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2011-03-11block: fix mis-synchronisation in blkdev_issue_zeroout()Lukas Czerner
BZ29402 https://bugzilla.kernel.org/show_bug.cgi?id=29402 We can hit serious mis-synchronization in bio completion path of blkdev_issue_zeroout() leading to a panic. The problem is that when we are going to wait_for_completion() in blkdev_issue_zeroout() we check if the bb.done equals issued (number of submitted bios). If it does, we can skip the wait_for_completition() and just out of the function since there is nothing to wait for. However, there is a ordering problem because bio_batch_end_io() is calling atomic_inc(&bb->done) before complete(), hence it might seem to blkdev_issue_zeroout() that all bios has been completed and exit. At this point when bio_batch_end_io() is going to call complete(bb->wait), bb and wait does not longer exist since it was allocated on stack in blkdev_issue_zeroout() ==> panic! (thread 1) (thread 2) bio_batch_end_io() blkdev_issue_zeroout() if(bb) { ... if (bb->end_io) ... bb->end_io(bio, err); ... atomic_inc(&bb->done); ... ... while (issued != atomic_read(&bb.done)) ... (let issued == bb.done) ... (do the rest of the function) ... return ret; complete(bb->wait); ^^^^^^^^ panic We can fix this easily by simplifying bio_batch and completion counting. Also remove bio_end_io_t *end_io since it is not used. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Reported-by: Eric Whitney <eric.whitney@hp.com> Tested-by: Eric Whitney <eric.whitney@hp.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> CC: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-03-02block: blk-flush shouldn't call directly into q->request_fn() __blk_run_queue()Tejun Heo
blk-flush decomposes a flush into sequence of multiple requests. On completion of a request, the next one is queued; however, block layer must not implicitly call into q->request_fn() directly from completion path. This makes the queue behave unexpectedly when seen from the drivers and violates the assumption that q->request_fn() is called with process context + queue_lock. This patch makes blk-flush the following two changes to make sure q->request_fn() is not called directly from request completion path. - blk_flush_complete_seq_end_io() now asks __blk_run_queue() to always use kblockd instead of calling directly into q->request_fn(). - queue_next_fseq() uses ELEVATOR_INSERT_REQUEUE instead of ELEVATOR_INSERT_FRONT so that elv_insert() doesn't try to unplug the request queue directly. Reported by Jan in the following threads. http://thread.gmane.org/gmane.linux.ide/48778 http://thread.gmane.org/gmane.linux.ide/48786 stable: applicable to v2.6.37. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Jan Beulich <JBeulich@novell.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-03-02block: add @force_kblockd to __blk_run_queue()Tejun Heo
__blk_run_queue() automatically either calls q->request_fn() directly or schedules kblockd depending on whether the function is recursed. blk-flush implementation needs to be able to explicitly choose kblockd. Add @force_kblockd. All the current users are converted to specify %false for the parameter and this patch doesn't introduce any behavior change. stable: This is prerequisite for fixing ide oops caused by the new blk-flush implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Jan Beulich <JBeulich@novell.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-03-01block: fix kernel-doc format for blkdev_issue_zerooutBen Hutchings
Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-03-01blk-throttle: Do not use kblockd workqueue for throtl workVivek Goyal
