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>
Link: https://lore.kernel.org/r/20240213073425.1621680-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-settings.c b/block/blk-settings.c
index 786b369..c4406aa 100644 (file)
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -51,6 +51,7 @@ void blk_set_stacking_limits(struct queue_limits *lim)
        lim->max_dev_sectors = UINT_MAX;
        lim->max_write_zeroes_sectors = UINT_MAX;
        lim->max_zone_append_sectors = UINT_MAX;
+       lim->max_user_discard_sectors = UINT_MAX;
 }
 EXPORT_SYMBOL(blk_set_stacking_limits);
 
@@ -162,7 +163,9 @@ 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;
 
@@ -228,6 +231,12 @@ 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);
 }
 
@@ -349,8 +358,11 @@ 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 26607f9..a1ec27f 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 d41d7fe..45746ba 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -291,6 +291,7 @@ 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;