Patch "block: Always check queue limits for cloned requests" has been added to the 4.3-stable tree

PATCH [email protected] 1 participant 1 message Feb 2, 2016

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2016-02-02 01:03 UTC #0 lore raw

This is a note to let you know that I've just added the patch titled

block: Always check queue limits for cloned requests

to the 4.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
block-always-check-queue-limits-for-cloned-requests.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From bf4e6b4e757488dee1b6a581f49c7ac34cd217f8 Mon Sep 17 00:00:00 2001

From: Hannes Reinecke <[email protected]>
Date: Thu, 26 Nov 2015 08:46:57 +0100
Subject: block: Always check queue limits for cloned requests

From: Hannes Reinecke <[email protected]>

commit bf4e6b4e757488dee1b6a581f49c7ac34cd217f8 upstream.

When a cloned request is retried on other queues it always needs to be checked against the queue limits of that queue. Otherwise the calculations for nr_phys_segments might be wrong, leading to a crash in scsi_init_sgtable().

To clarify this the patch renames blk_rq_check_limits() to blk_cloned_rq_check_limits() and removes the symbol export, as the new function should only be used for cloned requests and never exported.

Cc Mike Snitzer <[email protected]>

Cc Ewan Milne <[email protected]>

Cc Jeff Moyer <[email protected]>

Signed-off-by Hannes Reinecke <[email protected]>

Fixes e2a60da74 ("block: Clean up special command handling logic")

Acked-by Mike Snitzer <[email protected]>

Signed-off-by Jens Axboe <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 block/blk-core.c       |   21 +++++++--------------
 include/linux/blkdev.h |    1 -
 2 files changed, 7 insertions(+), 15 deletions(-)

block/blk-core.c +7 ~~-14~~

@@ -2023,7 +2023,8 @@ void submit_bio(int rw, struct bio *bio)
 EXPORT_SYMBOL(submit_bio);
 
 /**
- * blk_rq_check_limits - Helper function to check a request for the queue limit
+ * blk_cloned_rq_check_limits - Helper function to check a cloned request
+ *                              for new the queue limits
  * @q:  the queue
  * @rq: the request being checked
  *

@@ -2034,20 +2035,13 @@ EXPORT_SYMBOL(submit_bio);
  *    after it is inserted to @q, it should be checked against @q before
  *    the insertion using this generic function.
  *
- *    This function should also be useful for request stacking drivers
- *    in some cases below, so export this function.
  *    Request stacking drivers like request-based dm may change the queue
- *    limits while requests are in the queue (e.g. dm's table swapping).
- *    Such request stacking drivers should check those requests against
- *    the new queue limits again when they dispatch those requests,
- *    although such checkings are also done against the old queue limits
- *    when submitting requests.
+ *    limits when retrying requests on other queues. Those requests need
+ *    to be checked against the new queue limits again during dispatch.
  */
-int blk_rq_check_limits(struct request_queue *q, struct request *rq)
+static int blk_cloned_rq_check_limits(struct request_queue *q,
+				      struct request *rq)
 {
-	if (!rq_mergeable(rq))
-		return 0;
-
 	if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, rq->cmd_flags)) {
 		printk(KERN_ERR "%s: over max size limit.\n", __func__);
 		return -EIO;

@@ -2067,7 +2061,6 @@ int blk_rq_check_limits(struct request_q
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(blk_rq_check_limits);
 
 /**
  * blk_insert_cloned_request - Helper for stacking drivers to submit a request

@@ -2079,7 +2072,7 @@ int blk_insert_cloned_request(struct req
 	unsigned long flags;
 	int where = ELEVATOR_INSERT_BACK;
 
-	if (blk_rq_check_limits(q, rq))
+	if (blk_cloned_rq_check_limits(q, rq))
 		return -EIO;
 
 	if (rq->rq_disk &&

include/linux/blkdev.h +0 -1

@@ -767,7 +767,6 @@ extern void blk_rq_set_block_pc(struct r
 extern void blk_requeue_request(struct request_queue *, struct request *);
 extern void blk_add_request_payload(struct request *rq, struct page *page,
 		unsigned int len);
-extern int blk_rq_check_limits(struct request_queue *q, struct request *rq);
 extern int blk_lld_busy(struct request_queue *q);
 extern int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
 			     struct bio_set *bs, gfp_t gfp_mask,

Patches currently in stable-queue which might be from [email protected] are

queue-4.3/block-always-check-queue-limits-for-cloned-requests.patch