fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers

Btrfs needs to be able to control how filemap_write_and_wait_range() is called
in fsync to make it less of a painful operation, so push down taking i_mutex and
the calling of filemap_write_and_wait() down into the ->fsync() handlers.  Some
file systems can drop taking the i_mutex altogether it seems, like ext3 and
ocfs2.  For correctness sake I just pushed everything down in all cases to make
sure that we keep the current behavior the same for everybody, and then each
individual fs maintainer can make up their mind about what to do from there.
Thanks,

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 14 insertions, 3 deletions

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 89c39e5..f82cb5e 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -544,7 +544,9 @@ static int gfs2_close(struct inode *inode, struct file *file)
 
 /**
  * gfs2_fsync - sync the dirty data for a file (across the cluster)
- * @file: the file that points to the dentry (we ignore this)
+ * @file: the file that points to the dentry
+ * @start: the start position in the file to sync
+ * @end: the end position in the file to sync
  * @datasync: set if we can ignore timestamp changes
  *
  * The VFS will flush data for us. We only need to worry
@@ -553,23 +555,32 @@ static int gfs2_close(struct inode *inode, struct file *file)
  * Returns: errno
  */
 
-static int gfs2_fsync(struct file *file, int datasync)
+static int gfs2_fsync(struct file *file, loff_t start, loff_t end,
+		      int datasync)
 {
 	struct inode *inode = file->f_mapping->host;
 	int sync_state = inode->i_state & (I_DIRTY_SYNC|I_DIRTY_DATASYNC);
 	struct gfs2_inode *ip = GFS2_I(inode);
 	int ret;
 
+	ret = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (ret)
+		return ret;
+	mutex_lock(&inode->i_mutex);
+
 	if (datasync)
 		sync_state &= ~I_DIRTY_SYNC;
 
 	if (sync_state) {
 		ret = sync_inode_metadata(inode, 1);
-		if (ret)
+		if (ret) {
+			mutex_unlock(&inode->i_mutex);
 			return ret;
+		}
 		gfs2_ail_flush(ip->i_gl);
 	}
 
+	mutex_unlock(&inode->i_mutex);
 	return 0;
 }