[PATCH v7 00/16] Exposing case folding behavior

[PATCH v7 00/16] Exposing case folding behavior

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Following on from

https://lore.kernel.org/linux-nfs/20251021-zypressen-bazillus-545a44af57fd@brauner/T/#m0ba197d75b7921d994cf284f3cef3a62abb11aaa

I'm attempting to implement enough support in the Linux VFS to
enable file services like NFSD and ksmbd (and user space
equivalents) to provide the actual status of case folding support
in local file systems. The default behavior for local file systems
not explicitly supported in this series is to reflect the usual
POSIX behaviors:

  case-insensitive = false
  case-nonpreserving = true

The case-insensitivity and case-nonpreserving booleans can be
consumed immediately by NFSD. These two attributes have been part of
the NFSv3 and NFSv4 protocols for decades, in order to support NFS
client implementations on non-POSIX systems.

Support for user space file servers is why this series exposes case
folding information via a user-space API. I don't know of any other
category of user-space application that requires access to case
folding info.


The Linux NFS community has a growing interest in supporting NFS
clients on Windows and MacOS platforms, where file name behavior does
not align with traditional POSIX semantics.

One example of a Windows-based NFS client is [1]. This client
implementation explicitly requires servers to report
FATTR4_WORD0_CASE_INSENSITIVE = TRUE for proper operation, a hard
requirement for Windows client interoperability because Windows
applications expect case-insensitive behavior. When an NFS client
knows the server is case-insensitive, it can avoid issuing multiple
LOOKUP/READDIR requests to search for case variants, and applications
like Win32 programs work correctly without manual workarounds or
code changes.

Even the Linux client can take advantage of this information. Trond
merged patches 4 years ago [2] that introduce support for case
insensitivity, in support of the Hammerspace NFS server. In
particular, when a client detects a case-insensitive NFS share,
negative dentry caching must be disabled (a lookup for "FILE.TXT"
failing shouldn't cache a negative entry when "file.txt" exists)
and directory change invalidation must clear all cached case-folded
file name variants.

Hammerspace servers and several other NFS server implementations
operate in multi-protocol environments, where a single file service
instance caters to both NFS and SMB clients. In those cases, things
work more smoothly for everyone when the NFS client can see and adapt
to the case folding behavior that SMB users rely on and expect. NFSD
needs to support the case-insensitivity and case-nonpreserving
booleans properly in order to participate as a first-class citizen
in such environments.

Series based on v6.19-rc6.

[1] https://github.com/kofemann/ms-nfs41-client

[2] https://patchwork.kernel.org/project/linux-nfs/cover/20211217203658.439352-1-trondmy@kernel.org/

---

Changes since v6:
- Remove the memset from vfs_fileattr_get

Changes since v5:
- Finish the conversion to FS_XFLAGs
- NFSv4 GETATTR now clears the attr mask bit if nfsd_get_case_info()
  fails

Changes since v4:
- Observe the MSDOS "nocase" mount option
- Define new FS_XFLAGs for the user API

Changes since v3:
- Change fa->case_preserving to fa_case_nonpreserving
- VFAT is case preserving
- Make new fields available to user space

Changes since v2:
- Remove unicode labels
- Replace vfs_get_case_info
- Add support for several more local file system implementations
- Add support for in-kernel SMB server

Changes since RFC:
- Use file_getattr instead of statx
- Postpone exposing Unicode version until later
- Support NTFS and ext4 in addition to FAT
- Support NFSv4 fattr4 in addition to NFSv3 PATHCONF


Chuck Lever (16):
  fs: Add case sensitivity flags to file_kattr
  fat: Implement fileattr_get for case sensitivity
  exfat: Implement fileattr_get for case sensitivity
  ntfs3: Implement fileattr_get for case sensitivity
  hfs: Implement fileattr_get for case sensitivity
  hfsplus: Report case sensitivity in fileattr_get
  ext4: Report case sensitivity in fileattr_get
  xfs: Report case sensitivity in fileattr_get
  cifs: Implement fileattr_get for case sensitivity
  nfs: Implement fileattr_get for case sensitivity
  f2fs: Add case sensitivity reporting to fileattr_get
  vboxsf: Implement fileattr_get for case sensitivity
  isofs: Implement fileattr_get for case sensitivity
  nfsd: Report export case-folding via NFSv3 PATHCONF
  nfsd: Implement NFSv4 FATTR4_CASE_INSENSITIVE and
    FATTR4_CASE_PRESERVING
  ksmbd: Report filesystem case sensitivity via FS_ATTRIBUTE_INFORMATION

 fs/exfat/exfat_fs.h      |  2 ++
 fs/exfat/file.c          | 16 ++++++++++++++--
 fs/exfat/namei.c         |  1 +
 fs/ext4/ioctl.c          |  7 +++++++
 fs/f2fs/file.c           |  7 +++++++
 fs/fat/fat.h             |  3 +++
 fs/fat/file.c            | 21 +++++++++++++++++++++
 fs/fat/namei_msdos.c     |  1 +
 fs/fat/namei_vfat.c      |  1 +
 fs/file_attr.c           | 12 ++++--------
 fs/hfs/dir.c             |  1 +
 fs/hfs/hfs_fs.h          |  2 ++
 fs/hfs/inode.c           | 13 +++++++++++++
 fs/hfsplus/inode.c       |  8 ++++++++
 fs/isofs/dir.c           | 15 +++++++++++++++
 fs/nfs/client.c          |  9 +++++++--
 fs/nfs/inode.c           | 20 ++++++++++++++++++++
 fs/nfs/internal.h        |  3 +++
 fs/nfs/nfs3proc.c        |  2 ++
 fs/nfs/nfs3xdr.c         |  7 +++++--
 fs/nfs/nfs4proc.c        |  2 ++
 fs/nfs/proc.c            |  3 +++
 fs/nfs/symlink.c         |  3 +++
 fs/nfsd/nfs3proc.c       | 18 ++++++++++--------
 fs/nfsd/nfs4xdr.c        | 31 +++++++++++++++++++++++++++----
 fs/nfsd/vfs.c            | 25 +++++++++++++++++++++++++
 fs/nfsd/vfs.h            |  2 ++
 fs/ntfs3/file.c          | 23 +++++++++++++++++++++++
 fs/ntfs3/inode.c         |  1 +
 fs/ntfs3/namei.c         |  2 ++
 fs/ntfs3/ntfs_fs.h       |  1 +
 fs/smb/client/cifsfs.c   | 20 ++++++++++++++++++++
 fs/smb/server/smb2pdu.c  | 25 +++++++++++++++++++------
 fs/vboxsf/dir.c          |  1 +
 fs/vboxsf/file.c         |  6 ++++--
 fs/vboxsf/super.c        |  4 ++++
 fs/vboxsf/utils.c        | 31 +++++++++++++++++++++++++++++++
 fs/vboxsf/vfsmod.h       |  6 ++++++
 fs/xfs/xfs_ioctl.c       |  9 ++++++++-
 include/linux/fileattr.h |  3 ++-
 include/linux/nfs_xdr.h  |  2 ++
 include/uapi/linux/fs.h  |  2 ++
 42 files changed, 335 insertions(+), 36 deletions(-)

