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

3 files changed, 32 insertions, 18 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 069a61017c02..aa1e9535e358 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -196,6 +196,7 @@ enum cfqq_state_flags {
         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)                                              \
@@ -222,6 +223,7 @@ CFQ_CFQQ_FNS(prio_changed);
 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...)  \
@@ -945,10 +947,13 @@ static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd,
 {
         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;
 }
@@ -2051,7 +2056,7 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_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.
@@ -2066,8 +2071,16 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
          * 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;
 }
diff --git a/fs/bio.c b/fs/bio.c
index 402cb84a92a1..12da5db8682c 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -325,8 +325,16 @@ static void bio_fs_destructor(struct bio *bio)
  *      @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.
@@ -350,21 +358,13 @@ static void bio_kmalloc_destructor(struct bio *bio)
 }
 
 /**
- * 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)
@@ -407,7 +407,7 @@ EXPORT_SYMBOL(zero_fill_bio);
  *
  * 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)
 {
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 1065b715ef64..11aee09dd2a6 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -628,6 +628,8 @@ static void bdi_prune_sb(struct backing_dev_info *bdi)
 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);
@@ -697,7 +699,6 @@ void bdi_destroy(struct backing_dev_info *bdi)
                 spin_unlock(&inode_lock);
         }
 
-        bdi_prune_sb(bdi);
         bdi_unregister(bdi);
 
         for (i = 0; i < NR_BDI_STAT_ITEMS; i++)