xfs: fix deadlock in xfs_rtfree_extent

To fix the deadlock caused by repeatedly calling xfs_rtfree_extent

 - removed xfs_ilock() and xfs_trans_ijoin() from xfs_rtfree_extent(),
   instead added asserts that the inode is locked and has an inode_item
   attached to it.
 - in xfs_bunmapi() when dealing with an inode with the rt flag
   call xfs_ilock() and xfs_trans_ijoin() so that the
   reference count is bumped on the inode and attached it to the
   transaction before calling into xfs_bmap_del_extent, similar to
   what we do in xfs_bmap_rtalloc.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Ben Myers <bpm@sgi.com>

2 files changed, 13 insertions, 5 deletions

diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 3548c6f7559..85e7e327bcd 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -5124,6 +5124,15 @@ xfs_bunmapi(
                 cur->bc_private.b.flags = 0;
         } else
                 cur = NULL;
+
+        if (isrt) {
+                /*
+                 * Synchronize by locking the bitmap inode.
+                 */
+                xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL);
+                xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);
+        }
+
         extno = 0;
         while (bno != (xfs_fileoff_t)-1 && bno >= start && lastx >= 0 &&
                (nexts == 0 || extno < nexts)) {
diff --git a/fs/xfs/xfs_rtalloc.c b/fs/xfs/xfs_rtalloc.c
index 87323f1ded6..ca4f31534a0 100644
--- a/fs/xfs/xfs_rtalloc.c
+++ b/fs/xfs/xfs_rtalloc.c
@@ -183,6 +183,7 @@ error_cancel:
                 oblocks = map.br_startoff + map.br_blockcount;
         }
         return 0;
+
 error:
         return error;
 }
@@ -2139,11 +2140,9 @@ xfs_rtfree_extent(
         xfs_buf_t       *sumbp;         /* summary file block buffer */
 
         mp = tp->t_mountp;
-        /*
-         * Synchronize by locking the bitmap inode.
-         */
-        xfs_ilock(mp->m_rbmip, XFS_ILOCK_EXCL);
-        xfs_trans_ijoin(tp, mp->m_rbmip, XFS_ILOCK_EXCL);
+
+        ASSERT(mp->m_rbmip->i_itemp != NULL);
+        ASSERT(xfs_isilocked(mp->m_rbmip, XFS_ILOCK_EXCL));
 
 #if defined(__KERNEL__) && defined(DEBUG)
         /*