Merge branch '2.6.36-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/xfsdev

* '2.6.36-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/xfsdev:
  xfs: do not discard page cache data on EAGAIN
  xfs: don't do memory allocation under the CIL context lock
  xfs: Reduce log force overhead for delayed logging
  xfs: dummy transactions should not dirty VFS state
  xfs: ensure f_ffree returned by statfs() is non-negative
  xfs: handle negative wbc->nr_to_write during sync writeback
  writeback: write_cache_pages doesn't terminate at nr_to_write <= 0
  xfs: fix untrusted inode number lookup
  xfs: ensure we mark all inodes in a freed cluster XFS_ISTALE
  xfs: unlock items before allowing the CIL to commit

1 files changed, 18 insertions, 13 deletions

diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
index dbca5f5c37ba..43b1d5699335 100644
--- a/fs/xfs/xfs_fsops.c
+++ b/fs/xfs/xfs_fsops.c
@@ -604,31 +604,36 @@ out:
         return 0;
 }
 
+/*
+ * Dump a transaction into the log that contains no real change. This is needed
+ * to be able to make the log dirty or stamp the current tail LSN into the log
+ * during the covering operation.
+ *
+ * We cannot use an inode here for this - that will push dirty state back up
+ * into the VFS and then periodic inode flushing will prevent log covering from
+ * making progress. Hence we log a field in the superblock instead.
+ */
 int
 xfs_fs_log_dummy(
-        xfs_mount_t     *mp)
+        xfs_mount_t     *mp,
+        int             flags)
 {
         xfs_trans_t     *tp;
-        xfs_inode_t     *ip;
         int             error;
 
         tp = _xfs_trans_alloc(mp, XFS_TRANS_DUMMY1, KM_SLEEP);
-        error = xfs_trans_reserve(tp, 0, XFS_ICHANGE_LOG_RES(mp), 0, 0, 0);
+        error = xfs_trans_reserve(tp, 0, mp->m_sb.sb_sectsize + 128, 0, 0,
+                                        XFS_DEFAULT_LOG_COUNT);
         if (error) {
                 xfs_trans_cancel(tp, 0);
                 return error;
         }
 
-        ip = mp->m_rootip;
-        xfs_ilock(ip, XFS_ILOCK_EXCL);
-
-        xfs_trans_ijoin(tp, ip);
-        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
-        xfs_trans_set_sync(tp);
-        error = xfs_trans_commit(tp, 0);
-
-        xfs_iunlock(ip, XFS_ILOCK_EXCL);
-        return error;
+        /* log the UUID because it is an unchanging field */
+        xfs_mod_sb(tp, XFS_SB_UUID);
+        if (flags & SYNC_WAIT)
+                xfs_trans_set_sync(tp);
+        return xfs_trans_commit(tp, 0);
 }
 
 int