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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [mm/] [shmem.c] - Rev 1275
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/* * Resizable virtual memory filesystem for Linux. * * Copyright (C) 2000 Linus Torvalds. * 2000 Transmeta Corp. * 2000-2001 Christoph Rohland * 2000-2001 SAP AG * 2002 Red Hat Inc. * Copyright (C) 2002-2003 Hugh Dickins. * Copyright (C) 2002-2003 VERITAS Software Corporation. * * This file is released under the GPL. */ /* * This virtual memory filesystem is heavily based on the ramfs. It * extends ramfs by the ability to use swap and honor resource limits * which makes it a completely usable filesystem. */ #include <linux/config.h> #include <linux/module.h> #include <linux/init.h> #include <linux/devfs_fs_kernel.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/file.h> #include <linux/swap.h> #include <linux/pagemap.h> #include <linux/string.h> #include <linux/locks.h> #include <linux/smp_lock.h> #include <asm/uaccess.h> #include <asm/div64.h> /* This magic number is used in glibc for posix shared memory */ #define TMPFS_MAGIC 0x01021994 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) /* info->flags needs VM_flags to handle pagein/truncate race efficiently */ #define SHMEM_PAGEIN VM_READ #define SHMEM_TRUNCATE VM_WRITE /* Pretend that each entry is of this size in directory's i_size */ #define BOGO_DIRENT_SIZE 20 #define SHMEM_SB(sb) (&sb->u.shmem_sb) /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ enum sgp_type { SGP_READ, /* don't exceed i_size, don't allocate page */ SGP_CACHE, /* don't exceed i_size, may allocate page */ SGP_WRITE, /* may exceed i_size, may allocate page */ }; static int shmem_getpage(struct inode *inode, unsigned long idx, struct page **pagep, enum sgp_type sgp); static struct super_operations shmem_ops; static struct address_space_operations shmem_aops; static struct file_operations shmem_file_operations; static struct inode_operations shmem_inode_operations; static struct inode_operations shmem_dir_inode_operations; static struct vm_operations_struct shmem_vm_ops; LIST_HEAD(shmem_inodes); static spinlock_t shmem_ilock = SPIN_LOCK_UNLOCKED; static void shmem_free_block(struct inode *inode) { struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); spin_lock(&sbinfo->stat_lock); sbinfo->free_blocks++; inode->i_blocks -= BLOCKS_PER_PAGE; spin_unlock(&sbinfo->stat_lock); } static void shmem_removepage(struct page *page) { if (!PageLaunder(page)) shmem_free_block(page->mapping->host); } /* * shmem_swp_entry - find the swap vector position in the info structure * * @info: info structure for the inode * @index: index of the page to find * @page: optional page to add to the structure. Has to be preset to * all zeros * * If there is no space allocated yet it will return NULL when * page is 0, else it will use the page for the needed block, * setting it to 0 on return to indicate that it has been used. * * The swap vector is organized the following way: * * There are SHMEM_NR_DIRECT entries directly stored in the * shmem_inode_info structure. So small files do not need an addional * allocation. * * For pages with index > SHMEM_NR_DIRECT there is the pointer * i_indirect which points to a page which holds in the first half * doubly indirect blocks, in the second half triple indirect blocks: * * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the * following layout (for SHMEM_NR_DIRECT == 16): * * i_indirect -> dir --> 16-19 * | +-> 20-23 * | * +-->dir2 --> 24-27 * | +-> 28-31 * | +-> 32-35 * | +-> 36-39 * | * +-->dir3 --> 40-43 * +-> 44-47 * +-> 48-51 * +-> 52-55 */ static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, unsigned long *page) { unsigned long offset; void **dir; if (index < SHMEM_NR_DIRECT) return info->i_direct+index; if (!info->i_indirect) { if (page) { info->i_indirect = (void **) *page; *page = 0; } return NULL; /* need another page */ } index -= SHMEM_NR_DIRECT; offset = index % ENTRIES_PER_PAGE; index /= ENTRIES_PER_PAGE; dir = info->i_indirect; if (index >= ENTRIES_PER_PAGE/2) { index -= ENTRIES_PER_PAGE/2; dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; index %= ENTRIES_PER_PAGE; if (!*dir) { if (page) { *dir = (void *) *page; *page = 0; } return NULL; /* need another page */ } dir = (void **) *dir; } dir += index; if (!*dir) { if (!page || !*page) return NULL; /* need a page */ *dir = (void *) *page; *page = 0; } return (swp_entry_t *) *dir + offset; } /* * shmem_swp_alloc - get the position of the swap entry for the page. * If it does not exist allocate the entry. * * @info: info structure for the inode * @index: index of the page to find * @sgp: check and recheck i_size? skip allocation? */ static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) { struct inode *inode = info->inode; struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); unsigned long page = 0; swp_entry_t *entry; static const swp_entry_t unswapped = {0}; if (sgp != SGP_WRITE && ((loff_t) index << PAGE_CACHE_SHIFT) >= inode->i_size) return ERR_PTR(-EINVAL); while (!