[PATCH] resierfs: fix reiserfs_invalidatepage race against data=ordered

After a transaction has closed but before it has finished commit, there is
a window where data=ordered mode requires invalidatepage to pin pages
instead of freeing them.  This patch fixes a race between the
invalidatepage checks and data=ordered writeback, and it also adds a check
to the reiserfs write_ordered_buffers routines to write any anonymous
buffers that were dirtied after its first writeback loop.

That bug works like this:

proc1: transaction closes and a new one starts
proc1: write_ordered_buffers starts processing data=ordered list
proc1: buffer A is cleaned and written
proc2: buffer A is dirtied by another process
proc2: File is truncated to zero, page A goes through invalidatepage
proc2: reiserfs_invalidatepage sees dirty buffer A with reiserfs
       journal head, pins it
proc1: write_ordered_buffers frees the journal head on buffer A

At this point, buffer A stays dirty forever

Signed-off-by: Chris Mason <mason@suse.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/reiserfs/inode.c b/fs/reiserfs/inode.c
index ffa34b861bdb..60e2f2344703 100644
--- a/fs/reiserfs/inode.c
+++ b/fs/reiserfs/inode.c
@@ -2743,6 +2743,7 @@ static int invalidatepage_can_drop(struct inode *inode, struct buffer_head *bh)
         int ret = 1;
         struct reiserfs_journal *j = SB_JOURNAL(inode->i_sb);
 
+        lock_buffer(bh);
         spin_lock(&j->j_dirty_buffers_lock);
         if (!buffer_mapped(bh)) {
                 goto free_jh;
@@ -2758,7 +2759,7 @@ static int invalidatepage_can_drop(struct inode *inode, struct buffer_head *bh)
                 if (buffer_journaled(bh) || buffer_journal_dirty(bh)) {
                         ret = 0;
                 }
-        } else if (buffer_dirty(bh) || buffer_locked(bh)) {
+        } else  if (buffer_dirty(bh)) {
                 struct reiserfs_journal_list *jl;
                 struct reiserfs_jh *jh = bh->b_private;
 
@@ -2784,6 +2785,7 @@ static int invalidatepage_can_drop(struct inode *inode, struct buffer_head *bh)
                 reiserfs_free_jh(bh);
         }
         spin_unlock(&j->j_dirty_buffers_lock);
+        unlock_buffer(bh);
         return ret;
 }