Hi,
On Sun, Jun 17, 2007 at 11:38:55AM +0200, Bjoern Steinbrink wrote:
[SNIP]
> > - /* 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;
[SNAP]
> Hm, that actually ignores the "someone else" part of the comment and
> introduces a semantic change. No idea, if it breaks anything though.
Whoops, yes. ->bd_holder can be actually !NULL when it is == holder.
Same for ->bd_contains->bd_holder. Also the `is a whole unheld device'
was ignored - sorry. Second try:
This patch replaces some obscure code-paths in fs/block_dev.c with more
readable versions.
Signed-off-by: Johannes Weiner <[email protected]>
diff --git a/fs/block_dev.c b/fs/block_dev.c
index ea1480a..3a49adb 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -660,37 +660,32 @@ void bd_forget(struct inode *inode)
int bd_claim(struct block_device *bdev, void *holder)
{
- int res;
+ void *bd_holder;
+ struct block_device *bd_contains;
+
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 */
+ bd_holder = bdev->bd_holder;
+ bd_contains = bdev->bd_contains;
- /* now impose change */
- if (res==0) {
- /* 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;
- bdev->bd_holders++;
- bdev->bd_holder = holder;
+ if ((bd_holder && bd_holder != holder) ||
+ (bd_contains != bdev &&
+ bd_contains->bd_holder && bd_contains->bd_holder != bd_claim)) {
+ spin_unlock(&bdev_lock);
+ return -EBUSY;
}
+
+ /* 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;
+ bdev->bd_holders++;
+ bdev->bd_holder = holder;
+
spin_unlock(&bdev_lock);
- return res;
+ return 0;
}
EXPORT_SYMBOL(bd_claim);
@@ -874,7 +869,7 @@ static struct bd_holder *find_bd_holder(struct block_device *bdev,
*/
static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
{
- int ret;
+ int err;
if (!bo)
return -EINVAL;
@@ -882,14 +877,17 @@ static int add_bd_holder(struct block_device *bdev, struct bd_holder *bo)
if (!bd_holder_grab_dirs(bdev, bo))
return -EBUSY;
- ret = add_symlink(bo->sdir, bo->sdev);
- if (ret == 0) {
- ret = add_symlink(bo->hdir, bo->hdev);
- if (ret)
- del_symlink(bo->sdir, bo->sdev);
+ err = add_symlink(bo->sdir, bo->sdev);
+ if (err)
+ return err;
+
+ err = add_symlink(bo->hdir, bo->hdev);
+ if (err) {
+ del_symlink(bo->sdir, bo->sdev);
+ return err;
}
- if (ret == 0)
- list_add_tail(&bo->list, &bdev->bd_holder_list);
+
+ list_add_tail(&bo->list, &bdev->bd_holder_list);
return ret;
}
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