-- 
2.52.0

[PATCH v7 01/16] fs: Add case sensitivity flags to file_kattr

[Chuck Lever]

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.

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>
---
 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

[PATCH v7 02/16] fat: Implement fileattr_get for case sensitivity

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Report FAT's case sensitivity behavior via the FS_XFLAG_CASEFOLD
and FS_XFLAG_CASENONPRESERVING flags. FAT filesystems are
case-insensitive by default.

MSDOS supports a 'nocase' mount option that enables case-sensitive
behavior; check this option when reporting case sensitivity.

VFAT long filename entries preserve case; without VFAT, only
uppercased 8.3 short names are stored. MSDOS with 'nocase' also
preserves case since the name-formatting code skips upcasing when
'nocase' is set. Check both options when reporting case preservation.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/fat/fat.h         |  3 +++
 fs/fat/file.c        | 21 +++++++++++++++++++++
 fs/fat/namei_msdos.c |  1 +
 fs/fat/namei_vfat.c  |  1 +
 4 files changed, 26 insertions(+)

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index d3e426de5f01..9e208eeb46c4 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -10,6 +10,8 @@
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
 
+struct file_kattr;
+
 /*
  * vfat shortname flags
  */
@@ -407,6 +409,7 @@ extern void fat_truncate_blocks(struct inode *inode, loff_t offset);
 extern int fat_getattr(struct mnt_idmap *idmap,
 		       const struct path *path, struct kstat *stat,
 		       u32 request_mask, unsigned int flags);
+int fat_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
 extern int fat_file_fsync(struct file *file, loff_t start, loff_t end,
 			  int datasync);
 
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 4fc49a614fb8..f7f613cb763b 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -16,6 +16,7 @@
 #include <linux/fsnotify.h>
 #include <linux/security.h>
 #include <linux/falloc.h>
+#include <linux/fileattr.h>
 #include "fat.h"
 
 static long fat_fallocate(struct file *file, int mode,
@@ -395,6 +396,25 @@ void fat_truncate_blocks(struct inode *inode, loff_t offset)
 	fat_flush_inodes(inode->i_sb, inode, NULL);
 }
 
+int fat_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
+
+	/*
+	 * FAT filesystems are case-insensitive by default. MSDOS
+	 * supports a 'nocase' mount option for case-sensitive behavior.
+	 *
+	 * VFAT long filename entries preserve case. Without VFAT, only
+	 * uppercased 8.3 short names are stored. MSDOS with 'nocase'
+	 * also preserves case.
+	 */
+	if (!sbi->options.nocase)
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+	if (!sbi->options.isvfat && !sbi->options.nocase)
+		fa->fsx_xflags |= FS_XFLAG_CASENONPRESERVING;
+	return 0;
+}
+
 int fat_getattr(struct mnt_idmap *idmap, const struct path *path,
 		struct kstat *stat, u32 request_mask, unsigned int flags)
 {
@@ -574,5 +594,6 @@ EXPORT_SYMBOL_GPL(fat_setattr);
 const struct inode_operations fat_file_inode_operations = {
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.fileattr_get	= fat_fileattr_get,
 	.update_time	= fat_update_time,
 };
diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index 0b920ee40a7f..380add5c6c66 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -640,6 +640,7 @@ static const struct inode_operations msdos_dir_inode_operations = {
 	.rename		= msdos_rename,
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.fileattr_get	= fat_fileattr_get,
 	.update_time	= fat_update_time,
 };
 
diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index 5dbc4cbb8fce..6cf513f97afa 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -1180,6 +1180,7 @@ static const struct inode_operations vfat_dir_inode_operations = {
 	.rename		= vfat_rename2,
 	.setattr	= fat_setattr,
 	.getattr	= fat_getattr,
+	.fileattr_get	= fat_fileattr_get,
 	.update_time	= fat_update_time,
 };
 
-- 
2.52.0

[PATCH v7 03/16] exfat: Implement fileattr_get for case sensitivity

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Report exFAT's case sensitivity behavior via the FS_XFLAG_CASEFOLD
flag. exFAT is always case-insensitive (using an upcase table for
comparison) and always preserves case at rest.

Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/exfat/exfat_fs.h |  2 ++
 fs/exfat/file.c     | 16 ++++++++++++++--
 fs/exfat/namei.c    |  1 +
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 176fef62574c..11c782a28843 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -468,6 +468,8 @@ int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 int exfat_getattr(struct mnt_idmap *idmap, const struct path *path,
 		  struct kstat *stat, unsigned int request_mask,
 		  unsigned int query_flags);
+struct file_kattr;
+int exfat_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
 int exfat_file_fsync(struct file *file, loff_t start, loff_t end, int datasync);
 long exfat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg);
 long exfat_compat_ioctl(struct file *filp, unsigned int cmd,
diff --git a/fs/exfat/file.c b/fs/exfat/file.c
index 536c8078f0c1..eb01238e1189 100644
--- a/fs/exfat/file.c
+++ b/fs/exfat/file.c
@@ -12,6 +12,7 @@
 #include <linux/security.h>
 #include <linux/msdos_fs.h>
 #include <linux/writeback.h>
+#include <linux/fileattr.h>
 
 #include "exfat_raw.h"
 #include "exfat_fs.h"
@@ -281,6 +282,16 @@ int exfat_getattr(struct mnt_idmap *idmap, const struct path *path,
 	return 0;
 }
 
