snowball/igloo-kernel.git/block, branch u0

block: fix mis-synchronisation in blkdev_issue_zeroout()

2011-03-11T14:36:08+00:00

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 Reported-by: Eric Whitney Tested-by: Eric Whitney Reviewed-by: Jeff Moyer CC: Dmitry Monakhov Signed-off-by: Jens Axboe

block: blk-flush shouldn't call directly into q->request_fn() __blk_run_queue()

2011-03-02T13:48:06+00:00

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 Reported-by: Jan Beulich Cc: "David S. Miller" Cc: stable@kernel.org Signed-off-by: Jens Axboe

block: add @force_kblockd to __blk_run_queue()

2011-03-02T13:48:05+00:00

__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 Cc: Jan Beulich Cc: James Bottomley Cc: stable@kernel.org Signed-off-by: Jens Axboe

block: fix kernel-doc format for blkdev_issue_zeroout

2011-03-01T18:45:24+00:00

Signed-off-by: Ben Hutchings Signed-off-by: Andrew Morton Signed-off-by: Jens Axboe

blk-throttle: Do not use kblockd workqueue for throtl work

2011-03-01T18:41:53+00:00

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 Signed-off-by: Vivek Goyal Acked-by: Tejun Heo Signed-off-by: Jens Axboe

Merge branch 'for-linus' of git://neil.brown.name/md

2011-02-25T19:13:26+00:00

* '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

block: fix refcounting in BLKBSZSET

2011-02-24T16:54:21+00:00

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 Acked-by: Tejun Heo Signed-off-by: Miklos Szeredi Signed-off-by: Linus Torvalds

Fix over-zealous flush_disk when changing device size.

2011-02-24T06:25:47+00:00

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 Cc: Andrew Patterson Cc: Jens Axboe Signed-off-by: NeilBrown

Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

2011-02-09T19:45:21+00:00

* '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 -objs with -y loop: queue_lock NULL pointer derefence in blk_throtl_exit drivers/block/Makefile: replace the use of -objs with -y blktrace: Don't output messages if NOTIFY isn't set.

cfq-iosched: Don't wait if queue already has requests.

2011-02-09T13:22:36+00:00

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 Reviewed-by: Gui Jianfeng Acked-by: Vivek Goyal Signed-off-by: Jens Axboe