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=213357Reported-by: NJeroen van Wolffelaar <jeroen@wolffelaar.nl>
Signed-off-by: NLuís Henriques <lhenriques@suse.de>
Link: https://lore.kernel.org/r/20211214175058.19511-1-lhenriques@suse.deSigned-off-by: NTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org