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author | Anand Jain <anand.jain@oracle.com> | 2022-01-12 08:05:59 +0300 |
---|---|---|
committer | David Sterba <dsterba@suse.com> | 2022-03-14 15:13:46 +0300 |
commit | 770c79fb65506fc7c16459855c3839429f46cb32 (patch) | |
tree | f306d74b6040d9db7bef92e1dacec6b15237b03f /fs/btrfs/volumes.c | |
parent | bef16b52987b3cd18222109e2490b2f48018cd95 (diff) | |
download | linux-770c79fb65506fc7c16459855c3839429f46cb32.tar.xz |
btrfs: harden identification of a stale device
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.
Reported-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/volumes.c')
-rw-r--r-- | fs/btrfs/volumes.c | 45 |
1 files changed, 38 insertions, 7 deletions
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c index 76b6957c619b..188e2a61402d 100644 --- a/fs/btrfs/volumes.c +++ b/fs/btrfs/volumes.c @@ -534,15 +534,48 @@ error: 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; + dev_t dev_old; + dev_t dev_new; + int ret; + + /* + * 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; + ret = lookup_bdev(device_name, &dev_old); + kfree(device_name); + if (ret) + return false; + + ret = lookup_bdev(path, &dev_new); + if (ret) + return false; + + if (dev_old == dev_new) + return true; + + return false; } /* @@ -575,9 +608,7 @@ 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 */ |