o Dominik Klein reported a system hang issue while doing some blkio throttling testing. https://lkml.org/lkml/2011/2/24/173 o Some tracing revealed that CFQ was not dispatching any more jobs as queue unplug was not happening. And queue unplug was not happening because unplug work was not being called as there was one throttling work on same cpu which as not finished yet. And throttling work had not finished as it was tyring to dispatch a bio to CFQ but all the request descriptors were consume to it was put to sleep. o So basically it is a cyclic dependecny between CFQ unplug work and throtl dispatch work. Tejun suggested that use separate workqueue for such cases. o This patch uses a separate workqueue for throttle related work and does not rely on kblockd workqueue anymore. Cc: stable@kernel.org Reported-by: Dominik Klein <dk@in-telegence.net> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-02-25Merge branch 'for-linus' of git://neil.brown.name/mdLinus Torvalds
* 'for-linus' of git://neil.brown.name/md: md: Fix - again - partition detection when array becomes active Fix over-zealous flush_disk when changing device size. md: avoid spinlock problem in blk_throtl_exit md: correctly handle probe of an 'mdp' device. md: don't set_capacity before array is active. md: Fix raid1->raid0 takeover
2011-02-24block: fix refcounting in BLKBSZSETMiklos Szeredi
Adam Kovari and others reported that disconnecting an USB drive with an ntfs-3g filesystem would cause "kernel BUG at fs/inode.c:1421!" to be triggered. The BUG could be traced back to ioctl(BLKBSZSET), which would erroneously decrement the refcount on the bdev. This is because blkdev_get() expects the refcount to be already incremented and either returns success or decrements the refcount and returns an error. The bug was introduced by e525fd89 (block: make blkdev_get/put() handle exclusive access), which didn't take into account this behavior of blkdev_get(). This fixes https://bugzilla.kernel.org/show_bug.cgi?id=29202 (and likely 29792 too) Reported-by: Adam Kovari <kovariadam@gmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-24Fix over-zealous flush_disk when changing device size.NeilBrown
There are two cases when we call flush_disk. In one, the device has disappeared (check_disk_change) so any data will hold becomes irrelevant. In the oter, the device has changed size (check_disk_size_change) so data we hold may be irrelevant. In both cases it makes sense to discard any 'clean' buffers, so they will be read back from the device if needed. In the former case it makes sense to discard 'dirty' buffers as there will never be anywhere safe to write the data. In the second case it *does*not* make sense to discard dirty buffers as that will lead to file system corruption when you simply enlarge the containing devices. flush_disk calls __invalidate_devices. __invalidate_device calls both invalidate_inodes and invalidate_bdev. invalidate_inodes *does* discard I_DIRTY inodes and this does lead to fs corruption. invalidate_bev *does*not* discard dirty pages, but I don't really care about that at present. So this patch adds a flag to __invalidate_device (calling it __invalidate_device2) to indicate whether dirty buffers should be killed, and this is passed to invalidate_inodes which can choose to skip dirty inodes. flusk_disk then passes true from check_disk_change and false from check_disk_size_change. dm avoids tripping over this problem by calling i_size_write directly rathher than using check_disk_size_change. md does use check_disk_size_change and so is affected. This regression was introduced by commit 608aeef17a which causes check_disk_size_change to call flush_disk, so it is suitable for any kernel since 2.6.27. Cc: stable@kernel.org Acked-by: Jeff Moyer <jmoyer@redhat.com> Cc: Andrew Patterson <andrew.patterson@hp.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: NeilBrown <neilb@suse.de>
2011-02-09Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds
* 'for-linus' of git://git.kernel.dk/linux-2.6-block: cdrom: support devices that have check_events but not media_changed cfq-iosched: Don't wait if queue already has requests. blkio-throttle: Avoid calling blkiocg_lookup_group() for root group cfq: rename a function to give it more appropriate name cciss: make cciss_revalidate not loop through CISS_MAX_LUNS volumes unnecessarily. drivers/block/aoe/Makefile: replace the use of <module>-objs with <module>-y loop: queue_lock NULL pointer derefence in blk_throtl_exit drivers/block/Makefile: replace the use of <module>-objs with <module>-y blktrace: Don't output messages if NOTIFY isn't set.
