[PATCH 15/15] loop: use the atomic queue limits update API

Christoph Hellwig
2024-01-22T17:37:35Z

Pass the default limits to blk_mq_alloc_disk and then use the
queue_limits_{start,commit}_update API to change the limits in an
atomic way on existing loop gendisks.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/block/loop.c | 41 +++++++++++++++++++++++++----------------
1 file changed, 25 insertions(+), 16 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 26c8ea79086798..28a95fd366fea5 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -750,11 +750,11 @@ static void loop_sysfs_exit(struct loop_device *lo)
&loop_attribute_group);
}

-static void loop_config_discard(struct loop_device *lo)
+static void loop_config_discard(struct loop_device *lo,
+ struct queue_limits *lim)
{
struct file *file = lo->lo_backing_file;
struct inode *inode = file->f_mapping->host;
- struct request_queue *q = lo->lo_queue;
u32 granularity = 0, max_discard_sectors = 0;
struct kstatfs sbuf;

@@ -781,12 +781,12 @@ static void loop_config_discard(struct loop_device *lo)
granularity = sbuf.f_bsize;
}

- blk_queue_max_discard_sectors(q, max_discard_sectors);
- blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
+ lim->max_hw_discard_sectors = max_discard_sectors;
+ lim->max_write_zeroes_sectors = max_discard_sectors;
if (max_discard_sectors)
- q->limits.discard_granularity = granularity;
+ lim->discard_granularity = granularity;
else
- q->limits.discard_granularity = 0;
+ lim->discard_granularity = 0;
}

struct loop_worker {
@@ -975,6 +975,20 @@ loop_set_status_from_info(struct loop_device *lo,
return 0;
}

+static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize,
+ bool update_discard_settings)
+{
+ struct queue_limits lim;
+
+ lim = queue_limits_start_update(lo->lo_queue);
+ lim.logical_block_size = bsize;
+ lim.physical_block_size = bsize;
+ lim.io_min = bsize;
+ if (update_discard_settings)
+ loop_config_discard(lo, &lim);
+ return queue_limits_commit_update(lo->lo_queue, &lim);
+}
+
static int loop_configure(struct loop_device *lo, blk_mode_t mode,
struct block_device *bdev,
const struct loop_config *config)
@@ -1072,11 +1086,10 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
else
bsize = 512;

- blk_queue_logical_block_size(lo->lo_queue, bsize);
- blk_queue_physical_block_size(lo->lo_queue, bsize);
- blk_queue_io_min(lo->lo_queue, bsize);
+ error = loop_reconfigure_limits(lo, bsize, true);
+ if (WARN_ON_ONCE(error))
+ goto out_unlock;

- loop_config_discard(lo);
loop_update_rotational(lo);
loop_update_dio(lo);
loop_sysfs_init(lo);
@@ -1143,9 +1156,7 @@ static void __loop_clr_fd(struct loop_device *lo, bool release)
lo->lo_offset = 0;
lo->lo_sizelimit = 0;
memset(lo->lo_file_name, 0, LO_NAME_SIZE);
- blk_queue_logical_block_size(lo->lo_queue, 512);
- blk_queue_physical_block_size(lo->lo_queue, 512);
- blk_queue_io_min(lo->lo_queue, 512);
+ loop_reconfigure_limits(lo, 512, false);
invalidate_disk(lo->lo_disk);
loop_sysfs_exit(lo);
/* let user-space know about this change */
@@ -1477,9 +1488,7 @@ static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
invalidate_bdev(lo->lo_device);

blk_mq_freeze_queue(lo->lo_queue);
- blk_queue_logical_block_size(lo->lo_queue, arg);
- blk_queue_physical_block_size(lo->lo_queue, arg);
- blk_queue_io_min(lo->lo_queue, arg);
+ err = loop_reconfigure_limits(lo, arg, false);
loop_update_dio(lo);
blk_mq_unfreeze_queue(lo->lo_queue);

--
2.39.2