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, 16 insertions, 2 deletions

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index bb71471a4d9d..cef584451113 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -1401,7 +1401,8 @@ static int cifs_write_end(struct file *file, struct address_space *mapping,
 	return rc;
 }
 
-int cifs_strict_fsync(struct file *file, int datasync)
+int cifs_strict_fsync(struct file *file, loff_t start, loff_t end,
+		      int datasync)
 {
 	int xid;
 	int rc = 0;
@@ -1410,6 +1411,11 @@ int cifs_strict_fsync(struct file *file, int datasync)
 	struct inode *inode = file->f_path.dentry->d_inode;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
 
+	rc = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (rc)
+		return rc;
+	mutex_lock(&inode->i_mutex);
+
 	xid = GetXid();
 
 	cFYI(1, "Sync file - name: %s datasync: 0x%x",
@@ -1428,16 +1434,23 @@ int cifs_strict_fsync(struct file *file, int datasync)
 		rc = CIFSSMBFlush(xid, tcon, smbfile->netfid);
 
 	FreeXid(xid);
+	mutex_unlock(&inode->i_mutex);
 	return rc;
 }
 
-int cifs_fsync(struct file *file, int datasync)
+int cifs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 {
 	int xid;
 	int rc = 0;
 	struct cifs_tcon *tcon;
 	struct cifsFileInfo *smbfile = file->private_data;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(file->f_path.dentry->d_sb);
+	struct inode *inode = file->f_mapping->host;
+
+	rc = filemap_write_and_wait_range(inode->i_mapping, start, end);
+	if (rc)
+		return rc;
+	mutex_lock(&inode->i_mutex);
 
 	xid = GetXid();
 
@@ -1449,6 +1462,7 @@ int cifs_fsync(struct file *file, int datasync)
 		rc = CIFSSMBFlush(xid, tcon, smbfile->netfid);
 
 	FreeXid(xid);
+	mutex_unlock(&inode->i_mutex);
 	return rc;
 }