2011-02-09cfq-iosched: Don't wait if queue already has requests.Justin TerAvest
Commit 7667aa0630407bc07dc38dcc79d29cc0a65553c1 added logic to wait for the last queue of the group to become busy (have at least one request), so that the group does not lose out for not being continuously backlogged. The commit did not check for the condition that the last queue already has some requests. As a result, if the queue already has requests, wait_busy is set. Later on, cfq_select_queue() checks the flag, and decides that since the queue has a request now and wait_busy is set, the queue is expired. This results in early expiration of the queue. This patch fixes the problem by adding a check to see if queue already has requests. If it does, wait_busy is not set. As a result, time slices do not expire early. The queues with more than one request are usually buffered writers. Testing shows improvement in isolation between buffered writers. Cc: stable@kernel.org Signed-off-by: Justin TerAvest <teravest@google.com> Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-20kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERTDavid Rientjes
The meaning of CONFIG_EMBEDDED has long since been obsoleted; the option is used to configure any non-standard kernel with a much larger scope than only small devices. This patch renames the option to CONFIG_EXPERT in init/Kconfig and fixes references to the option throughout the kernel. A new CONFIG_EMBEDDED option is added that automatically selects CONFIG_EXPERT when enabled and can be used in the future to isolate options that should only be considered for embedded systems (RISC architectures, SLOB, etc). Calling the option "EXPERT" more accurately represents its intention: only expert users who understand the impact of the configuration changes they are making should enable it. Reviewed-by: Ingo Molnar <mingo@elte.hu> Acked-by: David Woodhouse <david.woodhouse@intel.com> Signed-off-by: David Rientjes <rientjes@google.com> Cc: Greg KH <gregkh@suse.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jens Axboe <axboe@kernel.dk> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Robin Holt <holt@sgi.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-01-19blkio-throttle: Avoid calling blkiocg_lookup_group() for root groupVivek Goyal
o Jeff Moyer was doing some testing on a RAM backed disk and blkiocg_lookup_group() showed up high overhead after memcpy(). Similarly somebody else reported that blkiocg_lookup_group() is eating 6% extra cpu. Though looking at the code I can't think why the overhead of this function is so high. One thing is that it is called with very high frequency (once for every IO). o For lot of folks blkio controller will be compiled in but they might not have actually created cgroups. Hence optimize the case of root cgroup where we can avoid calling blkiocg_lookup_group() if IO is happening in root group (common case). Reported-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-19cfq: rename a function to give it more appropriate nameVivek Goyal
o Rename a function to give it more approprate name. We are calculating cfq queue slice and function name gives the impression as if cfq group slice length is being calculated. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-14block cfq: compensate preempted queue even if it has no slice assignedShaohua Li
If a queue is preempted before it gets slice assigned, the queue doesn't get compensation, which looks unfair. For such queue, we compensate it for a whole slice. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-14block cfq: make queue preempt work for queues from different workloadShaohua Li
I got this: fio-874 [007] 2157.724514: 8,32 m N cfq874 preempt fio-874 [007] 2157.724519: 8,32 m N cfq830 slice expired t=1 fio-874 [007] 2157.724520: 8,32 m N cfq830 sl_used=1 disp=0 charge=1 iops=0 sect=0 fio-874 [007] 2157.724521: 8,32 m N cfq830 set_active wl_prio:0 wl_type:0 fio-874 [007] 2157.724522: 8,32 m N cfq830 Not idling. st->count:1 cfq830 is an async queue, and preempted by a sync queue cfq874. But since we have cfqg->saved_workload_slice mechanism, the preempt is a nop. Looks currently our preempt is totally broken if the two queues are not from the same workload type. Below patch fixes it. This will might make async queue starvation, but it's what our old code does before cgroup is added. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-13Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds
* 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block: (43 commits) block: ensure that completion error gets properly traced blktrace: add missing probe argument to block_bio_complete block cfq: don't use atomic_t for cfq_group block cfq: don't use atomic_t for cfq_queue block: trace event block fix unassigned field block: add internal hd part table references block: fix accounting bug on cross partition merges kref: add kref_test_and_get bio-integrity: mark kintegrityd_wq highpri and CPU intensive block: make kblockd_workqueue smarter Revert "sd: implement sd_check_events()" block: Clean up exit_io_context() source code. Fix compile warnings due to missing removal of a 'ret' variable fs/block: type signature of major_to_index(int) to major_to_index(unsigned) block: convert !IS_ERR(p) && p to !IS_ERR_NOR_NULL(p) cfq-iosched: don't check cfqg in choose_service_tree() fs/splice: Pull buf->ops->confirm() from splice_from_pipe actors cdrom: export cdrom_check_events() sd: implement sd_check_events() sr: implement sr_check_events() ...
