 |
|
|
* it alone. If some exec bits are set, it's a real sgid; kill it.
|
1614 |
|
|
*/
|
1615 |
|
|
if (unlikely((mode & S_ISGID) && (mode & S_IXGRP)))
|
1616 |
|
|
kill |= ATTR_KILL_SGID;
|
1617 |
|
|
|
1618 |
|
|
if (unlikely(kill && !capable(CAP_FSETID)))
|
1619 |
|
|
return kill;
|
1620 |
|
|
|
1621 |
|
|
return 0;
|
1622 |
|
|
}
|
1623 |
|
|
EXPORT_SYMBOL(should_remove_suid);
|
1624 |
|
|
|
1625 |
|
|
int __remove_suid(struct dentry *dentry, int kill)
|
1626 |
|
|
{
|
1627 |
|
|
struct iattr newattrs;
|
1628 |
|
|
|
1629 |
|
|
newattrs.ia_valid = ATTR_FORCE | kill;
|
1630 |
|
|
return notify_change(dentry, &newattrs);
|
1631 |
|
|
}
|
1632 |
|
|
|
1633 |
|
|
int remove_suid(struct dentry *dentry)
|
1634 |
|
|
{
|
1635 |
|
|
int killsuid = should_remove_suid(dentry);
|
1636 |
|
|
int killpriv = security_inode_need_killpriv(dentry);
|
1637 |
|
|
int error = 0;
|
1638 |
|
|
|
1639 |
|
|
if (killpriv < 0)
|
1640 |
|
|
return killpriv;
|
1641 |
|
|
if (killpriv)
|
1642 |
|
|
error = security_inode_killpriv(dentry);
|
1643 |
|
|
if (!error && killsuid)
|
1644 |
|
|
error = __remove_suid(dentry, killsuid);
|
1645 |
|
|
|
1646 |
|
|
return error;
|
1647 |
|
|
}
|
1648 |
|
|
EXPORT_SYMBOL(remove_suid);
|
1649 |
|
|
|
1650 |
|
|
static size_t __iovec_copy_from_user_inatomic(char *vaddr,
|
1651 |
|
|
const struct iovec *iov, size_t base, size_t bytes)
|
1652 |
|
|
{
|
1653 |
|
|
size_t copied = 0, left = 0;
|
1654 |
|
|
|
1655 |
|
|
while (bytes) {
|
1656 |
|
|
char __user *buf = iov->iov_base + base;
|
1657 |
|
|
int copy = min(bytes, iov->iov_len - base);
|
1658 |
|
|
|
1659 |
|
|
base = 0;
|
1660 |
|
|
left = __copy_from_user_inatomic_nocache(vaddr, buf, copy);
|
1661 |
|
|
copied += copy;
|
1662 |
|
|
bytes -= copy;
|
1663 |
|
|
vaddr += copy;
|
1664 |
|
|
iov++;
|
1665 |
|
|
|
1666 |
|
|
if (unlikely(left))
|
1667 |
|
|
break;
|
1668 |
|
|
}
|
1669 |
|
|
return copied - left;
|
1670 |
|
|
}
|
1671 |
|
|
|
1672 |
|
|
/*
|
1673 |
|
|
* Copy as much as we can into the page and return the number of bytes which
|
1674 |
|
|
* were sucessfully copied. If a fault is encountered then return the number of
|
1675 |
|
|
* bytes which were copied.
|
1676 |
|
|
*/
|
1677 |
|
|
size_t iov_iter_copy_from_user_atomic(struct page *page,
|
1678 |
|
|
struct iov_iter *i, unsigned long offset, size_t bytes)
|
1679 |
|
|
{
|
1680 |
|
|
char *kaddr;
|
1681 |
|
|
size_t copied;
|
1682 |
|
|
|
1683 |
|
|
BUG_ON(!in_atomic());
|
1684 |
|
|
kaddr = kmap_atomic(page, KM_USER0);
|
1685 |
|
|
if (likely(i->nr_segs == 1)) {
|
1686 |
|
|
int left;
|
1687 |
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
1688 |
|
|
left = __copy_from_user_inatomic_nocache(kaddr + offset,
|
1689 |
|
|
buf, bytes);
|
1690 |
|
|
copied = bytes - left;
|
1691 |
|
|
} else {
|
1692 |
|
|
copied = __iovec_copy_from_user_inatomic(kaddr + offset,
|
1693 |
|
|
i->iov, i->iov_offset, bytes);
|
1694 |
|
|
}
|
1695 |
|
|
kunmap_atomic(kaddr, KM_USER0);
|
1696 |
|
|
|
1697 |
|
|
return copied;
|
1698 |
|
|
}
|
1699 |
|
|
EXPORT_SYMBOL(iov_iter_copy_from_user_atomic);
|
1700 |
|
|
|
1701 |
|
|
/*
|
1702 |
|
|
* This has the same sideeffects and return value as
|
1703 |
|
|
* iov_iter_copy_from_user_atomic().
|
1704 |
|
|
* The difference is that it attempts to resolve faults.
|
1705 |
|
|
* Page must not be locked.
