diff options
| -rw-r--r-- | drivers/block/rbd.c | 43 |
1 files changed, 33 insertions, 10 deletions
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 8c90a39c2a91..ed0c91d81063 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -261,10 +261,10 @@ struct rbd_device { char name[DEV_NAME_LEN]; /* blkdev name, e.g. rbd3 */ - spinlock_t lock; /* queue lock */ + spinlock_t lock; /* queue, flags, open_count */ struct rbd_image_header header; - unsigned long flags; + unsigned long flags; /* possibly lock protected */ struct rbd_spec *spec; char *header_name; @@ -289,13 +289,19 @@ struct rbd_device { /* sysfs related */ struct device dev; - unsigned long open_count; + unsigned long open_count; /* protected by lock */ }; -/* Flag bits for rbd_dev->flags */ - +/* + * Flag bits for rbd_dev->flags. If atomicity is required, + * rbd_dev->lock is used to protect access. + * + * Currently, only the "removing" flag (which is coupled with the + * "open_count" field) requires atomic access. + */ enum rbd_dev_flags { RBD_DEV_FLAG_EXISTS, /* mapped snapshot has not been deleted */ + RBD_DEV_FLAG_REMOVING, /* this mapping is being removed */ }; static DEFINE_MUTEX(ctl_mutex); /* Serialize open/close/setup/teardown */ @@ -383,14 +389,23 @@ static int rbd_dev_v2_refresh(struct rbd_device *rbd_dev, u64 *hver); static int rbd_open(struct block_device *bdev, fmode_t mode) { struct rbd_device *rbd_dev = bdev->bd_disk->private_data; + bool removing = false; if ((mode & FMODE_WRITE) && rbd_dev->mapping.read_only) return -EROFS; + spin_lock(&rbd_dev->lock); + if (test_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags)) + removing = true; + else + rbd_dev->open_count++; + spin_unlock(&rbd_dev->lock); + if (removing) + return -ENOENT; + mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING); (void) get_device(&rbd_dev->dev); set_device_ro(bdev, rbd_dev->mapping.read_only); - rbd_dev->open_count++; mutex_unlock(&ctl_mutex); return 0; @@ -399,10 +414,14 @@ static int rbd_open(struct block_device *bdev, fmode_t mode) static int rbd_release(struct gendisk *disk, fmode_t mode) { struct rbd_device *rbd_dev = disk->private_data; + unsigned long open_count_before; + + spin_lock(&rbd_dev->lock); + open_count_before = rbd_dev->open_count--; + spin_unlock(&rbd_dev->lock); + rbd_assert(open_count_before > 0); mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING); - rbd_assert(rbd_dev->open_count > 0); - rbd_dev->open_count--; put_device(&rbd_dev->dev); mutex_unlock(&ctl_mutex); @@ -4083,10 +4102,14 @@ static ssize_t rbd_remove(struct bus_type *bus, goto done; } - if (rbd_dev->open_count) { + spin_lock(&rbd_dev->lock); + if (rbd_dev->open_count) ret = -EBUSY; + else + set_bit(RBD_DEV_FLAG_REMOVING, &rbd_dev->flags); + spin_unlock(&rbd_dev->lock); + if (ret < 0) goto done; - } rbd_remove_all_snaps(rbd_dev); rbd_bus_del_dev(rbd_dev); |