2011-01-13Merge branch 'for-2.6.38/event-handling' into for-2.6.38/coreJens Axboe
2011-01-07block cfq: don't use atomic_t for cfq_groupShaohua Li
cfq_group->ref is used with queue_lock hold, the only exception is cfq_set_request, which looks like a bug to me, so ref doesn't need to be an atomic and atomic operation is slower. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-07block cfq: don't use atomic_t for cfq_queueShaohua Li
cfq_queue->ref is used with queue_lock hold, so ref doesn't need to be an atomic and atomic operation is slower. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-07block: add internal hd part table referencesJens Axboe
We can't use krefs since it's apparently restricted to very basic reference counting. This reverts commit e4a683c8. Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-05block: fix accounting bug on cross partition mergesJerome Marchand
/proc/diskstats would display a strange output as follows. $ cat /proc/diskstats |grep sda 8 0 sda 90524 7579 102154 20464 0 0 0 0 0 14096 20089 8 1 sda1 19085 1352 21841 4209 0 0 0 0 4294967064 15689 4293424691 ~~~~~~~~~~ 8 2 sda2 71252 3624 74891 15950 0 0 0 0 232 23995 1562390 8 3 sda3 54 487 2188 92 0 0 0 0 0 88 92 8 4 sda4 4 0 8 0 0 0 0 0 0 0 0 8 5 sda5 81 2027 2130 138 0 0 0 0 0 87 137 Its reason is the wrong way of accounting hd_struct->in_flight. When a bio is merged into a request belongs to different partition by ELEVATOR_FRONT_MERGE. The detailed root cause is as follows. Assuming that there are two partition, sda1 and sda2. 1. A request for sda2 is in request_queue. Hence sda1's hd_struct->in_flight is 0 and sda2's one is 1. | hd_struct->in_flight --------------------------- sda1 | 0 sda2 | 1 --------------------------- 2. A bio belongs to sda1 is issued and is merged into the request mentioned on step1 by ELEVATOR_BACK_MERGE. The first sector of the request is changed from sda2 region to sda1 region. However the two partition's hd_struct->in_flight are not changed. | hd_struct->in_flight --------------------------- sda1 | 0 sda2 | 1 --------------------------- 3. The request is finished and blk_account_io_done() is called. In this case, sda2's hd_struct->in_flight, not a sda1's one, is decremented. | hd_struct->in_flight --------------------------- sda1 | -1 sda2 | 1 --------------------------- The patch fixes the problem by caching the partition lookup inside the request structure, hence making sure that the increment and decrement will always happen on the same partition struct. This also speeds up IO with accounting enabled, since it cuts down on the number of lookups we have to do. Also add a refcount to struct hd_struct to keep the partition in memory as long as users exist. We use kref_test_and_get() to ensure we don't add a reference to a partition which is going away. Signed-off-by: Jerome Marchand <jmarchan@redhat.com> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2011-01-03block: make kblockd_workqueue smarterTejun Heo
kblockd is used for unplugging and may affect IO latency and throughput and the max number of concurrent work items are bound by the number of block devices. Make it HIGHPRI workqueue w/ default max concurrency. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-22Merge branch 'master' into for-nextJiri Kosina
Conflicts: MAINTAINERS arch/arm/mach-omap2/pm24xx.c drivers/scsi/bfa/bfa_fcpim.c Needed to update to apply fixes for which the old branch was too outdated.
