From 53a08807c01989c6847bb135d8d43f61c5dfdda5 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Wed, 3 Dec 2008 12:41:26 +0100 Subject: block: internal dequeue shouldn't start timer blkdev_dequeue_request() and elv_dequeue_request() are equivalent and both start the timeout timer. Barrier code dequeues the original barrier request but doesn't passes the request itself to lower level driver, only broken down proxy requests; however, as the original barrier code goes through the same dequeue path and timeout timer is started on it. If barrier sequence takes long enough, this timer expires but the low level driver has no idea about this request and oops follows. Timeout timer shouldn't have been started on the original barrier request as it never goes through actual IO. This patch unexports elv_dequeue_request(), which has no external user anyway, and makes it operate on elevator proper w/o adding the timer and make blkdev_dequeue_request() call elv_dequeue_request() and add timer. Internal users which don't pass the request to driver - barrier code and end_that_request_last() - are converted to use elv_dequeue_request(). Signed-off-by: Tejun Heo Cc: Mike Anderson Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'include/linux') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index a135256b272..9cc7cc5fdce 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -786,6 +786,8 @@ static inline void blk_run_address_space(struct address_space *mapping) blk_run_backing_dev(mapping->backing_dev_info, NULL); } +extern void blkdev_dequeue_request(struct request *req); + /* * blk_end_request() and friends. * __blk_end_request() and end_request() must be called with @@ -820,11 +822,6 @@ extern void blk_update_request(struct request *rq, int error, extern unsigned int blk_rq_bytes(struct request *rq); extern unsigned int blk_rq_cur_bytes(struct request *rq); -static inline void blkdev_dequeue_request(struct request *req) -{ - elv_dequeue_request(req->q, req); -} - /* * Access functions for manipulating queue properties */ -- cgit v1.2.3 From 0e435ac26e3f951d83338ed3d4ab7dc0fe0055bc Mon Sep 17 00:00:00 2001 From: Milan Broz Date: Wed, 3 Dec 2008 12:55:08 +0100 Subject: block: fix setting of max_segment_size and seg_boundary mask Fix setting of max_segment_size and seg_boundary mask for stacked md/dm devices. When stacking devices (LVM over MD over SCSI) some of the request queue parameters are not set up correctly in some cases by default, namely max_segment_size and and seg_boundary mask. If you create MD device over SCSI, these attributes are zeroed. Problem become when there is over this mapping next device-mapper mapping - queue attributes are set in DM this way: request_queue max_segment_size seg_boundary_mask SCSI 65536 0xffffffff MD RAID1 0 0 LVM 65536 -1 (64bit) Unfortunately bio_add_page (resp. bio_phys_segments) calculates number of physical segments according to these parameters. During the generic_make_request() is segment cout recalculated and can increase bio->bi_phys_segments count over the allowed limit. (After bio_clone() in stack operation.) Thi is specially problem in CCISS driver, where it produce OOPS here BUG_ON(creq->nr_phys_segments > MAXSGENTRIES); (MAXSEGENTRIES is 31 by default.) Sometimes even this command is enough to cause oops: dd iflag=direct if=/dev// of=/dev/null bs=128000 count=10 This command generates bios with 250 sectors, allocated in 32 4k-pages (last page uses only 1024 bytes). For LVM layer, it allocates bio with 31 segments (still OK for CCISS), unfortunatelly on lower layer it is recalculated to 32 segments and this violates CCISS restriction and triggers BUG_ON(). The patch tries to fix it by: * initializing attributes above in queue request constructor blk_queue_make_request() * make sure that blk_queue_stack_limits() inherits setting (DM uses its own function to set the limits because it blk_queue_stack_limits() was introduced later. It should probably switch to use generic stack limit function too.) * sets the default seg_boundary value in one place (blkdev.h) * use this mask as default in DM (instead of -1, which differs in 64bit) Bugs related to this: https://bugzilla.redhat.com/show_bug.cgi?id=471639 http://bugzilla.kernel.org/show_bug.cgi?id=8672 Signed-off-by: Milan Broz Reviewed-by: Alasdair G Kergon Cc: Neil Brown Cc: FUJITA Tomonori Cc: Tejun Heo Cc: Mike Miller Signed-off-by: Jens Axboe --- include/linux/blkdev.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 9cc7cc5fdce..6dcd30d806c 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -918,6 +918,8 @@ extern void blk_set_cmd_filter_defaults(struct blk_cmd_filter *filter); #define MAX_SEGMENT_SIZE 65536 +#define BLK_SEG_BOUNDARY_MASK 0xFFFFFFFFUL + #define blkdev_entry_to_request(entry) list_entry((entry), struct request, queuelist) static inline int queue_hardsect_size(struct request_queue *q) -- cgit v1.2.3