[PATCH 09/10] loop: refactor queue limits updates

Christoph Hellwig
2025-01-08T09:26:06Z

Replace loop_reconfigure_limits with a slightly less encompassing
loop_update_limits that expects the aller to acquire and commit the
queue limits to prepare for sorting out the freeze vs limits lock
ordering.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/block/loop.c | 36 ++++++++++++++++++++----------------
1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 836a53eef4b4..560d6d5879d6 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -977,12 +977,12 @@ static unsigned int loop_default_blocksize(struct loop_device *lo,
return SECTOR_SIZE;
}

-static int loop_reconfigure_limits(struct loop_device *lo, unsigned int bsize)
+static void loop_update_limits(struct loop_device *lo, struct queue_limits *lim,
+ unsigned int bsize)
{
struct file *file = lo->lo_backing_file;
struct inode *inode = file->f_mapping->host;
struct block_device *backing_bdev = NULL;
- struct queue_limits lim;
u32 granularity = 0, max_discard_sectors = 0;

if (S_ISBLK(inode->i_mode))
@@ -995,22 +995,20 @@ static int loop_reconfigure_limits(struct loop_device *lo, unsigned int bsize)

loop_get_discard_config(lo, &granularity, &max_discard_sectors);

- lim = queue_limits_start_update(lo->lo_queue);
- lim.logical_block_size = bsize;
- lim.physical_block_size = bsize;
- lim.io_min = bsize;
- lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_ROTATIONAL);
+ lim->logical_block_size = bsize;
+ lim->physical_block_size = bsize;
+ lim->io_min = bsize;
+ lim->features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_ROTATIONAL);
if (file->f_op->fsync && !(lo->lo_flags & LO_FLAGS_READ_ONLY))
- lim.features |= BLK_FEAT_WRITE_CACHE;
+ lim->features |= BLK_FEAT_WRITE_CACHE;
if (backing_bdev && !bdev_nonrot(backing_bdev))
- lim.features |= BLK_FEAT_ROTATIONAL;
- lim.max_hw_discard_sectors = max_discard_sectors;
- lim.max_write_zeroes_sectors = max_discard_sectors;
+ lim->features |= BLK_FEAT_ROTATIONAL;
+ lim->max_hw_discard_sectors = max_discard_sectors;
+ lim->max_write_zeroes_sectors = max_discard_sectors;
if (max_discard_sectors)
- lim.discard_granularity = granularity;
+ lim->discard_granularity = granularity;
else
- lim.discard_granularity = 0;
- return queue_limits_commit_update(lo->lo_queue, &lim);
+ lim->discard_granularity = 0;
}

static int loop_configure(struct loop_device *lo, blk_mode_t mode,
@@ -1019,6 +1017,7 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
{
struct file *file = fget(config->fd);
struct address_space *mapping;
+ struct queue_limits lim;
int error;
loff_t size;
bool partscan;
@@ -1090,7 +1089,9 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode,
lo->old_gfp_mask = mapping_gfp_mask(mapping);
mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));

- error = loop_reconfigure_limits(lo, config->block_size);
+ lim = queue_limits_start_update(lo->lo_queue);
+ loop_update_limits(lo, &lim, config->block_size);
+ error = queue_limits_commit_update(lo->lo_queue, &lim);
if (error)
goto out_unlock;

@@ -1458,6 +1459,7 @@ static int loop_set_dio(struct loop_device *lo, unsigned long arg)

static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
{
+ struct queue_limits lim;
int err = 0;

if (lo->lo_state != Lo_bound)
@@ -1470,7 +1472,9 @@ 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);
- err = loop_reconfigure_limits(lo, arg);
+ lim = queue_limits_start_update(lo->lo_queue);
+ loop_update_limits(lo, &lim, arg);
+ err = queue_limits_commit_update(lo->lo_queue, &lim);
loop_update_dio(lo);
blk_mq_unfreeze_queue(lo->lo_queue);

--
2.45.2