btrfs-progs: Fix restoring image from multi devices fs into single device
PATCH 1/2 btrfs-progs: Fix restoring image from multi devices fs into single device
From: Filipe Manana <[email protected]>
We correctly build an image from a multiple devices filesystem but when restoring the image into a single device we were missing updating the number of devices in the superblock to the value 1 (we already took care of setting the number of stripes to 1 for each chunk item and setting the device id for each chunk item to match the device id from the super block).
This missing update of the number of devices makes it impossible to mount the restored filesystem on recent kernels, more specifically since the linux kernel commit 99e3ecfcb9f4ca35192d20a5bea158b81f600062 ("Btrfs: add more validation checks for superblock"), that produce the following message in the dmesg/syslog:
[21097.542047] BTRFS error (device sdi): super_num_devices 2 mismatch with num_devices 1 found here [21097.543972] BTRFS error (device sdi): failed to read chunk tree: -22 [21097.720360] BTRFS error (device sdi): open_ctree failed
So fix this by updating the number of devices to 1 in the superblock.
--- image/main.c | 1 + 1 file changed, 1 insertion(+)
image/main.c +1 -0
@@ -1500,6 +1500,7 @@ static int update_super(struct mdrestore_struct *mdres, u8 *buffer) flags |=BTRFS_SUPER_FLAG_METADUMP_V2 ;btrfs_set_super_flags (super, flags);btrfs_set_super_sys_array_size (super, new_array_size); +btrfs_set_super_num_devices (super,1 );csum_block (buffer,BTRFS_SUPER_INFO_SIZE );return 0 ;
Signature · 1 line
2.11.0
Quoted 15 lines · On Wed, May 17, 2017 at 02:41:21AM +0100, [email protected] wrote:
From: Filipe Manana <[email protected]>
We correctly build an image from a multiple devices filesystem but when restoring the image into a single device we were missing updating the number of devices in the superblock to the value 1 (we already took care of setting the number of stripes to 1 for each chunk item and setting the device id for each chunk item to match the device id from the super block).
This missing update of the number of devices makes it impossible to mount the restored filesystem on recent kernels, more specifically since the linux kernel commit
99e3ecfcb9f4ca35192d20a5bea158b81f600062("Btrfs: add more validation checks for superblock"), that produce the following message in the dmesg/syslog:
Quoted 7 lines
[21097.542047] BTRFS error (device sdi): super_num_devices 2 mismatch with num_devices 1 found here [21097.543972] BTRFS error (device sdi): failed to read chunk tree: -22 [21097.720360] BTRFS error (device sdi): open_ctree failedSo fix this by updating the number of devices to 1 in the superblock.
Signed-off-by Filipe Manana <[email protected]>
Looks good.
Thanks,
-liubo
David Sterba
AppliedQuoted 20 lines · Liu Bo
Quoted 19 lines · On Wed, May 17, 2017 at 02:41:21AM +0100, [email protected] wrote:
From: Filipe Manana <[email protected]>
We correctly build an image from a multiple devices filesystem but when restoring the image into a single device we were missing updating the number of devices in the superblock to the value 1 (we already took care of setting the number of stripes to 1 for each chunk item and setting the device id for each chunk item to match the device id from the super block).
This missing update of the number of devices makes it impossible to mount the restored filesystem on recent kernels, more specifically since the linux kernel commit
99e3ecfcb9f4ca35192d20a5bea158b81f600062("Btrfs: add more validation checks for superblock"), that produce the following message in the dmesg/syslog:[21097.542047] BTRFS error (device sdi): super_num_devices 2 mismatch with num_devices 1 found here [21097.543972] BTRFS error (device sdi): failed to read chunk tree: -22 [21097.720360] BTRFS error (device sdi): open_ctree failed
Quoted 7 lines
Quoted 3 lines
So fix this by updating the number of devices to 1 in the superblock.
Signed-off-by Filipe Manana <[email protected]>Looks good.
Reviewed-by Liu Bo <[email protected]>
Applied, thanks.