Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
cfq-iosched: limit coop preemption
cfq-iosched: fix bad return value cfq_should_preempt()
backing-dev: bdi sb prune should be in the unregister path, not destroy
Fix bio_alloc() and bio_kmalloc() documentation
bio_put(): add bio_clone() to the list of functions in the comment

block/cfq-iosched.c

···
 	CFQ_CFQQ_FLAG_slice_new,	/* no requests dispatched in slice */
 	CFQ_CFQQ_FLAG_sync,		/* synchronous queue */
 	CFQ_CFQQ_FLAG_coop,		/* has done a coop jump of the queue */
+	CFQ_CFQQ_FLAG_coop_preempt,	/* coop preempt */
 };
 
 #define CFQ_CFQQ_FNS(name)						\
···
 CFQ_CFQQ_FNS(slice_new);
 CFQ_CFQQ_FNS(sync);
 CFQ_CFQQ_FNS(coop);
+CFQ_CFQQ_FNS(coop_preempt);
 #undef CFQ_CFQQ_FNS
 
 #define cfq_log_cfqq(cfqd, cfqq, fmt, args...)	\
···
 {
 	if (!cfqq) {
 		cfqq = cfq_get_next_queue(cfqd);
-		if (cfqq)
+		if (cfqq && !cfq_cfqq_coop_preempt(cfqq))
 			cfq_clear_cfqq_coop(cfqq);
 	}
+
+	if (cfqq)
+		cfq_clear_cfqq_coop_preempt(cfqq);
 
 	__cfq_set_active_queue(cfqd, cfqq);
 	return cfqq;
···
 	 * it's a metadata request and the current queue is doing regular IO.
 	 */
 	if (rq_is_meta(rq) && !cfqq->meta_pending)
-		return false;
+		return true;
 
 	/*
 	 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
···
 	 * if this request is as-good as one we would expect from the
 	 * current cfqq, let it preempt
 	 */
-	if (cfq_rq_close(cfqd, rq))
+	if (cfq_rq_close(cfqd, rq) && (!cfq_cfqq_coop(new_cfqq) ||
+	    cfqd->busy_queues == 1)) {
+		/*
+		 * Mark new queue coop_preempt, so its coop flag will not be
+		 * cleared when new queue gets scheduled at the very first time
+		 */
+		cfq_mark_cfqq_coop_preempt(new_cfqq);
+		cfq_mark_cfqq_coop(new_cfqq);
 		return true;
+	}
 
 	return false;
 }

fs/bio.c

···
  *	@gfp_mask: allocation mask to use
  *	@nr_iovecs: number of iovecs
  *
- *	Allocate a new bio with @nr_iovecs bvecs.  If @gfp_mask
- *	contains __GFP_WAIT, the allocation is guaranteed to succeed.
+ *	bio_alloc will allocate a bio and associated bio_vec array that can hold
+ *	at least @nr_iovecs entries. Allocations will be done from the
+ *	fs_bio_set. Also see @bio_alloc_bioset and @bio_kmalloc.
+ *
+ *	If %__GFP_WAIT is set, then bio_alloc will always be able to allocate
+ *	a bio. This is due to the mempool guarantees. To make this work, callers
+ *	must never allocate more than 1 bio at a time from this pool. Callers
+ *	that need to allocate more than 1 bio must always submit the previously
+ *	allocated bio for IO before attempting to allocate a new one. Failure to
+ *	do so can cause livelocks under memory pressure.
  *
  *	RETURNS:
  *	Pointer to new bio on success, NULL on failure.
···
 }
 
 /**
- * bio_alloc - allocate a bio for I/O
+ * bio_kmalloc - allocate a bio for I/O using kmalloc()
  * @gfp_mask:   the GFP_ mask given to the slab allocator
  * @nr_iovecs:	number of iovecs to pre-allocate
  *
  * Description:
- *   bio_alloc will allocate a bio and associated bio_vec array that can hold
- *   at least @nr_iovecs entries. Allocations will be done from the
- *   fs_bio_set. Also see @bio_alloc_bioset.
- *
- *   If %__GFP_WAIT is set, then bio_alloc will always be able to allocate
- *   a bio. This is due to the mempool guarantees. To make this work, callers
- *   must never allocate more than 1 bio at a time from this pool. Callers
- *   that need to allocate more than 1 bio must always submit the previously
- *   allocated bio for IO before attempting to allocate a new one. Failure to
- *   do so can cause livelocks under memory pressure.
+ *   Allocate a new bio with @nr_iovecs bvecs.  If @gfp_mask contains
+ *   %__GFP_WAIT, the allocation is guaranteed to succeed.
  *
  **/
 struct bio *bio_kmalloc(gfp_t gfp_mask, int nr_iovecs)
···
  *
  * Description:
  *   Put a reference to a &struct bio, either one you have gotten with
- *   bio_alloc or bio_get. The last put of a bio will free it.
+ *   bio_alloc, bio_get or bio_clone. The last put of a bio will free it.
  **/
 void bio_put(struct bio *bio)
 {

mm/backing-dev.c

···
 void bdi_unregister(struct backing_dev_info *bdi)
 {
 	if (bdi->dev) {
+		bdi_prune_sb(bdi);
+
 		if (!bdi_cap_flush_forker(bdi))
 			bdi_wb_shutdown(bdi);
 		bdi_debug_unregister(bdi);
···
 		spin_unlock(&inode_lock);
 	}
 
-	bdi_prune_sb(bdi);
 	bdi_unregister(bdi);
 
 	for (i = 0; i < NR_BDI_STAT_ITEMS; i++)