|
1706 |
|
|
*/
|
1707 |
|
|
size_t iov_iter_copy_from_user(struct page *page,
|
1708 |
|
|
struct iov_iter *i, unsigned long offset, size_t bytes)
|
1709 |
|
|
{
|
1710 |
|
|
char *kaddr;
|
1711 |
|
|
size_t copied;
|
1712 |
|
|
|
1713 |
|
|
kaddr = kmap(page);
|
1714 |
|
|
if (likely(i->nr_segs == 1)) {
|
1715 |
|
|
int left;
|
1716 |
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
1717 |
|
|
left = __copy_from_user_nocache(kaddr + offset, buf, bytes);
|
1718 |
|
|
copied = bytes - left;
|
1719 |
|
|
} else {
|
1720 |
|
|
copied = __iovec_copy_from_user_inatomic(kaddr + offset,
|
1721 |
|
|
i->iov, i->iov_offset, bytes);
|
1722 |
|
|
}
|
1723 |
|
|
kunmap(page);
|
1724 |
|
|
return copied;
|
1725 |
|
|
}
|
1726 |
|
|
EXPORT_SYMBOL(iov_iter_copy_from_user);
|
1727 |
|
|
|
1728 |
|
|
static void __iov_iter_advance_iov(struct iov_iter *i, size_t bytes)
|
1729 |
|
|
{
|
1730 |
|
|
if (likely(i->nr_segs == 1)) {
|
1731 |
|
|
i->iov_offset += bytes;
|
1732 |
|
|
} else {
|
1733 |
|
|
const struct iovec *iov = i->iov;
|
1734 |
|
|
size_t base = i->iov_offset;
|
1735 |
|
|
|
1736 |
|
|
while (bytes) {
|
1737 |
|
|
int copy = min(bytes, iov->iov_len - base);
|
1738 |
|
|
|
1739 |
|
|
bytes -= copy;
|
1740 |
|
|
base += copy;
|
1741 |
|
|
if (iov->iov_len == base) {
|
1742 |
|
|
iov++;
|
1743 |
|
|
base = 0;
|
1744 |
|
|
}
|
1745 |
|
|
}
|
1746 |
|
|
i->iov = iov;
|
1747 |
|
|
i->iov_offset = base;
|
1748 |
|
|
}
|
1749 |
|
|
}
|
1750 |
|
|
|
1751 |
|
|
void iov_iter_advance(struct iov_iter *i, size_t bytes)
|
1752 |
|
|
{
|
1753 |
|
|
BUG_ON(i->count < bytes);
|
1754 |
|
|
|
1755 |
|
|
__iov_iter_advance_iov(i, bytes);
|
1756 |
|
|
i->count -= bytes;
|
1757 |
|
|
}
|
1758 |
|
|
EXPORT_SYMBOL(iov_iter_advance);
|
1759 |
|
|
|
1760 |
|
|
/*
|
1761 |
|
|
* Fault in the first iovec of the given iov_iter, to a maximum length
|
1762 |
|
|
* of bytes. Returns 0 on success, or non-zero if the memory could not be
|
1763 |
|
|
* accessed (ie. because it is an invalid address).
|
1764 |
|
|
*
|
1765 |
|
|
* writev-intensive code may want this to prefault several iovecs -- that
|
1766 |
|
|
* would be possible (callers must not rely on the fact that _only_ the
|
1767 |
|
|
* first iovec will be faulted with the current implementation).
|
1768 |
|
|
*/
|
1769 |
|
|
int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes)
|
1770 |
|
|
{
|
1771 |
|
|
char __user *buf = i->iov->iov_base + i->iov_offset;
|
1772 |
|
|
bytes = min(bytes, i->iov->iov_len - i->iov_offset);
|
1773 |
|
|
return fault_in_pages_readable(buf, bytes);
|
1774 |
|
|
}
|
1775 |
|
|
EXPORT_SYMBOL(iov_iter_fault_in_readable);
|
1776 |
|
|
|
1777 |
|
|
/*
|
1778 |
|
|
* Return the count of just the current iov_iter segment.
|
1779 |
|
|
*/
|
1780 |
|
|
size_t iov_iter_single_seg_count(struct iov_iter *i)
|
1781 |
|
|
{
|
1782 |
|
|
const struct iovec *iov = i->iov;
|
1783 |
|
|
if (i->nr_segs == 1)
|
1784 |
|
|
return i->count;
|
1785 |
|
|
else
|
1786 |
|
|
return min(i->count, iov->iov_len - i->iov_offset);
|
1787 |
|
|
}
|
1788 |
|
|
EXPORT_SYMBOL(iov_iter_single_seg_count);
|
1789 |
|
|
|
1790 |
|
|
/*
|
1791 |
|
|
* Performs necessary checks before doing a write
|
1792 |
|
|
*
|
1793 |
|
|
* Can adjust writing position or amount of bytes to write.
|
1794 |
|
|
* Returns appropriate error code that caller should return or
|
1795 |
|
|
* zero in case that write should be allowed.
|
1796 |
|
|
*/
|
1797 |
|
|
inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk)
|
1798 |
|
|
{
|
1799 |
|
|
struct inode *inode = file->f_mapping->host;
|
1800 |
|
|
unsigned long limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
|
1801 |
|
|
|
1802 |
|
|
if (unlikely(*pos < 0))
|
1803 |
|
|
return -EINVAL;
|
1804 |
|
|
|
1805 |
|
|
if (!isblk) {
|
1806 |
|
|
/* FIXME: this is for backwards compatibility with 2.4 */
|
1807 |
|
|
if (file->f_flags & O_APPEND)
|
1808 |
|
|
*pos = i_size_read(inode);
|
1809 |
|
|
|
1810 |
|
|
if (limit != RLIM_INFINITY) {
|
1811 |
|
|
if (*pos >= limit) {
|
1812 |
|
|
send_sig(SIGXFSZ, current, 0);
|
1813 |
|
|
return -EFBIG;
|
1814 |
|
|
}
|
1815 |
|
|
if (*count > limit - (typeof(limit))*pos) {
|
1816 |
|
|
*count = limit - (typeof(limit))*pos;
|
1817 |
|
|
}
|
1818 |
|
|
}
|
1819 |
|
|
}
|
1820 |
|
|
|
1821 |
|
|
/*
|
1822 |
|
|
* LFS rule
|
1823 |
|
|
*/
|
1824 |
|
|
if (unlikely(*pos + *count > MAX_NON_LFS &&
|
1825 |
|
|
!(file->f_flags & O_LARGEFILE))) {
|
1826 |
|
|
if (*pos >= MAX_NON_LFS) {
|
1827 |
|
|
return -EFBIG;
|
1828 |
|
|
}
|
1829 |
|
|
if (*count > MAX_NON_LFS - (unsigned long)*pos) {
|
1830 |
|
|
*count = MAX_NON_LFS - (unsigned long)*pos;
|
1831 |
|
|
}
|
1832 |
|
|
}
|
1833 |
|
|
|
1834 |
|
|
/*
|
1835 |
|
|
* Are we about to exceed the fs block limit ?
|
1836 |
|
|
*
|
1837 |
|
|
* If we have written data it becomes a short write. If we have
|
1838 |
|
|
* exceeded without writing data we send a signal and return EFBIG.
|
1839 |
|
|
* Linus frestrict idea will clean these up nicely..
