block: save user max_sectors limit
The user can set the max_sectors limit to any valid value via sysfs
/sys/block/<dev>/queue/max_sectors_kb attribute. If the device limits
are ever rescanned, though, the limit reverts back to the potentially
artificially low BLK_DEF_MAX_SECTORS value.
Preserve the user's setting as the max_sectors limit as long as it's
valid. The user can reset back to defaults by writing 0 to the sysfs
file.
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20230105205146.3610282-3-kbusch@meta.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 9875ca1..9c9713c 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -40,7 +40,7 @@ void blk_set_default_limits(struct queue_limits *lim)
lim->virt_boundary_mask = 0;
lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
lim->max_sectors = lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
- lim->max_dev_sectors = 0;
+ lim->max_user_sectors = lim->max_dev_sectors = 0;
lim->chunk_sectors = 0;
lim->max_write_zeroes_sectors = 0;
lim->max_zone_append_sectors = 0;
@@ -135,7 +135,12 @@ void blk_queue_max_hw_sectors(struct request_queue *q, unsigned int max_hw_secto
limits->max_hw_sectors = max_hw_sectors;
max_sectors = min_not_zero(max_hw_sectors, limits->max_dev_sectors);
- max_sectors = min(max_sectors, BLK_DEF_MAX_SECTORS);
+
+ if (limits->max_user_sectors)
+ max_sectors = min(max_sectors, limits->max_user_sectors);
+ else
+ max_sectors = min(max_sectors, BLK_DEF_MAX_SECTORS);
+
max_sectors = round_down(max_sectors,
limits->logical_block_size >> SECTOR_SHIFT);
limits->max_sectors = max_sectors;
