libext2fs: add ea_inode support to set xattr
This patch is a major update to how we decide where to put extended
attributes. The main motivation is to enable creating values in
extended attribute inodes. While doing this, we want to implement a
behavior that is as close to kernel as possible.
Existing set ea code deviates from kernel behavior which makes it harder
to implement ea_inode feature:
- kernel only sorts ea entries in xattr block, e2fsprogs implementation
sorts all entries on every update.
- e2fsprogs implementation shuffled things on every update so the order
of updates does not matter. Kernel does not reshuffle things.
- e2fsprogs could evacuate entries from inode body to xattr block and
vice versa. This behavior does not exist in kernel.
Such differences could lead to inconsistent behavior between fuse2fs and
a kernel mount.
With ea_inode feature, we also need to decide whether to put a value
in an inode or keep it 'inline'. In kernel implementation this
depends on current placement of entries.
To close the behavioral gap, ext2fs_xattr_set() now takes over the
decision about where to place ea values. This also allows it to raise
errors early instead of delaying them to a separate
ext2fs_xattrs_write() call later.
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
7 files changed