+int exfat_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	/*
+	 * exFAT is always case-insensitive (using upcase table).
+	 * Case is preserved at rest (the default).
+	 */
+	fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+	return 0;
+}
+
 int exfat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
 		  struct iattr *attr)
 {
@@ -775,6 +786,7 @@ const struct file_operations exfat_file_operations = {
 };
 
 const struct inode_operations exfat_file_inode_operations = {
-	.setattr     = exfat_setattr,
-	.getattr     = exfat_getattr,
+	.setattr	= exfat_setattr,
+	.getattr	= exfat_getattr,
+	.fileattr_get	= exfat_fileattr_get,
 };
diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index dfe957493d49..a3a854ddc83a 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -1323,4 +1323,5 @@ const struct inode_operations exfat_dir_inode_operations = {
 	.rename		= exfat_rename,
 	.setattr	= exfat_setattr,
 	.getattr	= exfat_getattr,
+	.fileattr_get	= exfat_fileattr_get,
 };
-- 
2.52.0

[PATCH v7 04/16] ntfs3: Implement fileattr_get for case sensitivity

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Report NTFS case sensitivity behavior via the FS_XFLAG_CASEFOLD
flag. NTFS always preserves case at rest.

Case sensitivity depends on mount options: with "nocase", NTFS
is case-insensitive; otherwise it is case-sensitive.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/ntfs3/file.c    | 23 +++++++++++++++++++++++
 fs/ntfs3/inode.c   |  1 +
 fs/ntfs3/namei.c   |  2 ++
 fs/ntfs3/ntfs_fs.h |  1 +
 4 files changed, 27 insertions(+)

diff --git a/fs/ntfs3/file.c b/fs/ntfs3/file.c
index 2e7b2e566ebe..6562768f4574 100644
--- a/fs/ntfs3/file.c
+++ b/fs/ntfs3/file.c
@@ -146,6 +146,28 @@ long ntfs_compat_ioctl(struct file *filp, u32 cmd, unsigned long arg)
 }
 #endif
 
+/*
+ * ntfs_fileattr_get - inode_operations::fileattr_get
+ */
+int ntfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct inode *inode = d_inode(dentry);
+	struct ntfs_sb_info *sbi = inode->i_sb->s_fs_info;
+
+	/* Avoid any operation if inode is bad. */
+	if (unlikely(is_bad_ni(ntfs_i(inode))))
+		return -EINVAL;
+
+	/*
+	 * NTFS preserves case (the default). Case sensitivity depends on
+	 * mount options: with "nocase", NTFS is case-insensitive;
+	 * otherwise it is case-sensitive.
+	 */
+	if (sbi->options && sbi->options->nocase)
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+	return 0;
+}
+
 /*
  * ntfs_getattr - inode_operations::getattr
  */
@@ -1460,6 +1482,7 @@ const struct inode_operations ntfs_file_inode_operations = {
 	.get_acl	= ntfs_get_acl,
 	.set_acl	= ntfs_set_acl,
 	.fiemap		= ntfs_fiemap,
+	.fileattr_get	= ntfs_fileattr_get,
 };
 
 const struct file_operations ntfs_file_operations = {
diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index 0a9ac5efeb67..205083e8a6e0 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -2089,6 +2089,7 @@ const struct inode_operations ntfs_link_inode_operations = {
 	.get_link	= ntfs_get_link,
 	.setattr	= ntfs_setattr,
 	.listxattr	= ntfs_listxattr,
+	.fileattr_get	= ntfs_fileattr_get,
 };
 
 const struct address_space_operations ntfs_aops = {
diff --git a/fs/ntfs3/namei.c b/fs/ntfs3/namei.c
index 3b24ca02de61..d09414711016 100644
--- a/fs/ntfs3/namei.c
+++ b/fs/ntfs3/namei.c
@@ -519,6 +519,7 @@ const struct inode_operations ntfs_dir_inode_operations = {
 	.getattr	= ntfs_getattr,
 	.listxattr	= ntfs_listxattr,
 	.fiemap		= ntfs_fiemap,
+	.fileattr_get	= ntfs_fileattr_get,
 };
 
 const struct inode_operations ntfs_special_inode_operations = {
@@ -527,6 +528,7 @@ const struct inode_operations ntfs_special_inode_operations = {
 	.listxattr	= ntfs_listxattr,
 	.get_acl	= ntfs_get_acl,
 	.set_acl	= ntfs_set_acl,
+	.fileattr_get	= ntfs_fileattr_get,
 };
 
 const struct dentry_operations ntfs_dentry_ops = {
diff --git a/fs/ntfs3/ntfs_fs.h b/fs/ntfs3/ntfs_fs.h
index a4559c9f64e6..a578b75f31fc 100644
--- a/fs/ntfs3/ntfs_fs.h
+++ b/fs/ntfs3/ntfs_fs.h
@@ -504,6 +504,7 @@ extern const struct file_operations ntfs_dir_operations;
 extern const struct file_operations ntfs_legacy_dir_operations;
 
 /* Globals from file.c */
+int ntfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
 int ntfs_getattr(struct mnt_idmap *idmap, const struct path *path,
 		 struct kstat *stat, u32 request_mask, u32 flags);
 int ntfs_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
-- 
2.52.0

[PATCH v7 05/16] hfs: Implement fileattr_get for case sensitivity

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Report HFS case sensitivity behavior via the FS_XFLAG_CASEFOLD
flag. HFS is always case-insensitive (using Mac OS Roman case
folding) and always preserves case at rest.

Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/hfs/dir.c    |  1 +
 fs/hfs/hfs_fs.h |  2 ++
 fs/hfs/inode.c  | 13 +++++++++++++
 3 files changed, 16 insertions(+)

diff --git a/fs/hfs/dir.c b/fs/hfs/dir.c
index 86a6b317b474..552156896105 100644
--- a/fs/hfs/dir.c
+++ b/fs/hfs/dir.c
@@ -321,4 +321,5 @@ const struct inode_operations hfs_dir_inode_operations = {
 	.rmdir		= hfs_remove,
 	.rename		= hfs_rename,
 	.setattr	= hfs_inode_setattr,
+	.fileattr_get	= hfs_fileattr_get,
 };
diff --git a/fs/hfs/hfs_fs.h b/fs/hfs/hfs_fs.h
index e94dbc04a1e4..a25cdda8ab34 100644
--- a/fs/hfs/hfs_fs.h
+++ b/fs/hfs/hfs_fs.h
@@ -177,6 +177,8 @@ extern int hfs_get_block(struct inode *inode, sector_t block,
 extern const struct address_space_operations hfs_aops;
 extern const struct address_space_operations hfs_btree_aops;
 
