[0/2] btrfs-progs: zoned: check existence of SB zone, not LBA

Message

Naohiro Aota Oct. 12, 2023, 2:19 p.m. UTC

Running btrfs check can fail on a certain zoned decice setup (e.g,
zone size = 128MB, device size = 16GB):

(from generic/330)
yes|/usr/local/bin/btrfs check --repair --force /dev/nullb1
[1/7] checking root items
Fixed 0 roots.
[2/7] checking extents
ERROR: zoned: failed to read zone info of 4096 and 4097: Invalid argument
ERROR: failed to write super block for devid 1: write error: Input/output error
failed to write new super block err -5
failed to repair damaged filesystem, aborting

This happens because write_dev_supers() is comparing the original
superblock location vs the device size to check if it can write out a
superblock copy or not.

For the above example, since the first copy location (64MB) < device size
(16GB), it tries to write out the copy. But, the copy must be written into
zone 4096 (512G / zone size (128M) = 4096), which is out of the device.

To address the issue, this series introduces check_sb_location() to check
if a SB copy can be written out.

The patch 1 is a preparation to factor out logic of converting the original
superblock location to SB log writing superblock zone. And, the second one
implements check_sb_location() to write_dev_supers().

Naohiro Aota (2):
  btrfs-progs: zoned: introduce sb_bytenr_to_sb_zone()
  btrfs-progs: zoned: check SB zone existence properly

 kernel-shared/disk-io.c |  9 ++++++++-
 kernel-shared/zoned.c   | 36 ++++++++++++++++++++++++------------
 kernel-shared/zoned.h   |  6 ++++++
 3 files changed, 38 insertions(+), 13 deletions(-)

Comments

David Sterba Oct. 12, 2023, 4:25 p.m. UTC | #1

On Thu, Oct 12, 2023 at 11:19:28PM +0900, Naohiro Aota wrote:
> Running btrfs check can fail on a certain zoned decice setup (e.g,
> zone size = 128MB, device size = 16GB):
> 
> (from generic/330)
> yes|/usr/local/bin/btrfs check --repair --force /dev/nullb1
> [1/7] checking root items
> Fixed 0 roots.
> [2/7] checking extents
> ERROR: zoned: failed to read zone info of 4096 and 4097: Invalid argument
> ERROR: failed to write super block for devid 1: write error: Input/output error
> failed to write new super block err -5
> failed to repair damaged filesystem, aborting
> 
> This happens because write_dev_supers() is comparing the original
> superblock location vs the device size to check if it can write out a
> superblock copy or not.
> 
> For the above example, since the first copy location (64MB) < device size
> (16GB), it tries to write out the copy. But, the copy must be written into
> zone 4096 (512G / zone size (128M) = 4096), which is out of the device.

I've added the text above to changelog of patch 2 as it's relevant for
the change.

> To address the issue, this series introduces check_sb_location() to check
> if a SB copy can be written out.
> 
> The patch 1 is a preparation to factor out logic of converting the original
> superblock location to SB log writing superblock zone. And, the second one
> implements check_sb_location() to write_dev_supers().
> 
> Naohiro Aota (2):
>   btrfs-progs: zoned: introduce sb_bytenr_to_sb_zone()
>   btrfs-progs: zoned: check SB zone existence properly

Added to devel, thanks.