From: Mike Snitzer <snitzer@redhat.com> To: axboe@kernel.dk Cc: martin.petersen@oracle.com, linux-block@vger.kernel.org, dm-devel@redhat.com, jdorminy@redhat.com, bjohnsto@redhat.com Subject: [PATCH v2] block: use gcd() to fix chunk_sectors limit stacking Date: Tue, 1 Dec 2020 11:07:09 -0500 [thread overview] Message-ID: <20201201160709.31748-1-snitzer@redhat.com> (raw) In-Reply-To: <20201130171805.77712-1-snitzer@redhat.com> commit 22ada802ede8 ("block: use lcm_not_zero() when stacking chunk_sectors") broke chunk_sectors limit stacking. chunk_sectors must reflect the most limited of all devices in the IO stack. Otherwise malformed IO may result. E.g.: prior to this fix, ->chunk_sectors = lcm_not_zero(8, 128) would result in blk_max_size_offset() splitting IO at 128 sectors rather than the required more restrictive 8 sectors. And since commit 07d098e6bbad ("block: allow 'chunk_sectors' to be non-power-of-2") care must be taken to properly stack chunk_sectors to be compatible with the possibility that a non-power-of-2 chunk_sectors may be stacked. This is why gcd() is used instead of reverting back to using min_not_zero(). Fixes: 22ada802ede8 ("block: use lcm_not_zero() when stacking chunk_sectors") Fixes: 07d098e6bbad ("block: allow 'chunk_sectors' to be non-power-of-2") Cc: stable@vger.kernel.org Reported-by: John Dorminy <jdorminy@redhat.com> Reported-by: Bruce Johnston <bjohnsto@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> --- block/blk-settings.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) v2: use gcd(), instead of min_not_zero(), as suggested by John Dorminy diff --git a/block/blk-settings.c b/block/blk-settings.c index 9741d1d83e98..659cdb8a07fe 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -547,7 +547,10 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, t->io_min = max(t->io_min, b->io_min); t->io_opt = lcm_not_zero(t->io_opt, b->io_opt); - t->chunk_sectors = lcm_not_zero(t->chunk_sectors, b->chunk_sectors); + + /* Set non-power-of-2 compatible chunk_sectors boundary */ + if (b->chunk_sectors) + t->chunk_sectors = gcd(t->chunk_sectors, b->chunk_sectors); /* Physical block size a multiple of the logical block size? */ if (t->physical_block_size & (t->logical_block_size - 1)) { -- 2.15.0
WARNING: multiple messages have this Message-ID (diff)
From: Mike Snitzer <snitzer@redhat.com> To: axboe@kernel.dk Cc: linux-block@vger.kernel.org, dm-devel@redhat.com, bjohnsto@redhat.com, jdorminy@redhat.com, martin.petersen@oracle.com Subject: [dm-devel] [PATCH v2] block: use gcd() to fix chunk_sectors limit stacking Date: Tue, 1 Dec 2020 11:07:09 -0500 [thread overview] Message-ID: <20201201160709.31748-1-snitzer@redhat.com> (raw) In-Reply-To: <20201130171805.77712-1-snitzer@redhat.com> commit 22ada802ede8 ("block: use lcm_not_zero() when stacking chunk_sectors") broke chunk_sectors limit stacking. chunk_sectors must reflect the most limited of all devices in the IO stack. Otherwise malformed IO may result. E.g.: prior to this fix, ->chunk_sectors = lcm_not_zero(8, 128) would result in blk_max_size_offset() splitting IO at 128 sectors rather than the required more restrictive 8 sectors. And since commit 07d098e6bbad ("block: allow 'chunk_sectors' to be non-power-of-2") care must be taken to properly stack chunk_sectors to be compatible with the possibility that a non-power-of-2 chunk_sectors may be stacked. This is why gcd() is used instead of reverting back to using min_not_zero(). Fixes: 22ada802ede8 ("block: use lcm_not_zero() when stacking chunk_sectors") Fixes: 07d098e6bbad ("block: allow 'chunk_sectors' to be non-power-of-2") Cc: stable@vger.kernel.org Reported-by: John Dorminy <jdorminy@redhat.com> Reported-by: Bruce Johnston <bjohnsto@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> --- block/blk-settings.