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/*

 * High-level sync()-related operations

 */

#include <linux/kernel.h>

#include <linux/file.h>

#include <linux/fs.h>

#include <linux/module.h>

#include <linux/sched.h>

#include <linux/writeback.h>

#include <linux/syscalls.h>

#include <linux/linkage.h>

#include <linux/pagemap.h>

#include <linux/quotaops.h>

#include <linux/buffer_head.h>

#define VALID_FLAGS (SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE| \

                        SYNC_FILE_RANGE_WAIT_AFTER)

/*

 * sync everything.  Start out by waking pdflush, because that writes back

 * all queues in parallel.

 */

static void do_sync(unsigned long wait)

{

        wakeup_pdflush(0);

        sync_inodes(0);          /* All mappings, inodes and their blockdevs */

        DQUOT_SYNC(NULL);

        sync_supers();          /* Write the superblocks */

        sync_filesystems(0);     /* Start syncing the filesystems */

        sync_filesystems(wait); /* Waitingly sync the filesystems */

        sync_inodes(wait);      /* Mappings, inodes and blockdevs, again. */

        if (!wait)

                printk("Emergency Sync complete\n");

        if (unlikely(laptop_mode))

                laptop_sync_completion();

}

asmlinkage long sys_sync(void)

{

        do_sync(1);

        return 0;

}

void emergency_sync(void)

{

        pdflush_operation(do_sync, 0);

}

/*

 * Generic function to fsync a file.

 *

 * filp may be NULL if called via the msync of a vma.

 */

int file_fsync(struct file *filp, struct dentry *dentry, int datasync)

{

        struct inode * inode = dentry->d_inode;

        struct super_block * sb;

        int ret, err;

        /* sync the inode to buffers */

        ret = write_inode_now(inode, 0);

        /* sync the superblock to buffers */

        sb = inode->i_sb;

        lock_super(sb);

        if (sb->s_op->write_super)

                sb->s_op->write_super(sb);

        unlock_super(sb);

        /* .. finally sync the buffers to disk */

        err = sync_blockdev(sb->s_bdev);

        if (!ret)

                ret = err;

        return ret;

}

long do_fsync(struct file *file, int datasync)

{

        int ret;

        int err;

        struct address_space *mapping = file->f_mapping;

        if (!file->f_op || !file->f_op->fsync) {

                /* Why?  We can still call filemap_fdatawrite */

                ret = -EINVAL;

                goto out;

        }

        ret = filemap_fdatawrite(mapping);

        /*

         * We need to protect against concurrent writers, which could cause

         * livelocks in fsync_buffers_list().

         */

        mutex_lock(&mapping->host->i_mutex);

        err = file->f_op->fsync(file, file->f_path.dentry, datasync);

        if (!ret)

                ret = err;

        mutex_unlock(&mapping->host->i_mutex);

        err = filemap_fdatawait(mapping);

        if (!ret)

                ret = err;

out:

        return ret;

}

static long __do_fsync(unsigned int fd, int datasync)

{

        struct file *file;

        int ret = -EBADF;

        file = fget(fd);

        if (file) {

                ret = do_fsync(file, datasync);

                fput(file);

        }

        return ret;

}

asmlinkage long sys_fsync(unsigned int fd)

{

        return __do_fsync(fd, 0);

}

asmlinkage long sys_fdatasync(unsigned int fd)

{

        return __do_fsync(fd, 1);

}

/*

 * sys_sync_file_range() permits finely controlled syncing over a segment of

 * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is

 * zero then sys_sync_file_range() will operate from offset out to EOF.

 *

 * The flag bits are:

 *

 * SYNC_FILE_RANGE_WAIT_BEFORE: wait upon writeout of all pages in the range

 * before performing the write.

 *

 * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the

 * range which are not presently under writeback.

 *

 * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range

 * after performing the write.

 *

 * Useful combinations of the flag bits are:

 *

 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE: ensures that all pages

 * in the range which were dirty on entry to sys_sync_file_range() are placed

 * under writeout.  This is a start-write-for-data-integrity operation.

 *

 * SYNC_FILE_RANGE_WRITE: start writeout of all dirty pages in the range which

 * are not presently under writeout.  This is an asynchronous flush-to-disk

 * operation.  Not suitable for data integrity operations.

