commit 770c79fb65506fc7c16459855c3839429f46cb32 upstream

Identifying and removing the stale device from the fs_uuids list is done by btrfs_free_stale_devices(). btrfs_free_stale_devices() in turn depends on device_path_matched() to check if the device appears in more than one btrfs_device structure.

The matching of the device happens by its path, the device path. However, when device mapper is in use, the dm device paths are nothing but a link to the actual block device, which leads to the device_path_matched() failing to match.

Fix this by matching the dev_t as provided by lookup_bdev() instead of plain string compare of the device paths.

CC: stable@vger.kernel.org #5.10 Reported-by: Josef Bacik josef@toxicpanda.com Signed-off-by: Anand Jain anand.jain@oracle.com Signed-off-by: David Sterba dsterba@suse.com --- fs/btrfs/volumes.c | 44 +++++++++++++++++++++++++++++++++++++------- 1 file changed, 37 insertions(+), 7 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 2fdf178aa76f..d4d89e0738ff 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -540,15 +540,47 @@ btrfs_get_bdev_and_sb(const char *device_path, fmode_t flags, void *holder, return ret; }

-static bool device_path_matched(const char *path, struct btrfs_device *device) +/* + * Check if the device in the path matches the device in the given struct device. + * + * Returns: + * true If it is the same device. + * false If it is not the same device or on error. + */ +static bool device_matched(const struct btrfs_device *device, const char *path) { - int found; + char *device_name; + struct block_device *bdev_old; + struct block_device *bdev_new; + + /* + * If we are looking for a device with the matching dev_t, then skip + * device without a name (a missing device). + */ + if (!device->name) + return false; + + device_name = kzalloc(BTRFS_PATH_NAME_MAX, GFP_KERNEL); + if (!device_name) + return false;

rcu_read_lock(); - found = strcmp(rcu_str_deref(device->name), path); + scnprintf(device_name, BTRFS_PATH_NAME_MAX, "%s", rcu_str_deref(device->name)); rcu_read_unlock();

- return found == 0; + bdev_old = lookup_bdev(device_name); + kfree(device_name); + if (IS_ERR(bdev_old)) + return false; + + bdev_new = lookup_bdev(path); + if (IS_ERR(bdev_new)) + return false; + + if (bdev_old == bdev_new) + return true; + + return false; }

/* @@ -581,9 +613,7 @@ static int btrfs_free_stale_devices(const char *path, &fs_devices->devices, dev_list) { if (skip_device && skip_device == device) continue; - if (path && !device->name) - continue; - if (path && !device_path_matched(path, device)) + if (path && !device_matched(device, path)) continue; if (fs_devices->opened) { /* for an already deleted device return 0 */