xfs: cleanup ->sync_fs

Sort out ->sync_fs to not perform a superblock writeback for the wait = 0 case
as that is just an optional first pass and the superblock will be written back
properly in the next call with wait = 1.  Instead perform an opportunistic
quota writeback to have less work later.  Also remove the freeze special case
as we do a proper wait = 1 call in the freeze code anyway.

Also rename the function to xfs_fs_sync_fs to match the normal naming
convention, update comments and avoid calling into the laptop_mode logic on
an error.

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

diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c
index 1ea65b6..eefea0d 100644 (file)
--- a/fs/xfs/linux-2.6/xfs_super.c
+++ b/fs/xfs/linux-2.6/xfs_super.c
@@ -1148,7 +1148,7 @@ xfs_fs_put_super(
 }
 
 STATIC int
-xfs_fs_sync_super(
+xfs_fs_sync_fs(
        struct super_block      *sb,
        int                     wait)
 {
@@ -1156,23 +1156,23 @@ xfs_fs_sync_super(
        int                     error;
 
        /*
-        * Treat a sync operation like a freeze.  This is to work
-        * around a race in sync_inodes() which works in two phases
-        * - an asynchronous flush, which can write out an inode
-        * without waiting for file size updates to complete, and a
-        * synchronous flush, which wont do anything because the
-        * async flush removed the inode's dirty flag.  Also
-        * sync_inodes() will not see any files that just have
-        * outstanding transactions to be flushed because we don't
-        * dirty the Linux inode until after the transaction I/O
-        * completes.
+        * Not much we can do for the first async pass.  Writing out the
+        * superblock would be counter-productive as we are going to redirty
+        * when writing out other data and metadata (and writing out a single
+        * block is quite fast anyway).
+        *
+        * Try to asynchronously kick off quota syncing at least.
         */
-       if (wait || unlikely(sb->s_frozen == SB_FREEZE_WRITE))
-               error = xfs_quiesce_data(mp);
-       else
-               error = xfs_sync_fsdata(mp, 0);
+       if (!wait) {
+               xfs_qm_sync(mp, SYNC_TRYLOCK);
+               return 0;
+       }
+
+       error = xfs_quiesce_data(mp);
+       if (error)
+               return -error;
 
-       if (unlikely(laptop_mode)) {
+       if (laptop_mode) {
                int     prev_sync_seq = mp->m_sync_seq;
 
                /*
@@ -1191,7 +1191,7 @@ xfs_fs_sync_super(
                                mp->m_sync_seq != prev_sync_seq);
        }
 
-       return -error;
+       return 0;
 }
 
 STATIC int
@@ -1565,7 +1565,7 @@ static struct super_operations xfs_super_operations = {
        .write_inode            = xfs_fs_write_inode,
        .clear_inode            = xfs_fs_clear_inode,
        .put_super              = xfs_fs_put_super,
-       .sync_fs                = xfs_fs_sync_super,
+       .sync_fs                = xfs_fs_sync_fs,
        .freeze_fs              = xfs_fs_freeze,
        .statfs                 = xfs_fs_statfs,
        .remount_fs             = xfs_fs_remount,