From 450adcbe518ab3a3953d8475309525d22de77cba Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Tue, 1 Mar 2011 13:40:54 -0500 Subject: blk-throttle: Do not use kblockd workqueue for throtl work 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 --- block/blk-core.c | 7 ------- block/blk-throttle.c | 29 ++++++++++++++++++----------- include/linux/blkdev.h | 3 --- 3 files changed, 18 insertions(+), 21 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 2f4002f79a2..792ece27616 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -2610,13 +2610,6 @@ int kblockd_schedule_work(struct request_queue *q, struct work_struct *work) } EXPORT_SYMBOL(kblockd_schedule_work); -int kblockd_schedule_delayed_work(struct request_queue *q, - struct delayed_work *dwork, unsigned long delay) -{ - return queue_delayed_work(kblockd_workqueue, dwork, delay); -} -EXPORT_SYMBOL(kblockd_schedule_delayed_work); - int __init blk_dev_init(void) { BUILD_BUG_ON(__REQ_NR_BITS > 8 * diff --git a/block/blk-throttle.c b/block/blk-throttle.c index a89043a3caa..e36cc10a346 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -20,6 +20,11 @@ static int throtl_quantum = 32; /* Throttling is performed over 100ms slice and after that slice is renewed */ static unsigned long throtl_slice = HZ/10; /* 100 ms */ +/* A workqueue to queue throttle related work */ +static struct workqueue_struct *kthrotld_workqueue; +static void throtl_schedule_delayed_work(struct throtl_data *td, + unsigned long delay); + struct throtl_rb_root { struct rb_root rb; struct rb_node *left; @@ -345,10 +350,9 @@ static void throtl_schedule_next_dispatch(struct throtl_data *td) update_min_dispatch_time(st); if (time_before_eq(st->min_disptime, jiffies)) - throtl_schedule_delayed_work(td->queue, 0); + throtl_schedule_delayed_work(td, 0); else - throtl_schedule_delayed_work(td->queue, - (st->min_disptime - jiffies)); + throtl_schedule_delayed_work(td, (st->min_disptime - jiffies)); } static inline void @@ -815,10 +819,10 @@ void blk_throtl_work(struct work_struct *work) } /* Call with queue lock held */ -void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay) +static void +throtl_schedule_delayed_work(struct throtl_data *td, unsigned long delay) { - struct throtl_data *td = q->td; struct delayed_work *dwork = &td->throtl_work; if (total_nr_queued(td) > 0) { @@ -827,12 +831,11 @@ void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay) * Cancel that and schedule a new one. */ __cancel_delayed_work(dwork); - kblockd_schedule_delayed_work(q, dwork, delay); + queue_delayed_work(kthrotld_workqueue, dwork, delay); throtl_log(td, "schedule work. delay=%lu jiffies=%lu", delay, jiffies); } } -EXPORT_SYMBOL(throtl_schedule_delayed_work); static void throtl_destroy_tg(struct throtl_data *td, struct throtl_grp *tg) @@ -920,7 +923,7 @@ static void throtl_update_blkio_group_read_bps(void *key, smp_mb__after_atomic_inc(); /* Schedule a work now to process the limit change */ - throtl_schedule_delayed_work(td->queue, 0); + throtl_schedule_delayed_work(td, 0); } static void throtl_update_blkio_group_write_bps(void *key, @@ -934,7 +937,7 @@ static void throtl_update_blkio_group_write_bps(void *key, smp_mb__before_atomic_inc(); atomic_inc(&td->limits_changed); smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td->queue, 0); + throtl_schedule_delayed_work(td, 0); } static void throtl_update_blkio_group_read_iops(void *key, @@ -948,7 +951,7 @@ static void throtl_update_blkio_group_read_iops(void *key, smp_mb__before_atomic_inc(); atomic_inc(&td->limits_changed); smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td->queue, 0); + throtl_schedule_delayed_work(td, 0); } static void throtl_update_blkio_group_write_iops(void *key, @@ -962,7 +965,7 @@ static void throtl_update_blkio_group_write_iops(void *key, smp_mb__before_atomic_inc(); atomic_inc(&td->limits_changed); smp_mb__after_atomic_inc(); - throtl_schedule_delayed_work(td->queue, 0); + throtl_schedule_delayed_work(td, 0); } void throtl_shutdown_timer_wq(struct request_queue *q) @@ -1135,6 +1138,10 @@ void blk_throtl_exit(struct request_queue *q) static int __init throtl_init(void) { + kthrotld_workqueue = alloc_workqueue("kthrotld", WQ_MEM_RECLAIM, 0); + if (!kthrotld_workqueue) + panic("Failed to create kthrotld\n"); + blkio_policy_register(&blkio_policy_throtl); return 0; } diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 4d18ff34670..dd8cd0f47e3 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1088,7 +1088,6 @@ static inline void put_dev_sector(Sector p) struct work_struct; int kblockd_schedule_work(struct request_queue *q, struct work_struct *work); -int kblockd_schedule_delayed_work(struct request_queue *q, struct delayed_work *dwork, unsigned long delay); #ifdef CONFIG_BLK_CGROUP /* @@ -1136,7 +1135,6 @@ static inline uint64_t rq_io_start_time_ns(struct request *req) extern int blk_throtl_init(struct request_queue *q); extern void blk_throtl_exit(struct request_queue *q); extern int blk_throtl_bio(struct request_queue *q, struct bio **bio); -extern void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay); extern void throtl_shutdown_timer_wq(struct request_queue *q); #else /* CONFIG_BLK_DEV_THROTTLING */ static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio) @@ -1146,7 +1144,6 @@ static inline int blk_throtl_bio(struct request_queue *q, struct bio **bio) static inline int blk_throtl_init(struct request_queue *q) { return 0; } static inline int blk_throtl_exit(struct request_queue *q) { return 0; } -static inline void throtl_schedule_delayed_work(struct request_queue *q, unsigned long delay) {} static inline void throtl_shutdown_timer_wq(struct request_queue *q) {} #endif /* CONFIG_BLK_DEV_THROTTLING */ -- cgit v1.2.3 From 291d24f6d9e7bbef81454fade8a44720665c7302 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Tue, 1 Mar 2011 13:45:24 -0500 Subject: block: fix kernel-doc format for blkdev_issue_zeroout Signed-off-by: Ben Hutchings Signed-off-by: Andrew Morton Signed-off-by: Jens Axboe --- block/blk-lib.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-lib.c b/block/blk-lib.c index 1a320d2406b..eec78becb35 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c @@ -132,7 +132,7 @@ static void bio_batch_end_io(struct bio *bio, int err) } /** - * blkdev_issue_zeroout generate number of zero filed write bios + * blkdev_issue_zeroout - generate number of zero filed write bios * @bdev: blockdev to issue * @sector: start sector * @nr_sects: number of sectors to write -- cgit v1.2.3 From 1654e7411a1ad4999fe7890ef51d2a2bbb1fcf76 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 2 Mar 2011 08:48:05 -0500 Subject: block: add @force_kblockd to __blk_run_queue() __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/blk-core.c | 11 ++++++----- block/blk-flush.c | 2 +- block/cfq-iosched.c | 6 +++--- block/elevator.c | 4 ++-- drivers/scsi/scsi_lib.c | 2 +- drivers/scsi/scsi_transport_fc.c | 2 +- include/linux/blkdev.h | 2 +- 7 files changed, 15 insertions(+), 14 deletions(-) diff --git a/block/blk-core.c b/block/blk-core.c index 792ece27616..518dd423a5f 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -352,7 +352,7 @@ void blk_start_queue(struct request_queue *q) WARN_ON(!irqs_disabled()); queue_flag_clear(QUEUE_FLAG_STOPPED, q); - __blk_run_queue(q); + __blk_run_queue(q, false); } EXPORT_SYMBOL(blk_start_queue); @@ -403,13 +403,14 @@ EXPORT_SYMBOL(blk_sync_queue); /** * __blk_run_queue - run a single device queue * @q: The queue to run + * @force_kblockd: Don't run @q->request_fn directly. Use kblockd. * * Description: * See @blk_run_queue. This variant must be