+struct file_kattr;
+int hfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
 int hfs_write_begin(const struct kiocb *iocb, struct address_space *mapping,
 		    loff_t pos, unsigned int len, struct folio **foliop,
 		    void **fsdata);
diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
index 524db1389737..8d7ef19af538 100644
--- a/fs/hfs/inode.c
+++ b/fs/hfs/inode.c
@@ -18,6 +18,7 @@
 #include <linux/uio.h>
 #include <linux/xattr.h>
 #include <linux/blkdev.h>
+#include <linux/fileattr.h>
 
 #include "hfs_fs.h"
 #include "btree.h"
@@ -698,6 +699,17 @@ static int hfs_file_fsync(struct file *filp, loff_t start, loff_t end,
 	return ret;
 }
 
+int hfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	/*
+	 * Report case-insensitive behavior: all name comparisons use
+	 * Mac OS Roman case folding. FS_XFLAG_CASENONPRESERVING remains
+	 * unset because original case is preserved on disk.
+	 */
+	fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+	return 0;
+}
+
 static const struct file_operations hfs_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read_iter	= generic_file_read_iter,
@@ -714,4 +726,5 @@ static const struct inode_operations hfs_file_inode_operations = {
 	.lookup		= hfs_file_lookup,
 	.setattr	= hfs_inode_setattr,
 	.listxattr	= generic_listxattr,
+	.fileattr_get	= hfs_fileattr_get,
 };
-- 
2.52.0

[PATCH v7 06/16] hfsplus: Report case sensitivity in fileattr_get

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Add case sensitivity reporting to the existing hfsplus_fileattr_get()
function via the FS_XFLAG_CASEFOLD flag. HFS+ always preserves case
at rest.

Case sensitivity depends on how the volume was formatted: HFSX
volumes may be either case-sensitive or case-insensitive, indicated
by the HFSPLUS_SB_CASEFOLD superblock flag.

Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/hfsplus/inode.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/hfsplus/inode.c b/fs/hfsplus/inode.c
index 7ae6745ca7ae..ec9a144aac02 100644
--- a/fs/hfsplus/inode.c
+++ b/fs/hfsplus/inode.c
@@ -694,6 +694,7 @@ int hfsplus_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
 {
 	struct inode *inode = d_inode(dentry);
 	struct hfsplus_inode_info *hip = HFSPLUS_I(inode);
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(inode->i_sb);
 	unsigned int flags = 0;
 
 	if (inode->i_flags & S_IMMUTABLE)
@@ -705,6 +706,13 @@ int hfsplus_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
 
 	fileattr_fill_flags(fa, flags);
 
+	/*
+	 * HFS+ preserves case (the default). Case sensitivity depends
+	 * on how the filesystem was formatted: HFSX volumes may be
+	 * either case-sensitive or case-insensitive.
+	 */
+	if (test_bit(HFSPLUS_SB_CASEFOLD, &sbi->flags))
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
 	return 0;
 }
 
-- 
2.52.0

[PATCH v7 07/16] ext4: Report case sensitivity in fileattr_get

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Report ext4's case sensitivity behavior via the FS_XFLAG_CASEFOLD
flag. ext4 always preserves case at rest.

Case sensitivity is a per-directory setting in ext4. If the queried
inode is a casefolded directory, report case-insensitive; otherwise
report case-sensitive (standard POSIX behavior).

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/ext4/ioctl.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 7ce0fc40aec2..462da7aadc80 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -996,6 +996,13 @@ int ext4_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
 	if (ext4_has_feature_project(inode->i_sb))
 		fa->fsx_projid = from_kprojid(&init_user_ns, ei->i_projid);
 
+	/*
+	 * Case folding is a directory attribute in ext4. Set FS_XFLAG_CASEFOLD
+	 * for directories with the casefold attribute; all other inodes use
+	 * standard case-sensitive semantics.
+	 */
+	if (IS_CASEFOLDED(inode))
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
 	return 0;
 }
 
-- 
2.52.0

[PATCH v7 08/16] xfs: Report case sensitivity in fileattr_get

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Upper layers such as NFSD need to query whether a filesystem is
case-sensitive. Report case sensitivity via the FS_XFLAG_CASEFOLD
flag in xfs_fileattr_get(). XFS always preserves case. XFS is
case-sensitive by default, but supports ASCII case-insensitive
lookups when formatted with the ASCIICI feature flag.

Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/xfs/xfs_ioctl.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index f0417c4d1fca..da98d4422b02 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -516,6 +516,13 @@ xfs_fileattr_get(
 	xfs_fill_fsxattr(ip, XFS_DATA_FORK, fa);
 	xfs_iunlock(ip, XFS_ILOCK_SHARED);
 
+	/*
+	 * FS_XFLAG_CASEFOLD indicates case-insensitive lookups with
+	 * case preservation. This matches ASCIICI behavior: lookups
+	 * fold ASCII case while filenames remain stored verbatim.
+	 */
+	if (xfs_has_asciici(ip->i_mount))
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
 	return 0;
 }
 
-- 
2.52.0

[PATCH v7 09/16] cifs: Implement fileattr_get for case sensitivity

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Upper layers such as NFSD need a way to query whether a filesystem
handles filenames in a case-sensitive manner. Report CIFS/SMB case
handling behavior via the FS_XFLAG_CASEFOLD flag.

CIFS servers (typically Windows or Samba) are usually case-insensitive
but case-preserving, meaning they ignore case during lookups but store
filenames exactly as provided.

The implementation reports case sensitivity based on the nocase mount
option, which reflects whether the client expects the server to perform
case-insensitive comparisons. When nocase is set, the mount is reported
as case-insensitive.

