3 files changed, 9 insertions, 4 deletions

diff --git a/block/blk-settings.c b/block/blk-settings.c
index cd3c428e194f..fa1eb0449a05 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -120,7 +120,7 @@ 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->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;
@@ -166,6 +166,7 @@ void blk_queue_make_request(struct request_queue *q, make_request_fn *mfn)
 
         blk_set_default_limits(&q->limits);
         blk_queue_max_hw_sectors(q, BLK_SAFE_MAX_SECTORS);
+        q->limits.discard_zeroes_data = 0;
 
         /*
          * by default assume old behaviour and bounce for any highmem page
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 6d735122bc59..53bd0c77bfda 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -152,7 +152,8 @@ static ssize_t queue_discard_granularity_show(struct request_queue *q, char *pag
 
 static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
 {
-        return queue_var_show(q->limits.max_discard_sectors << 9, page);
+        return sprintf(page, "%llu\n",
+                       (unsigned long long)q->limits.max_discard_sectors << 9);
 }
 
 static ssize_t queue_discard_zeroes_data_show(struct request_queue *q, char *page)
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 9f921bf4bf8c..520d8618ed76 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -257,7 +257,7 @@ struct queue_limits {
         unsigned char           misaligned;
         unsigned char           discard_misaligned;
         unsigned char           cluster;
-        signed char             discard_zeroes_data;
+        unsigned char           discard_zeroes_data;
 };
 
 struct request_queue
@@ -1069,13 +1069,16 @@ static inline int queue_limit_discard_alignment(struct queue_limits *lim, sector
 {
         unsigned int alignment = (sector << 9) & (lim->discard_granularity - 1);
 
+        if (!lim->max_discard_sectors)
+                return 0;
+
         return (lim->discard_granularity + lim->discard_alignment - alignment)
                 & (lim->discard_granularity - 1);
 }
 
 static inline unsigned int queue_discard_zeroes_data(struct request_queue *q)
 {
-        if (q->limits.discard_zeroes_data == 1)
+        if (q->limits.max_discard_sectors && q->limits.discard_zeroes_data == 1)
                 return 1;
 
         return 0;