|
1840 |
|
|
*/
|
1841 |
|
|
if (likely(!isblk)) {
|
1842 |
|
|
if (unlikely(*pos >= inode->i_sb->s_maxbytes)) {
|
1843 |
|
|
if (*count || *pos > inode->i_sb->s_maxbytes) {
|
1844 |
|
|
return -EFBIG;
|
1845 |
|
|
}
|
1846 |
|
|
/* zero-length writes at ->s_maxbytes are OK */
|
1847 |
|
|
}
|
1848 |
|
|
|
1849 |
|
|
if (unlikely(*pos + *count > inode->i_sb->s_maxbytes))
|
1850 |
|
|
*count = inode->i_sb->s_maxbytes - *pos;
|
1851 |
|
|
} else {
|
1852 |
|
|
#ifdef CONFIG_BLOCK
|
1853 |
|
|
loff_t isize;
|
1854 |
|
|
if (bdev_read_only(I_BDEV(inode)))
|
1855 |
|
|
return -EPERM;
|
1856 |
|
|
isize = i_size_read(inode);
|
1857 |
|
|
if (*pos >= isize) {
|
1858 |
|
|
if (*count || *pos > isize)
|
1859 |
|
|
return -ENOSPC;
|
1860 |
|
|
}
|
1861 |
|
|
|
1862 |
|
|
if (*pos + *count > isize)
|
1863 |
|
|
*count = isize - *pos;
|
1864 |
|
|
#else
|
1865 |
|
|
return -EPERM;
|
1866 |
|
|
#endif
|
1867 |
|
|
}
|
1868 |
|
|
return 0;
|
1869 |
|
|
}
|
1870 |
|
|
EXPORT_SYMBOL(generic_write_checks);
|
1871 |
|
|
|
1872 |
|
|
int pagecache_write_begin(struct file *file, struct address_space *mapping,
|
1873 |
|
|
loff_t pos, unsigned len, unsigned flags,
|
1874 |
|
|
struct page **pagep, void **fsdata)
|
1875 |
|
|
{
|
1876 |
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
1877 |
|
|
|
1878 |
|
|
if (aops->write_begin) {
|
1879 |
|
|
return aops->write_begin(file, mapping, pos, len, flags,
|
1880 |
|
|
pagep, fsdata);
|
1881 |
|
|
} else {
|
1882 |
|
|
int ret;
|
1883 |
|
|
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
|
1884 |
|
|
unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
|
1885 |
|
|
struct inode *inode = mapping->host;
|
1886 |
|
|
struct page *page;
|
1887 |
|
|
again:
|
1888 |
|
|
page = __grab_cache_page(mapping, index);
|
1889 |
|
|
*pagep = page;
|
1890 |
|
|
if (!page)
|
1891 |
|
|
return -ENOMEM;
|
1892 |
|
|
|
1893 |
|
|
if (flags & AOP_FLAG_UNINTERRUPTIBLE && !PageUptodate(page)) {
|
1894 |
|
|
/*
|
1895 |
|
|
* There is no way to resolve a short write situation
|
1896 |
|
|
* for a !Uptodate page (except by double copying in
|
1897 |
|
|
* the caller done by generic_perform_write_2copy).
|
1898 |
|
|
*
|
1899 |
|
|
* Instead, we have to bring it uptodate here.
|
1900 |
|
|
*/
|
1901 |
|
|
ret = aops->readpage(file, page);
|
1902 |
|
|
page_cache_release(page);
|
1903 |
|
|
if (ret) {
|
1904 |
|
|
if (ret == AOP_TRUNCATED_PAGE)
|
1905 |
|
|
goto again;
|
1906 |
|
|
return ret;
|
1907 |
|
|
}
|
1908 |
|
|
goto again;
|
1909 |
|
|
}
|
1910 |
|
|
|
1911 |
|
|
ret = aops->prepare_write(file, page, offset, offset+len);
|
1912 |
|
|
if (ret) {
|
1913 |
|
|
unlock_page(page);
|
1914 |
|
|
page_cache_release(page);
|
1915 |
|
|
if (pos + len > inode->i_size)
|
1916 |
|
|
vmtruncate(inode, inode->i_size);
|
1917 |
|
|
}
|
1918 |
|
|
return ret;
|
1919 |
|
|
}
|
1920 |
|
|
}
|
1921 |
|
|
EXPORT_SYMBOL(pagecache_write_begin);
|
1922 |
|
|
|
1923 |
|
|
int pagecache_write_end(struct file *file, struct address_space *mapping,
|
1924 |
|
|
loff_t pos, unsigned len, unsigned copied,
|
1925 |
|
|
struct page *page, void *fsdata)
|
1926 |
|
|
{
|
1927 |
|
|
const struct address_space_operations *aops = mapping->a_ops;
|
1928 |
|
|
int ret;
|
1929 |
|
|
|
1930 |
|
|
if (aops->write_end) {
|
1931 |
|
|
mark_page_accessed(page);
|
1932 |
|
|
ret = aops->write_end(file, mapping, pos, len, copied,
|
1933 |
|
|
page, fsdata);
|
1934 |
|
|
} else {
|
1935 |
|
|
unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
|
1936 |
|
|
struct inode *inode = mapping->host;
|
1937 |
|
|
|
1938 |
|
|
flush_dcache_page(page);
|
1939 |
|
|
ret = aops->commit_write(file, page, offset, offset+len);
|
1940 |
|
|
unlock_page(page);
|
1941 |
|
|
mark_page_accessed(page);
|
1942 |
|
|
page_cache_release(page);
|
1943 |
|
|
|
1944 |
|
|
if (ret < 0) {
|
1945 |
|
|
if (pos + len > inode->i_size)
|
1946 |
|
|
vmtruncate(inode, inode->i_size);
|
1947 |
|
|
} else if (ret > 0)
|
1948 |
|
|
ret = min_t(size_t, copied, ret);
|
1949 |
|
|
else
|
1950 |
|
|
ret = copied;
|
1951 |
|
|
}
|
1952 |
|
|
|
1953 |
|
|
return ret;
|
1954 |
|
|
}
|
1955 |
|
|
EXPORT_SYMBOL(pagecache_write_end);
|
1956 |
|
|
|
1957 |
|
|
ssize_t
|
1958 |
|
|
generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
|
1959 |
|
|
unsigned long *nr_segs, loff_t pos, loff_t *ppos,
|
1960 |
|
|
size_t count, size_t ocount)
|
1961 |
|
|
{
|
1962 |
|
|
struct file *file = iocb->ki_filp;
|
1963 |
|
|
struct address_space *mapping = file->f_mapping;
|
1964 |
|
|
struct inode *inode = mapping->host;
|
1965 |
|
|
ssize_t written;
|
1966 |
|
|
|
1967 |
|
|
if (count != ocount)
|
1968 |
|
|
*nr_segs = iov_shorten((struct iovec *)iov, *nr_segs, count);
|
1969 |
|
|
|
1970 |
|
|
written = generic_file_direct_IO(WRITE, iocb, iov, pos, *nr_segs);
|
1971 |
|
|
if (written > 0) {
|
1972 |
|
|
loff_t end = pos + written;
|
1973 |
|
|
if (end > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
|
1974 |
|
|
i_size_write(inode, end);
|
1975 |
|
|
mark_inode_dirty(inode);
|
1976 |
|
|
}
|
1977 |
|
|
*ppos = end;
|
1978 |
|
|
}
|
1979 |
|
|
|
1980 |
|
|
/*
|
1981 |
|
|
* Sync the fs metadata but not the minor inode changes and
|
1982 |
|
|
* of course not the data as we did direct DMA for the IO.
