Merge tag 'v3.7' into v4l_for_linus

Linux 3.7

* tag 'v3.7': (1545 commits)
  Linux 3.7
  Input: matrix-keymap - provide proper module license
  Revert "revert "Revert "mm: remove __GFP_NO_KSWAPD""" and associated damage
  ipv4: ip_check_defrag must not modify skb before unsharing
  Revert "mm: avoid waking kswapd for THP allocations when compaction is deferred or contended"
  inet_diag: validate port comparison byte code to prevent unsafe reads
  inet_diag: avoid unsafe and nonsensical prefix matches in inet_diag_bc_run()
  inet_diag: validate byte code to prevent oops in inet_diag_bc_run()
  inet_diag: fix oops for IPv4 AF_INET6 TCP SYN-RECV state
  mm: vmscan: fix inappropriate zone congestion clearing
  vfs: fix O_DIRECT read past end of block device
  net: gro: fix possible panic in skb_gro_receive()
  tcp: bug fix Fast Open client retransmission
  tmpfs: fix shared mempolicy leak
  mm: vmscan: do not keep kswapd looping forever due to individual uncompactable zones
  mm: compaction: validate pfn range passed to isolate_freepages_block
  mmc: sh-mmcif: avoid oops on spurious interrupts (second try)
  Revert misapplied "mmc: sh-mmcif: avoid oops on spurious interrupts"
  mmc: sdhci-s3c: fix missing clock for gpio card-detect
  lib/Makefile: Fix oid_registry build dependency
  ...

1 files changed, 18 insertions, 0 deletions

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index a8d0ed91119..becf4a97efc 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -526,7 +526,25 @@ xfs_buf_item_unpin(
 		}
 		xfs_buf_relse(bp);
 	} else if (freed && remove) {
+		/*
+		 * There are currently two references to the buffer - the active
+		 * LRU reference and the buf log item. What we are about to do
+		 * here - simulate a failed IO completion - requires 3
+		 * references.
+		 *
+		 * The LRU reference is removed by the xfs_buf_stale() call. The
+		 * buf item reference is removed by the xfs_buf_iodone()
+		 * callback that is run by xfs_buf_do_callbacks() during ioend
+		 * processing (via the bp->b_iodone callback), and then finally
+		 * the ioend processing will drop the IO reference if the buffer
+		 * is marked XBF_ASYNC.
+		 *
+		 * Hence we need to take an additional reference here so that IO
+		 * completion processing doesn't free the buffer prematurely.
+		 */
 		xfs_buf_lock(bp);
+		xfs_buf_hold(bp);
+		bp->b_flags |= XBF_ASYNC;
 		xfs_buf_ioerror(bp, EIO);
 		XFS_BUF_UNDONE(bp);
 		xfs_buf_stale(bp);