27 Jun, 2011
2 commits
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ioc->ioc_data is rcu protectd, so uses correct API to access it.
This doesn't change any behavior, but just make code consistent.Signed-off-by: Shaohua Li
Cc: stable@kernel.org # after ab4bd22d
Signed-off-by: Jens Axboe -
I got a rcu warnning at boot. the ioc->ioc_data is rcu_deferenced, but
doesn't hold rcu_read_lock.Signed-off-by: Shaohua Li
Cc: stable@kernel.org # after ab4bd22d
Signed-off-by: Jens Axboe
13 Jun, 2011
1 commit
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Use the compiler to verify format strings and arguments.
Fix fallout.
Signed-off-by: Joe Perches
Signed-off-by: Jens Axboe
10 Jun, 2011
3 commits
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disk_block_events() should guarantee that the event work is not in
flight on return and once blocked it shouldn't issue further
cancellations.Because there was no synchronization between the first blocker doing
cancel_delayed_work_sync() and the following blockers, the following
blockers could finish before cancellation was complete, which broke
both guarantees - event work could be in flight and cancellation could
happen after return.This bug triggered WARN_ON_ONCE() in disk_clear_events() reported in
bug#34662.https://bugzilla.kernel.org/show_bug.cgi?id=34662
Fix it by adding an outer mutex which protects both block count
manipulation and work cancellation.-v2: Use outer mutex instead of bit waitqueue per Linus.
Signed-off-by: Tejun Heo
Tested-by: Sitsofe Wheeler
Reported-by: Sitsofe Wheeler
Reported-by: Borislav Petkov
Reported-by: Meelis Roos
Reported-by: Linus Torvalds
Cc: Andrew Morton
Cc: Jens Axboe
Cc: Kay Sievers
Signed-off-by: Jens Axboe -
After the previous update to disk_check_events(), nobody is using
non-syncing __disk_block_events(). Remove @sync and, as this makes
__disk_block_events() virtually identical to disk_block_events(),
remove the underscore prefixed version.Signed-off-by: Tejun Heo
Cc: Jens Axboe
Signed-off-by: Jens Axboe -
This patch is part of fix for triggering of WARN_ON_ONCE() in
disk_clear_events() reported in bug#34662.https://bugzilla.kernel.org/show_bug.cgi?id=34662
disk_clear_events() blocks events, schedules and flushes the event
work. It expects the work to have started execution on schedule and
finished on return from flush. WARN_ON_ONCE() triggers if the event
work hasn't executed as expected. This problem happens because
__disk_block_events() fails to guarantee that the event work item is
not in flight on return from the function in race-free manner. The
problem is two-fold and this patch addresses one of them.When __disk_block_events() is called with @sync == %false, it bumps
event block count, calls cancel_delayed_work() and return. This makes
it impossible to guarantee that event polling is not in flight on
return from syncing __disk_block_events() - if the first blocker was
non-syncing, polling could still be in progress and later syncing ones
would assume that the first blocker already canceled it.Making __disk_block_events() cancel_sync regardless of block count
isn't feasible either as it may race with forced event checking in
disk_clear_events().As disk_check_events() is the only user of non-syncing
__disk_block_events(), updating it to directly cancel and schedule
event work is the easiest way to solve the issue.Note that there's another bug in __disk_block_events() and this patch
doesn't fix the issue completely. Later patch will fix the other bug.Signed-off-by: Tejun Heo
Tested-by: Sitsofe Wheeler
Reported-by: Sitsofe Wheeler
Reported-by: Borislav Petkov
Reported-by: Meelis Roos
Reported-by: Linus Torvalds
Cc: Andrew Morton
Cc: Jens Axboe
Cc: Kay Sievers
Signed-off-by: Jens Axboe
06 Jun, 2011
1 commit
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Since we are modifying this RCU pointer, we need to hold
the lock protecting it around it.This fixes a potential reuse and double free of a cfq
io_context structure. The bug has been in CFQ for a long
time, it hit very few people but those it did hit seemed
to see it a lot.Tracked in RH bugzilla here:
https://bugzilla.redhat.com/show_bug.cgi?id=577968
Credit goes to Paul Bolle for figuring out that the issue
was around the one-hit ioc->ioc_data cache. Thanks to his
hard work the issue is now fixed.Cc: stable@kernel.org
Signed-off-by: Jens Axboe
02 Jun, 2011
2 commits
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list_entry() and hlist_entry() are both simply aliases for
container_of(), but since io_context.cic_list.first is an hlist_node one
should at least use the correct alias.Signed-off-by: Paul Bolle
Signed-off-by: Jens Axboe -
queue_fail can only be reached if cic is NULL, so its check for cic must
be bogus.Signed-off-by: Paul Bolle
Signed-off-by: Jens Axboe
01 Jun, 2011
1 commit
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Fix comment typo and remove unnecessary semicolon at macro
Signed-off-by: Kyungmin Park
Signed-off-by: Jens Axboe
28 May, 2011
1 commit
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
loop: export module parameters
block: export blk_{get,put}_queue()
block: remove unused variable in bio_attempt_front_merge()
block: always allocate genhd->ev if check_events is implemented
brd: export module parameters
brd: fix comment on initial device creation
brd: handle on-demand devices correctly
brd: limit 'max_part' module param to DISK_MAX_PARTS
brd: get rid of unused members from struct brd_device
block: fix oops on !disk->queue and sysfs discard alignment display
27 May, 2011
4 commits
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We need them in SCSI to fix a bug, but currently they are not
exported to modules. Export them.Signed-off-by: Jens Axboe
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Add cgroup subsystem callbacks for per-thread attachment in atomic contexts
Add can_attach_task(), pre_attach(), and attach_task() as new callbacks
for cgroups's subsystem interface. Unlike can_attach and attach, these
are for per-thread operations, to be called potentially many times when
attaching an entire threadgroup.Also, the old "bool threadgroup" interface is removed, as replaced by
this. All subsystems are modified for the new interface - of note is
cpuset, which requires from/to nodemasks for attach to be globally scoped
(though per-cpuset would work too) to persist from its pre_attach to
attach_task and attach.This is a pre-patch for cgroup-procs-writable.patch.