called with the queue lock * held and interrupts disabled. * */ -void __blk_run_queue(struct request_queue *q) +void __blk_run_queue(struct request_queue *q, bool force_kblockd) { blk_remove_plug(q); @@ -423,7 +424,7 @@ void __blk_run_queue(struct request_queue *q) * Only recurse once to avoid overrunning the stack, let the unplug * handling reinvoke the handler shortly if we already got there. */ - if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { + if (!force_kblockd && !queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) { q->request_fn(q); queue_flag_clear(QUEUE_FLAG_REENTER, q); } else { @@ -446,7 +447,7 @@ void blk_run_queue(struct request_queue *q) unsigned long flags; spin_lock_irqsave(q->queue_lock, flags); - __blk_run_queue(q); + __blk_run_queue(q, false); spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL(blk_run_queue); @@ -1053,7 +1054,7 @@ void blk_insert_request(struct request_queue *q, struct request *rq, drive_stat_acct(rq, 1); __elv_add_request(q, rq, where, 0); - __blk_run_queue(q); + __blk_run_queue(q, false); spin_unlock_irqrestore(q->queue_lock, flags); } EXPORT_SYMBOL(blk_insert_request); diff --git a/block/blk-flush.c b/block/blk-flush.c index 54b123d6563..56adaa8d55c 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -69,7 +69,7 @@ static void blk_flush_complete_seq_end_io(struct request_queue *q, * queue. Kick the queue in those cases. */ if (was_empty && next_rq) - __blk_run_queue(q); + __blk_run_queue(q, false); } static void pre_flush_end_io(struct request *rq, int error) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 7be4c795962..ea83a4f0c27 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3355,7 +3355,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, cfqd->busy_queues > 1) { cfq_del_timer(cfqd, cfqq); cfq_clear_cfqq_wait_request(cfqq); - __blk_run_queue(cfqd->queue); + __blk_run_queue(cfqd->queue, false); } else { cfq_blkiocg_update_idle_time_stats( &cfqq->cfqg->blkg); @@ -3370,7 +3370,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, * this new queue is RT and the current one is BE */ cfq_preempt_queue(cfqd, cfqq); - __blk_run_queue(cfqd->queue); + __blk_run_queue(cfqd->queue, false); } } @@ -3731,7 +3731,7 @@ static void cfq_kick_queue(struct work_struct *work) struct request_queue *q = cfqd->queue; spin_lock_irq(q->queue_lock); - __blk_run_queue(cfqd->queue); + __blk_run_queue(cfqd->queue, false); spin_unlock_irq(q->queue_lock); } diff --git a/block/elevator.c b/block/elevator.c index 2569512830d..236e93c1f46 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -602,7 +602,7 @@ void elv_quiesce_start(struct request_queue *q) */ elv_drain_elevator(q); while (q->rq.elvpriv) { - __blk_run_queue(q); + __blk_run_queue(q, false); spin_unlock_irq(q->queue_lock); msleep(10); spin_lock_irq(q->queue_lock); @@ -651,7 +651,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where) * with anything. There's no point in delaying queue * processing. */ - __blk_run_queue(q); + __blk_run_queue(q, false); break; case ELEVATOR_INSERT_SORT: diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 9045c52abd2..fb2bb35c62c 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -443,7 +443,7 @@ static void scsi_run_queue(struct request_queue *q) &sdev->request_queue->queue_flags); if (flagset) queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue); - __blk_run_queue(sdev->request_queue); + __blk_run_queue(sdev->request_queue, false); if (flagset) queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue); spin_unlock(sdev->request_queue->queue_lock); diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c index 998c01be323..5c3ccfc6b62 100644 --- a/drivers/scsi/scsi_transport_fc.c +++ b/drivers/scsi/scsi_transport_fc.c @@ -3829,7 +3829,7 @@ fc_bsg_goose_queue(struct fc_rport *rport) !test_bit(QUEUE_FLAG_REENTER, &rport->rqst_q->queue_flags); if (flagset) queue_flag_set(QUEUE_FLAG_REENTER, rport->rqst_q); - __blk_run_queue(rport->rqst_q); + __blk_run_queue(rport->rqst_q, false); if (flagset) queue_flag_clear(QUEUE_FLAG_REENTER, rport->rqst_q); spin_unlock_irqrestore(rport->rqst_q->queue_lock, flags); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index dd8cd0f47e3..d5063e1b555 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -699,7 +699,7 @@ extern void blk_start_queue(struct request_queue *q); extern void blk_stop_queue(struct request_queue *q); extern void blk_sync_queue(struct request_queue *q); extern void __blk_stop_queue(struct request_queue *q); -extern void __blk_run_queue(struct request_queue *); +extern void __blk_run_queue(struct request_queue *q, bool force_kblockd); extern void blk_run_queue(struct request_queue *); extern int blk_rq_map_user(struct request_queue *, struct request *, struct rq_map_data *, void __user *, unsigned long, -- cgit v1.2.3 From 255bb490c8c27eed484d538efe6ef6a7473bd3f6 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 2 Mar 2011 08:48:06 -0500 Subject: block: blk-flush shouldn't call directly into q->request_fn() __blk_run_queue() 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/blk-flush.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/block/blk-flush.c b/block/blk-flush.c index 56adaa8d55c..b27d0208611 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -66,10 +66,12 @@ static void blk_flush_complete_seq_end_io(struct request_queue *q, /* * Moving a request silently to empty queue_head may stall the - * queue. Kick the queue in those cases. + * queue. Kick the queue in those cases. This function is called + * from request completion path and calling directly into + * request_fn may confuse the driver. Always use kblockd. */ if (was_empty && next_rq) - __blk_run_queue(q, false); + __blk_run_queue(q, true); } static void pre_flush_end_io(struct request *rq, int error) @@ -130,7 +132,7 @@ static struct request *queue_next_fseq(struct request_queue *q) BUG(); } - elv_insert(q, rq, ELEVATOR_INSERT_FRONT); + elv_insert(q, rq, ELEVATOR_INSERT_REQUEUE); return rq; } -- cgit v1.2.3 From 2d3a8497f8cc5aca14b722cd37d51f6c15ff9f74 Mon Sep 17 00:00:00 2001 From: Tao Ma Date: Thu, 3 Mar 2011 10:53:20 -0500 Subject: blktrace: Remove blk_fill_rwbs_rq. If we enable trace events to trace block actions, We use blk_fill_rwbs_rq to analyze the corresponding actions in request's cmd_flags, but we only choose the minor 2 bits from it, so most of other flags(e.g, REQ_SYNC) are missing. For example, with a sync write we get: write_test-2409 [001] 160.013869: block_rq_insert: 3,64 W 0 () 258135 + = 8 [write_test] Since now we have integrated the flags of both bio and request, it is safe to pass rq->cmd_flags directly to blk_fill_rwbs and blk_fill_rwbs_rq isn't needed any more. With this patch, after a sync write we get: write_test-2417 [000] 226.603878: block_rq_insert: 3,64 WS 0 () 258135 += 8 [write_test] Signed-off-by: Tao Ma Acked-by: Jeff Moyer Signed-off-by: Jens Axboe --- include/linux/blktrace_api.h | 1 - include/trace/events/block.h | 6 +++--- kernel/trace/blktrace.c | 16 ---------------- 3 files changed, 3 insertions(+), 20 deletions(-) diff --git a/include/linux/blktrace_api.h b/include/linux/blktrace_api.h index 3395cf7130f..b22fb0d3db0 100644 --- a/include/linux/blktrace_api.h +++ b/include/linux/blktrace_api.h @@ -245,7 +245,6 @@ static inline int blk_cmd_buf_len(struct request *rq) extern void blk_dump_cmd(char *buf, struct request *rq); extern void blk_fill_rwbs(char *rwbs, u32 rw, int bytes); -extern void blk_fill_rwbs_rq(char *rwbs, struct request *rq); #endif /* CONFIG_EVENT_TRACING && CONFIG_BLOCK */ diff --git a/include/trace/events/block.h b/include/trace/events/block.h