Re: [PATCH] Replace obscure constructs in fs/block_dev.c

From: Björn Steinbrink
Date: Sun Jun 17 2007 - 05:38:31 EST


On 2007.06.15 15:46:32 +0200, Johannes Weiner wrote:
> Hi,
>
> Andrew, I promised it [1], here goes. Patched against Linus' git-tree.
>
> [1] http://lkml.org/lkml/2007/3/22/226
>
> This patch replaces some obscure code-paths in fs/block_dev.c with more
> readable versions.
>
> Signed-off-by: Johannes Weiner <hannes-kernel@xxxxxxxxxxxx>
>

> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index ea1480a..1ffbb6d 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -660,26 +660,16 @@ void bd_forget(struct inode *inode)
>
> int bd_claim(struct block_device *bdev, void *holder)
> {
> - int res;
> + int res = 0;
> spin_lock(&bdev_lock);
>
> - /* first decide result */
> - if (bdev->bd_holder == holder)
> - res = 0; /* already a holder */
> - else if (bdev->bd_holder != NULL)
> - res = -EBUSY; /* held by someone else */
> - else if (bdev->bd_contains == bdev)
> - res = 0; /* 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
> - res = 0; /* is a partition of an un-held device */
> + /* If already held by someone else or we have a
> + * partition of a held device, we do nothing. */
>
> - /* now impose change */
> - if (res==0) {
> + if (bdev->bd_holder || bdev->bd_contains->bd_holder)
> + res = -EBUSY;

Hm, that actually ignores the "someone else" part of the comment and
introduces a semantic change. No idea, if it breaks anything though.

Björn
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