Signed-off-by: Ben Blum
Cc: "Eric W. Biederman"
Cc: Li Zefan
Cc: Matt Helsley
Reviewed-by: Paul Menage
Cc: Oleg Nesterov
Cc: David Rientjes
Cc: Miao Xie
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
sector is never read inside the function.
Signed-off-by: Luca Tettamanti
Signed-off-by: Jens Axboe -
9fd097b149 (block: unexport DISK_EVENT_MEDIA_CHANGE for legacy/fringe
drivers) removed DISK_EVENT_MEDIA_CHANGE from legacy/fringe block
drivers which have inadequate ->check_events(). Combined with earlier
change 7c88a168da (block: don't propagate unlisted DISK_EVENTs to
userland), this enables using ->check_events() for internal processing
while avoiding enabling in-kernel block event polling which can lead
to infinite event loop.Unfortunately, this made many drivers including floppy without any bit
set in disk->events and ->async_events in which case disk_add_events()
simply skipped allocation of disk->ev, which disables whole event
handling. As ->check_events() is still used during open processing
for revalidation, this can lead to open failure.This patch always allocates disk->ev if ->check_events is implemented.
In the long term, it would make sense to simply include the event
structure inline into genhd as it's now used by virtually all block
devices.Signed-off-by: Tejun Heo
Reported-by: Ondrej Zary
Reported-by: Alex Villacis Lasso
Cc: stable@kernel.org
Signed-off-by: Jens Axboe
24 May, 2011
5 commits
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When struct cfq_data allocation fails, cic_index need to be freed.
Signed-off-by: Namhyung Kim
Signed-off-by: Jens Axboe -
The 'group_changed' variable is initialized to 0 and never changed, so
checking the variable is meaningless.It is a leftover from 0bbfeb832042 ("cfq-iosched: Always provide group
iosolation."). Let's get rid of it.Signed-off-by: Namhyung Kim
Cc: Justin TerAvest
Signed-off-by: Jens Axboe -
Reduce the number of bit operations in cfq_choose_req() on average
(and worst) cases.Signed-off-by: Namhyung Kim
Signed-off-by: Jens Axboe -
Simplify the calculation in cfq_prio_to_maxrq(), plus replace CFQ_PRIO_LISTS to
IOPRIO_BE_NR since they are the same and IOPRIO_BE_NR looks more reasonable in
this context IMHO.Signed-off-by: Namhyung Kim
Signed-off-by: Jens Axboe -
If we don't explicitly initialize it to zero, CFQ might think that
cgroup of ioc has changed and it generates lots of unnecessary calls
to call_for_each_cic(changed_cgroup). Fix it.cfq_get_io_context()
cfq_ioc_set_cgroup()
call_for_each_cic(ioc, changed_cgroup)Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe
23 May, 2011
3 commits
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Commit 73c101011926 ("block: initial patch for on-stack per-task plugging")
removed calls to elv_bio_merged() when @bio merged with @req. Re-add them.This in turn will update merged stats in associated group. That
should be safe as long as request has got reference to the blkio_group.Signed-off-by: Namhyung Kim
Cc: Divyesh Shah
Signed-off-by: Jens Axboe -
Make BLKIO_STAT_MERGED per cpu hence gettring rid of need of taking
blkg->stats_lock.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
We allocated per cpu stats struct for root group but did not free it.
