6 files changed, 32 insertions, 0 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 1ebc1fdb9144..dd1f1e0e196f 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -101,6 +101,7 @@ void blk_set_default_limits(struct queue_limits *lim)
         lim->discard_granularity = 0;
         lim->discard_alignment = 0;
         lim->discard_misaligned = 0;
+        lim->discard_zeroes_data = -1;
         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;
@@ -544,6 +545,7 @@ int blk_stack_limits(struct queue_limits *t, struct queue_limits *b,
 
         t->io_min = max(t->io_min, b->io_min);
         t->no_cluster |= b->no_cluster;
+        t->discard_zeroes_data &= b->discard_zeroes_data;
 
         /* Bottom device offset aligned? */
         if (offset &&
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 3147145edc15..8606c9543fdd 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -136,6 +136,11 @@ static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
         return queue_var_show(q->limits.max_discard_sectors << 9, page);
 }
 
+static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
+{
+        return queue_var_show(queue_discard_zeroes_data(q), page);
+}
+
 static ssize_t
 queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
 {
@@ -313,6 +318,11 @@ static struct queue_sysfs_entry queue_discard_max_entry = {
         .show = queue_discard_max_show,
 };
 
+static struct queue_sysfs_entry queue_discard_zeroes_data_entry = {
+        .attr = {.name = "discard_zeroes_data", .mode = S_IRUGO },
+        .show = queue_discard_zeroes_data_show,
+};
+
 static struct queue_sysfs_entry queue_nonrot_entry = {
         .attr = {.name = "rotational", .mode = S_IRUGO | S_IWUSR },
         .show = queue_nonrot_show,
@@ -350,6 +360,7 @@ static struct attribute *default_attrs[] = {
         &queue_io_opt_entry.attr,
         &queue_discard_granularity_entry.attr,
         &queue_discard_max_entry.attr,
+        &queue_discard_zeroes_data_entry.attr,
         &queue_nonrot_entry.attr,
         &queue_nomerges_entry.attr,
         &queue_rq_affinity_entry.attr,
diff --git a/block/compat_ioctl.c b/block/compat_ioctl.c
index 9bd086c1a4d5..4eb8e9ea4af5 100644
--- a/block/compat_ioctl.c
+++ b/block/compat_ioctl.c
@@ -747,6 +747,8 @@ long compat_blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
                 return compat_put_uint(arg, bdev_io_opt(bdev));
         case BLKALIGNOFF:
                 return compat_put_int(arg, bdev_alignment_offset(bdev));
+        case BLKDISCARDZEROES:
+                return compat_put_uint(arg, bdev_discard_zeroes_data(bdev));
         case BLKFLSBUF:
         case BLKROSET:
         case BLKDISCARD:
diff --git a/block/ioctl.c b/block/ioctl.c
index 1f4d1de12b09..be48ea51faee 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -280,6 +280,8 @@ int blkdev_ioctl(struct block_device *bdev, fmode_t mode, unsigned cmd,
                 return put_uint(arg, bdev_io_opt(bdev));
         case BLKALIGNOFF:
                 return put_int(arg, bdev_alignment_offset(bdev));
+        case BLKDISCARDZEROES:
+                return put_uint(arg, bdev_discard_zeroes_data(bdev));
         case BLKSECTGET:
                 return put_ushort(arg, queue_max_sectors(bdev_get_queue(bdev)));
         case BLKRASET:
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index e727f6c44c44..784a919aa0d0 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -322,6 +322,7 @@ struct queue_limits {
         unsigned char           misaligned;
         unsigned char           discard_misaligned;
         unsigned char           no_cluster;
+        signed char             discard_zeroes_data;
 };
 
 struct request_queue
@@ -1150,6 +1151,19 @@ static inline int queue_sector_discard_alignment(struct request_queue *q,
                 & (q->limits.discard_granularity - 1);
 }
 
+static inline unsigned int queue_discard_zeroes_data(struct request_queue *q)
+{
+        if (q->limits.discard_zeroes_data == 1)
+                return 1;
+
+        return 0;
+}
+
+static inline unsigned int bdev_discard_zeroes_data(struct block_device *bdev)
+{
+        return queue_discard_zeroes_data(bdev_get_queue(bdev));
+}
+
 static inline int queue_dma_alignment(struct request_queue *q)
 {
         return q ? q->dma_alignment : 511;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 79cea8051736..891f7d642e5c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -304,6 +304,7 @@ struct inodes_stat_t {
 #define BLKIOOPT _IO(0x12,121)
 #define BLKALIGNOFF _IO(0x12,122)
 #define BLKPBSZGET _IO(0x12,123)
+#define BLKDISCARDZEROES _IO(0x12,124)
 
 #define BMAP_IOCTL 1            /* obsolete - kept for compatibility */
 #define FIBMAP     _IO(0x00,1)  /* bmap access */