From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>, linux-block@vger.kernel.org
Subject: [PATCH 2/4] block: refactor bd_start_claiming
Date: Thu, 16 Jul 2020 16:33:08 +0200 [thread overview]
Message-ID: <20200716143310.473136-3-hch@lst.de> (raw)
In-Reply-To: <20200716143310.473136-1-hch@lst.de>
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>
---
fs/block_dev.c | 33 +++++++++++++--------------------
1 file changed, 13 insertions(+), 20 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 376832250c8e91..b7b2ee4b288ae9 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -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 @@ static int bd_prepare_to_claim(struct block_device *bdev,
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);
--
2.27.0
next prev parent reply other threads:[~2020-07-16 14:33 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-16 14:33 simplify block device claiming (resend) Christoph Hellwig
2020-07-16 14:33 ` [PATCH 1/4] block: simplify the restart case in __blkdev_get Christoph Hellwig
2020-07-16 14:40 ` Tejun Heo
2020-07-16 17:40 ` Hannes Reinecke
2020-07-16 14:33 ` Christoph Hellwig [this message]
2020-07-16 14:41 ` [PATCH 2/4] block: refactor bd_start_claiming Tejun Heo
2020-07-16 17:41 ` Hannes Reinecke
2020-07-16 14:33 ` [PATCH 3/4] block: use bd_prepare_to_claim directly in the loop driver Christoph Hellwig
2020-07-16 17:43 ` Hannes Reinecke
2020-07-16 14:33 ` [PATCH 4/4] block: integrate bd_start_claiming into __blkdev_get Christoph Hellwig
2020-07-16 15:02 ` Tejun Heo
2020-07-16 17:47 ` Hannes Reinecke
2020-07-16 15:37 ` simplify block device claiming (resend) Jens Axboe
-- strict thread matches above, loose matches on Subject: below --
2020-07-02 8:49 simplify block device claiming Christoph Hellwig
2020-07-02 8:49 ` [PATCH 2/4] block: refactor bd_start_claiming Christoph Hellwig
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