Fix it.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe
21 May, 2011
16 commits
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We don't need them anymore, so kill:
- REQ_ON_PLUG checks in various places
- !rq_mergeable() check in plug mergingSigned-off-by: Jens Axboe
-
This patch merges in a fix that missed 2.6.39 final.
Conflicts:
block/blk.h -
Currently we take a queue lock on each bio to check if there are any
throttling rules associated with the group and also update the stats.
Now access the group under rcu and update the stats without taking
the queue lock. Queue lock is taken only if there are throttling rules
associated with the group.So the common case of root group when there are no rules, save
unnecessary pounding of request queue lock.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Now dispatch stats update is lock free. But reset of these stats still
takes blkg->stats_lock and is dependent on that. As stats are per cpu,
we should be able to just reset the stats on each cpu without any locks.
(Atleast for 64bit arch).On 32bit arch there is a small race where 64bit updates are not atomic.
The result of this race can be that in the presence of other writers,
one might not get 0 value after reset of a stat and might see something
intermediateOne can write more complicated code to cover this race like sending IPI
to other cpus to reset stats and for offline cpus, reset these directly.Right not I am not taking that path because reset_update is more of a
debug feature and it can happen only on 32bit arch and possibility of
it happening is small. Will fix it if it becomes a real problem. For
the time being going for code simplicity.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Some of the stats are 64bit and updation will be non atomic on 32bit
architecture. Use sequence counters on 32bit arch to make reading
of stats safe.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Currently we take blkg_stat lock for even updating the stats. So even if
a group has no throttling rules (common case for root group), we end
up taking blkg_lock, for updating the stats.Make dispatch stats per cpu so that these can be updated without taking
blkg lock.If cpu goes offline, these stats simply disappear. No protection has
been provided for that yet. Do we really need anything for that?Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Soon we will allow accessing a throtl_grp under rcu_read_lock(). Hence
start freeing up throtl_grp after one rcu grace period.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Use same helper function for root group as we use with dynamically
allocated groups to add it to various lists.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
A helper function for the code which is used at 2-3 places. Makes reading
code little easier.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Currently, we allocate root throtl_grp statically. But as we will be
introducing per cpu stat pointers and that will be allocated
dynamically even for root group, we might as well make whole root
throtl_grp allocation dynamic and treat it in same manner as other
groups.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Currently, all the cfq_group or throtl_group allocations happen while
we are holding ->queue_lock and sleeping is not allowed.Soon, we will move to per cpu stats and also need to allocate the
per group stats. As one can not call alloc_percpu() from atomic
context as it can sleep, we need to drop ->queue_lock, allocate the
group, retake the lock and continue processing.In throttling code, I check the queue DEAD flag again to make sure
that driver did not call blk_cleanup_queue() in the mean time.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
blkg->key = cfqd is an rcu protected pointer and hence we used to do
call_rcu(cfqd->rcu_head) to free up cfqd after one rcu grace period.The problem here is that even though cfqd is around, there are no
gurantees that associated request queue (td->queue) or q->queue_lock
is still around. A driver might have called blk_cleanup_queue() and
release the lock.It might happen that after freeing up the lock we call
blkg->key->queue->queue_ock and crash. This is possible in following
path.blkiocg_destroy()
blkio_unlink_group_fn()
cfq_unlink_blkio_group()Hence, wait for an rcu peirod if there are groups which have not
been unlinked from blkcg->blkg_list. That way, if there are any groups
which are taking cfq_unlink_blkio_group() path, can safely take queue
lock.This is how we have taken care of race in throttling logic also.
Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Nobody seems to be using cfq_find_alloc_cfqg() function parameter "create".
Get rid of that.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
cgroup unaccounted_time file is created only if CONFIG_DEBUG_BLK_CGROUP=y.
there are some fields which are out side this config option. Fix that.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Group initialization code seems to be at two places. root group
initialization in blk_throtl_init() and dynamically allocated group
in throtl_find_alloc_tg(). Create a common function and use at both
the places.Signed-off-by: Vivek Goyal
Signed-off-by: Jens Axboe -
Since for-2.6.40/core was forked off the 2.6.39 devel tree, we've
had churn in the core area that makes it difficult to handle
patches for eg cfq or blk-throttle. Instead of requiring that they
be based in older versions with bugs that have been fixed later
in the rc cycle, merge in 2.6.39 final.Also fixes up conflicts in the below files.
Conflicts:
drivers/block/paride/pcd.c
drivers/cdrom/viocd.c
drivers/ide/ide-cd.cSigned-off-by: Jens Axboe
19 May, 2011
1 commit
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blk_cleanup_queue() calls elevator_exit() and after this, we can't
touch the elevator without oopsing. __elv_next_request() must check
for this state because in the refcounted queue model, we can still
call it after blk_cleanup_queue() has been called.This was reported as causing an oops attributable to scsi.
Signed-off-by: James Bottomley
Cc: stable@kernel.org
Signed-off-by: Jens Axboe
