4 files changed, 24 insertions, 5 deletions

diff --git a/block/blk-barrier.c b/block/blk-barrier.c
index 21f5025c3945..8873b9b439ff 100644
--- a/block/blk-barrier.c
+++ b/block/blk-barrier.c
@@ -385,6 +385,8 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 
         while (nr_sects && !ret) {
                 unsigned int sector_size = q->limits.logical_block_size;
+                unsigned int max_discard_sectors =
+                        min(q->limits.max_discard_sectors, UINT_MAX >> 9);
 
                 bio = bio_alloc(gfp_mask, 1);
                 if (!bio)
@@ -411,10 +413,10 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
                  * touch many more blocks on disk than the actual payload
                  * length.
                  */
-                if (nr_sects > queue_max_hw_sectors(q)) {
-                        bio->bi_size = queue_max_hw_sectors(q) << 9;
-                        nr_sects -= queue_max_hw_sectors(q);
-                        sector += queue_max_hw_sectors(q);
+                if (nr_sects > max_discard_sectors) {
+                        bio->bi_size = max_discard_sectors << 9;
+                        nr_sects -= max_discard_sectors;
+                        sector += max_discard_sectors;
                 } else {
                         bio->bi_size = nr_sects << 9;
                         nr_sects = 0;
diff --git a/block/blk-core.c b/block/blk-core.c
index 80a020dd1580..34504f309728 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1436,7 +1436,8 @@ static inline void __generic_make_request(struct bio *bio)
                         goto end_io;
                 }
 
-                if (unlikely(nr_sectors > queue_max_hw_sectors(q))) {
+                if (unlikely(!bio_rw_flagged(bio, BIO_RW_DISCARD) &&
+                             nr_sectors > queue_max_hw_sectors(q))) {
                         printk(KERN_ERR "bio too big device %s (%u > %u)\n",
                                bdevname(bio->bi_bdev, b),
                                bio_sectors(bio),
diff --git a/block/blk-settings.c b/block/blk-settings.c
index d29498ef1eb5..e0695bca7027 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -96,6 +96,7 @@ void blk_set_default_limits(struct queue_limits *lim)
         lim->max_segment_size = MAX_SEGMENT_SIZE;
         lim->max_sectors = BLK_DEF_MAX_SECTORS;
         lim->max_hw_sectors = INT_MAX;
+        lim->max_discard_sectors = SAFE_MAX_SECTORS;
         lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
         lim->bounce_pfn = (unsigned long)(BLK_BOUNCE_ANY >> PAGE_SHIFT);
         lim->alignment_offset = 0;
@@ -239,6 +240,18 @@ void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_sectors)
 EXPORT_SYMBOL(blk_queue_max_hw_sectors);
 
 /**
+ * blk_queue_max_discard_sectors - set max sectors for a single discard
+ * @q:  the request queue for the device
+ * @max_discard: maximum number of sectors to discard
+ **/
+void blk_queue_max_discard_sectors(struct request_queue *q,
+                unsigned int max_discard_sectors)
+{
+        q->limits.max_discard_sectors = max_discard_sectors;
+}
+EXPORT_SYMBOL(blk_queue_max_discard_sectors);
+
+/**
  * blk_queue_max_phys_segments - set max phys segments for a request for this queue
  * @q:  the request queue for the device
  * @max_segments:  max number of segments
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index f62d45e87618..1a03b715dfad 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -311,6 +311,7 @@ struct queue_limits {
         unsigned int            alignment_offset;
         unsigned int            io_min;
         unsigned int            io_opt;
+        unsigned int            max_discard_sectors;
 
         unsigned short          logical_block_size;
         unsigned short          max_hw_segments;
@@ -928,6 +929,8 @@ extern void blk_queue_max_hw_sectors(struct request_queue *, unsigned int);
 extern void blk_queue_max_phys_segments(struct request_queue *, unsigned short);
 extern void blk_queue_max_hw_segments(struct request_queue *, unsigned short);
 extern void blk_queue_max_segment_size(struct request_queue *, unsigned int);
+extern void blk_queue_max_discard_sectors(struct request_queue *q,
+                unsigned int max_discard_sectors);
 extern void blk_queue_logical_block_size(struct request_queue *, unsigned short);
 extern void blk_queue_physical_block_size(struct request_queue *, unsigned short);
 extern void blk_queue_alignment_offset(struct request_queue *q,