block: add a max_user_discard_sectors queue limit

Add a new max_user_discard_sectors limit that mirrors max_user_sectors
and stores the value that the user manually set.  This now allows
updates of the max_hw_discard_sectors to not worry about the user
limit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 27b9b4a2a85395ec756d047736e2ef2106ced058..7139c13fe7348454bdb80f3dca449683e6534cb8 100644 (file)
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -37,6 +37,7 @@ void blk_set_stacking_limits(struct queue_limits *lim)
        memset(lim, 0, sizeof(*lim));
        lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
        lim->discard_granularity = 512;
+       lim->max_user_discard_sectors = UINT_MAX;
        lim->dma_alignment = 511;
        lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
 
@@ -160,7 +161,9 @@ static int blk_validate_limits(struct queue_limits *lim)
        if (!lim->max_segments)
                lim->max_segments = BLK_MAX_SEGMENTS;
 
-       lim->max_discard_sectors = lim->max_hw_discard_sectors;
+       lim->max_discard_sectors =
+               min(lim->max_hw_discard_sectors, lim->max_user_discard_sectors);
+
        if (!lim->max_discard_segments)
                lim->max_discard_segments = 1;
 
@@ -226,6 +229,12 @@ static int blk_validate_limits(struct queue_limits *lim)
  */
 int blk_set_default_limits(struct queue_limits *lim)
 {
+       /*
+        * Most defaults are set by capping the bounds in blk_validate_limits,
+        * but max_user_discard_sectors is special and needs an explicit
+        * initialization to the max value here.
+        */
+       lim->max_user_discard_sectors = UINT_MAX;
        return blk_validate_limits(lim);
 }
 
@@ -347,8 +356,11 @@ EXPORT_SYMBOL(blk_queue_chunk_sectors);
 void blk_queue_max_discard_sectors(struct request_queue *q,
                unsigned int max_discard_sectors)
 {
-       q->limits.max_hw_discard_sectors = max_discard_sectors;
-       q->limits.max_discard_sectors = max_discard_sectors;
+       struct queue_limits *lim = &q->limits;
+
+       lim->max_hw_discard_sectors = max_discard_sectors;
+       lim->max_discard_sectors =
+               min(max_discard_sectors, lim->max_user_discard_sectors);
 }
 EXPORT_SYMBOL(blk_queue_max_discard_sectors);
 

diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 26607f9825cb058e254a0867383a37f4ded48aa6..a1ec27f0ba4150d08e45eeae4b6dc12dc11636f2 100644 (file)
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -174,23 +174,22 @@ static ssize_t queue_discard_max_show(struct request_queue *q, char *page)
 static ssize_t queue_discard_max_store(struct request_queue *q,
                                       const char *page, size_t count)
 {
-       unsigned long max_discard;
-       ssize_t ret = queue_var_store(&max_discard, page, count);
+       unsigned long max_discard_bytes;
+       ssize_t ret;
 
+       ret = queue_var_store(&max_discard_bytes, page, count);
        if (ret < 0)
                return ret;
 
-       if (max_discard & (q->limits.discard_granularity - 1))
+       if (max_discard_bytes & (q->limits.discard_granularity - 1))
                return -EINVAL;
 
-       max_discard >>= 9;
-       if (max_discard > UINT_MAX)
+       if ((max_discard_bytes >> SECTOR_SHIFT) > UINT_MAX)
                return -EINVAL;
 
-       if (max_discard > q->limits.max_hw_discard_sectors)
-               max_discard = q->limits.max_hw_discard_sectors;
-
-       q->limits.max_discard_sectors = max_discard;
+       q->limits.max_user_discard_sectors = max_discard_bytes >> SECTOR_SHIFT;
+       q->limits.max_discard_sectors = min(q->limits.max_hw_discard_sectors,
+                                           q->limits.max_user_discard_sectors);
        return ret;
 }
 

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 97c01efed6825373b1c9b7ff2b9e1d638e898f27..64cca7236190835a2c54d2d418096a232fa9aa3e 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -290,6 +290,7 @@ struct queue_limits {
        unsigned int            io_opt;
        unsigned int            max_discard_sectors;
        unsigned int            max_hw_discard_sectors;
+       unsigned int            max_user_discard_sectors;
        unsigned int            max_secure_erase_sectors;
        unsigned int            max_write_zeroes_sectors;
        unsigned int            max_zone_append_sectors;