 *

 * SYNC_FILE_RANGE_WAIT_BEFORE (or SYNC_FILE_RANGE_WAIT_AFTER): wait for

 * completion of writeout of all pages in the range.  This will be used after an

 * earlier SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE operation to wait

 * for that operation to complete and to return the result.

 *

 * SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WRITE|SYNC_FILE_RANGE_WAIT_AFTER:

 * a traditional sync() operation.  This is a write-for-data-integrity operation

 * which will ensure that all pages in the range which were dirty on entry to

 * sys_sync_file_range() are committed to disk.

 *

 *

 * SYNC_FILE_RANGE_WAIT_BEFORE and SYNC_FILE_RANGE_WAIT_AFTER will detect any

 * I/O errors or ENOSPC conditions and will return those to the caller, after

 * clearing the EIO and ENOSPC flags in the address_space.

 *

 * It should be noted that none of these operations write out the file's

 * metadata.  So unless the application is strictly performing overwrites of

 * already-instantiated disk blocks, there are no guarantees here that the data

 * will be available after a crash.

 */

asmlinkage long sys_sync_file_range(int fd, loff_t offset, loff_t nbytes,

                                        unsigned int flags)

{

        int ret;

        struct file *file;

        loff_t endbyte;                 /* inclusive */

        int fput_needed;

        umode_t i_mode;

        ret = -EINVAL;

        if (flags & ~VALID_FLAGS)

                goto out;

        endbyte = offset + nbytes;

        if ((s64)offset < 0)

                goto out;

        if ((s64)endbyte < 0)

                goto out;

        if (endbyte < offset)

                goto out;

        if (sizeof(pgoff_t) == 4) {

                if (offset >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {

                        /*

                         * The range starts outside a 32 bit machine's

                         * pagecache addressing capabilities.  Let it "succeed"

                         */

                        ret = 0;

                        goto out;

                }

                if (endbyte >= (0x100000000ULL << PAGE_CACHE_SHIFT)) {

                        /*

                         * Out to EOF

                         */

                        nbytes = 0;

                }

        }

        if (nbytes == 0)

                endbyte = LLONG_MAX;

        else

                endbyte--;              /* inclusive */

        ret = -EBADF;

        file = fget_light(fd, &fput_needed);

        if (!file)

                goto out;

        i_mode = file->f_path.dentry->d_inode->i_mode;

        ret = -ESPIPE;

        if (!S_ISREG(i_mode) && !S_ISBLK(i_mode) && !S_ISDIR(i_mode) &&

                        !S_ISLNK(i_mode))

                goto out_put;

        ret = do_sync_mapping_range(file->f_mapping, offset, endbyte, flags);

out_put:

        fput_light(file, fput_needed);

out:

        return ret;

}

/* It would be nice if people remember that not all the world's an i386

   when they introduce new system calls */

asmlinkage long sys_sync_file_range2(int fd, unsigned int flags,

                                     loff_t offset, loff_t nbytes)

{

        return sys_sync_file_range(fd, offset, nbytes, flags);

}

/*

 * `endbyte' is inclusive

 */

int do_sync_mapping_range(struct address_space *mapping, loff_t offset,

                          loff_t endbyte, unsigned int flags)

{

        int ret;

        if (!mapping) {

                ret = -EINVAL;

                goto out;

        }

        ret = 0;

        if (flags & SYNC_FILE_RANGE_WAIT_BEFORE) {

                ret = wait_on_page_writeback_range(mapping,

                                        offset >> PAGE_CACHE_SHIFT,

                                        endbyte >> PAGE_CACHE_SHIFT);

                if (ret < 0)

                        goto out;

        }

        if (flags & SYNC_FILE_RANGE_WRITE) {

                ret = __filemap_fdatawrite_range(mapping, offset, endbyte,

                                                WB_SYNC_NONE);

                if (ret < 0)

                        goto out;

        }

        if (flags & SYNC_FILE_RANGE_WAIT_AFTER) {

                ret = wait_on_page_writeback_range(mapping,

                                        offset >> PAGE_CACHE_SHIFT,

                                        endbyte >> PAGE_CACHE_SHIFT);

        }

out:

        return ret;

}

EXPORT_SYMBOL_GPL(do_sync_mapping_range);