[0/2] btrfs-progs: mkfs: --rootdir related fixes

Message

Qu Wenruo Oct. 4, 2022, 7:43 a.m. UTC

I don't know if it's recent kernel tmpfs change or something else, but
I'm consistently get ino number smaller than 256 from my /tmp directory.

This behavior change exposed a new problem in mkfs.btrfs --rootdir, that
if some ino number (in the source directory, not in btrfs) is smaller
than 256, it can screw up the backref code.

As backref code is utilizing @owner to determine if a backref is data or
metadata.

And inode number smaller than 256 will make backref code to treat a data
backref as tree backref, and cause corruption.

Thankfully this should not happen that easily, only when --rootdir
points to a newly created fs.

Qu Wenruo (2):
  btrfs-progs: properly initialized extent generation for
    __btrfs_record_file_extent()
  btrfs-progs: avoid fs corruption if rootdir contains ino smaller than
    BTRFS_FIRST_FREE_OBJECTID

 kernel-shared/extent-tree.c | 8 +++++++-
 mkfs/rootdir.c              | 8 +++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

Comments

David Sterba Oct. 4, 2022, 9:04 a.m. UTC | #1

On Tue, Oct 04, 2022 at 03:43:37PM +0800, Qu Wenruo wrote:
> I don't know if it's recent kernel tmpfs change or something else, but
> I'm consistently get ino number smaller than 256 from my /tmp directory.
> 
> This behavior change exposed a new problem in mkfs.btrfs --rootdir, that
> if some ino number (in the source directory, not in btrfs) is smaller
> than 256, it can screw up the backref code.
> 
> As backref code is utilizing @owner to determine if a backref is data or
> metadata.
> 
> And inode number smaller than 256 will make backref code to treat a data
> backref as tree backref, and cause corruption.
> 
> Thankfully this should not happen that easily, only when --rootdir
> points to a newly created fs.
> 
> Qu Wenruo (2):
>   btrfs-progs: properly initialized extent generation for
>     __btrfs_record_file_extent()
>   btrfs-progs: avoid fs corruption if rootdir contains ino smaller than
>     BTRFS_FIRST_FREE_OBJECTID

Added to devel, thanks.