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authorLinus Torvalds <torvalds@linux-foundation.org>2010-06-10 10:26:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-06-10 10:26:42 -0700
commit8fade6aff706b2ae3f02864b4023d34b002cd226 (patch)
treec2c68afd662d5fbaef042e56d91d7813d3a5a9e6
parente1f38e2cea199ef2b8e117506fef8abbecbaae5e (diff)
parent6db40cf047a8723095caf79f5569d21b388d7b31 (diff)
Merge branch 'for-linus2' of git://git.kernel.dk/linux-2.6-block
* 'for-linus2' of git://git.kernel.dk/linux-2.6-block: pipe: fix check in "set size" fcntl pipe: fix pipe buffer resizing block: remove duplicate BUG_ON() in bd_finish_claiming() block: bd_start_claiming cleanup block: bd_start_claiming fix module refcount
-rw-r--r--fs/block_dev.c72
-rw-r--r--fs/pipe.c20
2 files changed, 62 insertions, 30 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 7346c96308a..99d6af81174 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -706,8 +706,13 @@ retry:
* @bdev is about to be opened exclusively. Check @bdev can be opened
* exclusively and mark that an exclusive open is in progress. Each
* successful call to this function must be matched with a call to
- * either bd_claim() or bd_abort_claiming(). If this function
- * succeeds, the matching bd_claim() is guaranteed to succeed.
+ * either bd_finish_claiming() or bd_abort_claiming() (which do not
+ * fail).
+ *
+ * This function is used to gain exclusive access to the block device
+ * without actually causing other exclusive open attempts to fail. It
+ * should be used when the open sequence itself requires exclusive
+ * access but may subsequently fail.
*
* CONTEXT:
* Might sleep.
@@ -734,6 +739,7 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
return ERR_PTR(-ENXIO);
whole = bdget_disk(disk, 0);
+ module_put(disk->fops->owner);
put_disk(disk);
if (!whole)
return ERR_PTR(-ENOMEM);
@@ -782,15 +788,46 @@ static void bd_abort_claiming(struct block_device *whole, void *holder)
__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_claim before being set to holder
+ */
+ whole->bd_holders++;
+ whole->bd_holder = bd_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 */
+}
+
/**
* bd_claim - claim a block device
* @bdev: block device to claim
* @holder: holder trying to claim @bdev
*
- * Try to claim @bdev which must have been opened successfully. This
- * function may be called with or without preceding
- * blk_start_claiming(). In the former case, this function is always
- * successful and terminates the claiming block.
+ * Try to claim @bdev which must have been opened successfully.
*
* CONTEXT:
* Might sleep.
@@ -806,23 +843,10 @@ int bd_claim(struct block_device *bdev, void *holder)
might_sleep();
spin_lock(&bdev_lock);
-
res = bd_prepare_to_claim(bdev, whole, holder);
- 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
- */
- whole->bd_holders++;
- whole->bd_holder = bd_claim;
- bdev->bd_holders++;
- bdev->bd_holder = holder;
- }
-
- if (whole->bd_claiming)
- __bd_abort_claiming(whole, holder); /* releases bdev_lock */
- else
- spin_unlock(&bdev_lock);
+ if (res == 0)
+ __bd_claim(bdev, whole, holder);
+ spin_unlock(&bdev_lock);
return res;
}
@@ -1476,7 +1500,7 @@ static int blkdev_open(struct inode * inode, struct file * filp)
if (whole) {
if (res == 0)
- BUG_ON(bd_claim(bdev, filp) != 0);
+ bd_finish_claiming(bdev, whole, filp);
else
bd_abort_claiming(whole, filp);
}
@@ -1712,7 +1736,7 @@ struct block_device *open_bdev_exclusive(const char *path, fmode_t mode, void *h
if ((mode & FMODE_WRITE) && bdev_read_only(bdev))
goto out_blkdev_put;
- BUG_ON(bd_claim(bdev, holder) != 0);
+ bd_finish_claiming(bdev, whole, holder);
return bdev;
out_blkdev_put:
diff --git a/fs/pipe.c b/fs/pipe.c
index 69c4c7c13ea..279eef96c51 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1145,13 +1145,20 @@ static long pipe_set_size(struct pipe_inode_info *pipe, unsigned long nr_pages)
* and adjust the indexes.
*/
if (pipe->nrbufs) {
- const unsigned int tail = pipe->nrbufs & (pipe->buffers - 1);
- const unsigned int head = pipe->nrbufs - tail;
+ unsigned int tail;
+ unsigned int head;
+ tail = pipe->curbuf + pipe->nrbufs;
+ if (tail < pipe->buffers)
+ tail = 0;
+ else
+ tail &= (pipe->buffers - 1);
+
+ head = pipe->nrbufs - tail;
if (head)
memcpy(bufs, pipe->bufs + pipe->curbuf, head * sizeof(struct pipe_buffer));
if (tail)
- memcpy(bufs + head, pipe->bufs + pipe->curbuf, tail * sizeof(struct pipe_buffer));
+ memcpy(bufs + head, pipe->bufs, tail * sizeof(struct pipe_buffer));
}
pipe->curbuf = 0;
@@ -1208,12 +1215,13 @@ long pipe_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
size = round_pipe_size(arg);
nr_pages = size >> PAGE_SHIFT;
+ ret = -EINVAL;
+ if (!nr_pages)
+ goto out;
+
if (!capable(CAP_SYS_RESOURCE) && size > pipe_max_size) {
ret = -EPERM;
goto out;
- } else if (nr_pages < PAGE_SIZE) {
- ret = -EINVAL;
- goto out;
}
ret = pipe_set_size(pipe, nr_pages);
break;