xfs: preallocation transactions do not need to be synchronous

Preallocation and hole punch transactions are currently synchronous
and this is causing performance problems in some cases. The
transactions don't need to be synchronous as we don't need to
guarantee the preallocation is persistent on disk until a
fdatasync, fsync, sync operation occurs. If the file is opened
O_SYNC or O_DATASYNC, only then should the transaction be issued
synchronously.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/xfs/linux-2.6/xfs_file.c b/fs/xfs/linux-2.6/xfs_file.c
index a55c1b46b219..52aadfbed132 100644
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -896,6 +896,7 @@ xfs_file_fallocate(
         xfs_flock64_t   bf;
         xfs_inode_t     *ip = XFS_I(inode);
         int             cmd = XFS_IOC_RESVSP;
+        int             attr_flags = XFS_ATTR_NOLOCK;
 
         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
                 return -EOPNOTSUPP;
@@ -918,7 +919,10 @@ xfs_file_fallocate(
                         goto out_unlock;
         }
 
-        error = -xfs_change_file_space(ip, cmd, &bf, 0, XFS_ATTR_NOLOCK);
+        if (file->f_flags & O_DSYNC)
+                attr_flags |= XFS_ATTR_SYNC;
+
+        error = -xfs_change_file_space(ip, cmd, &bf, 0, attr_flags);
         if (error)
                 goto out_unlock;