block: Deprecate QUEUE_FLAG_CLUSTER and use queue_limits instead

When stacking devices, a request_queue is not always available. This
forced us to have a no_cluster flag in the queue_limits that could be
used as a carrier until the request_queue had been set up for a
metadevice.

There were several problems with that approach. First of all it was up
to the stacking device to remember to set queue flag after stacking had
completed. Also, the queue flag and the queue limits had to be kept in
sync at all times. We got that wrong, which could lead to us issuing
commands that went beyond the max scatterlist limit set by the driver.

The proper fix is to avoid having two flags for tracking the same thing.
We deprecate QUEUE_FLAG_CLUSTER and use the queue limit directly in the
block layer merging functions. The queue_limit 'no_cluster' is turned
into 'cluster' to avoid double negatives and to ease stacking.
Clustering defaults to being enabled as before. The queue flag logic is
removed from the stacking function, and explicitly setting the cluster
flag is no longer necessary in DM and MD.

Reported-by: Ed Lin <ed.lin@promise.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 77b7c26df6b50fea7a38ba0825d91583f1c4031c..74bc4a768f32e0f01e5c43f100f8663eea34c3a4 100644 (file)
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -21,7 +21,7 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
                return 0;
 
        fbio = bio;
-       cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
+       cluster = blk_queue_cluster(q);
        seg_size = 0;
        nr_phys_segs = 0;
        for_each_bio(bio) {
@@ -87,7 +87,7 @@ EXPORT_SYMBOL(blk_recount_segments);
 static int blk_phys_contig_segment(struct request_queue *q, struct bio *bio,
                                   struct bio *nxt)
 {
-       if (!test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags))
+       if (!blk_queue_cluster(q))
                return 0;
 
        if (bio->bi_seg_back_size + nxt->bi_seg_front_size >
@@ -123,7 +123,7 @@ int blk_rq_map_sg(struct request_queue *q, struct request *rq,
        int nsegs, cluster;
 
        nsegs = 0;
-       cluster = test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags);
+       cluster = blk_queue_cluster(q);
 
        /*
         * for each bio in rq

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 701859fb9647c31a505f0218800744e3e6d0a775..e55f5fc4ca2200d420cfd2fe57b30b2f3541573a 100644 (file)
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -126,7 +126,7 @@ void blk_set_default_limits(struct queue_limits *lim)
        lim->alignment_offset = 0;
        lim->io_opt = 0;
        lim->misaligned = 0;
-       lim->no_cluster = 0;
+       lim->cluster = 1;
 }
 EXPORT_SYMBOL(blk_set_default_limits);
 
@@ -464,15 +464,6 @@ EXPORT_SYMBOL(blk_queue_io_opt);
 void blk_queue_stack_limits(struct request_queue *t, struct request_queue *b)
 {
        blk_stack_limits(&t->limits, &b->limits, 0);
-
-       if (!t->queue_lock)
-               WARN_ON_ONCE(1);
-       else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) {
-               unsigned long flags;
-               spin_lock_irqsave(t->queue_lock, flags);
-               queue_flag_clear(QUEUE_FLAG_CLUSTER, t);
-               spin_unlock_irqrestore(t->queue_lock, flags);
-       }
 }
 EXPORT_SYMBOL(blk_queue_stack_limits);
 
@@ -545,7 +536,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
        t->io_min = max(t->io_min, b->io_min);
        t->io_opt = lcm(t->io_opt, b->io_opt);
 
-       t->no_cluster |= b->no_cluster;
+       t->cluster &= b->cluster;
        t->discard_zeroes_data &= b->discard_zeroes_data;
 
        /* Physical block size a multiple of the logical block size? */
@@ -641,7 +632,6 @@ void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
                       sector_t offset)
 {
        struct request_queue *t = disk->queue;
-       struct request_queue *b = bdev_get_queue(bdev);
 
        if (bdev_stack_limits(&t->limits, bdev, offset >> 9) < 0) {
                char top[BDEVNAME_SIZE], bottom[BDEVNAME_SIZE];
@@ -652,17 +642,6 @@ void disk_stack_limits(struct gendisk *disk, struct block_device *bdev,
                printk(KERN_NOTICE "%s: Warning: Device %s is misaligned\n",
                       top, bottom);
        }
-
-       if (!t->queue_lock)
-               WARN_ON_ONCE(1);
-       else if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags)) {
-               unsigned long flags;
-
-               spin_lock_irqsave(t->queue_lock, flags);
-               if (!test_bit(QUEUE_FLAG_CLUSTER, &b->queue_flags))
-                       queue_flag_clear(QUEUE_FLAG_CLUSTER, t);
-               spin_unlock_irqrestore(t->queue_lock, flags);
-       }
 }
 EXPORT_SYMBOL(disk_stack_limits);
 