The callback is registered in all three inode_operations structures
(directory, file, and symlink) to ensure consistent reporting across
all inode types.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/smb/client/cifsfs.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
index d9664634144d..39426a128b3d 100644
--- a/fs/smb/client/cifsfs.c
+++ b/fs/smb/client/cifsfs.c
@@ -30,6 +30,7 @@
 #include <linux/xattr.h>
 #include <linux/mm.h>
 #include <linux/key-type.h>
+#include <linux/fileattr.h>
 #include <uapi/linux/magic.h>
 #include <net/ipv6.h>
 #include "cifsfs.h"
@@ -1193,6 +1194,22 @@ struct file_system_type smb3_fs_type = {
 MODULE_ALIAS_FS("smb3");
 MODULE_ALIAS("smb3");
 
+static int cifs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
+	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
+
+	/*
+	 * Case sensitivity is reported based on the nocase mount option.
+	 * CIFS servers typically perform case-insensitive lookups while
+	 * preserving case in stored filenames. The nocase option indicates
+	 * case-insensitive comparison is in effect for this mount.
+	 */
+	if (tcon->nocase)
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+	return 0;
+}
+
 const struct inode_operations cifs_dir_inode_ops = {
 	.create = cifs_create,
 	.atomic_open = cifs_atomic_open,
@@ -1210,6 +1227,7 @@ const struct inode_operations cifs_dir_inode_ops = {
 	.listxattr = cifs_listxattr,
 	.get_acl = cifs_get_acl,
 	.set_acl = cifs_set_acl,
+	.fileattr_get = cifs_fileattr_get,
 };
 
 const struct inode_operations cifs_file_inode_ops = {
@@ -1220,6 +1238,7 @@ const struct inode_operations cifs_file_inode_ops = {
 	.fiemap = cifs_fiemap,
 	.get_acl = cifs_get_acl,
 	.set_acl = cifs_set_acl,
+	.fileattr_get = cifs_fileattr_get,
 };
 
 const char *cifs_get_link(struct dentry *dentry, struct inode *inode,
@@ -1254,6 +1273,7 @@ const struct inode_operations cifs_symlink_inode_ops = {
 	.setattr = cifs_setattr,
 	.permission = cifs_permission,
 	.listxattr = cifs_listxattr,
+	.fileattr_get = cifs_fileattr_get,
 };
 
 /*
-- 
2.52.0

[PATCH v7 10/16] nfs: Implement fileattr_get for case sensitivity

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

An NFS server re-exporting an NFS mount point needs to report the
case sensitivity behavior of the underlying filesystem to its
clients. Without this, re-export servers cannot accurately convey
case handling semantics, potentially causing client applications to
make incorrect assumptions about filename collisions and lookups.

The NFS client already retrieves case sensitivity information from
servers during mount via PATHCONF (NFSv3) or the
FATTR4_CASE_INSENSITIVE/FATTR4_CASE_PRESERVING attributes (NFSv4).
Expose this information through fileattr_get by reporting the
FS_XFLAG_CASEFOLD and FS_XFLAG_CASENONPRESERVING flags. NFSv2 lacks
PATHCONF support, so mounts using that protocol version default to
standard POSIX behavior: case-sensitive and case-preserving.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfs/client.c         |  9 +++++++--
 fs/nfs/inode.c          | 20 ++++++++++++++++++++
 fs/nfs/internal.h       |  3 +++
 fs/nfs/nfs3proc.c       |  2 ++
 fs/nfs/nfs3xdr.c        |  7 +++++--
 fs/nfs/nfs4proc.c       |  2 ++
 fs/nfs/proc.c           |  3 +++
 fs/nfs/symlink.c        |  3 +++
 include/linux/nfs_xdr.h |  2 ++
 9 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 2aaea9c98c2c..da437d89e14a 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -935,13 +935,18 @@ static int nfs_probe_fsinfo(struct nfs_server *server, struct nfs_fh *mntfh, str
 
 	/* Get some general file system info */
 	if (server->namelen == 0) {
-		struct nfs_pathconf pathinfo;
+		struct nfs_pathconf pathinfo = { };
 
 		pathinfo.fattr = fattr;
 		nfs_fattr_init(fattr);
 
-		if (clp->rpc_ops->pathconf(server, mntfh, &pathinfo) >= 0)
+		if (clp->rpc_ops->pathconf(server, mntfh, &pathinfo) >= 0) {
 			server->namelen = pathinfo.max_namelen;
+			if (pathinfo.case_insensitive)
+				server->caps |= NFS_CAP_CASE_INSENSITIVE;
+			if (pathinfo.case_preserving)
+				server->caps |= NFS_CAP_CASE_PRESERVING;
+		}
 	}
 
 	if (clp->rpc_ops->discover_trunking != NULL &&
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index de2cce1d08f4..77b4de8a1050 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -41,6 +41,7 @@
 #include <linux/freezer.h>
 #include <linux/uaccess.h>
 #include <linux/iversion.h>
+#include <linux/fileattr.h>
 
 #include "nfs4_fs.h"
 #include "callback.h"
@@ -1102,6 +1103,25 @@ int nfs_getattr(struct mnt_idmap *idmap, const struct path *path,
 }
 EXPORT_SYMBOL_GPL(nfs_getattr);
 
+/**
+ * nfs_fileattr_get - Retrieve file attributes
+ * @dentry: object to query
+ * @fa: file attributes to fill in
+ *
+ * Return: 0 on success
+ */
+int nfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct inode *inode = d_inode(dentry);
+
+	if (nfs_server_capable(inode, NFS_CAP_CASE_INSENSITIVE))
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+	if (!nfs_server_capable(inode, NFS_CAP_CASE_PRESERVING))
+		fa->fsx_xflags |= FS_XFLAG_CASENONPRESERVING;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nfs_fileattr_get);
+
 static void nfs_init_lock_context(struct nfs_lock_context *l_ctx)
 {
 	refcount_set(&l_ctx->count, 1);
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 2e596244799f..a843e076aad7 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -453,6 +453,9 @@ extern void nfs_set_cache_invalid(struct inode *inode, unsigned long flags);
 extern bool nfs_check_cache_invalid(struct inode *, unsigned long);
 extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode);
 
