From 6c5e0c4d518a37e1d5d794c14433e80284415079 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 1 Aug 2008 20:31:32 +0200 Subject: [PATCH 1/2] block: add a blk_plug_device_unlocked() that grabs the queue lock blk_plug_device() must be called with the queue lock held, so callers often just grab and release the lock for that purpose. Add a helper that does just that. Signed-off-by: Jens Axboe --- block/blk-core.c | 18 ++++++++++++++++++ include/linux/blkdev.h | 1 + 2 files changed, 19 insertions(+) diff --git a/block/blk-core.c b/block/blk-core.c index fef79ccb2a11..4889eb86a39e 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -212,6 +212,24 @@ void blk_plug_device(struct request_queue *q) } EXPORT_SYMBOL(blk_plug_device); +/** + * blk_plug_device_unlocked - plug a device without queue lock held + * @q: The &struct request_queue to plug + * + * Description: + * Like @blk_plug_device(), but grabs the queue lock and disables + * interrupts. + **/ +void blk_plug_device_unlocked(struct request_queue *q) +{ + unsigned long flags; + + spin_lock_irqsave(q->queue_lock, flags); + blk_plug_device(q); + spin_unlock_irqrestore(q->queue_lock, flags); +} +EXPORT_SYMBOL(blk_plug_device_unlocked); + /* * remove the queue from the plugged list, if present. called with * queue lock held and interrupts disabled. diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 88d68081a0f1..e61f22be4d0e 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -655,6 +655,7 @@ extern struct request *blk_get_request(struct request_queue *, int, gfp_t); extern void blk_insert_request(struct request_queue *, struct request *, int, void *); extern void blk_requeue_request(struct request_queue *, struct request *); extern void blk_plug_device(struct request_queue *); +extern void blk_plug_device_unlocked(struct request_queue *); extern int blk_remove_plug(struct request_queue *); extern void blk_recount_segments(struct request_queue *, struct bio *); extern int scsi_cmd_ioctl(struct file *, struct request_queue *, From 93769f58078e2a066b56217cae1e343ac5a6b78c Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Fri, 1 Aug 2008 20:32:31 +0200 Subject: [PATCH 2/2] md: the bitmap code needs to use blk_plug_device_unlocked() It doesn't hold the queue lock, so it's both racey on the queue flags and thus spews a warning. Signed-off-by: Jens Axboe --- drivers/md/bitmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index 621a272a2c74..7e65bad522cb 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -1234,7 +1234,7 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect case 0: bitmap_file_set_bit(bitmap, offset); bitmap_count_page(bitmap,offset, 1); - blk_plug_device(bitmap->mddev->queue); + blk_plug_device_unlocked(bitmap->mddev->queue); /* fall through */ case 1: *bmc = 2;