(entry = shmem_swp_entry(info, index, &page))) { if (sgp == SGP_READ) return (swp_entry_t *) &unswapped; /* * Test free_blocks against 1 not 0, since we have 1 data * page (and perhaps indirect index pages) yet to allocate: * a waste to allocate index if we cannot allocate data. */ spin_lock(&sbinfo->stat_lock); if (sbinfo->free_blocks <= 1) { spin_unlock(&sbinfo->stat_lock); return ERR_PTR(-ENOSPC); } sbinfo->free_blocks--; inode->i_blocks += BLOCKS_PER_PAGE; spin_unlock(&sbinfo->stat_lock); spin_unlock(&info->lock); page = get_zeroed_page(GFP_USER); spin_lock(&info->lock); if (!page) { shmem_free_block(inode); return ERR_PTR(-ENOMEM); } if (sgp != SGP_WRITE && ((loff_t) index << PAGE_CACHE_SHIFT) >= inode->i_size) { entry = ERR_PTR(-EINVAL); break; } if (info->next_index <= index) info->next_index = index + 1; } if (page) { /* another task gave its page, or truncated the file */ shmem_free_block(inode); free_page(page); } if (info->next_index <= index && !IS_ERR(entry)) info->next_index = index + 1; return entry; } /* * shmem_free_swp - free some swap entries in a directory * * @dir: pointer to the directory * @edir: pointer after last entry of the directory */ static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) { swp_entry_t *ptr; int freed = 0; for (ptr = dir; ptr < edir; ptr++) { if (ptr->val) { free_swap_and_cache(*ptr); *ptr = (swp_entry_t){0}; freed++; } } return freed; } /* * shmem_truncate_direct - free the swap entries of a whole doubly * indirect block * * @info: the info structure of the inode * @dir: pointer to the pointer to the block * @start: offset to start from (in pages) * @len: how many pages are stored in this block */ static inline unsigned long shmem_truncate_direct(struct shmem_inode_info *info, swp_entry_t ***dir, unsigned long start, unsigned long len) { swp_entry_t **last, **ptr; unsigned long off, freed_swp, freed = 0; last = *dir + (len + ENTRIES_PER_PAGE - 1) / ENTRIES_PER_PAGE; off = start % ENTRIES_PER_PAGE; for (ptr = *dir + start/ENTRIES_PER_PAGE; ptr < last; ptr++, off = 0) { if (!*ptr) continue; if (info->swapped) { freed_swp = shmem_free_swp(*ptr + off, *ptr + ENTRIES_PER_PAGE); info->swapped -= freed_swp; freed += freed_swp; } if (!off) { freed++; free_page((unsigned long) *ptr); *ptr = 0; } } if (!start) { freed++; free_page((unsigned long) *dir); *dir = 0; } return freed; } /* * shmem_truncate_indirect - truncate an inode * * @info: the info structure of the inode * @index: the index to truncate * * This function locates the last doubly indirect block and calls * then shmem_truncate_direct to do the real work */ static inline unsigned long shmem_truncate_indirect(struct shmem_inode_info *info, unsigned long index) { swp_entry_t ***base; unsigned long baseidx, start; unsigned long len = info->next_index; unsigned long freed; if (len <= SHMEM_NR_DIRECT) { info->next_index = index; if (!info->swapped) return 0; freed = shmem_free_swp(info->i_direct + index, info->i_direct + len); info->swapped -= freed; return freed; } if (len <= ENTRIES_PER_PAGEPAGE/2 + SHMEM_NR_DIRECT) { len -= SHMEM_NR_DIRECT; base = (swp_entry_t ***) &info->i_indirect; baseidx = SHMEM_NR_DIRECT; } else { len -= ENTRIES_PER_PAGEPAGE/2 + SHMEM_NR_DIRECT; BUG_ON(len > ENTRIES_PER_PAGEPAGE*ENTRIES_PER_PAGE/2); baseidx = len - 1; baseidx -= baseidx % ENTRIES_PER_PAGEPAGE; base = (swp_entry_t ***) info->i_indirect + ENTRIES_PER_PAGE/2 + baseidx/ENTRIES_PER_PAGEPAGE; len -= baseidx; baseidx += ENTRIES_PER_PAGEPAGE/2 + SHMEM_NR_DIRECT; } if (index > baseidx) { info->next_index = index; start = index - baseidx; } else { info->next_index = baseidx; start = 0; } return *base? shmem_truncate_direct(info, base, start, len): 0; } static void shmem_truncate(struct inode *inode) { struct shmem_inode_info *info = SHMEM_I(inode); struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); unsigned long freed = 0; unsigned long index; inode->i_ctime = inode->i_mtime = CURRENT_TIME; index = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; if (index >= info->next_index) return; spin_lock(&info->lock); while (index < info->next_index) freed += shmem_truncate_indirect(info, index); BUG_ON(info->swapped > info->next_index); if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { /* * Call truncate_inode_pages again: racing shmem_unuse_inode * may have swizzled a page in from swap since vmtruncate or * generic_delete_inode did it, before we lowered next_index. * Also, though shmem_getpage checks i_size before adding to * cache, no recheck after: so fix the narrow window there too. */ info->flags |= SHMEM_TRUNCATE; spin_unlock(&info->lock); truncate_inode_pages(inode->i_mapping, inode->i_size); spin_lock(&info->lock); info->flags &= ~SHMEM_TRUNCATE; } spin_unlock(&info->lock); spin_lock(&sbinfo->stat_lock); sbinfo->free_blocks += freed; inode->i_blocks -= freed*BLOCKS_PER_PAGE; spin_unlock(&sbinfo->stat_lock); } static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) { struct inode *inode = dentry->d_inode; struct page *page = NULL; int error; if (attr->ia_valid & ATTR_SIZE) { if (attr->ia_size < inode->i_size) { /* * If truncating down to a partial page, then * if that page is already allocated, hold it * in memory until the truncation is over, so * truncate_partial_page cannnot miss it were * it assigned to swap. */ if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { (void) shmem_getpage(inode, attr->ia_size>>PAGE_CACHE_SHIFT, &page, SGP_READ); } /* * Reset SHMEM_PAGEIN flag so that shmem_truncate can * detect if any pages might have been added to cache * after truncate_inode_pages. But we needn't bother * if it's being fully truncated to zero-length: the * nrpages check is efficient enough in that case. */ if (attr->ia_size) { struct shmem_inode_info *info = SHMEM_I(inode); spin_lock(&info->lock); info->flags &= ~SHMEM_PAGEIN; spin_unlock(&info->lock); } } } error = inode_change_ok(inode, attr); if (!error) error = inode_setattr(inode, attr); if (page) page_cache_release(page); return error; } static void shmem_delete_inode(struct inode *inode) { struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); struct shmem_inode_info *info = SHMEM_I(inode); if (inode->i_op->truncate == shmem_truncate) { spin_lock(&shmem_ilock); list_del(&info->list); spin_unlock(&shmem_ilock); inode->i_size = 0; shmem_truncate(inode); } BUG_ON(inode->i_blocks); spin_lock(&sbinfo->stat_lock); sbinfo->free_inodes++; spin_unlock(&sbinfo->stat_lock); clear_inode(inode); } static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) { swp_entry_t *ptr; for (ptr = dir; ptr < edir; ptr++) { if (ptr->val == entry.val) return ptr - dir; } return -1; } static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) { struct inode *inode; struct address_space *mapping; swp_entry_t *ptr; unsigned long idx; int offset; idx = 0; ptr = info->i_direct; spin_lock(&info->lock); offset = info->next_index; if (offset > SHMEM_NR_DIRECT) offset = SHMEM_NR_DIRECT; offset = shmem_find_swp(entry, ptr, ptr + offset); if (offset >= 0) goto found; for (idx = SHMEM_NR_DIRECT; idx < info->next_index; idx += ENTRIES_PER_PAGE) { ptr = shmem_swp_entry(info, idx, NULL); if (!ptr) continue; offset = info->next_index - idx; if (offset > ENTRIES_PER_PAGE) offset = ENTRIES_PER_PAGE; offset = shmem_find_swp(entry, ptr, ptr + offset); if (offset >= 0) goto found; } spin_unlock(&info->lock); return 0; found: idx += offset; inode = info->inode; mapping = inode->i_mapping; delete_from_swap_cache(page); if (add_to_page_cache_unique(page, mapping, idx, page_hash(mapping, idx)) == 0) { info->flags |= SHMEM_PAGEIN; ptr[offset].val = 0; info->swapped--; } else if (add_to_swap_cache(page, entry) != 0) BUG(); spin_unlock(&info->lock); SetPageUptodate(page); /* * Decrement swap count even when the entry is left behind: * try_to_unuse will skip over mms, then reincrement count. */ swap_free(entry); return 1; } /* * shmem_unuse() search for an eventually swapped out shmem page. */ int shmem_unuse(swp_entry_t entry, struct page *page) { struct list_head *p; struct shmem_inode_info *info; int found = 0; spin_lock(&shmem_ilock); list_for_each(p, &shmem_inodes) { info = list_entry(p, struct shmem_inode_info, list); if (info->swapped && shmem_unuse_inode(info, entry, page)) { /* move head to start search for next from here */ list_move_tail(&shmem_inodes, &info->list); found = 1; break; } } spin_unlock(&shmem_ilock); return found; } /* * Move the page from the page cache to the swap cache. */ static int shmem_writepage(struct page *page) { struct shmem_inode_info *info; swp_entry_t *entry, swap; struct address_space *mapping; unsigned long index; struct inode *inode; BUG_ON(!PageLocked(page)); if (!PageLaunder(page)) goto fail; mapping = page->mapping; index = page->index; inode = mapping->host; info = SHMEM_I(inode); if (info->flags & VM_LOCKED) goto fail; getswap: swap = get_swap_page(); if (!swap.val) goto fail; spin_lock(&info->lock); if (index >= info->next_index) { BUG_ON(!(info->flags & SHMEM_TRUNCATE)); spin_unlock(&info->lock); swap_free(swap); goto fail; } entry = shmem_swp_entry(info, index, NULL); BUG_ON(!entry); BUG_ON(entry->val); /* Remove it from the page cache */ remove_inode_page(page); page_cache_release(page); /* Add it to the swap cache */ if (add_to_swap_cache(page, swap) != 0) { /* * Raced with "speculative" read_swap_cache_async. * Add page back to page cache, unref swap, try again. */ add_to_page_cache_locked(page, mapping, index); info->flags |= SHMEM_PAGEIN; spin_unlock(&info->lock); swap_free(swap); goto getswap; } *entry = swap; info->swapped++; spin_unlock(&info->lock); SetPageUptodate(page); set_page_dirty(page); UnlockPage(page); return 0; fail: return fail_writepage(page); } /* * shmem_getpage - either get the page from swap or allocate a new one * * If we allocate a new one we do not mark it