releases/2.6.32.12/xfs-fix-locking-for-inode-cache-radix-tree-tag-updates.patch

   1 From david@fromorbit.com  Fri Apr  2 11:12:53 2010
   2 From: Christoph Hellwig <hch@infradead.org>
   3 Date: Fri, 12 Mar 2010 09:42:17 +1100
   4 Subject: xfs: fix locking for inode cache radix tree tag updates
   5 To: stable@kernel.org
   6 Cc: xfs@oss.sgi.com
   7 Message-ID: <1268347337-7160-20-git-send-email-david@fromorbit.com>
   8
   9
  10 From: Christoph Hellwig <hch@infradead.org>
  11
  12 commit f1f724e4b523d444c5a598d74505aefa3d6844d2 upstream
  13
  14 The radix-tree code requires it's users to serialize tag updates
  15 against other updates to the tree.  While XFS protects tag updates
  16 against each other it does not serialize them against updates of the
  17 tree contents, which can lead to tag corruption.  Fix the inode
  18 cache to always take pag_ici_lock in exclusive mode when updating
  19 radix tree tags.
  20
  21 Signed-off-by: Christoph Hellwig <hch@lst.de>
  22 Reported-by: Patrick Schreurs <patrick@news-service.com>
  23 Tested-by: Patrick Schreurs <patrick@news-service.com>
  24 Signed-off-by: Alex Elder <aelder@sgi.com>
  25 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  26 ---
  27  fs/xfs/linux-2.6/xfs_sync.c |    4 ++--
  28  fs/xfs/xfs_iget.c           |   19 +++++++++++++------
  29  2 files changed, 15 insertions(+), 8 deletions(-)
  30
  31 --- a/fs/xfs/linux-2.6/xfs_sync.c
  32 +++ b/fs/xfs/linux-2.6/xfs_sync.c
  33 @@ -692,12 +692,12 @@ xfs_inode_set_reclaim_tag(
  34         xfs_mount_t     *mp = ip->i_mount;
  35         xfs_perag_t     *pag = xfs_get_perag(mp, ip->i_ino);
  36
  37 -       read_lock(&pag->pag_ici_lock);
  38 +       write_lock(&pag->pag_ici_lock);
  39         spin_lock(&ip->i_flags_lock);
  40         __xfs_inode_set_reclaim_tag(pag, ip);
  41         __xfs_iflags_set(ip, XFS_IRECLAIMABLE);
  42         spin_unlock(&ip->i_flags_lock);
  43 -       read_unlock(&pag->pag_ici_lock);
  44 +       write_unlock(&pag->pag_ici_lock);
  45         xfs_put_perag(mp, pag);
  46  }
  47
  48 --- a/fs/xfs/xfs_iget.c
  49 +++ b/fs/xfs/xfs_iget.c
  50 @@ -228,13 +228,12 @@ xfs_iget_cache_hit(
  51                 xfs_itrace_exit_tag(ip, "xfs_iget.alloc");
  52
  53                 /*
  54 -                * We need to set XFS_INEW atomically with clearing the
  55 -                * reclaimable tag so that we do have an indicator of the
  56 -                * inode still being initialized.
  57 +                * We need to set XFS_IRECLAIM to prevent xfs_reclaim_inode
  58 +                * from stomping over us while we recycle the inode.  We can't
  59 +                * clear the radix tree reclaimable tag yet as it requires
  60 +                * pag_ici_lock to be held exclusive.
  61                  */
  62 -               ip->i_flags |= XFS_INEW;
  63 -               ip->i_flags &= ~XFS_IRECLAIMABLE;
  64 -               __xfs_inode_clear_reclaim_tag(mp, pag, ip);
  65 +               ip->i_flags |= XFS_IRECLAIM;
  66
  67                 spin_unlock(&ip->i_flags_lock);
  68                 read_unlock(&pag->pag_ici_lock);
  69 @@ -253,7 +252,15 @@ xfs_iget_cache_hit(
  70                         __xfs_inode_set_reclaim_tag(pag, ip);
  71                         goto out_error;
  72                 }
  73 +
  74 +               write_lock(&pag->pag_ici_lock);
  75 +               spin_lock(&ip->i_flags_lock);
  76 +               ip->i_flags &= ~(XFS_IRECLAIMABLE | XFS_IRECLAIM);
  77 +               ip->i_flags |= XFS_INEW;
  78 +               __xfs_inode_clear_reclaim_tag(mp, pag, ip);
  79                 inode->i_state = I_LOCK|I_NEW;
  80 +               spin_unlock(&ip->i_flags_lock);
  81 +               write_unlock(&pag->pag_ici_lock);
  82         } else {
  83                 /* If the VFS inode is being torn down, pause and try again. */
  84                 if (!igrab(inode)) {