scsi: sd_zbc: Write unlock zone from sd_uninit_cmnd()
authorDamien Le Moal <damien.lemoal@wdc.com>
Wed, 9 Aug 2017 03:00:22 +0000 (12:00 +0900)
committerMartin K. Petersen <martin.petersen@oracle.com>
Thu, 17 Aug 2017 00:01:31 +0000 (20:01 -0400)
commit70e42fd02c46e2aa9ab07b766d418637e3a51de7
tree2f59f796eb5a19d660f3277869042a9bf144d52a
parentc80267324938a5517fd31fa4bbd2d63c564401f9
scsi: sd_zbc: Write unlock zone from sd_uninit_cmnd()

Releasing a zone write lock only when the write commnand that acquired
the lock completes can cause deadlocks due to potential command
reordering if the lock owning request is requeued and not executed. This
problem exists only with the scsi-mq path as, unlike the legacy path,
requests are moved out of the dispatch queue before being prepared and
so before locking a zone for a write command.

Since sd_uninit_cmnd() is now always called when a request is requeued,
call sd_zbc_write_unlock_zone() from that function for write requests
that acquired a zone lock instead of from sd_done(). Acquisition of a zone
lock by a write command is indicated using the new command
flag SCMD_ZONE_WRITE_LOCK.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
drivers/scsi/sd.c
drivers/scsi/sd_zbc.c
include/scsi/scsi_cmnd.h