From: Keith Busch <kbusch@xxxxxxxxxx>
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 kernel defined
BLK_DEF_MAX_SECTORS limit.
Preserve the user's setting for 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@xxxxxxxxxx>
---
block/blk-settings.c | 9 +++++++--
block/blk-sysfs.c | 10 +++++++++-
include/linux/blkdev.h | 1 +
3 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/block/blk-settings.c b/block/blk-settings.c
index 0477c4d527fee..e75304f853bd5 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_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
+
+ if (limits->max_user_sectors)
+ max_sectors = min_not_zero(max_sectors, limits->max_user_sectors);
+ else
+ max_sectors = min_t(unsigned int, max_sectors, BLK_DEF_MAX_SECTORS);
+
max_sectors = round_down(max_sectors,
limits->logical_block_size >> SECTOR_SHIFT);
limits->max_sectors = max_sectors;
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 93d9e9c9a6ea8..db5d1d908f5d9 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -250,8 +250,16 @@ queue_max_sectors_store(struct request_queue *q, const char *page, size_t count)
max_hw_sectors_kb = min_not_zero(max_hw_sectors_kb, (unsigned long)
q->limits.max_dev_sectors >> 1);
- if (max_sectors_kb > max_hw_sectors_kb || max_sectors_kb < page_kb)
+ if (max_sectors_kb == 0) {
+ q->limits.max_user_sectors = 0;
+ max_sectors_kb = min_t(unsigned int, max_hw_sectors_kb,
+ BLK_DEF_MAX_SECTORS >> 1);
+ } else if (max_sectors_kb > max_hw_sectors_kb ||
+ max_sectors_kb < page_kb) {
return -EINVAL;
+ } else {
+ q->limits.max_user_sectors = max_sectors_kb << 1;
+ }
spin_lock_irq(&q->queue_lock);
q->limits.max_sectors = max_sectors_kb << 1;
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 301cf1cf4f2fa..71e97f0a87264 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -288,6 +288,7 @@ struct queue_limits {
unsigned int max_dev_sectors;
unsigned int chunk_sectors;
unsigned int max_sectors;
+ unsigned int max_user_sectors;
unsigned int max_segment_size;
unsigned int physical_block_size;
unsigned int logical_block_size;
--
2.30.2
