block,scsi: fixup blk_get_request dead queue scenarios
The blk_get_request function may fail in low-memory conditions or during
device removal (even if __GFP_WAIT is set). To distinguish between these
errors, modify the blk_get_request call stack to return the appropriate
ERR_PTR. Verify that all callers check the return status and consider
IS_ERR instead of a simple NULL pointer check.
For consistency, make a similar change to the blk_mq_alloc_request leg
of blk_get_request. It may fail if the queue is dead, or the caller was
unwilling to wait.
Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
Acked-by: Jiri Kosina <jkosina@suse.cz> [for pktdvd]
Acked-by: Boaz Harrosh <bharrosh@panasas.com> [for osd]
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-core.c b/block/blk-core.c
index c359d72..93603e6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -933,9 +933,9 @@
* Get a free request from @q. This function may fail under memory
* pressure or if @q is dead.
*
- * Must be callled with @q->queue_lock held and,
- * Returns %NULL on failure, with @q->queue_lock held.
- * Returns !%NULL on success, with @q->queue_lock *not held*.
+ * Must be called with @q->queue_lock held and,
+ * Returns ERR_PTR on failure, with @q->queue_lock held.
+ * Returns request pointer on success, with @q->queue_lock *not held*.
*/
static struct request *__get_request(struct request_list *rl, int rw_flags,
struct bio *bio, gfp_t gfp_mask)
@@ -949,7 +949,7 @@
int may_queue;
if (unlikely(blk_queue_dying(q)))
- return NULL;
+ return ERR_PTR(-ENODEV);
may_queue = elv_may_queue(q, rw_flags);
if (may_queue == ELV_MQUEUE_NO)
@@ -974,7 +974,7 @@
* process is not a "batcher", and not
* exempted by the IO scheduler
*/
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
}
}
@@ -992,7 +992,7 @@
* allocated with any setting of ->nr_requests
*/
if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
- return NULL;
+ return ERR_PTR(-ENOMEM);
q->nr_rqs[is_sync]++;
rl->count[is_sync]++;
@@ -1097,7 +1097,7 @@
rq_starved:
if (unlikely(rl->count[is_sync] == 0))
rl->starved[is_sync] = 1;
- return NULL;
+ return ERR_PTR(-ENOMEM);
}
/**
@@ -1110,9 +1110,9 @@
* Get a free request from @q. If %__GFP_WAIT is set in @gfp_mask, this
* function keeps retrying under memory pressure and fails iff @q is dead.
*
- * Must be callled with @q->queue_lock held and,
- * Returns %NULL on failure, with @q->queue_lock held.
- * Returns !%NULL on success, with @q->queue_lock *not held*.
+ * Must be called with @q->queue_lock held and,
+ * Returns ERR_PTR on failure, with @q->queue_lock held.
+ * Returns request pointer on success, with @q->queue_lock *not held*.
*/
static struct request *get_request(struct request_queue *q, int rw_flags,
struct bio *bio, gfp_t gfp_mask)
@@ -1125,12 +1125,12 @@
rl = blk_get_rl(q, bio); /* transferred to @rq on success */
retry:
rq = __get_request(rl, rw_flags, bio, gfp_mask);
- if (rq)
+ if (!IS_ERR(rq))
return rq;
if (!(gfp_mask & __GFP_WAIT) || unlikely(blk_queue_dying(q))) {
blk_put_rl(rl);
- return NULL;
+ return rq;
}
/* wait on @rl and retry */
@@ -1167,7 +1167,7 @@
spin_lock_irq(q->queue_lock);
rq = get_request(q, rw, NULL, gfp_mask);
- if (!rq)
+ if (IS_ERR(rq))
spin_unlock_irq(q->queue_lock);
/* q->queue_lock is unlocked at this point */
@@ -1219,8 +1219,8 @@
{
struct request *rq = blk_get_request(q, bio_data_dir(bio), gfp_mask);
- if (unlikely(!rq))
- return ERR_PTR(-ENOMEM);
+ if (IS_ERR(rq))
+ return rq;
blk_rq_set_block_pc(rq);
@@ -1615,8 +1615,8 @@
* Returns with the queue unlocked.
*/
req = get_request(q, rw_flags, bio, GFP_NOIO);
- if (unlikely(!req)) {
- bio_endio(bio, -ENODEV); /* @q is dead */
+ if (IS_ERR(req)) {
+ bio_endio(bio, PTR_ERR(req)); /* @q is dead */
goto out_unlock;
}