On Fri, Jan 16, 2026 at 09:46:00AM -0500, Chuck Lever wrote:
> From: Chuck Lever <[email protected]>
>
> Enable upper layers such as NFSD to retrieve case sensitivity
> information from file systems by adding case_insensitive and
> case_nonpreserving boolean fields to struct file_kattr.
>
> The case_insensitive and case_nonpreserving fields in struct
> file_kattr default to false (POSIX semantics: case-sensitive and
> case-preserving), allowing filesystems to set them only when
> behavior differs from the default.
>
> Case sensitivity information is exported to userspace via the
> existing fa_xflags field using the new FS_XFLAG_CASEFOLD and
> FS_XFLAG_CASENONPRESERVING flags.
>
> Signed-off-by: Chuck Lever <[email protected]>
> ---
> fs/file_attr.c | 6 ++++++
> include/linux/fileattr.h | 6 +++++-
> include/uapi/linux/fs.h | 2 ++
> 3 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/fs/file_attr.c b/fs/file_attr.c
> index 13cdb31a3e94..2f83f3c6a170 100644
> --- a/fs/file_attr.c
> +++ b/fs/file_attr.c
> @@ -84,6 +84,8 @@ int vfs_fileattr_get(struct dentry *dentry, struct
> file_kattr *fa)
> struct inode *inode = d_inode(dentry);
> int error;
>
> + memset(fa, 0, sizeof(*fa));
Hrm. If you're going to memset the file_kattr here, then you might as
well remove the memset calls from fileattr_fill_*. It's not great
that filesystems have to know that a "fill_xflags" function assigns to
more than just xflags.
> +
> if (!inode->i_op->fileattr_get)
> return -ENOIOCTLCMD;
>
> @@ -106,6 +108,10 @@ static void fileattr_to_file_attr(const struct
> file_kattr *fa,
> fattr->fa_nextents = fa->fsx_nextents;
> fattr->fa_projid = fa->fsx_projid;
> fattr->fa_cowextsize = fa->fsx_cowextsize;
> + if (fa->case_insensitive)
> + fattr->fa_xflags |= FS_XFLAG_CASEFOLD;
> + if (fa->case_nonpreserving)
> + fattr->fa_xflags |= FS_XFLAG_CASENONPRESERVING;
> }
>
> /**
> diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h
> index f89dcfad3f8f..7f2e557255ce 100644
> --- a/include/linux/fileattr.h
> +++ b/include/linux/fileattr.h
> @@ -16,7 +16,8 @@
>
> /* Read-only inode flags */
> #define FS_XFLAG_RDONLY_MASK \
> - (FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR)
> + (FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR | \
> + FS_XFLAG_CASEFOLD | FS_XFLAG_CASENONPRESERVING)
>
> /* Flags to indicate valid value of fsx_ fields */
> #define FS_XFLAG_VALUES_MASK \
> @@ -51,6 +52,9 @@ struct file_kattr {
> /* selectors: */
> bool flags_valid:1;
> bool fsx_valid:1;
> + /* case sensitivity behavior: */
> + bool case_insensitive:1;
> + bool case_nonpreserving:1;
Er... if you're encoding fs name handling qualities through FS_XFLAG_*,
then filesystems can set them in fsx_xflags directly. No need for
separate bitfields here.
--D
> };
>
> int copy_fsxattr_to_user(const struct file_kattr *fa, struct fsxattr __user
> *ufa);
> diff --git a/include/uapi/linux/fs.h b/include/uapi/linux/fs.h
> index 66ca526cf786..919148beaa8c 100644
> --- a/include/uapi/linux/fs.h
> +++ b/include/uapi/linux/fs.h
> @@ -253,6 +253,8 @@ struct file_attr {
> #define FS_XFLAG_FILESTREAM 0x00004000 /* use filestream allocator */
> #define FS_XFLAG_DAX 0x00008000 /* use DAX for IO */
> #define FS_XFLAG_COWEXTSIZE 0x00010000 /* CoW extent size allocator
> hint */
> +#define FS_XFLAG_CASEFOLD 0x00020000 /* case-insensitive lookups */
> +#define FS_XFLAG_CASENONPRESERVING 0x00040000 /* case not preserved */
> #define FS_XFLAG_HASATTR 0x80000000 /* no DIFLAG for this */
>
> /* the read-only stuff doesn't really belong here, but any other place is
> --
> 2.52.0
>
>
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