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 013457f47fdc8b12eded858c852f588884b962c5..41fb69150b4d3c6758b0f5da6ff2005d4d7a0a3f 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -119,7 +119,7 @@ static ssize_t queue_max_integrity_segments_show(struct request_queue *q, char *
 
 static ssize_t queue_max_segment_size_show(struct request_queue *q, char *page)
 {
-       if (test_bit(QUEUE_FLAG_CLUSTER, &q->queue_flags))
+       if (blk_queue_cluster(q))
                return queue_var_show(queue_max_segment_size(q), (page));
 
        return queue_var_show(PAGE_CACHE_SIZE, (page));

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index 90267f8d64eeadf5d9e72afae174f6d4b22e6bf5..e2da1912a2cb9a886c427dceadb7b42d243ee5a8 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1131,11 +1131,6 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
         */
        q->limits = *limits;
 
-       if (limits->no_cluster)
-               queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q);
-       else
-               queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, q);
-
        if (!dm_table_supports_discards(t))
                queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
        else

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 84c46a161927999ebfc6c5d56d98e76247e66ae4..52694d29663d04f352017c6b315a9e1bd037f617 100644 (file)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4296,9 +4296,6 @@ static int md_alloc(dev_t dev, char *name)
                goto abort;
        mddev->queue->queuedata = mddev;
 
-       /* Can be unlocked because the queue is new: no concurrency */
-       queue_flag_set_unlocked(QUEUE_FLAG_CLUSTER, mddev->queue);
-
        blk_queue_make_request(mddev->queue, md_make_request);
 
        disk = alloc_disk(1 << shift);

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index eafeeda6e1942b7deda691f940c0f10efddee390..9d7ba07dc5ef73f2379bbf963cb6311e6624a290 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1642,9 +1642,8 @@ struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
 
        blk_queue_max_segment_size(q, dma_get_max_seg_size(dev));
 
-       /* New queue, no concurrency on queue_flags */
        if (!shost->use_clustering)
-               queue_flag_clear_unlocked(QUEUE_FLAG_CLUSTER, q);
+               q->limits.cluster = 0;
 
        /*
         * set a reasonable default alignment on word boundaries: the

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index aae86fd10c4f5dcea0eaf43cf6c39667a805dae4..95aeeeb49e8b0cd66b25fca73f055bf13441bca2 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -250,7 +250,7 @@ struct queue_limits {
 
        unsigned char           misaligned;
        unsigned char           discard_misaligned;
-       unsigned char           no_cluster;
+       unsigned char           cluster;
        signed char             discard_zeroes_data;
 };
 
@@ -380,7 +380,6 @@ struct request_queue
 #endif
 };
 
-#define QUEUE_FLAG_CLUSTER     0       /* cluster several segments into 1 */
 #define QUEUE_FLAG_QUEUED      1       /* uses generic tag queueing */
 #define QUEUE_FLAG_STOPPED     2       /* queue is stopped */
 #define        QUEUE_FLAG_SYNCFULL     3       /* read queue has been filled */
@@ -403,7 +402,6 @@ struct request_queue
 #define QUEUE_FLAG_SECDISCARD  19      /* supports SECDISCARD */
 
 #define QUEUE_FLAG_DEFAULT     ((1 << QUEUE_FLAG_IO_STAT) |            \
-                                (1 << QUEUE_FLAG_CLUSTER) |            \
                                 (1 << QUEUE_FLAG_STACKABLE)    |       \
                                 (1 << QUEUE_FLAG_SAME_COMP)    |       \
                                 (1 << QUEUE_FLAG_ADD_RANDOM))
@@ -510,6 +508,11 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 
 #define rq_data_dir(rq)                ((rq)->cmd_flags & 1)
 
+static inline unsigned int blk_queue_cluster(struct request_queue *q)
+{
+       return q->limits.cluster;
+}
+
 /*
  * We regard a request as sync, if either a read or a sync write
  */