4.7-stable patches

added patches:
	xfs-prevent-dropping-ioend-completions-during-buftarg-wait.patch

diff --git a/queue-4.7/series b/queue-4.7/series
index ecd73e89d614fb49beb99662b3eff0a7f51cb074..22cd9db68269235bbed960b31b0472791e484458 100644 (file)
--- a/queue-4.7/series
+++ b/queue-4.7/series
@@ -10,3 +10,4 @@ autofs-use-dentry-flags-to-block-walks-during-expire.patch
 disable-maybe-uninitialized-warning-globally.patch
 disable-frame-address-warning.patch
 makefile-mute-warning-for-__builtin_return_address-0-for-tracing-only.patch
+xfs-prevent-dropping-ioend-completions-during-buftarg-wait.patch

diff --git a/queue-4.7/xfs-prevent-dropping-ioend-completions-during-buftarg-wait.patch b/queue-4.7/xfs-prevent-dropping-ioend-completions-during-buftarg-wait.patch
new file mode 100644 (file)
index 0000000..678c4f5
--- /dev/null
+++ b/queue-4.7/xfs-prevent-dropping-ioend-completions-during-buftarg-wait.patch
@@ -0,0 +1,55 @@
+From 800b2694f890cc35a1bda63501fc71c94389d517 Mon Sep 17 00:00:00 2001
+From: Brian Foster <bfoster@redhat.com>
+Date: Fri, 26 Aug 2016 16:01:59 +1000
+Subject: xfs: prevent dropping ioend completions during buftarg wait
+
+From: Brian Foster <bfoster@redhat.com>
+
+commit 800b2694f890cc35a1bda63501fc71c94389d517 upstream.
+
+xfs_wait_buftarg() waits for all pending I/O, drains the ioend
+completion workqueue and walks the LRU until all buffers in the cache
+have been released. This is traditionally an unmount operation` but the
+mechanism is also reused during filesystem freeze.
+
+xfs_wait_buftarg() invokes drain_workqueue() as part of the quiesce,
+which is intended more for a shutdown sequence in that it indicates to
+the queue that new operations are not expected once the drain has begun.
+New work jobs after this point result in a WARN_ON_ONCE() and are
+otherwise dropped.
+
+With filesystem freeze, however, read operations are allowed and can
+proceed during or after the workqueue drain. If such a read occurs
+during the drain sequence, the workqueue infrastructure complains about
+the queued ioend completion work item and drops it on the floor. As a
+result, the buffer remains on the LRU and the freeze never completes.
+
+Despite the fact that the overall buffer cache cleanup is not necessary
+during freeze, fix up this operation such that it is safe to invoke
+during non-unmount quiesce operations. Replace the drain_workqueue()
+call with flush_workqueue(), which runs a similar serialization on
+pending workqueue jobs without causing new jobs to be dropped. This is
+safe for unmount as unmount independently locks out new operations by
+the time xfs_wait_buftarg() is invoked.
+
+cc: <stable@vger.kernel.org>
+Signed-off-by: Brian Foster <bfoster@redhat.com>
+Reviewed-by: Christoph Hellwig <hch@lst.de>
+Signed-off-by: Dave Chinner <david@fromorbit.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ fs/xfs/xfs_buf.c |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/fs/xfs/xfs_buf.c
++++ b/fs/xfs/xfs_buf.c
+@@ -1531,7 +1531,7 @@ xfs_wait_buftarg(
+        * ensure here that all reference counts have been dropped before we
+        * start walking the LRU list.
+        */
+-      drain_workqueue(btp->bt_mount->m_buf_workqueue);
++      flush_workqueue(btp->bt_mount->m_buf_workqueue);
+ 
+       /* loop until there is nothing left on the lru list. */
+       while (list_lru_count(&btp->bt_lru)) {