2010-12-21block: Clean up exit_io_context() source code.Bart Van Assche
This patch fixes a spelling error in a source code comment and removes superfluous braces in the function exit_io_context(). Signed-off-by: Bart Van Assche <bvanassche@acm.org> Cc: Jens Axboe <jaxboe@fusionio.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-20Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds
* 'for-linus' of git://git.kernel.dk/linux-2.6-block: cciss: fix cciss_revalidate panic block: max hardware sectors limit wrapper block: Deprecate QUEUE_FLAG_CLUSTER and use queue_limits instead blk-throttle: Correct the placement of smp_rmb() blk-throttle: Trim/adjust slice_end once a bio has been dispatched block: check for proper length of iov entries earlier in blk_rq_map_user_iov() drbd: fix for spin_lock_irqsave in endio callback drbd: don't recvmsg with zero length
2010-12-17fs/block: type signature of major_to_index(int) to major_to_index(unsigned)Yang Zhang
The major/minor device numbers are always defined and used as `unsigned'. Signed-off-by: Yang Zhang <kthreadd@gmail.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-17block: convert !IS_ERR(p) && p to !IS_ERR_NOR_NULL(p)Yang Zhang
Signed-off-by: Yang Zhang <kthreadd@gmail.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-17cfq-iosched: don't check cfqg in choose_service_tree()Gui Jianfeng
When cfq_choose_cfqg() is called in select_queue(), there must be at least one backlogged CFQ queue waiting for dispatching, hence there must be at least one backlogged CFQ group on service tree. So we never call choose_service_tree() with cfqg == NULL. Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-17block: max hardware sectors limit wrapperMike Snitzer
Implement blk_limits_max_hw_sectors() and make blk_queue_max_hw_sectors() a wrapper around it. DM needs this to avoid setting queue_limits' max_hw_sectors and max_sectors directly. dm_set_device_limits() now leverages blk_limits_max_hw_sectors() logic to establish the appropriate max_hw_sectors minimum (PAGE_SIZE). Fixes issue where DM was incorrectly setting max_sectors rather than max_hw_sectors (which caused dm_merge_bvec()'s max_hw_sectors check to be ineffective). Signed-off-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@kernel.org Acked-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-17block: Deprecate QUEUE_FLAG_CLUSTER and use queue_limits insteadMartin K. Petersen
When stacking devices, a request_queue is not always available. This forced us to have a no_cluster flag in the queue_limits that could be used as a carrier until the request_queue had been set up for a metadevice. There were several problems with that approach. First of all it was up to the stacking device to remember to set queue flag after stacking had completed. Also, the queue flag and the queue limits had to be kept in sync at all times. We got that wrong, which could lead to us issuing commands that went beyond the max scatterlist limit set by the driver. The proper fix is to avoid having two flags for tracking the same thing. We deprecate QUEUE_FLAG_CLUSTER and use the queue limit directly in the block layer merging functions. The queue_limit 'no_cluster' is turned into 'cluster' to avoid double negatives and to ease stacking. Clustering defaults to being enabled as before. The queue flag logic is removed from the stacking function, and explicitly setting the cluster flag is no longer necessary in DM and MD. Reported-by: Ed Lin <ed.lin@promise.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-16implement in-kernel gendisk events handlingTejun Heo
Currently, media presence polling for removeable block devices is done from userland. There are several issues with this. * Polling is done by periodically opening the device. For SCSI devices, the command sequence generated by such action involves a few different commands including TEST_UNIT_READY. This behavior, while perfectly legal, is different from Windows which only issues single command, GET_EVENT_STATUS_NOTIFICATION. Unfortunately, some ATAPI devices lock up after being periodically queried such command sequences. * There is no reliable and unintrusive way for a userland program to tell whether the target device is safe for media presence polling. For example, polling for media presence during an on-going burning session can make it fail. The polling program can avoid this by opening the device with O_EXCL but then it risks making a valid exclusive user of the device fail w/ -EBUSY. * Userland polling is unnecessarily heavy and in-kernel implementation is lighter and better coordinated (workqueue, timer slack). This patch implements framework for in-kernel disk event handling, which includes media presence polling. * bdops->check_events() is added, which supercedes ->media_changed(). It should check whether there's any pending event and return if so. Currently, two events are defined - DISK_EVENT_MEDIA_CHANGE and DISK_EVENT_EJECT_REQUEST. ->check_events() is guaranteed not to be called parallelly. * gendisk->events and ->async_events are added. These should be initialized by block driver before passing the device to add_disk(). The former contains the mask of all supported events and the latter the mask of all events which the device can report without polling. /sys/block/*/events[_async] export these to userland. * Kernel parameter block.events_dfl_poll_msecs controls the system polling interval (default is 0 which means disable) and /sys/block/*/events_poll_msecs control polling intervals for individual devices (default is -1 meaning use system setting). Note that if a device can report all supported events asynchronously and its polling interval isn't explicitly set, the device won't be polled regardless of the system polling interval. * If a device is opened exclusively with write access, event checking is automatically disabled until all write exclusive accesses are released. * There are event 'clearing' events. For example, both of currently defined events are cleared after the device has been successfully opened. This information is passed to ->check_events() callback using @clearing argument as a hint. * Event checking is always performed from system_nrt_wq and timer slack is set to 25% for polling. * Nothing changes for drivers which implement ->media_changed() but not ->check_events(). Going forward, all drivers will be converted to ->check_events() and ->media_change() will be dropped. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-16block: move register_disk() and del_gendisk() to block/genhd.cTejun Heo
There's no reason for register_disk() and del_gendisk() to be in fs/partitions/check.c. Move both to genhd.c. While at it, collapse unlink_gendisk(), which was artificially in a separate function due to genhd.c / check.c split, into del_gendisk(). Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-16block: kill genhd_media_change_notify()Tejun Heo
There's no user of the facility. Kill it. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-13block cfq: select new workload if priority changedShaohua Li writes
If priority is changed, continuing to check workload_expires and service tree count of the previous workload does not make sense. We should always choose the workload with lowest key of new priority in such case. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-09[SCSI] bsg: correct fault if queue object removed while dev_t openJames Smart
This patch corrects an issue in bsg that results in a general protection fault if an LLD is removed while an application is using an open file handle to a bsg device, and the application issues an ioctl. The fault occurs because the class_dev is NULL, having been cleared in bsg_unregister_queue() when the driver was removed. With this patch, a check is made for the class_dev, and the application will receive ENXIO if the related object is gone. Signed-off-by: Carl Lajeunesse <carl.lajeunesse@emulex.com> Signed-off-by: James Smart <james.smart@emulex.com> Signed-off-by: James Bottomley <James.Bottomley@suse.de>
2010-12-01blk-throttle: Correct the placement of smp_rmb()Vivek Goyal
o I was discussing what are the variable being updated without spin lock and why do we need barriers and Oleg pointed out that location of smp_rmb() should be between read of td->limits_changed and tg->limits_changed. This patch fixes it. o Following is one possible sequence of events. Say cpu0 is executing throtl_update_blkio_group_read_bps() and cpu1 is executing throtl_process_limit_change(). cpu0 cpu1 tg->limits_changed = true; smp_mb__before_atomic_inc(); atomic_inc(&td->limits_changed); if (!atomic_read(&td->limits_changed)) return; if (tg->limits_changed) do_something; If cpu0 has updated tg->limits_changed and td->limits_changed, we want to make sure that if update to td->limits_changed is visible on cpu1, then update to tg->limits_changed should also be visible. Oleg pointed out to ensure that we need to insert an smp_rmb() between td->limits_changed read and tg->limits_changed read. o I had erroneously put smp_rmb() before atomic_read(&td->limits_changed). This patch fixes it. Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-12-01blk-throttle: Trim/adjust slice_end once a bio has been dispatchedVivek Goyal