|
1983 |
|
|
* i_mutex is held, which protects generic_osync_inode() from
|
1984 |
|
|
* livelocking. AIO O_DIRECT ops attempt to sync metadata here.
|
1985 |
|
|
*/
|
1986 |
|
|
if ((written >= 0 || written == -EIOCBQUEUED) &&
|
1987 |
|
|
((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
1988 |
|
|
int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
|
1989 |
|
|
if (err < 0)
|
1990 |
|
|
written = err;
|
1991 |
|
|
}
|
1992 |
|
|
return written;
|
1993 |
|
|
}
|
1994 |
|
|
EXPORT_SYMBOL(generic_file_direct_write);
|
1995 |
|
|
|
1996 |
|
|
/*
|
1997 |
|
|
* Find or create a page at the given pagecache position. Return the locked
|
1998 |
|
|
* page. This function is specifically for buffered writes.
|
1999 |
|
|
*/
|
2000 |
|
|
struct page *__grab_cache_page(struct address_space *mapping, pgoff_t index)
|
2001 |
|
|
{
|
2002 |
|
|
int status;
|
2003 |
|
|
struct page *page;
|
2004 |
|
|
repeat:
|
2005 |
|
|
page = find_lock_page(mapping, index);
|
2006 |
|
|
if (likely(page))
|
2007 |
|
|
return page;
|
2008 |
|
|
|
2009 |
|
|
page = page_cache_alloc(mapping);
|
2010 |
|
|
if (!page)
|
2011 |
|
|
return NULL;
|
2012 |
|
|
status = add_to_page_cache_lru(page, mapping, index, GFP_KERNEL);
|
2013 |
|
|
if (unlikely(status)) {
|
2014 |
|
|
page_cache_release(page);
|
2015 |
|
|
if (status == -EEXIST)
|
2016 |
|
|
goto repeat;
|
2017 |
|
|
return NULL;
|
2018 |
|
|
}
|
2019 |
|
|
return page;
|
2020 |
|
|
}
|
2021 |
|
|
EXPORT_SYMBOL(__grab_cache_page);
|
2022 |
|
|
|
2023 |
|
|
static ssize_t generic_perform_write_2copy(struct file *file,
|
2024 |
|
|
struct iov_iter *i, loff_t pos)
|
2025 |
|
|
{
|
2026 |
|
|
struct address_space *mapping = file->f_mapping;
|
2027 |
|
|
const struct address_space_operations *a_ops = mapping->a_ops;
|
2028 |
|
|
struct inode *inode = mapping->host;
|
2029 |
|
|
long status = 0;
|
2030 |
|
|
ssize_t written = 0;
|
2031 |
|
|
|
2032 |
|
|
do {
|
2033 |
|
|
struct page *src_page;
|
2034 |
|
|
struct page *page;
|
2035 |
|
|
pgoff_t index; /* Pagecache index for current page */
|
2036 |
|
|
unsigned long offset; /* Offset into pagecache page */
|
2037 |
|
|
unsigned long bytes; /* Bytes to write to page */
|
2038 |
|
|
size_t copied; /* Bytes copied from user */
|
2039 |
|
|
|
2040 |
|
|
offset = (pos & (PAGE_CACHE_SIZE - 1));
|
2041 |
|
|
index = pos >> PAGE_CACHE_SHIFT;
|
2042 |
|
|
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
|
2043 |
|
|
iov_iter_count(i));
|
2044 |
|
|
|
2045 |
|
|
/*
|
2046 |
|
|
* a non-NULL src_page indicates that we're doing the
|
2047 |
|
|
* copy via get_user_pages and kmap.
|
2048 |
|
|
*/
|
2049 |
|
|
src_page = NULL;
|
2050 |
|
|
|
2051 |
|
|
/*
|
2052 |
|
|
* Bring in the user page that we will copy from _first_.
|
2053 |
|
|
* Otherwise there's a nasty deadlock on copying from the
|
2054 |
|
|
* same page as we're writing to, without it being marked
|
2055 |
|
|
* up-to-date.
|
2056 |
|
|
*
|
2057 |
|
|
* Not only is this an optimisation, but it is also required
|
2058 |
|
|
* to check that the address is actually valid, when atomic
|
2059 |
|
|
* usercopies are used, below.
|
2060 |
|
|
*/
|
2061 |
|
|
if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
|
2062 |
|
|
status = -EFAULT;
|
2063 |
|
|
break;
|
2064 |
|
|
}
|
2065 |
|
|
|
2066 |
|
|
page = __grab_cache_page(mapping, index);
|
2067 |
|
|
if (!page) {
|
2068 |
|
|
status = -ENOMEM;
|
2069 |
|
|
break;
|
2070 |
|
|
}
|
2071 |
|
|
|
2072 |
|
|
/*
|
2073 |
|
|
* non-uptodate pages cannot cope with short copies, and we
|
2074 |
|
|
* cannot take a pagefault with the destination page locked.
|
2075 |
|
|
* So pin the source page to copy it.
|
2076 |
|
|
*/
|
2077 |
|
|
if (!PageUptodate(page) && !segment_eq(get_fs(), KERNEL_DS)) {
|
2078 |
|
|
unlock_page(page);
|
2079 |
|
|
|
2080 |
|
|
src_page = alloc_page(GFP_KERNEL);
|
2081 |
|
|
if (!src_page) {
|
2082 |
|
|
page_cache_release(page);
|
2083 |
|
|
status = -ENOMEM;
|
2084 |
|
|
break;
|
2085 |
|
|
}
|
2086 |
|
|
|
2087 |
|
|
/*
|
2088 |
|
|
* Cannot get_user_pages with a page locked for the
|
2089 |
|
|
* same reason as we can't take a page fault with a
|
2090 |
|
|
* page locked (as explained below).
