isofs: Implement fileattr_get for case sensitivity

Upper layers such as NFSD need a way to query whether a
filesystem handles filenames in a case-sensitive manner so
they can provide correct semantics to remote clients. Without
this information, NFS exports of ISO 9660 filesystems cannot
advertise their filename case behavior.

Implement isofs_fileattr_get() to report ISO 9660 case handling
behavior. The 'check=r' (relaxed) mount option enables
case-insensitive lookups and is reported via FS_XFLAG_CASEFOLD.
By default, Joliet extensions operate in relaxed mode while
plain ISO 9660 uses strict (case-sensitive) mode.

Plain ISO 9660 names on the medium are uppercase. When neither
Rock Ridge nor Joliet is in effect, the default 'map=n' option
(and 'map=a') routes lookup and readdir through
isofs_name_translate(), which forces A-Z to a-z. The names
visible to userspace then differ in case from the on-disc form,
so report FS_XFLAG_CASENONPRESERVING in that configuration. Rock
Ridge and Joliet both deliver names as authored, and 'map=o'
emits the raw on-disc name unchanged, so those configurations
remain case-preserving.

Casefolding is a directory property, and the in-tree consumers
(NFSD, ksmbd) issue the query against a directory: NFSD walks
to the parent for non-directory dentries before calling
vfs_fileattr_get(), and ksmbd reports per-share attributes from
the share root. Wire .fileattr_get only on
isofs_dir_inode_operations. The CASEFOLD flag is set in both
fa->fsx_xflags and fa->flags so FS_IOC_FSGETXATTR and
FS_IOC_GETFLAGS agree.

Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Roland Mainz <roland.mainz@nrubsig.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://patch.msgid.link/20260507-case-sensitivity-v14-12-e62cc8200435@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

0 files changed, 0 insertions, 0 deletions