+struct file_kattr;
+int nfs_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
+
 #if IS_ENABLED(CONFIG_NFS_LOCALIO)
 /* localio.c */
 struct nfs_local_dio {
diff --git a/fs/nfs/nfs3proc.c b/fs/nfs/nfs3proc.c
index 1181f9cc6dbd..60344a83f400 100644
--- a/fs/nfs/nfs3proc.c
+++ b/fs/nfs/nfs3proc.c
@@ -1048,6 +1048,7 @@ static const struct inode_operations nfs3_dir_inode_operations = {
 	.permission	= nfs_permission,
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,
+	.fileattr_get	= nfs_fileattr_get,
 #ifdef CONFIG_NFS_V3_ACL
 	.listxattr	= nfs3_listxattr,
 	.get_inode_acl	= nfs3_get_acl,
@@ -1059,6 +1060,7 @@ static const struct inode_operations nfs3_file_inode_operations = {
 	.permission	= nfs_permission,
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,
+	.fileattr_get	= nfs_fileattr_get,
 #ifdef CONFIG_NFS_V3_ACL
 	.listxattr	= nfs3_listxattr,
 	.get_inode_acl	= nfs3_get_acl,
diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index e17d72908412..e745e78faab0 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -2276,8 +2276,11 @@ static int decode_pathconf3resok(struct xdr_stream *xdr,
 	if (unlikely(!p))
 		return -EIO;
 	result->max_link = be32_to_cpup(p++);
-	result->max_namelen = be32_to_cpup(p);
-	/* ignore remaining fields */
+	result->max_namelen = be32_to_cpup(p++);
+	p++;	/* ignore no_trunc */
+	p++;	/* ignore chown_restricted */
+	result->case_insensitive = be32_to_cpup(p++) != 0;
+	result->case_preserving = be32_to_cpup(p) != 0;
 	return 0;
 }
 
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index a0885ae55abc..7bb1ea77d20e 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -11072,6 +11072,7 @@ static const struct inode_operations nfs4_dir_inode_operations = {
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,
 	.listxattr	= nfs4_listxattr,
+	.fileattr_get	= nfs_fileattr_get,
 };
 
 static const struct inode_operations nfs4_file_inode_operations = {
@@ -11079,6 +11080,7 @@ static const struct inode_operations nfs4_file_inode_operations = {
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,
 	.listxattr	= nfs4_listxattr,
+	.fileattr_get	= nfs_fileattr_get,
 };
 
 static struct nfs_server *nfs4_clone_server(struct nfs_server *source,
diff --git a/fs/nfs/proc.c b/fs/nfs/proc.c
index 39df80e4ae6f..48f02a80b800 100644
--- a/fs/nfs/proc.c
+++ b/fs/nfs/proc.c
@@ -597,6 +597,7 @@ nfs_proc_pathconf(struct nfs_server *server, struct nfs_fh *fhandle,
 {
 	info->max_link = 0;
 	info->max_namelen = NFS2_MAXNAMLEN;
+	info->case_preserving = true;
 	return 0;
 }
 
@@ -718,12 +719,14 @@ static const struct inode_operations nfs_dir_inode_operations = {
 	.permission	= nfs_permission,
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,
+	.fileattr_get	= nfs_fileattr_get,
 };
 
 static const struct inode_operations nfs_file_inode_operations = {
 	.permission	= nfs_permission,
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,
+	.fileattr_get	= nfs_fileattr_get,
 };
 
 const struct nfs_rpc_ops nfs_v2_clientops = {
diff --git a/fs/nfs/symlink.c b/fs/nfs/symlink.c
index 58146e935402..74a072896f8d 100644
--- a/fs/nfs/symlink.c
+++ b/fs/nfs/symlink.c
@@ -22,6 +22,8 @@
 #include <linux/mm.h>
 #include <linux/string.h>
 
+#include "internal.h"
+
 /* Symlink caching in the page cache is even more simplistic
  * and straight-forward than readdir caching.
  */
@@ -74,4 +76,5 @@ const struct inode_operations nfs_symlink_inode_operations = {
 	.get_link	= nfs_get_link,
 	.getattr	= nfs_getattr,
 	.setattr	= nfs_setattr,
+	.fileattr_get	= nfs_fileattr_get,
 };
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 79fe2dfb470f..5f061a9db2c2 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -182,6 +182,8 @@ struct nfs_pathconf {
 	struct nfs_fattr	*fattr; /* Post-op attributes */
 	__u32			max_link; /* max # of hard links */
 	__u32			max_namelen; /* max name length */
+	bool			case_insensitive;
+	bool			case_preserving;
 };
 
 struct nfs4_change_info {
-- 
2.52.0

[PATCH v7 11/16] f2fs: Add case sensitivity reporting to fileattr_get

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

NFS and other remote filesystem protocols need to determine
whether a local filesystem performs case-insensitive lookups
so they can provide correct semantics to clients. Without
this information, f2fs exports cannot properly advertise
their filename case behavior.

Report f2fs case sensitivity behavior via the FS_XFLAG_CASEFOLD
flag. Like ext4, f2fs supports per-directory case folding via
the casefold flag (IS_CASEFOLDED). Files are always case-preserving.

Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/f2fs/file.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index d7047ca6b98d..91c255bbbf48 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3439,6 +3439,13 @@ int f2fs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
 	if (f2fs_sb_has_project_quota(F2FS_I_SB(inode)))
 		fa->fsx_projid = from_kprojid(&init_user_ns, fi->i_projid);
 
+	/*
+	 * f2fs preserves case (the default). If this inode is a
+	 * casefolded directory, report case-insensitive; otherwise
+	 * report case-sensitive (standard POSIX behavior).
+	 */
+	if (IS_CASEFOLDED(inode))
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
 	return 0;
 }
 
-- 
2.52.0

[PATCH v7 12/16] vboxsf: Implement fileattr_get for case sensitivity

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

Upper layers such as NFSD need a way to query whether a
filesystem handles filenames in a case-sensitive manner. Report
VirtualBox shared folder case handling behavior via the
FS_XFLAG_CASEFOLD flag.

The case sensitivity property is queried from the VirtualBox host
service at mount time and cached in struct vboxsf_sbi. The host
determines case sensitivity based on the underlying host filesystem
(for example, Windows NTFS is case-insensitive while Linux ext4 is
case-sensitive).

VirtualBox shared folders always preserve filename case exactly
as provided by the guest. The host interface does not expose a
case_preserving property, so this is hardcoded to true.