|
2091 |
|
|
*/
|
2092 |
|
|
copied = iov_iter_copy_from_user(src_page, i,
|
2093 |
|
|
offset, bytes);
|
2094 |
|
|
if (unlikely(copied == 0)) {
|
2095 |
|
|
status = -EFAULT;
|
2096 |
|
|
page_cache_release(page);
|
2097 |
|
|
page_cache_release(src_page);
|
2098 |
|
|
break;
|
2099 |
|
|
}
|
2100 |
|
|
bytes = copied;
|
2101 |
|
|
|
2102 |
|
|
lock_page(page);
|
2103 |
|
|
/*
|
2104 |
|
|
* Can't handle the page going uptodate here, because
|
2105 |
|
|
* that means we would use non-atomic usercopies, which
|
2106 |
|
|
* zero out the tail of the page, which can cause
|
2107 |
|
|
* zeroes to become transiently visible. We could just
|
2108 |
|
|
* use a non-zeroing copy, but the APIs aren't too
|
2109 |
|
|
* consistent.
|
2110 |
|
|
*/
|
2111 |
|
|
if (unlikely(!page->mapping || PageUptodate(page))) {
|
2112 |
|
|
unlock_page(page);
|
2113 |
|
|
page_cache_release(page);
|
2114 |
|
|
page_cache_release(src_page);
|
2115 |
|
|
continue;
|
2116 |
|
|
}
|
2117 |
|
|
}
|
2118 |
|
|
|
2119 |
|
|
status = a_ops->prepare_write(file, page, offset, offset+bytes);
|
2120 |
|
|
if (unlikely(status))
|
2121 |
|
|
goto fs_write_aop_error;
|
2122 |
|
|
|
2123 |
|
|
if (!src_page) {
|
2124 |
|
|
/*
|
2125 |
|
|
* Must not enter the pagefault handler here, because
|
2126 |
|
|
* we hold the page lock, so we might recursively
|
2127 |
|
|
* deadlock on the same lock, or get an ABBA deadlock
|
2128 |
|
|
* against a different lock, or against the mmap_sem
|
2129 |
|
|
* (which nests outside the page lock). So increment
|
2130 |
|
|
* preempt count, and use _atomic usercopies.
|
2131 |
|
|
*
|
2132 |
|
|
* The page is uptodate so we are OK to encounter a
|
2133 |
|
|
* short copy: if unmodified parts of the page are
|
2134 |
|
|
* marked dirty and written out to disk, it doesn't
|
2135 |
|
|
* really matter.
|
2136 |
|
|
*/
|
2137 |
|
|
pagefault_disable();
|
2138 |
|
|
copied = iov_iter_copy_from_user_atomic(page, i,
|
2139 |
|
|
offset, bytes);
|
2140 |
|
|
pagefault_enable();
|
2141 |
|
|
} else {
|
2142 |
|
|
void *src, *dst;
|
2143 |
|
|
src = kmap_atomic(src_page, KM_USER0);
|
2144 |
|
|
dst = kmap_atomic(page, KM_USER1);
|
2145 |
|
|
memcpy(dst + offset, src + offset, bytes);
|
2146 |
|
|
kunmap_atomic(dst, KM_USER1);
|
2147 |
|
|
kunmap_atomic(src, KM_USER0);
|
2148 |
|
|
copied = bytes;
|
2149 |
|
|
}
|
2150 |
|
|
flush_dcache_page(page);
|
2151 |
|
|
|
2152 |
|
|
status = a_ops->commit_write(file, page, offset, offset+bytes);
|
2153 |
|
|
if (unlikely(status < 0))
|
2154 |
|
|
goto fs_write_aop_error;
|
2155 |
|
|
if (unlikely(status > 0)) /* filesystem did partial write */
|
2156 |
|
|
copied = min_t(size_t, copied, status);
|
2157 |
|
|
|
2158 |
|
|
unlock_page(page);
|
2159 |
|
|
mark_page_accessed(page);
|
2160 |
|
|
page_cache_release(page);
|
2161 |
|
|
if (src_page)
|
2162 |
|
|
page_cache_release(src_page);
|
2163 |
|
|
|
2164 |
|
|
iov_iter_advance(i, copied);
|
2165 |
|
|
pos += copied;
|
2166 |
|
|
written += copied;
|
2167 |
|
|
|
2168 |
|
|
balance_dirty_pages_ratelimited(mapping);
|
2169 |
|
|
cond_resched();
|
2170 |
|
|
continue;
|
2171 |
|
|
|
2172 |
|
|
fs_write_aop_error:
|
2173 |
|
|
unlock_page(page);
|
2174 |
|
|
page_cache_release(page);
|
2175 |
|
|
if (src_page)
|
2176 |
|
|
page_cache_release(src_page);
|
2177 |
|
|
|
2178 |
|
|
/*
|
2179 |
|
|
* prepare_write() may have instantiated a few blocks
|
2180 |
|
|
* outside i_size. Trim these off again. Don't need
|
2181 |
|
|
* i_size_read because we hold i_mutex.
|
2182 |
|
|
*/
|
2183 |
|
|
if (pos + bytes > inode->i_size)
|
2184 |
|
|
vmtruncate(inode, inode->i_size);
|
2185 |
|
|
break;
|
2186 |
|
|
} while (iov_iter_count(i));
|
2187 |
|
|
|
2188 |
|
|
return written ? written : status;
|
2189 |
|
|
}
|
2190 |
|
|
|
2191 |
|
|
static ssize_t generic_perform_write(struct file *file,
|
2192 |
|
|
struct iov_iter *i, loff_t pos)
|
2193 |
|
|
{
|
2194 |
|
|
struct address_space *mapping = file->f_mapping;
|
2195 |
|
|
const struct address_space_operations *a_ops = mapping->a_ops;
|
2196 |
|
|
long status = 0;
|
2197 |
|
|
ssize_t written = 0;
|
2198 |
|
|
unsigned int flags = 0;
|
2199 |
|
|
|
2200 |
|
|
/*
|
2201 |
|
|
* Copies from kernel address space cannot fail (NFSD is a big user).
