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block: reorganize claim/release implementation 

With claim/release rolled into blkdev_get/put(), there's no reason to
keep bd_abort/finish_claim(), __bd_claim() and bd_release() as
separate functions.  It only makes the code difficult to follow.
Collapse them into blkdev_get/put().  This will ease future changes
around claim/release.

Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Tejun Heo 2010-11-13 11:55:17 +01:00
parent e525fd89d3
commit 6a027eff62
1 changed files with 48 additions and 79 deletions
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127
fs/block_dev.c
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@ -772,79 +772,6 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
}
}
/* releases bdev_lock */
static void __bd_abort_claiming(struct block_device *whole, void *holder)
{
BUG_ON(whole->bd_claiming != holder);
whole->bd_claiming = NULL;
wake_up_bit(&whole->bd_claiming, 0);
spin_unlock(&bdev_lock);
bdput(whole);
}
/**
* bd_abort_claiming - abort claiming a block device
* @whole: whole block device returned by bd_start_claiming()
* @holder: holder trying to claim @bdev
*
* Abort a claiming block started by bd_start_claiming(). Note that
* @whole is not the block device to be claimed but the whole device
* returned by bd_start_claiming().
*
* CONTEXT:
* Grabs and releases bdev_lock.
*/
static void bd_abort_claiming(struct block_device *whole, void *holder)
{
spin_lock(&bdev_lock);
__bd_abort_claiming(whole, holder); /* releases bdev_lock */
}
/* increment holders when we have a legitimate claim. requires bdev_lock */
static void __bd_claim(struct block_device *bdev, struct block_device *whole,
void *holder)
{
/* note that for a whole device bd_holders
* will be incremented twice, and bd_holder will
* be set to bd_may_claim before being set to holder
*/
whole->bd_holders++;
whole->bd_holder = bd_may_claim;
bdev->bd_holders++;
bdev->bd_holder = holder;
}
/**
* bd_finish_claiming - finish claiming a block device
* @bdev: block device of interest (passed to bd_start_claiming())
* @whole: whole block device returned by bd_start_claiming()
* @holder: holder trying to claim @bdev
*
* Finish a claiming block started by bd_start_claiming().
*
* CONTEXT:
* Grabs and releases bdev_lock.
*/
static void bd_finish_claiming(struct block_device *bdev,
struct block_device *whole, void *holder)
{
spin_lock(&bdev_lock);
BUG_ON(!bd_may_claim(bdev, whole, holder));
__bd_claim(bdev, whole, holder);
__bd_abort_claiming(whole, holder); /* not actually an abort */
}
static void bd_release(struct block_device *bdev)
{
spin_lock(&bdev_lock);
if (!--bdev->bd_contains->bd_holders)
bdev->bd_contains->bd_holder = NULL;
if (!--bdev->bd_holders)
bdev->bd_holder = NULL;
spin_unlock(&bdev_lock);
}
#ifdef CONFIG_SYSFS
static int add_symlink(struct kobject *from, struct kobject *to)
{
@ -1223,10 +1150,30 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
res = __blkdev_get(bdev, mode, 0);
if (whole) {
if (res == 0)
bd_finish_claiming(bdev, whole, holder);
else
bd_abort_claiming(whole, holder);
/* finish claiming */
spin_lock(&bdev_lock);
if (res == 0) {
BUG_ON(!bd_may_claim(bdev, whole, holder));
/*
* Note that for a whole device bd_holders
* will be incremented twice, and bd_holder
* will be set to bd_may_claim before being
* set to holder
*/
whole->bd_holders++;
whole->bd_holder = bd_may_claim;
bdev->bd_holders++;
bdev->bd_holder = holder;
}
/* tell others that we're done */
BUG_ON(whole->bd_claiming != holder);
whole->bd_claiming = NULL;
wake_up_bit(&whole->bd_claiming, 0);
spin_unlock(&bdev_lock);
bdput(whole);
}
return res;
@ -1272,6 +1219,7 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
bdev->bd_part_count--;
if (!--bdev->bd_openers) {
WARN_ON_ONCE(bdev->bd_holders);
sync_blockdev(bdev);
kill_bdev(bdev);
}
@ -1303,10 +1251,31 @@ static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
int blkdev_put(struct block_device *bdev, fmode_t mode)
{
if (mode & FMODE_EXCL) {
bool bdev_free;
/*
* Release a claim on the device. The holder fields
* are protected with bdev_lock. bd_mutex is to
* synchronize disk_holder unlinking.
*/
mutex_lock(&bdev->bd_mutex);
bd_release(bdev);
if (!bdev->bd_holders)
spin_lock(&bdev_lock);
WARN_ON_ONCE(--bdev->bd_holders < 0);
WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
/* bd_contains might point to self, check in a separate step */
if ((bdev_free = !bdev->bd_holders))
bdev->bd_holder = NULL;
if (!bdev->bd_contains->bd_holders)
bdev->bd_contains->bd_holder = NULL;
spin_unlock(&bdev_lock);
/* if this was the last claim, holder link should go too */
if (bdev_free)
bd_unlink_disk_holder(bdev);
mutex_unlock(&bdev->bd_mutex);
}
return __blkdev_put(bdev, mode, 0);