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md: factor out the rdev overlaps check from rdev_size_store

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This splits the code into nicely readable chunks and also avoids
the refcount inc/dec manipulations.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2022-07-19 11:18:19 +02:00 committed by Jens Axboe
parent 33b614e334
commit 2652a1bd2e
1 changed files with 39 additions and 45 deletions
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84
drivers/md/md.c
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@ -3343,14 +3343,33 @@ rdev_size_show(struct md_rdev *rdev, char *page)
return sprintf(page, "%llu\n", (unsigned long long)rdev->sectors / 2);
}
static int overlaps(sector_t s1, sector_t l1, sector_t s2, sector_t l2)
static int md_rdevs_overlap(struct md_rdev *a, struct md_rdev *b)
{
/* check if two start/length pairs overlap */
if (s1+l1 <= s2)
return 0;
if (s2+l2 <= s1)
return 0;
return 1;
if (a->data_offset + a->sectors <= b->data_offset)
return false;
if (b->data_offset + b->sectors <= a->data_offset)
return false;
return true;
}
static bool md_rdev_overlaps(struct md_rdev *rdev)
{
struct mddev *mddev;
struct md_rdev *rdev2;
spin_lock(&all_mddevs_lock);
list_for_each_entry(mddev, &all_mddevs, all_mddevs) {
rdev_for_each(rdev2, mddev) {
if (rdev != rdev2 && rdev->bdev == rdev2->bdev &&
md_rdevs_overlap(rdev, rdev2)) {
spin_unlock(&all_mddevs_lock);
return true;
}
}
}
spin_unlock(&all_mddevs_lock);
return false;
}
static int strict_blocks_to_sectors(const char *buf, sector_t *sectors)
@ -3402,46 +3421,21 @@ rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
return -EINVAL; /* component must fit device */
rdev->sectors = sectors;
if (sectors > oldsectors && my_mddev->external) {
/* Need to check that all other rdevs with the same
* ->bdev do not overlap. 'rcu' is sufficient to walk
* the rdev lists safely.
* This check does not provide a hard guarantee, it
* just helps avoid dangerous mistakes.
/*
* Check that all other rdevs with the same bdev do not overlap. This
* check does not provide a hard guarantee, it just helps avoid
* dangerous mistakes.
*/
if (sectors > oldsectors && my_mddev->external &&
md_rdev_overlaps(rdev)) {
/*
* Someone else could have slipped in a size change here, but
* doing so is just silly. We put oldsectors back because we
* know it is safe, and trust userspace not to race with itself.
*/
struct mddev *mddev;
int overlap = 0;
struct list_head *tmp;
rcu_read_lock();
for_each_mddev(mddev, tmp) {
struct md_rdev *rdev2;
rdev_for_each(rdev2, mddev)
if (rdev->bdev == rdev2->bdev &&
rdev != rdev2 &&
overlaps(rdev->data_offset, rdev->sectors,
rdev2->data_offset,
rdev2->sectors)) {
overlap = 1;
break;
}
if (overlap) {
mddev_put(mddev);
break;
}
}
rcu_read_unlock();
if (overlap) {
/* Someone else could have slipped in a size
* change here, but doing so is just silly.
* We put oldsectors back because we *know* it is
* safe, and trust userspace not to race with
* itself
*/
rdev->sectors = oldsectors;
return -EBUSY;
}
rdev->sectors = oldsectors;
return -EBUSY;
}
return len;
}