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) v2: use gcd(), instead of min_not_zero(), as suggested by John Dorminy diff --git a/block/blk-settings.c b/block/blk-settings.c index 9741d1d83e98..659cdb8a07fe 100644 --- a/block/blk-settings.c +++ b/block/blk-settings.c @@ -547,7 +547,10 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b, t->io_min = max(t->io_min, b->io_min); t->io_opt = lcm_not_zero(t->io_opt, b->io_opt); - t->chunk_sectors = lcm_not_zero(t->chunk_sectors, b->chunk_sectors); + + /* Set non-power-of-2 compatible chunk_sectors boundary */ + if (b->chunk_sectors) + t->chunk_sectors = gcd(t->chunk_sectors, b->chunk_sectors); /* Physical block size a multiple of the logical block size? */ if (t->physical_block_size & (t->logical_block_size - 1)) { -- 2.15.0 -- dm-devel mailing list dm-devel@redhat.com https://www.redhat.com/mailman/listinfo/dm-devel
next prev parent reply other threads:[~2020-12-01 16:07 UTC|newest] Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-30 17:18 [PATCH] block: revert to using min_not_zero() when stacking chunk_sectors Mike Snitzer 2020-11-30 17:18 ` [dm-devel] " Mike Snitzer 2020-11-30 20:51 ` John Dorminy 2020-11-30 20:51 ` [dm-devel] " John Dorminy 2020-11-30 23:24 ` Mike Snitzer 2020-11-30 23:24 ` [dm-devel] " Mike Snitzer 2020-12-01 0:21 ` John Dorminy 2020-12-01 0:21 ` [dm-devel] " John Dorminy 2020-12-01 2:12 ` Mike Snitzer 2020-12-01 2:12 ` [dm-devel] " Mike Snitzer 2020-12-01 16:07 ` Mike Snitzer [this message] 2020-12-01 16:07 ` [dm-devel] [PATCH v2] block: use gcd() to fix chunk_sectors limit stacking Mike Snitzer 2020-12-01 17:43 ` John Dorminy 2020-12-01 17:43 ` [dm-devel] " John Dorminy 2020-12-01 17:53 ` Jens Axboe 2020-12-01 17:53 ` [dm-devel] " Jens Axboe 2020-12-01 18:02 ` Martin K. Petersen 2020-12-01 18:02 ` [dm-devel] " Martin K. Petersen 2020-12-02 3:38 ` [PATCH] dm: " Jeffle Xu 2020-12-02 3:38 ` [dm-devel] " Jeffle Xu 2020-12-02 3:38 ` Jeffle Xu 2020-12-02 3:38 ` [dm-devel] " Jeffle Xu 2020-12-02 3:57 ` JeffleXu 2020-12-02 3:57 ` [dm-devel] " JeffleXu 2020-12-02 5:03 ` Mike Snitzer 2020-12-02 5:03 ` [dm-devel] " Mike Snitzer 2020-12-02 5:14 ` Mike Snitzer 2020-12-02 5:14 ` [dm-devel] " Mike Snitzer 2020-12-02 6:31 ` JeffleXu 2020-12-02 6:31 ` [dm-devel] " JeffleXu 2020-12-02 6:35 ` JeffleXu 2020-12-02 6:35 ` [dm-devel] " JeffleXu 2020-12-02 6:28 ` JeffleXu 2020-12-02 6:28 ` [dm-devel] " JeffleXu 2020-12-02 7:10 ` JeffleXu 2020-12-02 7:10 ` [dm-devel] " JeffleXu 2020-12-02 15:11 ` Mike Snitzer 2020-12-02 15:11 ` [dm-devel] " Mike Snitzer 2020-12-03 1:48 ` JeffleXu 2020-12-03 1:48 ` JeffleXu 2020-12-03 3:26 ` [PATCH v2] block: " Ming Lei 2020-12-03 3:26 ` [dm-devel] " Ming Lei 2020-12-03 14:33 ` Mike Snitzer 2020-12-03 14:33 ` [dm-devel] " Mike Snitzer 2020-12-03 16:27 ` Keith Busch 2020-12-03 16:27 ` [dm-devel] " Keith Busch 2020-12-03 17:56 ` Mike Snitzer 2020-12-03 17:56 ` [dm-devel] " Mike Snitzer 2020-12-04 1:45 ` Ming Lei 2020-12-04 1:45 ` [dm-devel] " Ming Lei 2020-12-04 2:11 ` Mike Snitzer 2020-12-04 2:11 ` [dm-devel] " Mike Snitzer 2020-12-04 6:22 ` Damien Le Moal 2020-12-04 6:22 ` Damien Le Moal 2020-12-04 1:12 ` Ming Lei 2020-12-04 1:12 ` [dm-devel] " Ming Lei 2020-12-04 2:03 ` Mike Snitzer 2020-12-04 2:03 ` [dm-devel] " Mike Snitzer 2020-12-04 3:59 ` Ming Lei 2020-12-04 3:59 ` [dm-devel] " Ming Lei 2020-12-04 16:47 ` Mike Snitzer 2020-12-04 16:47 ` [dm-devel] " Mike Snitzer 2020-12-04 17:32 ` [RFC PATCH] dm: fix IO splitting [was: Re: [PATCH v2] block: use gcd() to fix chunk_sectors limit stacking] Mike Snitzer 2020-12-04 17:32 ` [dm-devel] " Mike Snitzer 2020-12-04 17:49 ` Mike Snitzer 2020-12-04 17:49 ` [dm-devel] " Mike Snitzer
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