|
2202 |
|
|
*/
|
2203 |
|
|
if (segment_eq(get_fs(), KERNEL_DS))
|
2204 |
|
|
flags |= AOP_FLAG_UNINTERRUPTIBLE;
|
2205 |
|
|
|
2206 |
|
|
do {
|
2207 |
|
|
struct page *page;
|
2208 |
|
|
pgoff_t index; /* Pagecache index for current page */
|
2209 |
|
|
unsigned long offset; /* Offset into pagecache page */
|
2210 |
|
|
unsigned long bytes; /* Bytes to write to page */
|
2211 |
|
|
size_t copied; /* Bytes copied from user */
|
2212 |
|
|
void *fsdata;
|
2213 |
|
|
|
2214 |
|
|
offset = (pos & (PAGE_CACHE_SIZE - 1));
|
2215 |
|
|
index = pos >> PAGE_CACHE_SHIFT;
|
2216 |
|
|
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
|
2217 |
|
|
iov_iter_count(i));
|
2218 |
|
|
|
2219 |
|
|
again:
|
2220 |
|
|
|
2221 |
|
|
/*
|
2222 |
|
|
* Bring in the user page that we will copy from _first_.
|
2223 |
|
|
* Otherwise there's a nasty deadlock on copying from the
|
2224 |
|
|
* same page as we're writing to, without it being marked
|
2225 |
|
|
* up-to-date.
|
2226 |
|
|
*
|
2227 |
|
|
* Not only is this an optimisation, but it is also required
|
2228 |
|
|
* to check that the address is actually valid, when atomic
|
2229 |
|
|
* usercopies are used, below.
|
2230 |
|
|
*/
|
2231 |
|
|
if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
|
2232 |
|
|
status = -EFAULT;
|
2233 |
|
|
break;
|
2234 |
|
|
}
|
2235 |
|
|
|
2236 |
|
|
status = a_ops->write_begin(file, mapping, pos, bytes, flags,
|
2237 |
|
|
&page, &fsdata);
|
2238 |
|
|
if (unlikely(status))
|
2239 |
|
|
break;
|
2240 |
|
|
|
2241 |
|
|
pagefault_disable();
|
2242 |
|
|
copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
|
2243 |
|
|
pagefault_enable();
|
2244 |
|
|
flush_dcache_page(page);
|
2245 |
|
|
|
2246 |
|
|
status = a_ops->write_end(file, mapping, pos, bytes, copied,
|
2247 |
|
|
page, fsdata);
|
2248 |
|
|
if (unlikely(status < 0))
|
2249 |
|
|
break;
|
2250 |
|
|
copied = status;
|
2251 |
|
|
|
2252 |
|
|
cond_resched();
|
2253 |
|
|
|
2254 |
|
|
if (unlikely(copied == 0)) {
|
2255 |
|
|
/*
|
2256 |
|
|
* If we were unable to copy any data at all, we must
|
2257 |
|
|
* fall back to a single segment length write.
|
2258 |
|
|
*
|
2259 |
|
|
* If we didn't fallback here, we could livelock
|
2260 |
|
|
* because not all segments in the iov can be copied at
|
2261 |
|
|
* once without a pagefault.
|
2262 |
|
|
*/
|
2263 |
|
|
bytes = min_t(unsigned long, PAGE_CACHE_SIZE - offset,
|
2264 |
|
|
iov_iter_single_seg_count(i));
|
2265 |
|
|
goto again;
|
2266 |
|
|
}
|
2267 |
|
|
iov_iter_advance(i, copied);
|
2268 |
|
|
pos += copied;
|
2269 |
|
|
written += copied;
|
2270 |
|
|
|
2271 |
|
|
balance_dirty_pages_ratelimited(mapping);
|
2272 |
|
|
|
2273 |
|
|
} while (iov_iter_count(i));
|
2274 |
|
|
|
2275 |
|
|
return written ? written : status;
|
2276 |
|
|
}
|
2277 |
|
|
|
2278 |
|
|
ssize_t
|
2279 |
|
|
generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
|
2280 |
|
|
unsigned long nr_segs, loff_t pos, loff_t *ppos,
|
2281 |
|
|
size_t count, ssize_t written)
|
2282 |
|
|
{
|
2283 |
|
|
struct file *file = iocb->ki_filp;
|
2284 |
|
|
struct address_space *mapping = file->f_mapping;
|
2285 |
|
|
const struct address_space_operations *a_ops = mapping->a_ops;
|
2286 |
|
|
struct inode *inode = mapping->host;
|
2287 |
|
|
ssize_t status;
|
2288 |
|
|
struct iov_iter i;
|
2289 |
|
|
|
2290 |
|
|
iov_iter_init(&i, iov, nr_segs, count, written);
|
2291 |
|
|
if (a_ops->write_begin)
|
2292 |
|
|
status = generic_perform_write(file, &i, pos);
|
2293 |
|
|
else
|
2294 |
|
|
status = generic_perform_write_2copy(file, &i, pos);
|
2295 |
|
|
|
2296 |
|
|
if (likely(status >= 0)) {
|
2297 |
|
|
written += status;
|
2298 |
|
|
*ppos = pos + status;
|
2299 |
|
|
|
2300 |
|
|
/*
|
2301 |
|
|
* For now, when the user asks for O_SYNC, we'll actually give
|
2302 |
|
|
* O_DSYNC
|
2303 |
|
|
*/
|
2304 |
|
|
if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
2305 |
|
|
if (!a_ops->writepage || !is_sync_kiocb(iocb))
|
2306 |
|
|
status = generic_osync_inode(inode, mapping,
|
2307 |
|
|
OSYNC_METADATA|OSYNC_DATA);
|
2308 |
|
|
}
|
2309 |
|
|
}
|
2310 |
|
|
|
2311 |
|
|
/*
|
2312 |
|
|
* If we get here for O_DIRECT writes then we must have fallen through
|
2313 |
|
|
* to buffered writes (block instantiation inside i_size). So we sync
|
2314 |
|
|
* the file data here, to try to honour O_DIRECT expectations.