index aba421d68f6..78f18adb49c 100644 --- a/include/trace/events/block.h +++ b/include/trace/events/block.h @@ -31,7 +31,7 @@ DECLARE_EVENT_CLASS(block_rq_with_error, 0 : blk_rq_sectors(rq); __entry->errors = rq->errors; - blk_fill_rwbs_rq(__entry->rwbs, rq); + blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, blk_rq_bytes(rq)); blk_dump_cmd(__get_str(cmd), rq); ), @@ -118,7 +118,7 @@ DECLARE_EVENT_CLASS(block_rq, __entry->bytes = (rq->cmd_type == REQ_TYPE_BLOCK_PC) ? blk_rq_bytes(rq) : 0; - blk_fill_rwbs_rq(__entry->rwbs, rq); + blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, blk_rq_bytes(rq)); blk_dump_cmd(__get_str(cmd), rq); memcpy(__entry->comm, current->comm, TASK_COMM_LEN); ), @@ -563,7 +563,7 @@ TRACE_EVENT(block_rq_remap, __entry->nr_sector = blk_rq_sectors(rq); __entry->old_dev = dev; __entry->old_sector = from; - blk_fill_rwbs_rq(__entry->rwbs, rq); + blk_fill_rwbs(__entry->rwbs, rq->cmd_flags, blk_rq_bytes(rq)); ), TP_printk("%d,%d %s %llu + %u <- (%d,%d) %llu", diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c index d95721f3370..cbafed7d4f3 100644 --- a/kernel/trace/blktrace.c +++ b/kernel/trace/blktrace.c @@ -1827,21 +1827,5 @@ void blk_fill_rwbs(char *rwbs, u32 rw, int bytes) rwbs[i] = '\0'; } -void blk_fill_rwbs_rq(char *rwbs, struct request *rq) -{ - int rw = rq->cmd_flags & 0x03; - int bytes; - - if (rq->cmd_flags & REQ_DISCARD) - rw |= REQ_DISCARD; - - if (rq->cmd_flags & REQ_SECURE) - rw |= REQ_SECURE; - - bytes = blk_rq_bytes(rq); - - blk_fill_rwbs(rwbs, rw, bytes); -} - #endif /* CONFIG_EVENT_TRACING */ -- cgit v1.2.3 From fd51469fb68b987032e46297e0a4fe9020063c20 Mon Sep 17 00:00:00 2001 From: Petr Uzel Date: Thu, 3 Mar 2011 11:48:50 -0500 Subject: block: kill loop_mutex Following steps lead to deadlock in kernel: dd if=/dev/zero of=img bs=512 count=1000 losetup -f img mkfs.ext2 /dev/loop0 mount -t ext2 -o loop /dev/loop0 mnt umount mnt/ Stacktrace: [] irq_exit+0x36/0x59 [] smp_apic_timer_interrupt+0x6b/0x75 [] apic_timer_interrupt+0x31/0x38 [] mutex_spin_on_owner+0x54/0x5b [] lo_release+0x12/0x67 [loop] [] __blkdev_put+0x7c/0x10c [] fput+0xd5/0x1aa [] loop_clr_fd+0x1a9/0x1b1 [loop] [] lo_release+0x39/0x67 [loop] [] __blkdev_put+0x7c/0x10c [] deactivate_locked_super+0x17/0x36 [] sys_umount+0x27e/0x2a5 [] sys_oldumount+0xb/0xe [] sysenter_do_call+0x12/0x26 [] 0xffffffff Regression since 2a48fc0ab24241755dc9, which introduced the private loop_mutex as part of the BKL removal process. As per [1], the mutex can be safely removed. [1] http://www.gossamer-threads.com/lists/linux/kernel/1341930 Addresses: https://bugzilla.novell.com/show_bug.cgi?id=669394 Addresses: https://bugzilla.kernel.org/show_bug.cgi?id=29172 Signed-off-by: Petr Uzel Cc: stable@kernel.org Reviewed-by: Nikanth Karthikesan Acked-by: Arnd Bergmann Signed-off-by: Jens Axboe --- drivers/block/loop.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 49e6a545eb6..dbf31ec9114 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -78,7 +78,6 @@ #include -static DEFINE_MUTEX(loop_mutex); static LIST_HEAD(loop_devices); static DEFINE_MUTEX(loop_devices_mutex); @@ -1501,11 +1500,9 @@ static int lo_open(struct block_device *bdev, fmode_t mode) { struct loop_device *lo = bdev->bd_disk->private_data; - mutex_lock(&loop_mutex); mutex_lock(&lo->lo_ctl_mutex); lo->lo_refcnt++; mutex_unlock(&lo->lo_ctl_mutex); - mutex_unlock(&loop_mutex); return 0; } @@ -1515,7 +1512,6 @@ static int lo_release(struct gendisk *disk, fmode_t mode) struct loop_device *lo = disk->private_data; int err; - mutex_lock(&loop_mutex); mutex_lock(&lo->lo_ctl_mutex); if (--lo->lo_refcnt) @@ -1540,7 +1536,6 @@ static int lo_release(struct gendisk *disk, fmode_t mode) out: mutex_unlock(&lo->lo_ctl_mutex); out_unlocked: - mutex_unlock(&loop_mutex); return 0; } -- cgit v1.2.3