kernel_optimize_test/lcm.h at 588c43a7bd5a53ae523b318e1db16bdd59963a3c - kernel_optimize_test - AcoSail's gitea

AcoSail/kernel_optimize_test

forked from luck/tmp_suning_uos_patched

Mike Snitzer e9637415a9 block: fix blk_stack_limits() regression due to lcm() change

Linux 3.19 commit 69c953c ("lib/lcm.c: lcm(n,0)=lcm(0,n) is 0, not n")
caused blk_stack_limits() to not properly stack queue_limits for stacked
devices (e.g. DM).

Fix this regression by establishing lcm_not_zero() and switching
blk_stack_limits() over to using it.

DM uses blk_set_stacking_limits() to establish the initial top-level
queue_limits that are then built up based on underlying devices' limits
using blk_stack_limits().  In the case of optimal_io_size (io_opt)
blk_set_stacking_limits() establishes a default value of 0.  With commit
69c953c, lcm(0, n) is no longer n, which compromises proper stacking of
the underlying devices' io_opt.

Test:
$ modprobe scsi_debug dev_size_mb=10 num_tgts=1 opt_blks=1536
$ cat /sys/block/sde/queue/optimal_io_size
786432
$ dmsetup create node --table "0 100 linear /dev/sde 0"

Before this fix:
$ cat /sys/block/dm-5/queue/optimal_io_size
0

After this fix:
$ cat /sys/block/dm-5/queue/optimal_io_size
786432

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org # 3.19+
Acked-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

2015-03-31 09:45:50 -06:00

10 lines

236 B

C

Raw Blame History

 #ifndef _LCM_H
 #define _LCM_H
 #include <linux/compiler.h>
 unsigned long lcm(unsigned long a, unsigned long b) __attribute_const__;
 unsigned long lcm_not_zero(unsigned long a, unsigned long b) __attribute_const__;
 #endif /* _LCM_H */