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  1. 19 Oct, 2011 9 commits
    • Tejun Heo's avatar
      block: make get_request[_wait]() fail if queue is dead · da8303c6
      Tejun Heo authored 
      Currently get_request[_wait]() allocates request whether queue is dead
or not.  This patch makes get_request[_wait]() return NULL if @q is
dead.  blk_queue_bio() is updated to fail the submitted bio if request
allocation fails.  While at it, add docbook comments for
get_request[_wait]().

Note that the current code has rather unclear (there are spurious DEAD
tests scattered around) assumption that the owner of a queue
guarantees that no request travels block layer if the queue is dead
and this patch in itself doesn't change much; however, this will allow
fixing the broken assumption in the next patch.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      da8303c6
    • Tejun Heo's avatar
      block: reorganize throtl_get_tg() and blk_throtl_bio() · bc16a4f9
      Tejun Heo authored 
      blk_throtl_bio() and throtl_get_tg() have rather unusual interface.

* throtl_get_tg() returns pointer to a valid tg or ERR_PTR(-ENODEV),
  and drops queue_lock in the latter case.  Different locking context
  depending on return value is error-prone and DEAD state is scheduled
  to be protected by queue_lock anyway.  Move DEAD check inside
  queue_lock and return valid tg or NULL.

* blk_throtl_bio() indicates return status both with its return value
  and in/out param **@bio.  The former is used to indicate whether
  queue is found to be dead during throtl processing.  The latter
  whether the bio is throttled.

  There's no point in returning DEAD check result from
  blk_throtl_bio().  The queue can die after blk_throtl_bio() is
  finished but before make_request_fn() grabs queue lock.

  Make it take *@bio instead and return boolean result indicating
  whether the request is throttled or not.

This patch doesn't cause any visible functional difference.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      bc16a4f9
    • Tejun Heo's avatar
      block: reorganize queue draining · e3c78ca5
      Tejun Heo authored 
      Reorganize queue draining related code in preparation of queue exit
changes.

* Factor out actual draining from elv_quiesce_start() to
  blk_drain_queue().

* Make elv_quiesce_start/end() responsible for their own locking.

* Replace open-coded ELVSWITCH clearing in elevator_switch() with
  elv_quiesce_end().

This patch doesn't cause any visible functional difference.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      e3c78ca5
    • Tejun Heo's avatar
      block: drop unnecessary blk_get/put_queue() in scsi_cmd_ioctl() and blk_get_tg() · 315fceee
      Tejun Heo authored 
      blk_get/put_queue() in scsi_cmd_ioctl() and throtl_get_tg() are
completely bogus.  The caller must have a reference to the queue on
entry and taking an extra reference doesn't change anything.

For scsi_cmd_ioctl(), the only effect is that it ends up checking
QUEUE_FLAG_DEAD on entry; however, this is bogus as queue can die
right after blk_get_queue().  Dead queue should be and is handled in
request issue path (it's somewhat broken now but that's a separate
problem and doesn't affect this one much).

throtl_get_tg() incorrectly assumes that q is rcu freed.  Also, it
doesn't check return value of blk_get_queue().  If the queue is
already dead, it ends up doing an extra put.

Drop them.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      315fceee
    • Tejun Heo's avatar
      block: pass around REQ_* flags instead of broken down booleans during request alloc/free · 75eb6c37
      Tejun Heo authored 
      blk_alloc_request() and freed_request() take different combinations of
REQ_* @flags, @priv and @is_sync when @flags is superset of the latter
two.  Make them take @flags only.  This cleans up the code a bit and
will ease updating allocation related REQ_* flags.

This patch doesn't introduce any functional difference.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      75eb6c37
    • Tejun Heo's avatar
      block: move blk_throtl prototypes to block/blk.h · bc9fcbf9
      Tejun Heo authored 
      blk_throtl interface is block internal and there's no reason to have
them in linux/blkdev.h.  Move them to block/blk.h.

