[PATCH 02/21] block: Limit atomic writes according to bio and queue limits
STALE1031d
From: John Garry <john.g.garry@oracle.com>
Date: 2023-09-29 10:28:28
Also in:
linux-block, linux-fsdevel, linux-nvme, linux-xfs, lkml
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
Revision v1 of 9 in this series.
Revisions (9)
We rely the block layer always being able to send a bio of size atomic_write_unit_max without being required to split it due to request queue or other bio limits. A bio may contain min(BIO_MAX_VECS, limits->max_segments) vectors, and each vector is at worst case the device logical block size from direct IO alignment requirement. Signed-off-by: John Garry <john.g.garry@oracle.com> --- block/blk-settings.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index d151be394c98..57d487a00c64 100644
--- a/block/blk-settings.c
+++ b/block/blk-settings.c@@ -213,6 +213,18 @@ void blk_queue_atomic_write_boundary_bytes(struct request_queue *q, } EXPORT_SYMBOL(blk_queue_atomic_write_boundary_bytes); +static unsigned int blk_queue_max_guaranteed_bio_size_sectors( + struct request_queue *q) +{ + struct queue_limits *limits = &q->limits; + unsigned int max_segments = min_t(unsigned int, BIO_MAX_VECS, + limits->max_segments); + /* Limit according to dev sector size as we only support direct-io */ + unsigned int limit = max_segments * queue_logical_block_size(q); + + return rounddown_pow_of_two(limit >> SECTOR_SHIFT); +} + /** * blk_queue_atomic_write_unit_min_sectors - smallest unit that can be written * atomically to the device.
@@ -223,8 +235,10 @@ void blk_queue_atomic_write_unit_min_sectors(struct request_queue *q, unsigned int sectors) { struct queue_limits *limits = &q->limits; + unsigned int guaranteed_sectors = + blk_queue_max_guaranteed_bio_size_sectors(q); - limits->atomic_write_unit_min_sectors = sectors; + limits->atomic_write_unit_min_sectors = min(guaranteed_sectors, sectors); } EXPORT_SYMBOL(blk_queue_atomic_write_unit_min_sectors);
@@ -238,8 +252,10 @@ void blk_queue_atomic_write_unit_max_sectors(struct request_queue *q, unsigned int sectors) { struct queue_limits *limits = &q->limits; + unsigned int guaranteed_sectors = + blk_queue_max_guaranteed_bio_size_sectors(q); - limits->atomic_write_unit_max_sectors = sectors; + limits->atomic_write_unit_max_sectors = min(guaranteed_sectors, sectors); } EXPORT_SYMBOL(blk_queue_atomic_write_unit_max_sectors);
--
2.31.1