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author | Tejun Heo <tj@kernel.org> | 2010-04-07 18:52:29 +0900 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2010-04-27 10:57:54 +0200 |
commit | 1a3cbbc5a5e8a66934aa0947896a4aca6fd77298 (patch) | |
tree | b8425cd193874adee8ba36181e64294ef39335cc /fs/block_dev.c | |
parent | afc24d49c1e5dbeef745c1c1246f5ae6ebd97c71 (diff) | |
download | linux-3.10-1a3cbbc5a5e8a66934aa0947896a4aca6fd77298.tar.gz linux-3.10-1a3cbbc5a5e8a66934aa0947896a4aca6fd77298.tar.bz2 linux-3.10-1a3cbbc5a5e8a66934aa0947896a4aca6fd77298.zip |
block: factor out bd_may_claim()
Factor out bd_may_claim() from bd_claim(), add comments and apply a
couple of cosmetic edits. This is to prepare for further updates to
claim path.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'fs/block_dev.c')
-rw-r--r-- | fs/block_dev.c | 65 |
1 files changed, 47 insertions, 18 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index 2a6d0193f13..e59440c7e1c 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -661,41 +661,70 @@ void bd_forget(struct inode *inode) iput(bdev->bd_inode); } -int bd_claim(struct block_device *bdev, void *holder) +/** + * bd_may_claim - test whether a block device can be claimed + * @bdev: block device of interest + * @whole: whole block device containing @bdev, may equal @bdev + * @holder: holder trying to claim @bdev + * + * Test whther @bdev can be claimed by @holder. + * + * CONTEXT: + * spin_lock(&bdev_lock). + * + * RETURNS: + * %true if @bdev can be claimed, %false otherwise. + */ +static bool bd_may_claim(struct block_device *bdev, struct block_device *whole, + void *holder) { - int res; - spin_lock(&bdev_lock); - - /* first decide result */ if (bdev->bd_holder == holder) - res = 0; /* already a holder */ + return true; /* already a holder */ else if (bdev->bd_holder != NULL) - res = -EBUSY; /* held by someone else */ + return false; /* held by someone else */ else if (bdev->bd_contains == bdev) - res = 0; /* is a whole device which isn't held */ + return true; /* is a whole device which isn't held */ - else if (bdev->bd_contains->bd_holder == bd_claim) - res = 0; /* is a partition of a device that is being partitioned */ - else if (bdev->bd_contains->bd_holder != NULL) - res = -EBUSY; /* is a partition of a held device */ + else if (whole->bd_holder == bd_claim) + return true; /* is a partition of a device that is being partitioned */ + else if (whole->bd_holder != NULL) + return false; /* is a partition of a held device */ else - res = 0; /* is a partition of an un-held device */ + return true; /* is a partition of an un-held device */ +} - /* now impose change */ - if (res==0) { +/** + * bd_claim - claim a block device + * @bdev: block device to claim + * @holder: holder trying to claim @bdev + * + * Try to claim @bdev. + * + * RETURNS: + * 0 if successful, -EBUSY if @bdev is already claimed. + */ +int bd_claim(struct block_device *bdev, void *holder) +{ + struct block_device *whole = bdev->bd_contains; + int res = -EBUSY; + + spin_lock(&bdev_lock); + + if (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_claim before being set to holder */ - bdev->bd_contains->bd_holders ++; - bdev->bd_contains->bd_holder = bd_claim; + whole->bd_holders++; + whole->bd_holder = bd_claim; bdev->bd_holders++; bdev->bd_holder = holder; + res = 0; } + spin_unlock(&bdev_lock); return res; } - EXPORT_SYMBOL(bd_claim); void bd_release(struct block_device *bdev) |