This patch doesn't introduce any functional change.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      bc9fcbf9
    • Tejun Heo's avatar
      block: fix genhd refcounting in blkio_policy_parse_and_set() · ece84241
      Tejun Heo authored 
      blkio_policy_parse_and_set() calls blkio_check_dev_num() to check
whether the given dev_t is valid.  blkio_check_dev_num() uses
get_gendisk() for verification but never puts the returned genhd
leaking the reference.

This patch collapses blkio_check_dev_num() into its caller and updates
it such that the genhd is put before returning.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      ece84241
    • Tejun Heo's avatar
      block: make gendisk hold a reference to its queue · 523e1d39
      Tejun Heo authored 
      The following command sequence triggers an oops.

# mount /dev/sdb1 /mnt
# echo 1 > /sys/class/scsi_device/0\:0\:1\:0/device/delete
# umount /mnt

 general protection fault: 0000 [#1] PREEMPT SMP
 CPU 2
 Modules linked in:

 Pid: 791, comm: umount Not tainted 3.1.0-rc3-work+ #8 Bochs Bochs
 RIP: 0010:[<ffffffff810d0879>]  [<ffffffff810d0879>] __lock_acquire+0x389/0x1d60
...
 Call Trace:
  [<ffffffff810d2845>] lock_acquire+0x95/0x140
  [<ffffffff81aed87b>] _raw_spin_lock+0x3b/0x50
  [<ffffffff811573bc>] bdi_lock_two+0x5c/0x70
  [<ffffffff811c2f6c>] bdev_inode_switch_bdi+0x4c/0xf0
  [<ffffffff811c3fcb>] __blkdev_put+0x11b/0x1d0
  [<ffffffff811c4010>] __blkdev_put+0x160/0x1d0
  [<ffffffff811c40df>] blkdev_put+0x5f/0x190
  [<ffffffff8118f18d>] kill_block_super+0x4d/0x80
  [<ffffffff8118f4a5>] deactivate_locked_super+0x45/0x70
  [<ffffffff8119003a>] deactivate_super+0x4a/0x70
  [<ffffffff811ac4ad>] mntput_no_expire+0xed/0x130
  [<ffffffff811acf2e>] sys_umount+0x7e/0x3a0
  [<ffffffff81aeeeab>] system_call_fastpath+0x16/0x1b

This is because bdev holds on to disk but disk doesn't pin the
associated queue.  If a SCSI device is removed while the device is
still open, the sdev puts the base reference to the queue on release.
When the bdev is finally released, the associated queue is already
gone along with the bdi and bdev_inode_switch_bdi() ends up
dereferencing already freed bdi.

Even if it were not for this bug, disk not holding onto the associated
queue is very unusual and error-prone.

Fix it by making add_disk() take an extra reference to its queue and
put it on disk_release() and ensuring that disk and its fops owner are
put in that order after all accesses to the disk and queue are
complete.
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Cc: stable@kernel.org
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      523e1d39
    • Jens Axboe's avatar
      Merge branch 'v3.1-rc10' into for-3.2/core · 5c04b426
      Jens Axboe authored 
      Conflicts:
	block/blk-core.c
	include/linux/blkdev.h
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      5c04b426
  3. 18 Oct, 2011 1 commit
  5. 17 Oct, 2011 1 commit
    • Linus Torvalds's avatar
      Avoid using variable-length arrays in kernel/sys.c · a84a79e4
      Linus Torvalds authored 
      The size is always valid, but variable-length arrays generate worse code
for no good reason (unless the function happens to be inlined and the
compiler sees the length for the simple constant it is).

Also, there seems to be some code generation problem on POWER, where
Henrik Bakken reports that register r28 can get corrupted under some
subtle circumstances (interrupt happening at the wrong time?).  That all
indicates some seriously broken compiler issues, but since variable
length arrays are bad regardless, there's little point in trying to
chase it down.

"Just don't do that, then".
Reported-by: default avatarHenrik Grindal Bakken <henribak@cisco.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: stable@kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a84a79e4
  7. 16 Oct, 2011 1 commit
  9. 15 Oct, 2011 3 commits
  11. 14 Oct, 2011 6 commits
  13. 13 Oct, 2011 7 commits
  15. 11 Oct, 2011 5 commits
  17. 10 Oct, 2011 7 commits
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