The callback is registered in all three inode_operations
structures (directory, file, and symlink) to ensure consistent
reporting across all inode types.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/vboxsf/dir.c    |  1 +
 fs/vboxsf/file.c   |  6 ++++--
 fs/vboxsf/super.c  |  4 ++++
 fs/vboxsf/utils.c  | 31 +++++++++++++++++++++++++++++++
 fs/vboxsf/vfsmod.h |  6 ++++++
 5 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/fs/vboxsf/dir.c b/fs/vboxsf/dir.c
index 42bedc4ec7af..c5bd3271aa96 100644
--- a/fs/vboxsf/dir.c
+++ b/fs/vboxsf/dir.c
@@ -477,4 +477,5 @@ const struct inode_operations vboxsf_dir_iops = {
 	.symlink = vboxsf_dir_symlink,
 	.getattr = vboxsf_getattr,
 	.setattr = vboxsf_setattr,
+	.fileattr_get = vboxsf_fileattr_get,
 };
diff --git a/fs/vboxsf/file.c b/fs/vboxsf/file.c
index 4bebd947314a..06308e38a70d 100644
--- a/fs/vboxsf/file.c
+++ b/fs/vboxsf/file.c
@@ -223,7 +223,8 @@ const struct file_operations vboxsf_reg_fops = {
 
 const struct inode_operations vboxsf_reg_iops = {
 	.getattr = vboxsf_getattr,
-	.setattr = vboxsf_setattr
+	.setattr = vboxsf_setattr,
+	.fileattr_get = vboxsf_fileattr_get,
 };
 
 static int vboxsf_read_folio(struct file *file, struct folio *folio)
@@ -390,5 +391,6 @@ static const char *vboxsf_get_link(struct dentry *dentry, struct inode *inode,
 }
 
 const struct inode_operations vboxsf_lnk_iops = {
-	.get_link = vboxsf_get_link
+	.get_link = vboxsf_get_link,
+	.fileattr_get = vboxsf_fileattr_get,
 };
diff --git a/fs/vboxsf/super.c b/fs/vboxsf/super.c
index 241647b060ee..fcabeca2a339 100644
--- a/fs/vboxsf/super.c
+++ b/fs/vboxsf/super.c
@@ -185,6 +185,10 @@ static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc)
 	if (err)
 		goto fail_unmap;
 
+	err = vboxsf_query_case_sensitive(sbi);
+	if (err)
+		goto fail_unmap;
+
 	sb->s_magic = VBOXSF_SUPER_MAGIC;
 	sb->s_blocksize = 1024;
 	sb->s_maxbytes = MAX_LFS_FILESIZE;
diff --git a/fs/vboxsf/utils.c b/fs/vboxsf/utils.c
index 9515bbf0b54c..658b8b0ebbd7 100644
--- a/fs/vboxsf/utils.c
+++ b/fs/vboxsf/utils.c
@@ -11,6 +11,7 @@
 #include <linux/sizes.h>
 #include <linux/pagemap.h>
 #include <linux/vfs.h>
+#include <linux/fileattr.h>
 #include "vfsmod.h"
 
 struct inode *vboxsf_new_inode(struct super_block *sb)
@@ -567,3 +568,33 @@ int vboxsf_dir_read_all(struct vboxsf_sbi *sbi, struct vboxsf_dir_info *sf_d,
 
 	return err;
 }
+
+int vboxsf_query_case_sensitive(struct vboxsf_sbi *sbi)
+{
+	struct shfl_volinfo volinfo = {};
+	u32 buf_len;
+	int err;
+
+	buf_len = sizeof(volinfo);
+	err = vboxsf_fsinfo(sbi->root, 0, SHFL_INFO_GET | SHFL_INFO_VOLUME,
+			    &buf_len, &volinfo);
+	if (err)
+		return err;
+
+	sbi->case_insensitive = !volinfo.properties.case_sensitive;
+	return 0;
+}
+
+int vboxsf_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct vboxsf_sbi *sbi = VBOXSF_SBI(dentry->d_sb);
+
+	/*
+	 * VirtualBox shared folders preserve filename case exactly as
+	 * provided by the guest (the default). The host interface does
+	 * not expose a case-preservation property.
+	 */
+	if (sbi->case_insensitive)
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+	return 0;
+}
diff --git a/fs/vboxsf/vfsmod.h b/fs/vboxsf/vfsmod.h
index 05973eb89d52..b61afd0ce842 100644
--- a/fs/vboxsf/vfsmod.h
+++ b/fs/vboxsf/vfsmod.h
@@ -47,6 +47,7 @@ struct vboxsf_sbi {
 	u32 next_generation;
 	u32 root;
 	int bdi_id;
+	bool case_insensitive;
 };
 
 /* per-inode information */
@@ -111,6 +112,11 @@ void vboxsf_dir_info_free(struct vboxsf_dir_info *p);
 int vboxsf_dir_read_all(struct vboxsf_sbi *sbi, struct vboxsf_dir_info *sf_d,
 			u64 handle);
 
+int vboxsf_query_case_sensitive(struct vboxsf_sbi *sbi);
+
+struct file_kattr;
+int vboxsf_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
+
 /* from vboxsf_wrappers.c */
 int vboxsf_connect(void);
 void vboxsf_disconnect(void);
-- 
2.52.0

[PATCH v7 13/16] isofs: Implement fileattr_get for case sensitivity

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

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
properly advertise their filename case behavior.

Implement isofs_fileattr_get() to report ISO 9660 case handling
behavior via the FS_XFLAG_CASEFOLD flag. The 'check=r' (relaxed)
mount option enables case-insensitive lookups, and this setting
determines the value reported. By default, Joliet extensions
operate in relaxed mode while plain ISO 9660 uses strict
(case-sensitive) mode. All ISO 9660 variants are case-preserving,
meaning filenames are stored exactly as they appear on the disc.

The callback is registered only on isofs_dir_inode_operations
because isofs has no custom inode_operations for regular
files, and symlinks use the generic page_symlink_inode_operations.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/isofs/dir.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/fs/isofs/dir.c b/fs/isofs/dir.c
index 09df40b612fb..e1a708f219f7 100644
--- a/fs/isofs/dir.c
+++ b/fs/isofs/dir.c
@@ -13,6 +13,7 @@
  */
 #include <linux/gfp.h>
 #include "isofs.h"
+#include <linux/fileattr.h>
 
 int isofs_name_translate(struct iso_directory_record *de, char *new, struct inode *inode)
 {
@@ -266,6 +267,19 @@ static int isofs_readdir(struct file *file, struct dir_context *ctx)
 	return result;
 }
 
+static int isofs_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
+{
+	struct isofs_sb_info *sbi = ISOFS_SB(dentry->d_sb);
+
+	/*
+	 * FS_XFLAG_CASEFOLD indicates case-insensitive lookups.
+	 * When check=r (relaxed) is set, lookups ignore case.
+	 */
+	if (sbi->s_check == 'r')
+		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
+	return 0;
+}
+
 const struct file_operations isofs_dir_operations =
 {
 	.llseek = generic_file_llseek,
@@ -279,6 +293,7 @@ const struct file_operations isofs_dir_operations =
 const struct inode_operations isofs_dir_inode_operations =
 {
 	.lookup = isofs_lookup,
+	.fileattr_get = isofs_fileattr_get,
 };
 
 
-- 
2.52.0

[PATCH v7 14/16] nfsd: Report export case-folding via NFSv3 PATHCONF

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

The hard-coded MSDOS_SUPER_MAGIC check in nfsd3_proc_pathconf()
only recognizes FAT filesystems as case-insensitive. Modern
filesystems like F2FS, exFAT, and CIFS support case-insensitive
directories, but NFSv3 clients cannot discover this capability.

