linux/drivers/md
Milan Broz 0e435ac26e block: fix setting of max_segment_size and seg_boundary mask
Fix setting of max_segment_size and seg_boundary mask for stacked md/dm
devices.

When stacking devices (LVM over MD over SCSI) some of the request queue
parameters are not set up correctly in some cases by default, namely
max_segment_size and and seg_boundary mask.

If you create MD device over SCSI, these attributes are zeroed.

Problem become when there is over this mapping next device-mapper mapping
- queue attributes are set in DM this way:

request_queue   max_segment_size  seg_boundary_mask
SCSI                65536             0xffffffff
MD RAID1                0                      0
LVM                 65536                 -1 (64bit)

Unfortunately bio_add_page (resp.  bio_phys_segments) calculates number of
physical segments according to these parameters.

During the generic_make_request() is segment cout recalculated and can
increase bio->bi_phys_segments count over the allowed limit.  (After
bio_clone() in stack operation.)

Thi is specially problem in CCISS driver, where it produce OOPS here

    BUG_ON(creq->nr_phys_segments > MAXSGENTRIES);

(MAXSEGENTRIES is 31 by default.)

Sometimes even this command is enough to cause oops:

  dd iflag=direct if=/dev/<vg>/<lv> of=/dev/null bs=128000 count=10

This command generates bios with 250 sectors, allocated in 32 4k-pages
(last page uses only 1024 bytes).

For LVM layer, it allocates bio with 31 segments (still OK for CCISS),
unfortunatelly on lower layer it is recalculated to 32 segments and this
violates CCISS restriction and triggers BUG_ON().

The patch tries to fix it by:

 * initializing attributes above in queue request constructor
   blk_queue_make_request()

 * make sure that blk_queue_stack_limits() inherits setting

 (DM uses its own function to set the limits because it
 blk_queue_stack_limits() was introduced later.  It should probably switch
 to use generic stack limit function too.)

 * sets the default seg_boundary value in one place (blkdev.h)

 * use this mask as default in DM (instead of -1, which differs in 64bit)

Bugs related to this:
https://bugzilla.redhat.com/show_bug.cgi?id=471639
http://bugzilla.kernel.org/show_bug.cgi?id=8672

Signed-off-by: Milan Broz <mbroz@redhat.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>
Cc: Neil Brown <neilb@suse.de>
Cc: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Tejun Heo <htejun@gmail.com>
Cc: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-12-03 12:55:55 +01:00
..
raid6test md: raid6: clean up the style of raid6test/test.c 2008-02-06 10:41:18 -08:00
.gitignore
bitmap.c Fix problem with waiting while holding rcu read lock in md/bitmap.c 2008-09-01 12:48:13 +10:00
dm-bio-list.h dm: bio_list macro renaming 2007-10-20 02:01:11 +01:00
dm-bio-record.h
dm-crypt.c dm crypt: remove waitqueue 2008-10-21 17:45:03 +01:00
dm-delay.c dm: remove dm header from targets 2008-10-21 17:44:59 +01:00
dm-exception-store.c dm: remove dm header from targets 2008-10-21 17:44:59 +01:00
dm-io.c dm: remove dm header from targets 2008-10-21 17:44:59 +01:00
dm-ioctl.c [PATCH] introduce fmode_t, do annotations 2008-10-21 07:47:06 -04:00
dm-kcopyd.c dm: remove dm header from targets 2008-10-21 17:44:59 +01:00
dm-linear.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/viro/bdev 2008-10-23 10:23:07 -07:00
dm-log.c dm: remove dm header from targets 2008-10-21 17:44:59 +01:00
dm-mpath.c dm mpath: warn if args ignored 2008-11-13 23:39:06 +00:00
dm-mpath.h dm mpath: remove is_active from struct dm_path 2008-10-10 13:36:58 +01:00
dm-path-selector.c dm: remove dm header from targets 2008-10-21 17:44:59 +01:00
dm-path-selector.h
dm-raid1.c dm raid1: flush workqueue before destruction 2008-11-13 23:38:52 +00:00
dm-region-hash.c dm raid1: separate region_hash interface part1 2008-10-21 17:45:06 +01:00
dm-round-robin.c dm: remove dm header from targets 2008-10-21 17:44:59 +01:00
dm-snap.c dm snapshot: wait for chunks in destructor 2008-10-30 13:33:16 +00:00
dm-snap.h dm snapshot: wait for chunks in destructor 2008-10-30 13:33:16 +00:00
dm-stripe.c dm stripe: fix init failure 2008-11-13 23:38:56 +00:00
dm-table.c block: fix setting of max_segment_size and seg_boundary mask 2008-12-03 12:55:55 +01:00
dm-target.c dm: use kzalloc 2007-10-20 02:01:07 +01:00
dm-uevent.c md: replace remaining __FUNCTION__ occurrences 2008-04-28 08:58:42 -07:00
dm-uevent.h dm: uevent generate events 2007-10-20 02:01:26 +01:00
dm-zero.c dm: remove dm header from targets 2008-10-21 17:44:59 +01:00
dm.c dm: avoid destroying table in dm_any_congested 2008-11-13 23:39:14 +00:00
dm.h dm: publish array_too_big 2008-10-21 17:44:57 +01:00
faulty.c md: check for memory allocation failure in faulty personality 2008-10-16 14:16:53 +11:00
Kconfig raid, fastboot: hide RAID autodetect option if MD is compiled as a module 2008-10-12 08:25:14 -07:00
linear.c md: linear: Fix a division by zero bug for very small arrays. 2008-11-06 19:41:24 +11:00
Makefile dm raid1: separate region_hash interface part1 2008-10-21 17:45:06 +01:00
md.c md: revert the recent addition of a call to the BLKRRPART ioctl. 2008-11-06 17:28:01 +11:00
mktables.c md: raid6: Fix mktable.c 2008-02-06 10:41:18 -08:00
multipath.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6 2008-10-17 09:00:23 -07:00
raid0.c md: Remove unnecessary #includes, #defines, and function declarations. 2008-10-13 11:55:12 +11:00
raid1.c md: build failure due to missing delay.h 2008-10-15 21:57:05 +11:00
raid5.c md: Relax minimum size restrictions on chunk_size. 2008-10-13 11:55:12 +11:00
raid6.h md: Remove unnecessary #includes, #defines, and function declarations. 2008-10-13 11:55:12 +11:00
raid6algos.c drivers/md: use time_before, time_before_eq, etc 2008-04-28 08:58:42 -07:00
raid6altivec.uc
raid6int.uc
raid6mmx.c x86 merge fallout: uml 2007-10-29 07:41:32 -07:00
raid6recov.c
raid6sse1.c x86 merge fallout: uml 2007-10-29 07:41:32 -07:00
raid6sse2.c x86 merge fallout: uml 2007-10-29 07:41:32 -07:00
raid6x86.h x86 merge fallout: uml 2007-10-29 07:41:32 -07:00
raid10.c md: fix bug in raid10 recovery. 2008-11-06 17:28:20 +11:00
unroll.pl