Merge tag 'fs.acl.rework.prep.v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping
Pull vfs acl updates from Christian Brauner:
"These are general fixes and preparatory changes related to the ongoing
posix acl rework. The actual rework where we build a type safe posix
acl api wasn't ready for this merge window but we're hopeful for the
next merge window.
General fixes:
- Some filesystems like 9p and cifs have to implement custom posix
acl handlers because they require access to the dentry in order to
set and get posix acls while the set and get inode operations
currently don't. But the ntfs3 filesystem has no such requirement
and thus implemented custom posix acl xattr handlers when it really
didn't have to. So this pr contains patch that just implements set
and get inode operations for ntfs3 and switches it to rely on the
generic posix acl xattr handlers. (We would've appreciated reviews
from the ntfs3 maintainers but we didn't get any. But hey, if we
really broke it we'll fix it. But fstests for ntfs3 said it's
fine.)
- The posix_acl_fix_xattr_common() helper has been adapted so it can
be used by a few more callers and avoiding open-coding the same
checks over and over.
Other than the two general fixes this series introduces a new helper
vfs_set_acl_prepare(). The reason for this helper is so that we can
mitigate one of the source that change {g,u}id values directly in the
uapi struct. With the vfs_set_acl_prepare() helper we can move the
idmapped mount fixup into the generic posix acl set handler.
The advantage of this is that it allows us to remove the
posix_acl_setxattr_idmapped_mnt() helper which so far we had to call
in vfs_setxattr() to account for idmapped mounts. While semantically
correct the problem with this approach was that we had to keep the
value parameter of the generic vfs_setxattr() call as non-const. This
is rectified in this series.
Ultimately, we will get rid of all the extreme kludges and type
unsafety once we have merged the posix api - hopefully during the next
merge window - built solely around get and set inode operations. Which
incidentally will also improve handling of posix acls in security and
especially in integrity modesl. While this will come with temporarily
having two inode operation for posix acls that is nothing compared to
the problems we have right now and so well worth it. We'll end up with
something that we can actually reason about instead of needing to
write novels to explain what's going on"
* tag 'fs.acl.rework.prep.v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/idmapping:
xattr: always us is_posix_acl_xattr() helper
acl: fix the comments of posix_acl_xattr_set
xattr: constify value argument in vfs_setxattr()
ovl: use vfs_set_acl_prepare()
acl: move idmapping handling into posix_acl_xattr_set()
acl: add vfs_set_acl_prepare()
acl: return EOPNOTSUPP in posix_acl_fix_xattr_common()
ntfs3: rework xattr handlers and switch to POSIX ACL VFS helpers
