From f7b58a69fad9d2c4c90cab0247811155dd0d48e7 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 30 Mar 2023 14:56:38 -0400 Subject: [PATCH 1/2] dm: fix improper splitting for abnormal bios "Abnormal" bios include discards, write zeroes and secure erase. By no longer passing the calculated 'len' pointer, commit 7dd06a2548b2 ("dm: allow dm_accept_partial_bio() for dm_io without duplicate bios") took a senseless approach to disallowing dm_accept_partial_bio() from working for duplicate bios processed using __send_duplicate_bios(). It inadvertently and incorrectly stopped the use of 'len' when initializing a target's io (in alloc_tio). As such the resulting tio could address more area of a device than it should. For example, when discarding an entire DM striped device with the following DM table: vg-lvol0: 0 159744 striped 2 128 7:0 2048 7:1 2048 vg-lvol0: 159744 45056 striped 2 128 7:2 2048 7:3 2048 Before this fix: device-mapper: striped: target_stripe=0, bdev=7:0, start=2048 len=102400 blkdiscard: attempt to access beyond end of device loop0: rw=2051, sector=2048, nr_sectors = 102400 limit=81920 device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=102400 blkdiscard: attempt to access beyond end of device loop1: rw=2051, sector=2048, nr_sectors = 102400 limit=81920 After this fix; device-mapper: striped: target_stripe=0, bdev=7:0, start=2048 len=79872 device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=79872 Fixes: 7dd06a2548b2 ("dm: allow dm_accept_partial_bio() for dm_io without duplicate bios") Cc: stable@vger.kernel.org Reported-by: Orange Kao Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 2d0f934ba6e6..e67a2757c53e 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1467,7 +1467,8 @@ static void setup_split_accounting(struct clone_info *ci, unsigned int len) } static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci, - struct dm_target *ti, unsigned int num_bios) + struct dm_target *ti, unsigned int num_bios, + unsigned *len) { struct bio *bio; int try; @@ -1478,7 +1479,7 @@ static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci, if (try) mutex_lock(&ci->io->md->table_devices_lock); for (bio_nr = 0; bio_nr < num_bios; bio_nr++) { - bio = alloc_tio(ci, ti, bio_nr, NULL, + bio = alloc_tio(ci, ti, bio_nr, len, try ? GFP_NOIO : GFP_NOWAIT); if (!bio) break; @@ -1514,7 +1515,7 @@ static int __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti, break; default: /* dm_accept_partial_bio() is not supported with shared tio->len_ptr */ - alloc_multiple_bios(&blist, ci, ti, num_bios); + alloc_multiple_bios(&blist, ci, ti, num_bios, len); while ((clone = bio_list_pop(&blist))) { dm_tio_set_flag(clone_to_tio(clone), DM_TIO_IS_DUPLICATE_BIO); __map_bio(clone); From 666eed46769d929c3e13636134ecfc67d75ef548 Mon Sep 17 00:00:00 2001 From: Mike Snitzer Date: Thu, 30 Mar 2023 15:09:29 -0400 Subject: [PATCH 2/2] dm: fix __send_duplicate_bios() to always allow for splitting IO Commit 7dd76d1feec70 ("dm: improve bio splitting and associated IO accounting") only called setup_split_accounting() from __send_duplicate_bios() if a single bio were being issued. But the case where duplicate bios are issued must call it too. Otherwise the bio won't be split and resubmitted (via recursion through block core back to DM) to submit the later portions of a bio (which may map to an entirely different target). For example, when discarding an entire DM striped device with the following DM table: vg-lvol0: 0 159744 striped 2 128 7:0 2048 7:1 2048 vg-lvol0: 159744 45056 striped 2 128 7:2 2048 7:3 2048 Before (broken, discards the first striped target's devices twice): device-mapper: striped: target_stripe=0, bdev=7:0, start=2048 len=79872 device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=79872 device-mapper: striped: target_stripe=0, bdev=7:0, start=2049 len=22528 device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=22528 After (works as expected): device-mapper: striped: target_stripe=0, bdev=7:0, start=2048 len=79872 device-mapper: striped: target_stripe=1, bdev=7:1, start=2048 len=79872 device-mapper: striped: target_stripe=0, bdev=7:2, start=2048 len=22528 device-mapper: striped: target_stripe=1, bdev=7:3, start=2048 len=22528 Fixes: 7dd76d1feec70 ("dm: improve bio splitting and associated IO accounting") Cc: stable@vger.kernel.org Reported-by: Orange Kao Signed-off-by: Mike Snitzer --- drivers/md/dm.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index e67a2757c53e..dfde0088147a 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1514,6 +1514,8 @@ static int __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti, ret = 1; break; default: + if (len) + setup_split_accounting(ci, *len); /* dm_accept_partial_bio() is not supported with shared tio->len_ptr */ alloc_multiple_bios(&blist, ci, ti, num_bios, len); while ((clone = bio_list_pop(&blist))) {