dirty. That's up to the * vm. If we swap it in we mark it dirty since we also free the swap * entry since a page cannot live in both the swap and page cache */ static int shmem_getpage(struct inode *inode, unsigned long idx, struct page **pagep, enum sgp_type sgp) { struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); struct shmem_sb_info *sbinfo; struct page *filepage = *pagep; struct page *swappage; swp_entry_t *entry; swp_entry_t swap; int error = 0; if (idx >= SHMEM_MAX_INDEX) return -EFBIG; /* * Normally, filepage is NULL on entry, and either found * uptodate immediately, or allocated and zeroed, or read * in under swappage, which is then assigned to filepage. * But shmem_readpage and shmem_prepare_write pass in a locked * filepage, which may be found not uptodate by other callers * too, and may need to be copied from the swappage read in. */ repeat: if (!filepage) filepage = find_lock_page(mapping, idx); if (filepage && Page_Uptodate(filepage)) goto done; spin_lock(&info->lock); entry = shmem_swp_alloc(info, idx, sgp); if (IS_ERR(entry)) { spin_unlock(&info->lock); error = PTR_ERR(entry); goto failed; } swap = *entry; if (swap.val) { /* Look it up and read it in.. */ swappage = lookup_swap_cache(swap); if (!swappage) { spin_unlock(&info->lock); swapin_readahead(swap); swappage = read_swap_cache_async(swap); if (!swappage) { spin_lock(&info->lock); entry = shmem_swp_alloc(info, idx, sgp); if (IS_ERR(entry)) error = PTR_ERR(entry); else if (entry->val == swap.val) error = -ENOMEM; spin_unlock(&info->lock); if (error) goto failed; goto repeat; } wait_on_page(swappage); page_cache_release(swappage); goto repeat; } /* We have to do this with page locked to prevent races */ if (TryLockPage(swappage)) { spin_unlock(&info->lock); wait_on_page(swappage); page_cache_release(swappage); goto repeat; } if (!Page_Uptodate(swappage)) { spin_unlock(&info->lock); UnlockPage(swappage); page_cache_release(swappage); error = -EIO; goto failed; } delete_from_swap_cache(swappage); if (filepage) { entry->val = 0; info->swapped--; spin_unlock(&info->lock); flush_page_to_ram(swappage); copy_highpage(filepage, swappage); UnlockPage(swappage); page_cache_release(swappage); flush_dcache_page(filepage); SetPageUptodate(filepage); SetPageDirty(filepage); swap_free(swap); } else if (add_to_page_cache_unique(swappage, mapping, idx, page_hash(mapping, idx)) == 0) { info->flags |= SHMEM_PAGEIN; entry->val = 0; info->swapped--; spin_unlock(&info->lock); filepage = swappage; SetPageUptodate(filepage); SetPageDirty(filepage); swap_free(swap); } else { if (add_to_swap_cache(swappage, swap) != 0) BUG(); spin_unlock(&info->lock); SetPageUptodate(swappage); SetPageDirty(swappage); UnlockPage(swappage); page_cache_release(swappage); goto repeat; } } else if (sgp == SGP_READ && !filepage) { filepage = find_get_page(mapping, idx); if (filepage && (!Page_Uptodate(filepage) || TryLockPage(filepage))) { spin_unlock(&info->lock); wait_on_page(filepage); page_cache_release(filepage); filepage = NULL; goto repeat; } spin_unlock(&info->lock); } else { sbinfo = SHMEM_SB(inode->i_sb); spin_lock(&sbinfo->stat_lock); if (sbinfo->free_blocks == 0) { spin_unlock(&sbinfo->stat_lock); spin_unlock(&info->lock); error = -ENOSPC; goto failed; } sbinfo->free_blocks--; inode->i_blocks += BLOCKS_PER_PAGE; spin_unlock(&sbinfo->stat_lock); if (!filepage) { spin_unlock(&info->lock); filepage = page_cache_alloc(mapping); if (!filepage) { shmem_free_block(inode); error = -ENOMEM; goto failed; } spin_lock(&info->lock); entry = shmem_swp_alloc(info, idx, sgp); if (IS_ERR(entry)) error = PTR_ERR(entry); if (error || entry->val || add_to_page_cache_unique(filepage, mapping, idx, page_hash(mapping, idx)) != 0) { spin_unlock(&info->lock); page_cache_release(filepage); shmem_free_block(inode); filepage = NULL; if (error) goto failed; goto repeat; } info->flags |= SHMEM_PAGEIN; } spin_unlock(&info->lock); clear_highpage(filepage); flush_dcache_page(filepage); SetPageUptodate(filepage); } done: if (!*pagep) { if (filepage) { UnlockPage(filepage); *pagep = filepage; } else *pagep = ZERO_PAGE(0); } return 0; failed: if (*pagep != filepage) { UnlockPage(filepage); page_cache_release(filepage); } return error; } struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int unused) { struct inode *inode = vma->vm_file->f_dentry->d_inode; struct page *page = NULL; unsigned long idx; int error; idx = (address - vma->vm_start) >> PAGE_SHIFT; idx += vma->vm_pgoff; idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; error = shmem_getpage(inode, idx, &page, SGP_CACHE); if (error) return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; mark_page_accessed(page); flush_page_to_ram(page); return page; } void shmem_lock(struct file *file, int lock) { struct inode *inode = file->f_dentry->d_inode; struct shmem_inode_info *info = SHMEM_I(inode); spin_lock(&info->lock); if (lock) info->flags |= VM_LOCKED; else info->flags &= ~VM_LOCKED; spin_unlock(&info->lock); } static