o During some testing I did following and noticed throttling stops working. - Put a very low limit on a cgroup, say 1 byte per second. - Start some reads, this will set slice_end to a very high value. - Change the limit to higher value say 1MB/s - Now IO unthrottles and finishes as expected. - Try to do the read again but IO is not limited to 1MB/s as expected. o What is happening. - Initially low value of limit sets slice_end to a very high value. - During updation of limit, slice_end is not being truncated. - Very high value of slice_end leads to keeping the existing slice valid for a very long time and new slice does not start. - tg_may_dispatch() is called in blk_throtle_bio(), and trim_slice() is not called in this path. So slice_start is some old value and practically we are able to do huge amount of IO. o There are many ways it can be fixed. I have fixed it by trying to adjust/cleanup slice_end in trim_slice(). Generally we extend slices if bio is big and can't be dispatched in one slice. After dispatch of bio, readjust the slice_end to make sure we don't end up with huge values. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-11-30cfq-iosched: Get rid of on_st flagGui Jianfeng
It's able to check whether a CFQ group on a service tree by checking "cfqg->rb_node". There's no need to maintain an extra flag here. Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-11-30cfq-iosched: Get rid of st->activeGui Jianfeng
When a cfq group is running, it won't be dequeued from service tree, so there's no need to store the active one in st->active. Just gid rid of it. Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-11-29block: check for proper length of iov entries earlier in blk_rq_map_user_iov()Xiaotian Feng
commit 9284bcf checks for proper length of iov entries in blk_rq_map_user_iov(). But if the map is unaligned, kernel will break out the loop without checking for the proper length. So we need to check the proper length before the unalign check. Signed-off-by: Xiaotian Feng <dfeng@redhat.com> Cc: stable@kernel.org Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-11-27Merge branch 'cleanup-bd_claim' of ↵Jens Axboe
git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into for-2.6.38/core
2010-11-27Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-blockLinus Torvalds
* 'for-linus' of git://git.kernel.dk/linux-2.6-block: cciss: fix build for PROC_FS disabled block: fix amiga and atari floppy driver compile warning blk-throttle: Fix calculation of max number of WRITES to be dispatched ioprio: grab rcu_read_lock in sys_ioprio_{set,get}() xen/blkfront: cope with backend that fail empty BLKIF_OP_WRITE_BARRIER requests xen/blkfront: Implement FUA with BLKIF_OP_WRITE_BARRIER xen/blkfront: change blk_shadow.request to proper pointer xen/blkfront: map REQ_FLUSH into a full barrier
2010-11-17BKL: remove extraneous #include <smp_lock.h>Arnd Bergmann
The big kernel lock has been removed from all these files at some point, leaving only the #include. Remove this too as a cleanup. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-11-16block: Rename "block_remap" tracepoint to "block_bio_remap" to clarify the ↵Mike Snitzer
event. Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-11-16Merge branch 'for-2.6.38/rc2-holder' into for-2.6.38/coreJens Axboe
2010-11-16Merge branch 'v2.6.37-rc2' into for-2.6.38/coreJens Axboe
2010-11-15blk-cgroup: Allow creation of hierarchical cgroupsVivek Goyal
o Allow hierarchical cgroup creation for blkio controller o Currently we disallow it as both the io controller policies (throttling as well as proportion bandwidth) do not support hierarhical accounting and control. But the flip side is that blkio controller can not be used with libvirt as libvirt creates a cgroup hierarchy deeper than 1 level. <top-level-cgroup-dir>/<controller>/libvirt/qemu/<virtual-machine-groups> o So this patch will allow creation of cgroup hierarhcy but at the backend everything will be treated as flat. So if somebody created a an hierarchy like as follows. root / \ test1 test2 | test3 CFQ and throttling will practically treat all groups at same level. pivot / | \ \ root test1 test2 test3 o Once we have actual support for hierarchical accounting and control then we can introduce another cgroup tunable file "blkio.use_hierarchy" which will be 0 by default but if user wants to enforce hierarhical control then it can be set to 1. This way there should not be any ABI problems down the line. o The only not so pretty part is introduction of extra file "use_hierarchy" down the line. Kame-san had mentioned that hierarhical accounting is expensive in memory controller hence they keep it off by default. I suspect same will be the case for IO controller also as for each IO completion we shall have to account IO through hierarchy up to the root. if yes, then it probably is not a very bad idea to introduce this extra file so that it will be used only when somebody needs it and some people might enable hierarchy only in part of the hierarchy. o This is how basically memory controller also uses "use_hierarhcy" and they also allowed creation of hierarchies when actual backend support was not available. