From cea67ab92d3d4da9f2b4141d87cb8664757daca0 Mon Sep 17 00:00:00 2001 From: Jeff Mahoney Date: Tue, 20 Sep 2016 08:50:21 -0400 Subject: 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 Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/volumes.c | 38 +++++++++++--------------------------- 1 file changed, 11 insertions(+), 27 deletions(-) (limited to 'fs/btrfs') 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; -- cgit v1.2.3-58-ga151