[XFS] Fix ABBA deadlock between i_mutex and iolock. Avoid calling

__blockdev_direct_IO for the DIO_OWN_LOCKING case for direct I/O reads
since it drops and reacquires the i_mutex while holding the iolock and
this violates the locking order.

SGI-PV: 955696
SGI-Modid: xfs-linux-melb:xfs-kern:26898a

Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: David Chatterton <chatz@sgi.com>

1 files changed, 6 insertions, 5 deletions

diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c
index 5d9cfd91ad08..110c038910ff 100644
--- a/fs/xfs/linux-2.6/xfs_lrw.c
+++ b/fs/xfs/linux-2.6/xfs_lrw.c
@@ -264,7 +264,9 @@ xfs_read(
                                         dmflags, &locktype);
                 if (ret) {
                         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
-                        goto unlock_mutex;
+                        if (unlikely(ioflags & IO_ISDIRECT))
+                                mutex_unlock(&inode->i_mutex);
+                        return ret;
                 }
         }
 
@@ -272,6 +274,9 @@ xfs_read(
                 bhv_vop_flushinval_pages(vp, ctooff(offtoct(*offset)),
                                                 -1, FI_REMAPF_LOCKED);
 
+        if (unlikely(ioflags & IO_ISDIRECT))
+                mutex_unlock(&inode->i_mutex);
+
         xfs_rw_enter_trace(XFS_READ_ENTER, &ip->i_iocore,
                                 (void *)iovp, segs, *offset, ioflags);
         ret = __generic_file_aio_read(iocb, iovp, segs, offset);
@@ -281,10 +286,6 @@ xfs_read(
                 XFS_STATS_ADD(xs_read_bytes, ret);
 
         xfs_iunlock(ip, XFS_IOLOCK_SHARED);
-
-unlock_mutex:
-        if (unlikely(ioflags & IO_ISDIRECT))
-                mutex_unlock(&inode->i_mutex);
         return ret;
 }