int shmem_mmap(struct file *file, struct vm_area_struct *vma) { struct vm_operations_struct *ops; struct inode *inode = file->f_dentry->d_inode; ops = &shmem_vm_ops; if (!S_ISREG(inode->i_mode)) return -EACCES; UPDATE_ATIME(inode); vma->vm_ops = ops; return 0; } static struct inode *shmem_get_inode(struct super_block *sb, int mode, int dev) { struct inode *inode; struct shmem_inode_info *info; struct shmem_sb_info *sbinfo = SHMEM_SB(sb); spin_lock(&sbinfo->stat_lock); if (!sbinfo->free_inodes) { spin_unlock(&sbinfo->stat_lock); return NULL; } sbinfo->free_inodes--; spin_unlock(&sbinfo->stat_lock); inode = new_inode(sb); if (inode) { inode->i_mode = mode; inode->i_uid = current->fsuid; inode->i_gid = current->fsgid; inode->i_blksize = PAGE_CACHE_SIZE; inode->i_blocks = 0; inode->i_rdev = NODEV; inode->i_mapping->a_ops = &shmem_aops; inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; info = SHMEM_I(inode); info->inode = inode; spin_lock_init(&info->lock); switch (mode & S_IFMT) { default: init_special_inode(inode, mode, dev); break; case S_IFREG: inode->i_op = &shmem_inode_operations; inode->i_fop = &shmem_file_operations; spin_lock(&shmem_ilock); list_add_tail(&info->list, &shmem_inodes); spin_unlock(&shmem_ilock); break; case S_IFDIR: inode->i_nlink++; /* Some things misbehave if size == 0 on a directory */ inode->i_size = 2 * BOGO_DIRENT_SIZE; inode->i_op = &shmem_dir_inode_operations; inode->i_fop = &dcache_dir_ops; break; case S_IFLNK: break; } } return inode; } static int shmem_set_size(struct shmem_sb_info *info, unsigned long max_blocks, unsigned long max_inodes) { int error; unsigned long blocks, inodes; spin_lock(&info->stat_lock); blocks = info->max_blocks - info->free_blocks; inodes = info->max_inodes - info->free_inodes; error = -EINVAL; if (max_blocks < blocks) goto out; if (max_inodes < inodes) goto out; error = 0; info->max_blocks = max_blocks; info->free_blocks = max_blocks - blocks; info->max_inodes = max_inodes; info->free_inodes = max_inodes - inodes; out: spin_unlock(&info->stat_lock); return error; } #ifdef CONFIG_TMPFS static struct inode_operations shmem_symlink_inode_operations; static struct inode_operations shmem_symlink_inline_operations; /* * tmpfs itself makes no use of generic_file_read, generic_file_mmap * or generic_file_write; but shmem_readpage, shmem_prepare_write and * shmem_commit_write let a tmpfs file be used below the loop driver, * and shmem_readpage lets a tmpfs file be used by sendfile. */ static int shmem_readpage(struct file *file, struct page *page) { struct inode *inode = page->mapping->host; int error = shmem_getpage(inode, page->index, &page, SGP_CACHE); UnlockPage(page); return error; } static int shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) { struct inode *inode = page->mapping->host; return shmem_getpage(inode, page->index, &page, SGP_WRITE); } static int shmem_commit_write(struct file *file, struct page *page, unsigned offset, unsigned to) { struct inode *inode = page->mapping->host; loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to; if (pos > inode->i_size) inode->i_size = pos; SetPageDirty(page); return 0; } static ssize_t shmem_file_write(struct file *file, const char *buf, size_t count, loff_t *ppos) { struct inode *inode = file->f_dentry->d_inode; loff_t pos; unsigned long written; int err; if ((ssize_t) count < 0) return -EINVAL; if (!access_ok(VERIFY_READ, buf, count)) return -EFAULT; down(&inode->i_sem); pos = *ppos; written = 0; err = precheck_file_write(file, inode, &count, &pos); if (err || !count) goto out; remove_suid(inode); inode->i_ctime = inode->i_mtime = CURRENT_TIME; do { struct page *page = NULL; unsigned long bytes, index, offset; char *kaddr; int left; offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ index = pos >> PAGE_CACHE_SHIFT; bytes = PAGE_CACHE_SIZE - offset; if (bytes > count) bytes = count; /* * We don't hold page lock across copy from user - * what would it guard against? - so no deadlock here. */ err = shmem_getpage(inode, index, &page, SGP_WRITE); if (err) break; kaddr = kmap(page); left = __copy_from_user(kaddr + offset, buf, bytes); kunmap(page); written += bytes; count -= bytes; pos += bytes; buf += bytes; if (pos > inode->i_size) inode->i_size = pos; flush_dcache_page(page); SetPageDirty(page); SetPageReferenced(page); page_cache_release(page); if (left) { pos -= left; written -= left; err = -EFAULT; break; } } while (count); *ppos = pos; if (written) err = written; out: up(&inode->i_sem); return err; } static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc) { struct inode *inode = filp->f_dentry->d_inode; struct address_space *mapping = inode->i_mapping; unsigned long index, offset; index = *ppos >> PAGE_CACHE_SHIFT; offset = *ppos & ~PAGE_CACHE_MASK; for (;;) { struct page *page = NULL; unsigned long end_index, nr, ret; end_index = inode->i_size >> PAGE_CACHE_SHIFT; if (index > end_index) break; if (index == end_index) { nr = inode->i_size & ~PAGE_CACHE_MASK; if (nr <= offset) break; } desc->error = shmem_getpage(inode, index, &page, SGP_READ); if (desc->error) { if (desc->error == -EINVAL) desc->error = 0; break; } /* * We must evaluate after, since reads (unlike writes) * are called without i_sem protection against truncate */ nr = PAGE_CACHE_SIZE; end_index = inode->i_size >> PAGE_CACHE_SHIFT; if (index == end_index) { nr = inode->i_size & ~PAGE_CACHE_MASK; if (nr <= offset) { page_cache_release(page); break; } } nr -= offset; if (page != ZERO_PAGE(0)) { /* * If users can be writing to this page using arbitrary * virtual addresses, take care about potential aliasing * before reading the page on the kernel side. */ if (mapping->i_mmap_shared != NULL) flush_dcache_page(page); /* * Mark the page accessed if we read the * beginning or we just did an lseek. */ if (!offset || !filp->f_reada) mark_page_accessed(page); } /* * Ok, we have the page, and it's up-to-date, so * now we can copy it to user space... * * The actor routine returns how many bytes were actually used.. * NOTE! This may not be the same as how much of a user buffer * we filled up (we may be padding etc), so we can only update * "pos" here (the actor routine has to update the user buffer * pointers and the remaining count). */ ret = file_read_actor(desc, page, offset, nr); offset += ret; index += offset >> PAGE_CACHE_SHIFT; offset &= ~PAGE_CACHE_MASK; page_cache_release(page); if (ret != nr || !desc->count) break; } *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; filp->f_reada = 1; UPDATE_ATIME(inode); } static ssize_t shmem_file_read(struct file *filp, char *buf, size_t count, loff_t *ppos) { read_descriptor_t desc; if ((ssize_t) count < 0) return -EINVAL; if (!access_ok(VERIFY_WRITE, buf, count)) return -EFAULT; if (!count) return 0; desc.written = 0; desc.count = count; desc.buf = buf; desc.error = 0; do_shmem_file_read(filp, ppos, &desc); if (desc.written) return desc.written; return desc.error; } static int shmem_statfs(struct super_block *sb, struct statfs *buf) { struct shmem_sb_info *sbinfo = SHMEM_SB(sb); buf->f_type = TMPFS_MAGIC; buf->f_bsize = PAGE_CACHE_SIZE; spin_lock(&sbinfo->stat_lock); buf->f_blocks = sbinfo->max_blocks; buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; buf->f_files = sbinfo->max_inodes; buf->f_ffree = sbinfo->free_inodes; spin_unlock(&sbinfo->stat_lock); buf->f_namelen = NAME_MAX; return 0; } /* * Lookup the data. This is trivial - if the dentry didn't already * exist, we know it is negative. */ static struct dentry *shmem_lookup(struct inode *dir, struct dentry *dentry) { if (dentry->d_name.len > NAME_MAX) return ERR_PTR(-ENAMETOOLONG); d_add(dentry, NULL); return NULL; } /* * File creation. Allocate an inode, and we're done.. */ static int shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, int dev) { struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); int error = -ENOSPC; if (inode) { if (dir->i_mode & S_ISGID) { inode->i_gid = dir->i_gid; if (S_ISDIR(mode)) inode->i_mode |= S_ISGID; } dir->i_size += BOGO_DIRENT_SIZE; dir->i_ctime = dir->i_mtime = CURRENT_TIME; d_instantiate(dentry, inode); dget(dentry); /* Extra count - pin the dentry in core */ error = 0; } return error; } static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) { int error; if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) return error; dir->i_nlink++; return 0; } static int shmem_create(struct inode *dir, struct dentry *dentry, int mode) { return shmem_mknod(dir, dentry, mode | S_IFREG, 0); } /* * Link a file.. */ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) { struct inode *inode = old_dentry->d_inode; if (S_ISDIR(inode->i_mode)) return -EPERM; dir->i_size += BOGO_DIRENT_SIZE; inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; inode->i_nlink++; atomic_inc(&inode->i_count); /* New dentry reference */ dget(dentry); /* Extra pinning count for the created dentry */ d_instantiate(dentry, inode); return 0; } static inline int shmem_positive(struct dentry *dentry) { return dentry->d_inode && !d_unhashed(dentry); } /* * Check that a directory is empty (this works * for regular files too, they'll just always be * considered empty..). * * Note that an empty directory can still have * children, they just all have to be negative.. */ static int shmem_empty(struct dentry *dentry) { struct list_head *list; spin_lock(&dcache_lock); list = dentry->d_subdirs.next; while (list != &dentry->d_subdirs) { struct dentry *de = list_entry(list, struct dentry, d_child); if (shmem_positive(de)) { spin_unlock(&dcache_lock); return 0; } list = list->next; } spin_unlock(&dcache_lock); return 1; } static int shmem_unlink(struct inode *dir, struct dentry *dentry) { struct inode *inode = dentry->d_inode; dir->i_size -= BOGO_DIRENT_SIZE; inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; inode->i_nlink--; dput(dentry); /* Undo the count from "create" - this does all the work */ return 0; } static int shmem_rmdir(struct inode *dir, struct dentry *dentry) { if (!shmem_empty(dentry)) return -ENOTEMPTY; dir->i_nlink--; return shmem_unlink(dir, dentry); } /* * The VFS layer already does all the dentry stuff for rename, * we just have to decrement the usage count for the target if * it exists so that the VFS layer correctly free's it when it * gets overwritten. */ static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) { struct inode *inode = old_dentry->d_inode; int they_are_dirs = S_ISDIR(inode->i_mode); if (!shmem_empty(new_dentry)) return -ENOTEMPTY; if (new_dentry->d_inode) { (void) shmem_unlink(new_dir, new_dentry); if (they_are_dirs) old_dir->i_nlink--; } else if (they_are_dirs) { old_dir->i_nlink--; new_dir->i_nlink++; } old_dir->i_size -= BOGO_DIRENT_SIZE; new_dir->i_size += BOGO_DIRENT_SIZE; old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; return 0; } static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) { int error; int len; struct inode *inode; struct page *page = NULL; char *kaddr; struct shmem_inode_info *info; len = strlen(symname) + 1; if (len > PAGE_CACHE_SIZE) return -ENAMETOOLONG; inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); if (!inode) return -ENOSPC; info = SHMEM_I(inode); inode->i_size = len-1; if (len <= sizeof(struct shmem_inode_info)) { /* do it inline */ memcpy(info, symname, len); inode->i_op = &shmem_symlink_inline_operations; } else { error = shmem_getpage(inode, 0, &page, SGP_WRITE); if (error) { iput(inode); return error; } inode->i_op = &shmem_symlink_inode_operations; spin_lock(&shmem_ilock); list_add_tail(&info->list, &shmem_inodes); spin_unlock(&shmem_ilock); kaddr = kmap(page); memcpy(kaddr, symname, len); kunmap(page); SetPageDirty(page); page_cache_release(page); } if (dir->i_mode & S_ISGID) inode->i_gid = dir->i_gid; dir->i_size += BOGO_DIRENT_SIZE; dir->i_ctime = dir->i_mtime = CURRENT_TIME; d_instantiate(dentry, inode); dget(dentry); return 0; } static int shmem_readlink_inline(struct dentry *dentry, char *buffer, int buflen) { return vfs_readlink(dentry, buffer, buflen, (const char *)SHMEM_I(dentry->d_inode)); } static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) { return vfs_follow_link(nd, (const char *)SHMEM_I(dentry->d_inode)); } static int shmem_readlink(struct dentry *dentry, char *buffer, int buflen) { struct page *page = NULL; int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ); if (res) return res; res = vfs_readlink(dentry, buffer, buflen, kmap(page)); kunmap(page); mark_page_accessed(page); page_cache_release(page); return res; } static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd) { struct page *page = NULL; int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ); if (res) return res; res = vfs_follow_link(nd, kmap(page)); kunmap(page); mark_page_accessed(page); page_cache_release(page); return res; } static struct inode_operations shmem_symlink_inline_operations = { readlink: shmem_readlink_inline, follow_link: shmem_follow_link_inline, }; static struct inode_operations shmem_symlink_inode_operations = { truncate: shmem_truncate, readlink: shmem_readlink, follow_link: shmem_follow_link, }; static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes) { char *this_char, *value, *rest; while ((this_char = strsep(&options, ",")) != NULL) { if (!*this_char) continue; if ((value = strchr(this_char,'=')) != NULL) { *value++ = 0; } else { printk(KERN_ERR "tmpfs: No value for mount option '%s'\n", this_char); return 1; } if (!strcmp(this_char,"size")) { unsigned long long size; size = memparse(value,&rest); if (*rest == '%') { struct sysinfo si; si_meminfo(&si); size <<= PAGE_SHIFT; size *= si.totalram; do_div(size, 100); rest++; } if (*rest) goto bad_val; *blocks = size >> PAGE_CACHE_SHIFT; } else if (!strcmp(this_char,"nr_blocks")) { *blocks = memparse(value,&rest); if (*rest) goto bad_val; } else if (!strcmp(this_char,"nr_inodes")) { *inodes = memparse(value,&rest); if (*rest) goto bad_val; } else if (!strcmp(this_char,"mode")) { if (!mode) continue; *mode = simple_strtoul(value,&rest,8); if (*rest) goto bad_val; } else if (!strcmp(this_char,"uid")) { if (!uid) continue; *uid = simple_strtoul(value,&rest,0); if (*rest) goto bad_val; } else if (!strcmp(this_char,"gid")) { if (!gid) continue; *gid = simple_strtoul(value,&rest,0); if (*rest) goto bad_val; } else { printk(KERN_ERR "tmpfs: Bad mount option %s\n", this_char); return 1; } } return 0; bad_val: printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", value, this_char); return 1; } static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) { struct shmem_sb_info *sbinfo = SHMEM_SB(sb); unsigned long max_blocks = sbinfo->max_blocks; unsigned long max_inodes = sbinfo->max_inodes; if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, &max_inodes)) return -EINVAL; return shmem_set_size(sbinfo, max_blocks, max_inodes); } static int shmem_sync_file(struct file *file, struct dentry *dentry, int datasync) { return 0; } #endif static struct super_block *shmem_read_super(struct super_block *sb, void *data, int silent) { struct inode *inode; struct dentry *root; unsigned long blocks, inodes; int mode = S_IRWXUGO | S_ISVTX; uid_t uid = current->fsuid; gid_t gid = current->fsgid; struct shmem_sb_info *sbinfo = SHMEM_SB(sb); struct sysinfo si; /* * Per default we only allow half of the physical ram per * tmpfs instance */ si_meminfo(&si); blocks = inodes = si.totalram / 2; #ifdef CONFIG_TMPFS if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, &inodes)) return NULL; #endif spin_lock_init(&sbinfo->stat_lock); sbinfo->max_blocks = blocks; sbinfo->free_blocks = blocks; sbinfo->max_inodes = inodes; sbinfo->free_inodes = inodes; sb->s_maxbytes = SHMEM_MAX_BYTES; sb->s_blocksize = PAGE_CACHE_SIZE; sb->s_blocksize_bits = PAGE_CACHE_SHIFT; sb->s_magic = TMPFS_MAGIC; sb->s_op = &shmem_ops; inode = shmem_get_inode(sb, S_IFDIR | mode, 0); if (!inode) return NULL; inode->i_uid = uid; inode->i_gid = gid; root = d_alloc_root(inode); if (!root) { iput(inode); return NULL; } sb->s_root = root; return sb; } static struct address_space_operations shmem_aops = { removepage: shmem_removepage, writepage: shmem_writepage, #ifdef CONFIG_TMPFS readpage: shmem_readpage, prepare_write: shmem_prepare_write, commit_write: shmem_commit_write, #endif }; static struct file_operations shmem_file_operations = { mmap: shmem_mmap, #ifdef CONFIG_TMPFS read: shmem_file_read, write: shmem_file_write, fsync: shmem_sync_file, #endif }; static struct inode_operations shmem_inode_operations = { truncate: shmem_truncate, setattr: shmem_notify_change, }; static struct inode_operations shmem_dir_inode_operations = { #ifdef CONFIG_TMPFS create: shmem_create, lookup: shmem_lookup, link: shmem_link, unlink: shmem_unlink, symlink: shmem_symlink, mkdir: shmem_mkdir, rmdir: shmem_rmdir, mknod: shmem_mknod, rename: shmem_rename, #endif }; static struct super_operations shmem_ops = { #ifdef CONFIG_TMPFS statfs: shmem_statfs, remount_fs: shmem_remount_fs, #endif delete_inode: shmem_delete_inode, put_inode: force_delete, }; static struct vm_operations_struct shmem_vm_ops = { nopage: shmem_nopage, }; #ifdef CONFIG_TMPFS /* type "shm" will be tagged obsolete in 2.5 */ static DECLARE_FSTYPE(shmem_fs_type, "shm", shmem_read_super, FS_LITTER); static DECLARE_FSTYPE(tmpfs_fs_type, "tmpfs", shmem_read_super, FS_LITTER); #else static DECLARE_FSTYPE(tmpfs_fs_type, "tmpfs", shmem_read_super, FS_LITTER|FS_NOMOUNT); #endif static struct vfsmount *shm_mnt; static int __init init_tmpfs(void) { int error; error = register_filesystem(&tmpfs_fs_type); if (error) { printk(KERN_ERR "Could not register tmpfs\n"); goto out3; } #ifdef CONFIG_TMPFS error = register_filesystem(&shmem_fs_type); if (error) { printk(KERN_ERR "Could not register shm fs\n"); goto out2; } devfs_mk_dir(NULL, "shm", NULL); #endif shm_mnt = kern_mount(&tmpfs_fs_type); if (IS_ERR(shm_mnt)) { error = PTR_ERR(shm_mnt); printk(KERN_ERR "Could not kern_mount tmpfs\n"); goto out1; } /* The internal instance should not do size checking */ shmem_set_size(SHMEM_SB(shm_mnt->mnt_sb), ULONG_MAX, ULONG_MAX); return 0; out1: #ifdef CONFIG_TMPFS unregister_filesystem(&shmem_fs_type); out2: #endif unregister_filesystem(&tmpfs_fs_type); out3: shm_mnt = ERR_PTR(error); return error; } module_init(init_tmpfs) /* * shmem_file_setup - get an unlinked file living in tmpfs * * @name: name for dentry (to be seen in /proc/<pid>/maps * @size: size to be set for the file * */ struct file *shmem_file_setup(char *name, loff_t size) { int error; struct file *file; struct inode *inode; struct dentry *dentry, *root; struct qstr this; int vm_enough_memory(long pages); if (IS_ERR(shm_mnt)) return (void *)shm_mnt; if (size > SHMEM_MAX_BYTES) return ERR_PTR(-EINVAL); if (!vm_enough_memory(VM_ACCT(size))) return ERR_PTR(-ENOMEM); this.name = name; this.len = strlen(name); this.hash = 0; /* will go */ root = shm_mnt->mnt_root; dentry = d_alloc(root, &this); if (!dentry) return ERR_PTR(-ENOMEM); error = -ENFILE; file = get_empty_filp(); if (!file) goto put_dentry; error = -ENOSPC; inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); if (!inode) goto close_file; d_instantiate(dentry, inode); inode->i_size = size; inode->i_nlink = 0; /* It is unlinked */ file->f_vfsmnt = mntget(shm_mnt); file->f_dentry = dentry; file->f_op = &shmem_file_operations; file->f_mode = FMODE_WRITE | FMODE_READ; return file; close_file: put_filp(file); put_dentry: dput(dentry); return ERR_PTR(error); } /* * shmem_zero_setup - setup a shared anonymous mapping * * @vma: the vma to be mmapped is prepared by do_mmap_pgoff */ int shmem_zero_setup(struct vm_area_struct *vma) { struct file *file; loff_t size = vma->vm_end - vma->vm_start; file = shmem_file_setup("dev/zero", size); if (IS_ERR(file)) return PTR_ERR(file); if (vma->vm_file) fput(vma->vm_file); vma->vm_file = file; vma->vm_ops = &shmem_vm_ops; return 0; } EXPORT_SYMBOL(shmem_file_setup);
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