btrfs-rescue(8)
-==============
+===============
NAME
----
SUBCOMMAND
----------
+
*chunk-recover* [options] <device>::
Recover the chunk tree by scanning the devices
+
NOTE: Since *chunk-recover* will scan the whole device, it will be *VERY* slow
especially executed on a large device.
+*fix-device-size* <device>::
+fix device size and super block total bytes values that are do not match
++
+Kernel 4.11 starts to check the device size more strictly and this might
+mismatch the stored value of total bytes. See the exact error message below.
+Newer kernel will refuse to mount the filesystem where the values do not match.
+This error is not fatal and can be fixed. This command will fix the device
+size values if possible.
++
+----
+BTRFS error (device sdb): super_total_bytes 92017859088384 mismatch with fs_devices total_rw_bytes 92017859094528
+----
++
+The mismatch may also exhibit as a kernel warning:
++
+----
+WARNING: CPU: 3 PID: 439 at fs/btrfs/ctree.h:1559 btrfs_update_device+0x1c5/0x1d0 [btrfs]
+----
+
*super-recover* [options] <device>::
Recover bad superblocks from good copies.
+
set of problem when the filesystem mount fails due to the log replay. See below
for sample stacktraces that may show up in system log.
+
-The common case where this happens has been fixed a long time ago,
-so it is unlikely that you will see this particular problem, but the utility is
+The common case where this happens was fixed a long time ago,
+so it is unlikely that you will see this particular problem, but the command is
kept around.
+
NOTE: clearing the log may lead to loss of changes that were made since the
for are 'open_ctree' which says that it's during mount and function names
that contain 'replay', 'recover' or 'log_tree'.
-*fix-device-size* <device>::
-fix device size and super block total bytes
-+
-This command will fix the following problems, by re-aligning all devices' total
-bytes and re-calculating super block total bytes.
-+
-1. Newer kernel refuse to mount btrfs caused by mismatch super block total bytes
-+
-----
-BTRFS error (device sdb): super_total_bytes 92017859088384 mismatch with fs_devices total_rw_bytes 92017859094528
-----
-+
-2. Noisy kernel warning for newer kernels
-+
-----
-WARNING: CPU: 3 PID: 439 at fs/btrfs/ctree.h:1559 btrfs_update_device+0x1c5/0x1d0 [btrfs]
-----
-+
-And the corresponding line is the `WARN_ON()` line below:
-+
-----
-{
- BUILD_BUG_ON(sizeof(u64) !=
- sizeof(((struct btrfs_dev_item *)0))->total_bytes);
- WARN_ON(!IS_ALIGNED(val, eb->fs_info->sectorsize));
- btrfs_set_64(eb, s, offsetof(struct btrfs_dev_item, total_bytes), val);
-}
-----
-
EXIT STATUS
-----------
*btrfs rescue* returns a zero exit status if it succeeds. Non zero is