This is a note to let you know that I've just added the patch titled
bcache: fix sequential large write IO bypass
to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
bcache-fix-sequential-large-write-io-bypass.patch
and it can be found in the queue-4.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From c81ffa32a214c84b08900fbc9d432187bd948eba Mon Sep 17 00:00:00 2001
From: Tang Junhui <tang.junhui@xxxxxxxxxx>
Date: Wed, 6 Sep 2017 14:25:52 +0800
Subject: bcache: fix sequential large write IO bypass
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From: Tang Junhui <tang.junhui@xxxxxxxxxx>
commit c81ffa32a214c84b08900fbc9d432187bd948eba upstream.
Sequential write IOs were tested with bs=1M by FIO in writeback cache
mode, these IOs were expected to be bypassed, but actually they did not.
We debug the code, and find in check_should_bypass():
if (!congested &&
mode == CACHE_MODE_WRITEBACK &&
op_is_write(bio_op(bio)) &&
(bio-＞bi_opf & REQ_SYNC))
goto rescale
that means, If in writeback mode, a write IO with REQ_SYNC flag will not
be bypassed though it is a sequential large IO, It's not a correct thing
to do actually, so this patch remove these codes.
Signed-off-by: tang.junhui <tang.junhui@xxxxxxxxxx>
Reviewed-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Reviewed-by: Eric Wheeler <bcache@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/bcache/request.c | 6 ------
1 file changed, 6 deletions(-)
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -400,12 +400,6 @@ static bool check_should_bypass(struct c
if (!congested && !dc->sequential_cutoff)
goto rescale;
- if (!congested &&
- mode == CACHE_MODE_WRITEBACK &&
- op_is_write(bio->bi_opf) &&
- op_is_sync(bio->bi_opf))
- goto rescale;
-
spin_lock(&dc->io_lock);
hlist_for_each_entry(i, iohash(dc, bio->bi_iter.bi_sector), hash)
Patches currently in stable-queue which might be from tang.junhui@xxxxxxxxxx are
queue-4.13/bcache-do-not-subtract-sectors_to_gc-for-bypassed-io.patch
queue-4.13/bcache-correct-cache_dirty_target-in-__update_writeback_rate.patch
queue-4.13/bcache-fix-for-gc-and-write-back-race.patch
queue-4.13/bcache-initialize-dirty-stripes-in-flash_dev_run.patch
queue-4.13/bcache-fix-sequential-large-write-io-bypass.patch