On Tue, Dec 14, 2021 at 05:50:58PM +0000, Luís Henriques wrote: > When migrating to extents, the temporary inode will have it's own checksum > seed. This means that, when swapping the inodes data, the inode checksums > will be incorrect. > > This can be fixed by recalculating the extents checksums again. Or simply > by copying the seed into the temporary inode. > > Link: https://bugzilla.kernel.org/show_bug.cgi?id=213357 > Reported-by: Jeroen van Wolffelaar <jeroen@xxxxxxxxxxxxx> > Signed-off-by: Luís Henriques <lhenriques@xxxxxxx> > --- > fs/ext4/migrate.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > changes since v1: > > * Dropped tmp_ei variable > * ->i_csum_seed is now initialised immediately after tmp_inode is created > * New comment about the seed initialization and stating that recovery > needs to be fixed. > > Cheers, > -- > Luís > > diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c > index 7e0b4f81c6c0..36dfc88ce05b 100644 > --- a/fs/ext4/migrate.c > +++ b/fs/ext4/migrate.c > @@ -459,6 +459,17 @@ int ext4_ext_migrate(struct inode *inode) > ext4_journal_stop(handle); > goto out_unlock; > } > + /* > + * Use the correct seed for checksum (i.e. the seed from 'inode'). This > + * is so that the metadata blocks will have the correct checksum after > + * the migration. > + * > + * Note however that, if a crash occurs during the migration process, > + * the recovery process is broken because the tmp_inode checksums will > + * be wrong and the orphans cleanup will fail. ...and then what does the user do? --D > + */ > + ei = EXT4_I(inode); > + EXT4_I(tmp_inode)->i_csum_seed = ei->i_csum_seed; > i_size_write(tmp_inode, i_size_read(inode)); > /* > * Set the i_nlink to zero so it will be deleted later > @@ -502,7 +513,6 @@ int ext4_ext_migrate(struct inode *inode) > goto out_tmp_inode; > } > > - ei = EXT4_I(inode); > i_data = ei->i_data; > memset(&lb, 0, sizeof(lb)); >
