From 148f948ba877f4d3cdef036b1ff6d9f68986706a Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 17 Aug 2009 19:52:36 +0200 Subject: vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode Introduce new function for generic inode syncing (vfs_fsync_range) and use it from fsync() path. Introduce also new helper for syncing after a sync write (generic_write_sync) using the generic function. Use these new helpers for syncing from generic VFS functions. This makes O_SYNC writes to block devices acquire i_mutex for syncing. If we really care about this, we can make block_fsync() drop the i_mutex and reacquire it before it returns. CC: Evgeniy Polyakov CC: ocfs2-devel@oss.oracle.com CC: Joel Becker CC: Felix Blyakher CC: xfs@oss.sgi.com CC: Anton Altaparmakov CC: linux-ntfs-dev@lists.sourceforge.net CC: OGAWA Hirofumi CC: linux-ext4@vger.kernel.org CC: tytso@mit.edu Acked-by: Christoph Hellwig Signed-off-by: Jan Kara --- fs/sync.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 48 insertions(+), 7 deletions(-) (limited to 'fs/sync.c') diff --git a/fs/sync.c b/fs/sync.c index 103cc7fdd3df..4e15da01923c 100644 --- a/fs/sync.c +++ b/fs/sync.c @@ -178,19 +178,23 @@ int file_fsync(struct file *filp, struct dentry *dentry, int datasync) } /** - * vfs_fsync - perform a fsync or fdatasync on a file + * vfs_fsync_range - helper to sync a range of data & metadata to disk * @file: file to sync * @dentry: dentry of @file - * @data: only perform a fdatasync operation + * @start: offset in bytes of the beginning of data range to sync + * @end: offset in bytes of the end of data range (inclusive) + * @datasync: perform only datasync * - * Write back data and metadata for @file to disk. If @datasync is - * set only metadata needed to access modified file data is written. + * Write back data in range @start..@end and metadata for @file to disk. If + * @datasync is set only metadata needed to access modified file data is + * written. * * In case this function is called from nfsd @file may be %NULL and * only @dentry is set. This can only happen when the filesystem * implements the export_operations API. */ -int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) +int vfs_fsync_range(struct file *file, struct dentry *dentry, loff_t start, + loff_t end, int datasync) { const struct file_operations *fop; struct address_space *mapping; @@ -214,7 +218,7 @@ int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) goto out; } - ret = filemap_fdatawrite(mapping); + ret = filemap_fdatawrite_range(mapping, start, end); /* * We need to protect against concurrent writers, which could cause @@ -225,12 +229,32 @@ int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) if (!ret) ret = err; mutex_unlock(&mapping->host->i_mutex); - err = filemap_fdatawait(mapping); + + err = filemap_fdatawait_range(mapping, start, end); if (!ret) ret = err; out: return ret; } +EXPORT_SYMBOL(vfs_fsync_range); + +/** + * vfs_fsync - perform a fsync or fdatasync on a file + * @file: file to sync + * @dentry: dentry of @file + * @datasync: only perform a fdatasync operation + * + * Write back data and metadata for @file to disk. If @datasync is + * set only metadata needed to access modified file data is written. + * + * In case this function is called from nfsd @file may be %NULL and + * only @dentry is set. This can only happen when the filesystem + * implements the export_operations API. + */ +int vfs_fsync(struct file *file, struct dentry *dentry, int datasync) +{ + return vfs_fsync_range(file, dentry, 0, LLONG_MAX, datasync); +} EXPORT_SYMBOL(vfs_fsync); static int do_fsync(unsigned int fd, int datasync) @@ -256,6 +280,23 @@ SYSCALL_DEFINE1(fdatasync, unsigned int, fd) return do_fsync(fd, 1); } +/** + * generic_write_sync - perform syncing after a write if file / inode is sync + * @file: file to which the write happened + * @pos: offset where the write started + * @count: length of the write + * + * This is just a simple wrapper about our general syncing function. + */ +int generic_write_sync(struct file *file, loff_t pos, loff_t count) +{ + if (!(file->f_flags & O_SYNC) && !IS_SYNC(file->f_mapping->host)) + return 0; + return vfs_fsync_range(file, file->f_path.dentry, pos, + pos + count - 1, 1); +} +EXPORT_SYMBOL(generic_write_sync); + /* * 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 -- cgit v1.2.3