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block: make segment size limit workable for > 4K PAGE_SIZE

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Using PAGE_SIZE as a minimum expected DMA segment size in consideration
of devices which have a max DMA segment size of < 64k when used on 64k
PAGE_SIZE systems leads to devices not being able to probe such as
eMMC and Exynos UFS controller [0] [1] you can end up with a probe failure
as follows:

WARNING: CPU: 2 PID: 397 at block/blk-settings.c:339 blk_validate_limits+0x364/0x3c0

Ensure we use min(max_seg_size, seg_boundary_mask + 1) as the new min segment
size when max segment size is < PAGE_SIZE for 16k and 64k base page size systems.

If anyone need to backport this patch, the following commits are depended:

	commit 6aeb4f8364 ("block: remove bio_add_pc_page")
	commit 02ee5d69e3 ("block: remove blk_rq_bio_prep")
	commit b7175e24d6 ("block: add a dma mapping iterator")

Link: https://lore.kernel.org/linux-block/20230612203314.17820-1-bvanassche@acm.org/ # [0]
Link: https://lore.kernel.org/linux-block/1d55e942-5150-de4c-3a02-c3d066f87028@acm.org/ # [1]
Cc: Yi Zhang <yi.zhang@redhat.com>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Keith Busch <kbusch@kernel.org>
Tested-by: Paul Bunyan <pbunyan@redhat.com>
Reviewed-by: Daniel Gomez <da.gomez@kernel.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250225022141.2154581-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2025-02-25 10:21:41 +08:00 • committed by Jens Axboe
parent 70550442f2
commit 889c57066c
4 changed files with 20 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
block/blk-merge.c
View file

@ -329,7 +329,7 @@ int bio_split_rw_at(struct bio *bio, const struct queue_limits *lim,
if (nsegs < lim->max_segments &&
bytes + bv.bv_len <= max_bytes &&
bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
bv.bv_offset + bv.bv_len <= lim->min_segment_size) {
nsegs++;
bytes += bv.bv_len;
} else {

14
block/blk-settings.c
View file

@ -246,6 +246,7 @@ int blk_validate_limits(struct queue_limits *lim)
{
unsigned int max_hw_sectors;
unsigned int logical_block_sectors;
unsigned long seg_size;
int err;
/*
@ -303,7 +304,7 @@ int blk_validate_limits(struct queue_limits *lim)
max_hw_sectors = min_not_zero(lim->max_hw_sectors,
lim->max_dev_sectors);
if (lim->max_user_sectors) {
if (lim->max_user_sectors < PAGE_SIZE / SECTOR_SIZE)
if (lim->max_user_sectors < BLK_MIN_SEGMENT_SIZE / SECTOR_SIZE)
return -EINVAL;
lim->max_sectors = min(max_hw_sectors, lim->max_user_sectors);
} else if (lim->io_opt > (BLK_DEF_MAX_SECTORS_CAP << SECTOR_SHIFT)) {
@ -341,7 +342,7 @@ int blk_validate_limits(struct queue_limits *lim)
*/
if (!lim->seg_boundary_mask)
lim->seg_boundary_mask = BLK_SEG_BOUNDARY_MASK;
if (WARN_ON_ONCE(lim->seg_boundary_mask < PAGE_SIZE - 1))
if (WARN_ON_ONCE(lim->seg_boundary_mask < BLK_MIN_SEGMENT_SIZE - 1))
return -EINVAL;
/*
@ -362,10 +363,17 @@ int blk_validate_limits(struct queue_limits *lim)
*/
if (!lim->max_segment_size)
lim->max_segment_size = BLK_MAX_SEGMENT_SIZE;
if (WARN_ON_ONCE(lim->max_segment_size < PAGE_SIZE))
if (WARN_ON_ONCE(lim->max_segment_size < BLK_MIN_SEGMENT_SIZE))
return -EINVAL;
}
/* setup min segment size for building new segment in fast path */
if (lim->seg_boundary_mask > lim->max_segment_size - 1)
seg_size = lim->max_segment_size;
else
seg_size = lim->seg_boundary_mask + 1;
lim->min_segment_size = min_t(unsigned int, seg_size, PAGE_SIZE);
/*
* We require drivers to at least do logical block aligned I/O, but
* historically could not check for that due to the separate calls

9
block/blk.h
View file

@ -14,6 +14,7 @@
struct elevator_type;
#define BLK_DEV_MAX_SECTORS (LLONG_MAX >> 9)
#define BLK_MIN_SEGMENT_SIZE 4096
/* Max future timer expiry for timeouts */
#define BLK_MAX_TIMEOUT (5 * HZ)
@ -358,8 +359,12 @@ struct bio *bio_split_zone_append(struct bio *bio,
static inline bool bio_may_need_split(struct bio *bio,
const struct queue_limits *lim)
{
return lim->chunk_sectors || bio->bi_vcnt != 1 ||
bio->bi_io_vec->bv_len + bio->bi_io_vec->bv_offset > PAGE_SIZE;
if (lim->chunk_sectors)
return true;
if (bio->bi_vcnt != 1)
return true;
return bio->bi_io_vec->bv_len + bio->bi_io_vec->bv_offset >
lim->min_segment_size;
}
/**

1
include/linux/blkdev.h
View file

@ -367,6 +367,7 @@ struct queue_limits {
unsigned int max_sectors;
unsigned int max_user_sectors;
unsigned int max_segment_size;
unsigned int min_segment_size;
unsigned int physical_block_size;
unsigned int logical_block_size;
unsigned int alignment_offset;