|
2315 |
|
|
*/
|
2316 |
|
|
if (unlikely(file->f_flags & O_DIRECT) && written)
|
2317 |
|
|
status = filemap_write_and_wait(mapping);
|
2318 |
|
|
|
2319 |
|
|
return written ? written : status;
|
2320 |
|
|
}
|
2321 |
|
|
EXPORT_SYMBOL(generic_file_buffered_write);
|
2322 |
|
|
|
2323 |
|
|
static ssize_t
|
2324 |
|
|
__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
|
2325 |
|
|
unsigned long nr_segs, loff_t *ppos)
|
2326 |
|
|
{
|
2327 |
|
|
struct file *file = iocb->ki_filp;
|
2328 |
|
|
struct address_space * mapping = file->f_mapping;
|
2329 |
|
|
size_t ocount; /* original count */
|
2330 |
|
|
size_t count; /* after file limit checks */
|
2331 |
|
|
struct inode *inode = mapping->host;
|
2332 |
|
|
loff_t pos;
|
2333 |
|
|
ssize_t written;
|
2334 |
|
|
ssize_t err;
|
2335 |
|
|
|
2336 |
|
|
ocount = 0;
|
2337 |
|
|
err = generic_segment_checks(iov, &nr_segs, &ocount, VERIFY_READ);
|
2338 |
|
|
if (err)
|
2339 |
|
|
return err;
|
2340 |
|
|
|
2341 |
|
|
count = ocount;
|
2342 |
|
|
pos = *ppos;
|
2343 |
|
|
|
2344 |
|
|
vfs_check_frozen(inode->i_sb, SB_FREEZE_WRITE);
|
2345 |
|
|
|
2346 |
|
|
/* We can write back this queue in page reclaim */
|
2347 |
|
|
current->backing_dev_info = mapping->backing_dev_info;
|
2348 |
|
|
written = 0;
|
2349 |
|
|
|
2350 |
|
|
err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
|
2351 |
|
|
if (err)
|
2352 |
|
|
goto out;
|
2353 |
|
|
|
2354 |
|
|
if (count == 0)
|
2355 |
|
|
goto out;
|
2356 |
|
|
|
2357 |
|
|
err = remove_suid(file->f_path.dentry);
|
2358 |
|
|
if (err)
|
2359 |
|
|
goto out;
|
2360 |
|
|
|
2361 |
|
|
file_update_time(file);
|
2362 |
|
|
|
2363 |
|
|
/* coalesce the iovecs and go direct-to-BIO for O_DIRECT */
|
2364 |
|
|
if (unlikely(file->f_flags & O_DIRECT)) {
|
2365 |
|
|
loff_t endbyte;
|
2366 |
|
|
ssize_t written_buffered;
|
2367 |
|
|
|
2368 |
|
|
written = generic_file_direct_write(iocb, iov, &nr_segs, pos,
|
2369 |
|
|
ppos, count, ocount);
|
2370 |
|
|
if (written < 0 || written == count)
|
2371 |
|
|
goto out;
|
2372 |
|
|
/*
|
2373 |
|
|
* direct-io write to a hole: fall through to buffered I/O
|
2374 |
|
|
* for completing the rest of the request.
|
2375 |
|
|
*/
|
2376 |
|
|
pos += written;
|
2377 |
|
|
count -= written;
|
2378 |
|
|
written_buffered = generic_file_buffered_write(iocb, iov,
|
2379 |
|
|
nr_segs, pos, ppos, count,
|
2380 |
|
|
written);
|
2381 |
|
|
/*
|
2382 |
|
|
* If generic_file_buffered_write() retuned a synchronous error
|
2383 |
|
|
* then we want to return the number of bytes which were
|
2384 |
|
|
* direct-written, or the error code if that was zero. Note
|
2385 |
|
|
* that this differs from normal direct-io semantics, which
|
2386 |
|
|
* will return -EFOO even if some bytes were written.
|
2387 |
|
|
*/
|
2388 |
|
|
if (written_buffered < 0) {
|
2389 |
|
|
err = written_buffered;
|
2390 |
|
|
goto out;
|
2391 |
|
|
}
|
2392 |
|
|
|
2393 |
|
|
/*
|
2394 |
|
|
* We need to ensure that the page cache pages are written to
|
2395 |
|
|
* disk and invalidated to preserve the expected O_DIRECT
|
2396 |
|
|
* semantics.
|
2397 |
|
|
*/
|
2398 |
|
|
endbyte = pos + written_buffered - written - 1;
|
2399 |
|
|
err = do_sync_mapping_range(file->f_mapping, pos, endbyte,
|
2400 |
|
|
SYNC_FILE_RANGE_WAIT_BEFORE|
|
2401 |
|
|
SYNC_FILE_RANGE_WRITE|
|
2402 |
|
|
SYNC_FILE_RANGE_WAIT_AFTER);
|
2403 |
|
|
if (err == 0) {
|
2404 |
|
|
written = written_buffered;
|
2405 |
|
|
invalidate_mapping_pages(mapping,
|
2406 |
|
|
pos >> PAGE_CACHE_SHIFT,
|
2407 |
|
|
endbyte >> PAGE_CACHE_SHIFT);
|
2408 |
|
|
} else {
|
2409 |
|
|
/*
|
2410 |
|
|
* We don't know how much we wrote, so just return
|
2411 |
|
|
* the number of bytes which were direct-written
|
2412 |
|
|
*/
|
2413 |
|
|
}
|
2414 |
|
|
} else {
|
2415 |
|
|
written = generic_file_buffered_write(iocb, iov, nr_segs,
|
2416 |
|
|
pos, ppos, count, written);
|
2417 |
|
|
}
|
2418 |
|
|
out:
|
2419 |
|
|
current->backing_dev_info = NULL;
|
2420 |
|
|
return written ? written : err;
|
2421 |
|
|
}
|
2422 |
|
|
|
2423 |
|
|
ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
|
2424 |
|
|
const struct iovec *iov, unsigned long nr_segs, loff_t pos)
|
2425 |
|
|
{
|
2426 |
|
|
struct file *file = iocb->ki_filp;
|
2427 |
|
|
struct address_space *mapping = file->f_mapping;
|
2428 |
|
|
struct inode *inode = mapping->host;
|
2429 |
|
|
ssize_t ret;
|
2430 |
|
|
|
2431 |
|
|
BUG_ON(iocb->ki_pos != pos);
|
2432 |
|
|
|
2433 |
|
|
ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
|
2434 |
|
|
&iocb->ki_pos);
|
2435 |
|
|
|
2436 |
|
|
if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
2437 |
|
|
ssize_t err;
|
2438 |
|
|
|
2439 |
|
|
err = sync_page_range_nolock(inode, mapping, pos, ret);
|
2440 |
|
|
if (err < 0)
|
2441 |
|
|
ret = err;
|
2442 |
|
|
}
|
2443 |
|
|
return ret;
|
2444 |
|
|
}
|
2445 |
|
|
EXPORT_SYMBOL(generic_file_aio_write_nolock);
|
2446 |
|
|
|
2447 |
|
|
ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
|
2448 |
|
|
unsigned long nr_segs, loff_t pos)
|
2449 |
|
|
{
|
2450 |
|
|
struct file *file = iocb->ki_filp;
|
2451 |
|
|
struct address_space *mapping = file->f_mapping;
|
2452 |
|
|
struct inode *inode = mapping->host;
|
2453 |
|
|
ssize_t ret;
|
2454 |
|
|
|
2455 |
|
|
BUG_ON(iocb->ki_pos != pos);
|
2456 |
|
|
|
2457 |
|
|
mutex_lock(&inode->i_mutex);
|
2458 |
|
|
ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
|
2459 |
|
|
&iocb->ki_pos);
|
2460 |
|
|
mutex_unlock(&inode->i_mutex);
|
2461 |
|
|
|
2462 |
|
|
if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
|
2463 |
|
|
ssize_t err;
|
2464 |
|
|
|
2465 |
|
|
err = sync_page_range(inode, mapping, pos, ret);
|
2466 |
|
|
if (err < 0)
|
2467 |
|
|
ret = err;
|
2468 |
|
|
}
|
2469 |
|
|
return ret;
|
2470 |
|
|
}
|
2471 |
|
|
EXPORT_SYMBOL(generic_file_aio_write);
|
2472 |
|
|
|
2473 |
|
|
/*
|
2474 |
|
|
* Called under i_mutex for writes to S_ISREG files. Returns -EIO if something
|
2475 |
|
|
* went wrong during pagecache shootdown.
