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block: refactor bd_start_claiming 

Move the locking and assignment of bd_claiming from bd_start_claiming to
bd_prepare_to_claim.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2020-07-16 16:33:08 +02:00 committed by Jens Axboe
parent c5638ab417
commit 58e46ed9cc
1 changed files with 13 additions and 20 deletions
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33
fs/block_dev.c
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@ -1015,19 +1015,14 @@ static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
}
/**
* bd_prepare_to_claim - prepare to claim a block device
* bd_prepare_to_claim - claim a block device
* @bdev: block device of interest
* @whole: the whole device containing @bdev, may equal @bdev
* @holder: holder trying to claim @bdev
*
* Prepare to claim @bdev. This function fails if @bdev is already
* claimed by another holder and waits if another claiming is in
* progress. This function doesn't actually claim. On successful
* return, the caller has ownership of bd_claiming and bd_holder[s].
*
* CONTEXT:
* spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
* it multiple times.
* Claim @bdev. This function fails if @bdev is already claimed by another
* holder and waits if another claiming is in progress. return, the caller
* has ownership of bd_claiming and bd_holder[s].
*
* RETURNS:
* 0 if @bdev can be claimed, -EBUSY otherwise.
@ -1036,9 +1031,12 @@ static int bd_prepare_to_claim(struct block_device *bdev,
struct block_device *whole, void *holder)
{
retry:
spin_lock(&bdev_lock);
/* if someone else claimed, fail */
if (!bd_may_claim(bdev, whole, holder))
if (!bd_may_claim(bdev, whole, holder)) {
spin_unlock(&bdev_lock);
return -EBUSY;
}
/* if claiming is already in progress, wait for it to finish */
if (whole->bd_claiming) {
@ -1049,11 +1047,12 @@ retry:
spin_unlock(&bdev_lock);
schedule();
finish_wait(wq, &wait);
spin_lock(&bdev_lock);
goto retry;
}
/* yay, all mine */
whole->bd_claiming = holder;
spin_unlock(&bdev_lock);
return 0;
}
@ -1134,19 +1133,13 @@ struct block_device *bd_start_claiming(struct block_device *bdev, void *holder)
if (!whole)
return ERR_PTR(-ENOMEM);
/* prepare to claim, if successful, mark claiming in progress */
spin_lock(&bdev_lock);
err = bd_prepare_to_claim(bdev, whole, holder);
if (err == 0) {
whole->bd_claiming = holder;
spin_unlock(&bdev_lock);
return whole;
} else {
spin_unlock(&bdev_lock);
if (err) {
bdput(whole);
return ERR_PTR(err);
}
return whole;
}
EXPORT_SYMBOL(bd_start_claiming);