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  1. 23 5月, 2009 1 次提交
  3. 09 4月, 2009 2 次提交
  5. 03 4月, 2009 1 次提交
    • A
      dm table: fix upgrade mode race · 570b9d96
      由 Alasdair G Kergon 提交于 
      upgrade_mode() sets bdev to NULL temporarily, and does not have any
locking to exclude anything from seeing that NULL.

In dm_table_any_congested() bdev_get_queue() can dereference that NULL and
cause a reported oops.

Fix this by not changing that field during the mode upgrade.

Cc: stable@kernel.org
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      570b9d96
  7. 06 1月, 2009 2 次提交
    • M
      dm table: rework reference counting · d5816876
      由 Mikulas Patocka 提交于 
      Rework table reference counting.

The existing code uses a reference counter. When the last reference is
dropped and the counter reaches zero, the table destructor is called.
Table reference counters are acquired/released from upcalls from other
kernel code (dm_any_congested, dm_merge_bvec, dm_unplug_all).
If the reference counter reaches zero in one of the upcalls, the table
destructor is called from almost random kernel code.

This leads to various problems:
* dm_any_congested being called under a spinlock, which calls the
  destructor, which calls some sleeping function.
* the destructor attempting to take a lock that is already taken by the
  same process.
* stale reference from some other kernel code keeps the table
  constructed, which keeps some devices open, even after successful
  return from "dmsetup remove". This can confuse lvm and prevent closing
  of underlying devices or reusing device minor numbers.

The patch changes reference counting so that the table destructor can be
called only at predetermined places.

The table has always exactly one reference from either mapped_device->map
or hash_cell->new_map. After this patch, this reference is not counted
in table->holders.  A pair of dm_create_table/dm_destroy_table functions
is used for table creation/destruction.

Temporary references from the other code increase table->holders. A pair
of dm_table_get/dm_table_put functions is used to manipulate it.

When the table is about to be destroyed, we wait for table->holders to
reach 0. Then, we call the table destructor.  We use active waiting with
msleep(1), because the situation happens rarely (to one user in 5 years)
and removing the device isn't performance-critical task: the user doesn't
care if it takes one tick more or not.

This way, the destructor is called only at specific points
(dm_table_destroy function) and the above problems associated with lazy
destruction can't happen.

Finally remove the temporary protection added to dm_any_congested().
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      d5816876
    • A
      dm: support barriers on simple devices · ab4c1424
      由 Andi Kleen 提交于 
      Implement barrier support for single device DM devices

This patch implements barrier support in DM for the common case of dm linear
just remapping a single underlying device. In this case we can safely
pass the barrier through because there can be no reordering between
devices.

 NB. Any DM device might cease to support barriers if it gets
     reconfigured so code must continue to allow for a possible
     -EOPNOTSUPP on every barrier bio submitted.  - agk
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      ab4c1424
  9. 03 12月, 2008 1 次提交
    • M
      block: fix setting of max_segment_size and seg_boundary mask · 0e435ac2
      由 Milan Broz 提交于 
      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=8672Signed-off-by: NMilan Broz <mbroz@redhat.com>
Reviewed-by: NAlasdair 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: NJens Axboe <jens.axboe@oracle.com>
      0e435ac2
  11. 23 10月, 2008 1 次提交
  13. 21 10月, 2008 2 次提交
  15. 10 10月, 2008 2 次提交
  17. 01 8月, 2008 1 次提交
  19. 21 7月, 2008 1 次提交
  21. 30 4月, 2008 1 次提交
  23. 29 4月, 2008 1 次提交
  25. 25 4月, 2008 2 次提交
  27. 15 2月, 2008 2 次提交
  29. 08 2月, 2008 3 次提交
  31. 21 12月, 2007 2 次提交
    • N
      dm: merge max_hw_sector · 91212507
      由 Neil Brown 提交于 
      Make sure dm honours max_hw_sectors of underlying devices

  We still have no firm testing evidence in support of this patch but
  believe it may help to resolve some bug reports.  - agk
Signed-off-by: NNeil Brown <neilb@suse.de>
Signed-off-by: NAlasdair G Kergon <agk@redhat.com>
      91212507
    • J
      dm: table detect io beyond device · 512875bd
      由 Jun'ichi Nomura 提交于 
      This patch fixes a panic on shrinking a DM device if there is
outstanding I/O to the part of the device that is being removed.
(Normally this doesn't happen - a filesystem would be resized first,
for example.)

The bug is that __clone_and_map() assumes dm_table_find_target()
always returns a valid pointer.  It may fail if a bio arrives from the
block layer but its target sector is no longer included in the DM
btree.

This patch appends an empty entry to table->targets[] which will
be returned by a lookup beyond the end of the device.

After calling dm_table_find_target(), __clone_and_map() and target_message()
check for this condition using
dm_target_is_valid().

Sample test script to trigger oops:
      512875bd
  33. 09 11月, 2007 1 次提交
  35. 02 11月, 2007 1 次提交
  37. 20 10月, 2007 1 次提交
  39. 16 10月, 2007 1 次提交
  41. 24 7月, 2007 1 次提交
  43. 10 5月, 2007 1 次提交
  45. 03 10月, 2006 3 次提交
  47. 27 6月, 2006 4 次提交
  49. 28 3月, 2006 2 次提交