FAILED: patch "[PATCH] xfs: prevent dropping ioend completions during buftarg wait" failed to apply to 4.7-stable tree
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[email protected]
maintainerThe patch below does not apply to the 4.7-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
Quoted 1 line
From
800b2694f890cc35a1bda63501fc71c94389d517Mon Sep 17 00:00:00 2001
From: Brian Foster <[email protected]>
Date: Fri, 26 Aug 2016 16:01:59 +1000
Subject: [PATCH] xfs: prevent dropping ioend completions during buftarg wait
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.
fs/xfs/xfs_buf.c +1 -1
@@ -1611,7 +1611,7 @@ xfs_wait_buftarg(*/ while (percpu_counter_sum (&btp->bt_io_count))delay (100 ); -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)) {
PATCH 1/1 xfs: prevent dropping ioend completions during buftarg wait
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.
---
Note that this applies to linux-4.7.y.
Brian
fs/xfs/xfs_buf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
fs/xfs/xfs_buf.c +1 -1
@@ -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)) {
Signature · 1 line
2.5.5
Re: [PATCH] xfs: prevent dropping ioend completions during buftarg wait
Quoted 27 lines · Brian Foster
commit
800b2694f890cc35a1bda63501fc71c94389d517upstream.
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()invokesdrain_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 aWARN_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 withflush_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 timexfs_wait_buftarg()is invoked.
Quoted 7 lines
cc <[email protected]>Signed-off-by Brian Foster <[email protected]>Reviewed-by Christoph Hellwig <[email protected]>Signed-off-by Dave Chinner <[email protected]>---
Note that this applies to linux-4.7.y.
It also applied to 4.4-stable, should I put it there as well?
thanks,
greg k-h
Re: [PATCH] xfs: prevent dropping ioend completions during buftarg wait
Quoted 34 lines · Greg KH
Quoted 33 lines · Brian Foster
commit
800b2694f890cc35a1bda63501fc71c94389d517upstream.
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()invokesdrain_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 aWARN_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 withflush_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 timexfs_wait_buftarg()is invoked.cc <[email protected]>Signed-off-by Brian Foster <[email protected]>Reviewed-by Christoph Hellwig <[email protected]>Signed-off-by Dave Chinner <[email protected]>---
Quoted 4 lines
Quoted 1 line
Note that this applies to linux-4.7.y.
It also applied to 4.4-stable, should I put it there as well?
Yeah, it looks like we included "xfs: log mount failures don't wait for buffers to be released" there so that probably makes sense. Thanks!
Brian
Quoted 3 lines
thanks,
greg k-h