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-rw-r--r--drivers/block/loop.c16
-rw-r--r--fs/block_dev.c83
-rw-r--r--include/linux/fs.h6
3 files changed, 73 insertions, 32 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 44c9985f352a..3036883fc9f8 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -924,6 +924,7 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
struct file *file;
struct inode *inode;
struct address_space *mapping;
+ struct block_device *claimed_bdev = NULL;
int lo_flags = 0;
int error;
loff_t size;
@@ -942,10 +943,11 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
* here to avoid changing device under exclusive owner.
*/
if (!(mode & FMODE_EXCL)) {
- bdgrab(bdev);
- error = blkdev_get(bdev, mode | FMODE_EXCL, loop_set_fd);
- if (error)
+ claimed_bdev = bd_start_claiming(bdev, loop_set_fd);
+ if (IS_ERR(claimed_bdev)) {
+ error = PTR_ERR(claimed_bdev);
goto out_putf;
+ }
}
error = mutex_lock_killable(&loop_ctl_mutex);
@@ -1015,15 +1017,15 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
mutex_unlock(&loop_ctl_mutex);
if (partscan)
loop_reread_partitions(lo, bdev);
- if (!(mode & FMODE_EXCL))
- blkdev_put(bdev, mode | FMODE_EXCL);
+ if (claimed_bdev)
+ bd_abort_claiming(bdev, claimed_bdev, loop_set_fd);
return 0;
out_unlock:
mutex_unlock(&loop_ctl_mutex);
out_bdev:
- if (!(mode & FMODE_EXCL))
- blkdev_put(bdev, mode | FMODE_EXCL);
+ if (claimed_bdev)
+ bd_abort_claiming(bdev, claimed_bdev, loop_set_fd);
out_putf:
fput(file);
out:
diff --git a/fs/block_dev.c b/fs/block_dev.c
index c2a85b587922..22591bad9353 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1181,8 +1181,7 @@ static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno)
* Pointer to the block device containing @bdev on success, ERR_PTR()
* value on failure.
*/
-static struct block_device *bd_start_claiming(struct block_device *bdev,
- void *holder)
+struct block_device *bd_start_claiming(struct block_device *bdev, void *holder)
{
struct gendisk *disk;
struct block_device *whole;
@@ -1229,6 +1228,62 @@ static struct block_device *bd_start_claiming(struct block_device *bdev,
return ERR_PTR(err);
}
}
+EXPORT_SYMBOL(bd_start_claiming);
+
+static void bd_clear_claiming(struct block_device *whole, void *holder)
+{
+ lockdep_assert_held(&bdev_lock);
+ /* tell others that we're done */
+ BUG_ON(whole->bd_claiming != holder);
+ whole->bd_claiming = NULL;
+ wake_up_bit(&whole->bd_claiming, 0);
+}
+
+/**
+ * bd_finish_claiming - finish claiming of a block device
+ * @bdev: block device of interest
+ * @whole: whole block device (returned from bd_start_claiming())
+ * @holder: holder that has claimed @bdev
+ *
+ * Finish exclusive open of a block device. Mark the device as exlusively
+ * open by the holder and wake up all waiters for exclusive open to finish.
+ */
+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));
+ /*
+ * 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_clear_claiming(whole, holder);
+ spin_unlock(&bdev_lock);
+}
+EXPORT_SYMBOL(bd_finish_claiming);
+
+/**
+ * bd_abort_claiming - abort claiming of a block device
+ * @bdev: block device of interest
+ * @whole: whole block device (returned from bd_start_claiming())
+ * @holder: holder that has claimed @bdev
+ *
+ * Abort claiming of a block device when the exclusive open failed. This can be
+ * also used when exclusive open is not actually desired and we just needed
+ * to block other exclusive openers for a while.
+ */
+void bd_abort_claiming(struct block_device *bdev, struct block_device *whole,
+ void *holder)
+{
+ spin_lock(&bdev_lock);
+ bd_clear_claiming(whole, holder);
+ spin_unlock(&bdev_lock);
+}
+EXPORT_SYMBOL(bd_abort_claiming);
#ifdef CONFIG_SYSFS
struct bd_holder_disk {
@@ -1698,29 +1753,7 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
/* finish claiming */
mutex_lock(&bdev->bd_mutex);
- spin_lock(&bdev_lock);
-
- if (!res) {
- 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);
-
+ bd_finish_claiming(bdev, whole, holder);
/*
* Block event polling for write claims if requested. Any
* write holder makes the write_holder state stick until
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 56b8e358af5c..997a530ff4e9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2598,6 +2598,12 @@ extern struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
void *holder);
extern struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode,
void *holder);
+extern struct block_device *bd_start_claiming(struct block_device *bdev,
+ void *holder);
+extern void bd_finish_claiming(struct block_device *bdev,
+ struct block_device *whole, void *holder);
+extern void bd_abort_claiming(struct block_device *bdev,
+ struct block_device *whole, void *holder);
extern void blkdev_put(struct block_device *bdev, fmode_t mode);
extern int __blkdev_reread_part(struct block_device *bdev);
extern int blkdev_reread_part(struct block_device *bdev);