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com> Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com> Reviewed-by: Ciju Rajan K <ciju@linux.vnet.ibm.com> Tested-by: Ciju Rajan K <ciju@linux.vnet.ibm.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-11-15blk-throttle: Fix calculation of max number of WRITES to be dispatchedVivek Goyal
o Currently we try to dispatch more READS and less WRITES (75%, 25%) in one dispatch round. ummy pointed out that there is a bug in max_nr_writes calculation. This patch fixes it. Reported-by: ummy y <yummylln@yahoo.com.cn> Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
2010-11-13block: make blkdev_get/put() handle exclusive accessTejun Heo
Over time, block layer has accumulated a set of APIs dealing with bdev open, close, claim and release. * blkdev_get/put() are the primary open and close functions. * bd_claim/release() deal with exclusive open. * open/close_bdev_exclusive() are combination of open and claim and the other way around, respectively. * bd_link/unlink_disk_holder() to create and remove holder/slave symlinks. * open_by_devnum() wraps bdget() + blkdev_get(). The interface is a bit confusing and the decoupling of open and claim makes it impossible to properly guarantee exclusive access as in-kernel open + claim sequence can disturb the existing exclusive open even before the block layer knows the current open if for another exclusive access. Reorganize the interface such that, * blkdev_get() is extended to include exclusive access management. @holder argument is added and, if is @FMODE_EXCL specified, it will gain exclusive access atomically w.r.t. other exclusive accesses. * blkdev_put() is similarly extended. It now takes @mode argument and if @FMODE_EXCL is set, it releases an exclusive access. Also, when the last exclusive claim is released, the holder/slave symlinks are removed automatically. * bd_claim/release() and close_bdev_exclusive() are no longer necessary and either made static or removed. * bd_link_disk_holder() remains the same but bd_unlink_disk_holder() is no longer necessary and removed. * open_bdev_exclusive() becomes a simple wrapper around lookup_bdev() and blkdev_get(). It also has an unexpected extra bdev_read_only() test which probably should be moved into blkdev_get(). * open_by_devnum() is modified to take @holder argument and pass it to blkdev_get(). Most of bdev open/close operations are unified into blkdev_get/put() and most exclusive accesses are tested atomically at the open time (as it should). This cleans up code and removes some, both valid and invalid, but unnecessary all the same, corner cases. open_bdev_exclusive() and open_by_devnum() can use further cleanup - rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop special features. Well, let's leave them for another day. Most conversions are straight-forward. drbd conversion is a bit more involved as there was some reordering, but the logic should stay the same. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Neil Brown <neilb@suse.de> Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Acked-by: Mike Snitzer <snitzer@redhat.com> Acked-by: Philipp Reisner <philipp.reisner@linbit.com> Cc: Peter Osterlund <petero2@telia.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Jan Kara <jack@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <joel.becker@oracle.com> Cc: Alex Elder <aelder@sgi.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: dm-devel@redhat.com Cc: drbd-dev@lists.linbit.com Cc: Leo Chen <leochen@broadcom.com> Cc: Scott Branden <sbranden@broadcom.com> Cc: Chris Mason <chris.mason@oracle.com> Cc: Steven Whitehouse <swhiteho@redhat.com> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: Joern Engel <joern@logfs.org> Cc: reiserfs-devel@vger.kernel.org Cc: Alexander Viro <viro@zeniv.linux.org.uk>
2010-11-11block: remove unused copy_io_context()Jens Axboe
Reported-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Jens Axboe <jaxboe@fusionio.com>