During mount context, we aren't verifying the superblock checksum
for all the devices, instead, we verify it only for the
struct btrfs_fs_device::latest_bdev. This patch fixes it by moving
the checksum verification code from the function open_ctree() into
the function btrfs_read_dev_one_super().
By doing this now we are verifying the superblock checksum in the
mount-context, device-replace and, device-delete context. The
device-replace and device-delete call-chain is as show below after
this patch.
delete-device/replace:
btrfs_rm_device() || btrfs_dev_replace_by_ioctl()
|_btrfs_find_device_by_devspec()
|_btrfs_find_device_missing_or_by_path()
|_btrfs_find_device_by_path()
|_btrfs_get_bdev_and_sb()
|_btrfs_read_dev_super()
|_btrfs_read_dev_one_super()
|_btrfs_check_super_csum()
Test case:
Before:
mkfs.btrfs -fq -draid1 -mraid1 /dev/sdb /dev/sdc
dd if=/dev/urandom of=/dev/sdc ibs=1 obs=1 count=1 seek=64K
mount /dev/sdb /btrfs <-- success as kernel does not check csum
for non-btrfs_fs_devices::latest_bdev.
After:
mkfs.btrfs -fq -draid1 -mraid1 /dev/sdb /dev/sdc
dd if=/dev/urandom of=/dev/sdc ibs=1 obs=1 count=1 seek=64K
mount /dev/sdb /btrfs
mount: mount /dev/sdc on /btrfs failed: Structure needs cleaning
mount -o degraded /dev/sdc /btrfs
mount: mount /dev/sdc on /btrfs failed: Structure needs cleaning
So the current recovery step is to fix the primary superblock, by
using the btrfs-progs cli.
Signed-off-by: Anand Jain <anand.jain@xxxxxxxxxx>
Reviewed-by: Nikolay Borisov <nborisov@xxxxxxxx>
v1->v2:
git commit log update. With the call-chain (which I believe will
go away in the long term, we need the uuid from the userland not
the disk-path). And add test case.
Check err < 0 explicitly and drop check for "else if (err == -EUCLEAN)"
v1:
err = btrfs_check_super_csum(bh->b_data);
if (err) {
if (err == -EINVAL)
pr_err("BTRFS error (device %pg): unsupported checksum algorithm",
bdev);
else if (err == -EUCLEAN)
pr_err("BTRFS error (device %pg): superblock checksum mismatch",
bdev);
brelse(bh);
return err;
}
---
fs/btrfs/disk-io.c | 33 +++++++++++++++++----------------
1 file changed, 17 insertions(+), 16 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 35dbbdc613cd..110465bec775 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2565,22 +2565,6 @@ int open_ctree(struct super_block *sb,
}
/*
- * We want to check superblock checksum, the type is stored inside.
- * Pass the whole disk block of size BTRFS_SUPER_INFO_SIZE (4k).
- */
- err = btrfs_check_super_csum(bh->b_data);
- if (err) {
- if (err == -EINVAL)
- pr_err("BTRFS error (device %pg): unsupported checksum algorithm",
- fs_devices->latest_bdev);
- else
- pr_err("BTRFS error (device %pg): superblock checksum mismatch",
- fs_devices->latest_bdev);
- brelse(bh);
- goto fail_alloc;
- }
-
- /*
* super_copy is zeroed at allocation time and we never touch the
* following bytes up to INFO_SIZE, the checksum is calculated from
* the whole block of INFO_SIZE
@@ -3126,6 +3110,7 @@ int btrfs_read_dev_one_super(struct block_device *bdev, int copy_num,
struct buffer_head *bh;
struct btrfs_super_block *super;
u64 bytenr;
+ int err;
bytenr = btrfs_sb_offset(copy_num);
if (bytenr + BTRFS_SUPER_INFO_SIZE >= i_size_read(bdev->bd_inode))
@@ -3146,6 +3131,22 @@ int btrfs_read_dev_one_super(struct block_device *bdev, int copy_num,
return -EINVAL;
}
+ /*
+ * Check the superblock checksum, the type is stored inside.
+ * Pass the whole disk block of size BTRFS_SUPER_INFO_SIZE (4k).
+ */
+ err = btrfs_check_super_csum(bh->b_data);
+ if (err < 0) {
+ if (err == -EINVAL)
+ pr_err("BTRFS error (device %pg): unsupported checksum algorithm",
+ bdev);
+ else
+ pr_err("BTRFS error (device %pg): superblock checksum mismatch",
+ bdev);
+ brelse(bh);
+ return err;
+ }
+
*bh_ret = bh;
return 0;
}
--
2.7.0
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