Re: [PATCH v7 01/16] fs: Add case sensitivity flags to file_kattr
From: "Darrick J. Wong" <djwong@kernel.org>
Date: 2026-01-23 00:26:47
Also in:
linux-cifs, linux-ext4, linux-f2fs-devel, linux-fsdevel, linux-nfs, linux-xfs
On Thu, Jan 22, 2026 at 11:02:56AM -0500, Chuck Lever wrote:
From: Chuck Lever <chuck.lever@oracle.com> Enable upper layers such as NFSD to retrieve case sensitivity information from file systems by adding FS_XFLAG_CASEFOLD and FS_XFLAG_CASENONPRESERVING flags. Filesystems report case-insensitive or case-nonpreserving behavior by setting these flags directly in fa->fsx_xflags. The default (flags unset) indicates POSIX semantics: case-sensitive and case-preserving. These flags are read-only; userspace cannot set them via ioctl. Remove struct file_kattr initialization from fileattr_fill_xflags() and fileattr_fill_flags(). Callers at ioctl/syscall entry points zero-initialize the struct themselves, which allows them to pass hints (flags_valid, fsx_valid) to the filesystem's ->fileattr_get() callback via the fa argument. Filesystem handlers that invoke these fill functions can now set flags directly in fa->fsx_xflags before calling them, without the fill functions zeroing those values.
In hindsight I regret not asking for the file_kattr initialization change to be in a separate patch.
Case sensitivity information is exported to userspace via the fa_xflags field in the FS_IOC_FSGETXATTR ioctl and file_getattr() system call. Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
The UAPI changes still look ok to me. AFAICT the file_kattr initialization now seem like they don't zap fields to confuse vfs_fileattr_get. Reviewed-by: "Darrick J. Wong" <djwong@kernel.org> --D
quoted hunk ↗ jump to hunk
--- fs/file_attr.c | 12 ++++-------- fs/xfs/xfs_ioctl.c | 2 +- include/linux/fileattr.h | 3 ++- include/uapi/linux/fs.h | 2 ++ 4 files changed, 9 insertions(+), 10 deletions(-)diff --git a/fs/file_attr.c b/fs/file_attr.c index 13cdb31a3e94..6e37040fc5fa 100644 --- a/fs/file_attr.c +++ b/fs/file_attr.c@@ -15,12 +15,10 @@ * @fa: fileattr pointer * @xflags: FS_XFLAG_* flags * - * Set ->fsx_xflags, ->fsx_valid and ->flags (translated xflags). All - * other fields are zeroed. + * Set ->fsx_xflags, ->fsx_valid and ->flags (translated xflags). */ void fileattr_fill_xflags(struct file_kattr *fa, u32 xflags) { - memset(fa, 0, sizeof(*fa)); fa->fsx_valid = true; fa->fsx_xflags = xflags; if (fa->fsx_xflags & FS_XFLAG_IMMUTABLE)@@ -46,11 +44,9 @@ EXPORT_SYMBOL(fileattr_fill_xflags); * @flags: FS_*_FL flags * * Set ->flags, ->flags_valid and ->fsx_xflags (translated flags). - * All other fields are zeroed. */ void fileattr_fill_flags(struct file_kattr *fa, u32 flags) { - memset(fa, 0, sizeof(*fa)); fa->flags_valid = true; fa->flags = flags; if (fa->flags & FS_SYNC_FL)@@ -323,7 +319,7 @@ int ioctl_setflags(struct file *file, unsigned int __user *argp) { struct mnt_idmap *idmap = file_mnt_idmap(file); struct dentry *dentry = file->f_path.dentry; - struct file_kattr fa; + struct file_kattr fa = {}; unsigned int flags; int err;@@ -355,7 +351,7 @@ int ioctl_fssetxattr(struct file *file, void __user *argp) { struct mnt_idmap *idmap = file_mnt_idmap(file); struct dentry *dentry = file->f_path.dentry; - struct file_kattr fa; + struct file_kattr fa = {}; int err; err = copy_fsxattr_from_user(&fa, argp);@@ -434,7 +430,7 @@ SYSCALL_DEFINE5(file_setattr, int, dfd, const char __user *, filename, struct filename *name __free(putname) = NULL; unsigned int lookup_flags = 0; struct file_attr fattr; - struct file_kattr fa; + struct file_kattr fa = {}; int error; BUILD_BUG_ON(sizeof(struct file_attr) < FILE_ATTR_SIZE_VER0);diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 59eaad774371..f0417c4d1fca 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c@@ -496,7 +496,7 @@ xfs_ioc_fsgetxattra( xfs_inode_t *ip, void __user *arg) { - struct file_kattr fa; + struct file_kattr fa = {}; xfs_ilock(ip, XFS_ILOCK_SHARED); xfs_fill_fsxattr(ip, XFS_ATTR_FORK, &fa);diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h index f89dcfad3f8f..709de829659f 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 \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