kernel/linux.git/block/blk-flush.c, branch v4.9.166

block: flush: fix IO hang in case of flood fua req

2016-10-26T13:49:27+00:00

This patch fixes one issue reported by Kent, which can be triggered in bcachefs over sata disk. Actually it is a generic issue in block flush vs. blk-tag. Cc: Christoph Hellwig Reported-by: Kent Overstreet Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

blk-mq: remove ->map_queue

2016-09-15T14:42:03+00:00

All drivers use the default, so provide an inline version of it. If we ever need other queue mapping we can add an optional method back, although supporting will also require major changes to the queue setup code. This provides better code generation, and better debugability as well. Signed-off-by: Christoph Hellwig Reviewed-by: Keith Busch Signed-off-by: Jens Axboe

block, drivers, fs: rename REQ_FLUSH to REQ_PREFLUSH

2016-06-07T19:41:38+00:00

To avoid confusion between REQ_OP_FLUSH, which is handled by request_fn drivers, and upper layers requesting the block layer perform a flush sequence along with possibly a WRITE, this patch renames REQ_FLUSH to REQ_PREFLUSH. Signed-off-by: Mike Christie Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe

block, drivers: add REQ_OP_FLUSH operation

2016-06-07T19:41:38+00:00

This adds a REQ_OP_FLUSH operation that is sent to request_fn based drivers by the block layer's flush code, instead of sending requests with the request->cmd_flags REQ_FLUSH bit set. Signed-off-by: Mike Christie Reviewed-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe

block, fs, mm, drivers: use bio set/get op accessors

2016-06-07T19:41:38+00:00

This patch converts the simple bi_rw use cases in the block, drivers, mm and fs code to set/get the bio operation using bio_set_op_attrs/bio_op These should be simple one or two liner cases, so I just did them in one patch. The next patches handle the more complicated cases in a module per patch. Signed-off-by: Mike Christie Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe

block/fs/drivers: remove rw argument from submit_bio

2016-06-07T19:41:38+00:00

This has callers of submit_bio/submit_bio_wait set the bio->bi_rw instead of passing it in. This makes that use the same as generic_make_request and how we set the other bio fields. Signed-off-by: Mike Christie Fixed up fs/ext4/crypto.c Signed-off-by: Jens Axboe

block: kill off q->flush_flags

2016-04-13T19:33:19+00:00

Now that we converted everything to the newer block write cache interface, kill off the queue flush_flags and queueable flush entries. Signed-off-by: Jens Axboe

Revert "blk-flush: Queue through IO scheduler when flush not required"

2015-11-25T17:12:54+00:00

This reverts commit 1b2ff19e6a957b1ef0f365ad331b608af80e932e. Jan writes: -- Thanks for report! After some investigation I found out we allocate elevator specific data in __get_request() only for non-flush requests. And this is actually required since the flush machinery uses the space in struct request for something else. Doh. So my patch is just wrong and not easy to fix since at the time __get_request() is called we are not sure whether the flush machinery will be used in the end. Jens, please revert 1b2ff19e6a957b1ef0f365ad331b608af80e932e. Thanks! I'm somewhat surprised that you can reliably hit the race where flushing gets disabled for the device just while the request is in flight. But I guess during boot it makes some sense. -- So let's just revert it, we can fix the queue run manually after the fact. This race is rare enough that it didn't trigger in testing, it requires the specific disable-while-in-flight scenario to trigger.

blk-flush: Queue through IO scheduler when flush not required

2015-11-16T22:23:51+00:00

Currently blk_insert_flush() just adds flush request to q->queue_head when flush is not required. That completely bypasses IO scheduler so e.g. CFQ can be idling waiting for new request to arrive and will idle through the whole window unnecessarily. Luckily this only happens in rare cases as usually checks in generic_make_request_checks() clear FLUSH and FUA flags early if they are not needed. When no flushing is actually required, we can easily fix the problem by properly queueing the request through the IO scheduler. Ideally IO scheduler should be also made aware of requests queued via blk_flush_queue_rq(). However inserting flush request through IO scheduler can have unwanted side-effects since due to flush batching delaying the flush request in IO scheduler will delay all flush requests possibly coming from other processes. So we keep adding the request directly to q->queue_head. Signed-off-by: Jan Kara Reviewed-by: Jeff Moyer Signed-off-by: Jens Axboe

