6.12-stable review patch. If anyone has any objections, please let me know.
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From: Shin'ichiro Kawasaki shinichiro.kawasaki@wdc.com
commit 675f940576351bb049f5677615140b9d0a7712d0 upstream.
Commit 2df7168717b7 ("dm: Always split write BIOs to zoned device limits") updates the device-mapper driver to perform splits for the write BIOs. However, it did not address the cases where DM targets do not emulate zone append, such as in the cases of dm-linear or dm-flakey. For these targets, when the write BIOs span across zone boundaries, they trigger WARN_ON_ONCE(bio_straddles_zones(bio)) in blk_zone_wplug_handle_write(). This results in I/O errors. The errors are reproduced by running blktests test case zbd/004 using zoned dm-linear or dm-flakey devices.
To avoid the I/O errors, handle the write BIOs regardless whether DM targets emulate zone append or not, so that all write BIOs are split at zone boundaries. For that purpose, drop the check for zone append emulation in dm_zone_bio_needs_split(). Its argument 'md' is no longer used then drop it also.
Fixes: 2df7168717b7 ("dm: Always split write BIOs to zoned device limits") Signed-off-by: Shin'ichiro Kawasaki shinichiro.kawasaki@wdc.com Reviewed-by: Damien Le Moal dlemoal@kernel.org Reviewed-by: Mikulas Patocka mpatocka@redhat.com Link: https://lore.kernel.org/r/20250717103539.37279-1-shinichiro.kawasaki@wdc.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/md/dm.c | 18 +++++++----------- 1 file changed, 7 insertions(+), 11 deletions(-)
--- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -1788,8 +1788,7 @@ static void init_clone_info(struct clone }
#ifdef CONFIG_BLK_DEV_ZONED -static inline bool dm_zone_bio_needs_split(struct mapped_device *md, - struct bio *bio) +static inline bool dm_zone_bio_needs_split(struct bio *bio) { /* * Special case the zone operations that cannot or should not be split. @@ -1805,13 +1804,11 @@ static inline bool dm_zone_bio_needs_spl }
/* - * Mapped devices that require zone append emulation will use the block - * layer zone write plugging. In such case, we must split any large BIO - * to the mapped device limits to avoid potential deadlocks with queue - * freeze operations. + * When mapped devices use the block layer zone write plugging, we must + * split any large BIO to the mapped device limits to not submit BIOs + * that span zone boundaries and to avoid potential deadlocks with + * queue freeze operations. */ - if (!dm_emulate_zone_append(md)) - return false; return bio_needs_zone_write_plugging(bio) || bio_straddles_zones(bio); }
@@ -1935,8 +1932,7 @@ static blk_status_t __send_zone_reset_al }
#else -static inline bool dm_zone_bio_needs_split(struct mapped_device *md, - struct bio *bio) +static inline bool dm_zone_bio_needs_split(struct bio *bio) { return false; } @@ -1963,7 +1959,7 @@ static void dm_split_and_process_bio(str
is_abnormal = is_abnormal_io(bio); if (static_branch_unlikely(&zoned_enabled)) { - need_split = is_abnormal || dm_zone_bio_needs_split(md, bio); + need_split = is_abnormal || dm_zone_bio_needs_split(bio); } else { need_split = is_abnormal; }