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vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode

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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 <zbr@ioremap.net>
CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
CC: Felix Blyakher <felixb@sgi.com>
CC: xfs@oss.sgi.com
CC: Anton Altaparmakov <aia21@cantab.net>
CC: linux-ntfs-dev@lists.sourceforge.net
CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
CC: linux-ext4@vger.kernel.org
CC: tytso@mit.edu
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara
2009-08-17 19:52:36 +02:00
parent eef9938067
commit 148f948ba8
4 changed files with 61 additions and 30 deletions
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55
fs/sync.c
View File

@@ -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