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authorJeff Mahoney <jeffm@suse.com>2016-09-20 08:50:21 -0400
committerDavid Sterba <dsterba@suse.com>2016-09-26 18:08:44 +0200
commitcea67ab92d3d4da9f2b4141d87cb8664757daca0 (patch)
tree75f6575c0d9aecef3d981ff0083222b2c4932be9 /fs/btrfs
parent02794222c4132ac003e7281fb71f4ec1645ffc87 (diff)
btrfs: clean the old superblocks before freeing the device
btrfs_rm_device frees the block device but then re-opens it using the saved device name. A race exists between the close and the re-open that allows the block size to be changed. The result is getting stuck forever in the reclaim loop in __getblk_slow. This patch moves the superblock cleanup before closing the block device, which is also consistent with other callers. We also don't need a private copy of dev_name as the whole routine operates under the uuid_mutex. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs')
-rw-r--r--fs/btrfs/volumes.c38
1 files changed, 11 insertions, 27 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index c356ce332229..be2c8b35c3ae 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1846,7 +1846,6 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path, u64 devid)
u64 num_devices;
int ret = 0;
bool clear_super = false;
- char *dev_name = NULL;
mutex_lock(&uuid_mutex);
@@ -1882,11 +1881,6 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path, u64 devid)
list_del_init(&device->dev_alloc_list);
device->fs_devices->rw_devices--;
unlock_chunks(root);
- dev_name = kstrdup(device->name->str, GFP_KERNEL);
- if (!dev_name) {
- ret = -ENOMEM;
- goto error_undo;
- }
clear_super = true;
}
@@ -1936,14 +1930,21 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path, u64 devid)
btrfs_sysfs_rm_device_link(root->fs_info->fs_devices, device);
}
- btrfs_close_bdev(device);
-
- call_rcu(&device->rcu, free_device);
-
num_devices = btrfs_super_num_devices(root->fs_info->super_copy) - 1;
btrfs_set_super_num_devices(root->fs_info->super_copy, num_devices);
mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
+ /*
+ * at this point, the device is zero sized and detached from
+ * the devices list. All that's left is to zero out the old
+ * supers and free the device.
+ */
+ if (device->writeable)
+ btrfs_scratch_superblocks(device->bdev, device->name->str);
+
+ btrfs_close_bdev(device);
+ call_rcu(&device->rcu, free_device);
+
if (cur_devices->open_devices == 0) {
struct btrfs_fs_devices *fs_devices;
fs_devices = root->fs_info->fs_devices;
@@ -1962,24 +1963,7 @@ int btrfs_rm_device(struct btrfs_root *root, char *device_path, u64 devid)
root->fs_info->num_tolerated_disk_barrier_failures =
btrfs_calc_num_tolerated_disk_barrier_failures(root->fs_info);
- /*
- * at this point, the device is zero sized. We want to
- * remove it from the devices list and zero out the old super
- */
- if (clear_super) {
- struct block_device *bdev;
-
- bdev = blkdev_get_by_path(dev_name, FMODE_READ | FMODE_EXCL,
- root->fs_info->bdev_holder);
- if (!IS_ERR(bdev)) {
- btrfs_scratch_superblocks(bdev, dev_name);
- blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
- }
- }
-
out:
- kfree(dev_name);
-
mutex_unlock(&uuid_mutex);
return ret;