blk-mq: fix race between timeout and freeing request

2015-08-15T15:45:21+00:00

Inside timeout handler, blk_mq_tag_to_rq() is called to retrieve the request from one tag. This way is obviously wrong because the request can be freed any time and some fiedds of the request can't be trusted, then kernel oops might be triggered[1]. Currently wrt. blk_mq_tag_to_rq(), the only special case is that the flush request can share same tag with the request cloned from, and the two requests can't be active at the same time, so this patch fixes the above issue by updating tags->rqs[tag] with the active request(either flush rq or the request cloned from) of the tag. Also blk_mq_tag_to_rq() gets much simplified with this patch. Given blk_mq_tag_to_rq() is mainly for drivers and the caller must make sure the request can't be freed, so in bt_for_each() this helper is replaced with tags->rqs[tag]. [1] kernel oops log [ 439.696220] BUG: unable to handle kernel NULL pointer dereference at 0000000000000158^M [ 439.697162] IP: [] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.700653] PGD 7ef765067 PUD 7ef764067 PMD 0 ^M [ 439.700653] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M [ 439.700653] Dumping ftrace buffer:^M [ 439.700653] (ftrace buffer empty)^M [ 439.700653] Modules linked in: nbd ipv6 kvm_intel kvm serio_raw^M [ 439.700653] CPU: 6 PID: 2779 Comm: stress-ng-sigfd Not tainted 4.2.0-rc5-next-20150805+ #265^M [ 439.730500] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011^M [ 439.730500] task: ffff880605308000 ti: ffff88060530c000 task.ti: ffff88060530c000^M [ 439.730500] RIP: 0010:[] [] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.730500] RSP: 0018:ffff880819203da0 EFLAGS: 00010283^M [ 439.730500] RAX: ffff880811b0e000 RBX: ffff8800bb465f00 RCX: 0000000000000002^M [ 439.730500] RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000^M [ 439.730500] RBP: ffff880819203db0 R08: 0000000000000002 R09: 0000000000000000^M [ 439.730500] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000202^M [ 439.730500] R13: ffff880814104800 R14: 0000000000000002 R15: ffff880811a2ea00^M [ 439.730500] FS: 00007f165b3f5740(0000) GS:ffff880819200000(0000) knlGS:0000000000000000^M [ 439.730500] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b^M [ 439.730500] CR2: 0000000000000158 CR3: 00000007ef766000 CR4: 00000000000006e0^M [ 439.730500] Stack:^M [ 439.730500] 0000000000000008 ffff8808114eed90 ffff880819203e00 ffffffff812dc104^M [ 439.755663] ffff880819203e40 ffffffff812d9f5e 0000020000000000 ffff8808114eed80^M [ 439.755663] Call Trace:^M [ 439.755663] ^M [ 439.755663] [] bt_for_each+0x6e/0xc8^M [ 439.755663] [] ? blk_mq_rq_timed_out+0x6a/0x6a^M [ 439.755663] [] ? blk_mq_rq_timed_out+0x6a/0x6a^M [ 439.755663] [] blk_mq_tag_busy_iter+0x55/0x5e^M [ 439.755663] [] ? blk_mq_bio_to_request+0x38/0x38^M [ 439.755663] [] blk_mq_rq_timer+0x5d/0xd4^M [ 439.755663] [] call_timer_fn+0xf7/0x284^M [ 439.755663] [] ? call_timer_fn+0x5/0x284^M [ 439.755663] [] ? blk_mq_bio_to_request+0x38/0x38^M [ 439.755663] [] run_timer_softirq+0x1ce/0x1f8^M [ 439.755663] [] __do_softirq+0x181/0x3a4^M [ 439.755663] [] irq_exit+0x40/0x94^M [ 439.755663] [] smp_apic_timer_interrupt+0x33/0x3e^M [ 439.755663] [] apic_timer_interrupt+0x84/0x90^M [ 439.755663] ^M [ 439.755663] [] ? _raw_spin_unlock_irq+0x32/0x4a^M [ 439.755663] [] finish_task_switch+0xe0/0x163^M [ 439.755663] [] ? finish_task_switch+0xa2/0x163^M [ 439.755663] [] __schedule+0x469/0x6cd^M [ 439.755663] [] schedule+0x82/0x9a^M [ 439.789267] [] signalfd_read+0x186/0x49a^M [ 439.790911] [] ? wake_up_q+0x47/0x47^M [ 439.790911] [] __vfs_read+0x28/0x9f^M [ 439.790911] [] ? __fget_light+0x4d/0x74^M [ 439.790911] [] vfs_read+0x7a/0xc6^M [ 439.790911] [] SyS_read+0x49/0x7f^M [ 439.790911] [] entry_SYSCALL_64_fastpath+0x12/0x6f^M [ 439.790911] Code: 48 89 e5 e8 a9 b8 e7 ff 5d c3 0f 1f 44 00 00 55 89 f2 48 89 e5 41 54 41 89 f4 53 48 8b 47 60 48 8b 1c d0 48 8b 7b 30 48 8b 53 38 <48> 8b 87 58 01 00 00 48 85 c0 75 09 48 8b 97 88 0c 00 00 eb 10 ^M [ 439.790911] RIP [] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.790911] RSP ^M [ 439.790911] CR2: 0000000000000158^M [ 439.790911] ---[ end trace d40af58949325661 ]---^M Cc: Signed-off-by: Ming Lei Signed-off-by: Jens Axboe