block: default the discard granularity to sector size

Current the discard granularity defaults to 0 and must be initialized by
any driver that wants to support discard.  Default to the sector size
instead, which is the smallest possible value, and a very useful default.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231228075545.362768-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-settings.c b/block/blk-settings.c
index ba6e0e97118c084e84d8ea98b2aca26331b248ad..d993d20dab3c6db56218f6d13cc7af7608722355 100644 (file)
--- a/block/blk-settings.c
+++ b/block/blk-settings.c
@@ -48,7 +48,7 @@ void blk_set_default_limits(struct queue_limits *lim)
        lim->max_discard_sectors = 0;
        lim->max_hw_discard_sectors = 0;
        lim->max_secure_erase_sectors = 0;
-       lim->discard_granularity = 0;
+       lim->discard_granularity = 512;
        lim->discard_alignment = 0;
        lim->discard_misaligned = 0;
        lim->logical_block_size = lim->physical_block_size = lim->io_min = 512;
@@ -309,6 +309,9 @@ void blk_queue_logical_block_size(struct request_queue *q, unsigned int size)
 
        limits->logical_block_size = size;
 
+       if (limits->discard_granularity < limits->logical_block_size)
+               limits->discard_granularity = limits->logical_block_size;
+
        if (limits->physical_block_size < size)
                limits->physical_block_size = size;