|
2476 |
|
|
*/
|
2477 |
|
|
static ssize_t
|
2478 |
|
|
generic_file_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
|
2479 |
|
|
loff_t offset, unsigned long nr_segs)
|
2480 |
|
|
{
|
2481 |
|
|
struct file *file = iocb->ki_filp;
|
2482 |
|
|
struct address_space *mapping = file->f_mapping;
|
2483 |
|
|
ssize_t retval;
|
2484 |
|
|
size_t write_len;
|
2485 |
|
|
pgoff_t end = 0; /* silence gcc */
|
2486 |
|
|
|
2487 |
|
|
/*
|
2488 |
|
|
* If it's a write, unmap all mmappings of the file up-front. This
|
2489 |
|
|
* will cause any pte dirty bits to be propagated into the pageframes
|
2490 |
|
|
* for the subsequent filemap_write_and_wait().
|
2491 |
|
|
*/
|
2492 |
|
|
if (rw == WRITE) {
|
2493 |
|
|
write_len = iov_length(iov, nr_segs);
|
2494 |
|
|
end = (offset + write_len - 1) >> PAGE_CACHE_SHIFT;
|
2495 |
|
|
if (mapping_mapped(mapping))
|
2496 |
|
|
unmap_mapping_range(mapping, offset, write_len, 0);
|
2497 |
|
|
}
|
2498 |
|
|
|
2499 |
|
|
retval = filemap_write_and_wait(mapping);
|
2500 |
|
|
if (retval)
|
2501 |
|
|
goto out;
|
2502 |
|
|
|
2503 |
|
|
/*
|
2504 |
|
|
* After a write we want buffered reads to be sure to go to disk to get
|
2505 |
|
|
* the new data. We invalidate clean cached page from the region we're
|
2506 |
|
|
* about to write. We do this *before* the write so that we can return
|
2507 |
|
|
* -EIO without clobbering -EIOCBQUEUED from ->direct_IO().
|
2508 |
|
|
*/
|
2509 |
|
|
if (rw == WRITE && mapping->nrpages) {
|
2510 |
|
|
retval = invalidate_inode_pages2_range(mapping,
|
2511 |
|
|
offset >> PAGE_CACHE_SHIFT, end);
|
2512 |
|
|
if (retval)
|
2513 |
|
|
goto out;
|
2514 |
|
|
}
|
2515 |
|
|
|
2516 |
|
|
retval = mapping->a_ops->direct_IO(rw, iocb, iov, offset, nr_segs);
|
2517 |
|
|
|
2518 |
|
|
/*
|
2519 |
|
|
* Finally, try again to invalidate clean pages which might have been
|
2520 |
|
|
* cached by non-direct readahead, or faulted in by get_user_pages()
|
2521 |
|
|
* if the source of the write was an mmap'ed region of the file
|
2522 |
|
|
* we're writing. Either one is a pretty crazy thing to do,
|
2523 |
|
|
* so we don't support it 100%. If this invalidation
|
2524 |
|
|
* fails, tough, the write still worked...
|
2525 |
|
|
*/
|
2526 |
|
|
if (rw == WRITE && mapping->nrpages) {
|
2527 |
|
|
invalidate_inode_pages2_range(mapping, offset >> PAGE_CACHE_SHIFT, end);
|
2528 |
|
|
}
|
2529 |
|
|
out:
|
2530 |
|
|
return retval;
|
2531 |
|
|
}
|
2532 |
|
|
|
2533 |
|
|
/**
|
2534 |
|
|
* try_to_release_page() - release old fs-specific metadata on a page
|
2535 |
|
|
*
|
2536 |
|
|
* @page: the page which the kernel is trying to free
|
2537 |
|
|
* @gfp_mask: memory allocation flags (and I/O mode)
|
2538 |
|
|
*
|
2539 |
|
|
* The address_space is to try to release any data against the page
|
2540 |
|
|
* (presumably at page->private). If the release was successful, return `1'.
|
2541 |
|
|
* Otherwise return zero.
|
2542 |
|
|
*
|
2543 |
|
|
* The @gfp_mask argument specifies whether I/O may be performed to release
|
2544 |
|
|
* this page (__GFP_IO), and whether the call may block (__GFP_WAIT).
|
2545 |
|
|
*
|
2546 |
|
|
* NOTE: @gfp_mask may go away, and this function may become non-blocking.
|
2547 |
|
|
*/
|
2548 |
|
|
int try_to_release_page(struct page *page, gfp_t gfp_mask)
|
2549 |
|
|
{
|
2550 |
|
|
struct address_space * const mapping = page->mapping;
|
2551 |
|
|
|
2552 |
|
|
BUG_ON(!PageLocked(page));
|
2553 |
|
|
if (PageWriteback(page))
|
2554 |
|
|
return 0;
|
2555 |
|
|
|
2556 |
|
|
if (mapping && mapping->a_ops->releasepage)
|
2557 |
|
|
return mapping->a_ops->releasepage(page, gfp_mask);
|
2558 |
|
|
return try_to_free_buffers(page);
|
2559 |
|
|
}
|
2560 |
|
|
|
2561 |
|
|
EXPORT_SYMBOL(try_to_release_page);
|