Query the export's actual case behavior through ->fileattr_get
instead. This allows NFSv3 clients to correctly handle case
sensitivity for any filesystem that implements the fileattr
interface. Filesystems without ->fileattr_get continue to report
the default POSIX behavior (case-sensitive, case-preserving).

This change assumes the ("fat: Implement fileattr_get for case
sensitivity") has been applied, which ensures FAT filesystems
report their case behavior correctly via the fileattr interface.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs3proc.c | 18 ++++++++++--------
 fs/nfsd/vfs.c      | 25 +++++++++++++++++++++++++
 fs/nfsd/vfs.h      |  2 ++
 3 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/fs/nfsd/nfs3proc.c b/fs/nfsd/nfs3proc.c
index 42adc5461db0..9be0aca01de0 100644
--- a/fs/nfsd/nfs3proc.c
+++ b/fs/nfsd/nfs3proc.c
@@ -717,17 +717,19 @@ nfsd3_proc_pathconf(struct svc_rqst *rqstp)
 
 	if (resp->status == nfs_ok) {
 		struct super_block *sb = argp->fh.fh_dentry->d_sb;
+		bool case_insensitive, case_preserving;
 
-		/* Note that we don't care for remote fs's here */
-		switch (sb->s_magic) {
-		case EXT2_SUPER_MAGIC:
+		if (sb->s_magic == EXT2_SUPER_MAGIC) {
 			resp->p_link_max = EXT2_LINK_MAX;
 			resp->p_name_max = EXT2_NAME_LEN;
-			break;
-		case MSDOS_SUPER_MAGIC:
-			resp->p_case_insensitive = 1;
-			resp->p_case_preserving  = 0;
-			break;
+		}
+
+		resp->status = nfsd_get_case_info(&argp->fh,
+						  &case_insensitive,
+						  &case_preserving);
+		if (resp->status == nfs_ok) {
+			resp->p_case_insensitive = case_insensitive;
+			resp->p_case_preserving = case_preserving;
 		}
 	}
 
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 168d3ccc8155..55cf0c0165c9 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -32,6 +32,7 @@
 #include <linux/writeback.h>
 #include <linux/security.h>
 #include <linux/sunrpc/xdr.h>
+#include <linux/fileattr.h>
 
 #include "xdr3.h"
 
@@ -2871,3 +2872,27 @@ nfsd_permission(struct svc_cred *cred, struct svc_export *exp,
 
 	return err? nfserrno(err) : 0;
 }
+
+/**
+ * nfsd_get_case_info - get case sensitivity info for a file handle
+ * @fhp: file handle that has already been verified
+ * @case_insensitive: output, true if the filesystem is case-insensitive
+ * @case_preserving: output, true if the filesystem preserves case
+ *
+ * Returns nfs_ok on success, or an nfserr on failure.
+ */
+__be32
+nfsd_get_case_info(struct svc_fh *fhp, bool *case_insensitive,
+		   bool *case_preserving)
+{
+	struct file_kattr fa = {};
+	int err;
+
+	err = vfs_fileattr_get(fhp->fh_dentry, &fa);
+	if (err && err != -ENOIOCTLCMD)
+		return nfserrno(err);
+
+	*case_insensitive = fa.fsx_xflags & FS_XFLAG_CASEFOLD;
+	*case_preserving = !(fa.fsx_xflags & FS_XFLAG_CASENONPRESERVING);
+	return nfs_ok;
+}
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index e192dca4a679..1ff62eecec09 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -155,6 +155,8 @@ __be32		nfsd_readdir(struct svc_rqst *, struct svc_fh *,
 			     loff_t *, struct readdir_cd *, nfsd_filldir_t);
 __be32		nfsd_statfs(struct svc_rqst *, struct svc_fh *,
 				struct kstatfs *, int access);
+__be32		nfsd_get_case_info(struct svc_fh *fhp, bool *case_insensitive,
+				   bool *case_preserving);
 
 __be32		nfsd_permission(struct svc_cred *cred, struct svc_export *exp,
 				struct dentry *dentry, int acc);
-- 
2.52.0

[PATCH v7 15/16] nfsd: Implement NFSv4 FATTR4_CASE_INSENSITIVE and FATTR4_CASE_PRESERVING

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

NFSD currently provides NFSv4 clients with hard-coded responses
indicating all exported filesystems are case-sensitive and
case-preserving. This is incorrect for case-insensitive filesystems
and ext4 directories with casefold enabled.

Query the underlying filesystem's actual case sensitivity via
nfsd_get_case_info() and return accurate values to clients. This
supports per-directory settings for filesystems that allow mixing
case-sensitive and case-insensitive directories within an export.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/nfsd/nfs4xdr.c | 31 +++++++++++++++++++++++++++----
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 51ef97c25456..a4988a643d12 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2933,6 +2933,8 @@ struct nfsd4_fattr_args {
 	u32			rdattr_err;
 	bool			contextsupport;
 	bool			ignore_crossmnt;
+	bool			case_insensitive;
+	bool			case_preserving;
 };
 
 typedef __be32(*nfsd4_enc_attr)(struct xdr_stream *xdr,
@@ -3131,6 +3133,18 @@ static __be32 nfsd4_encode_fattr4_acl(struct xdr_stream *xdr,
 	return nfs_ok;
 }
 
+static __be32 nfsd4_encode_fattr4_case_insensitive(struct xdr_stream *xdr,
+					const struct nfsd4_fattr_args *args)
+{
+	return nfsd4_encode_bool(xdr, args->case_insensitive);
+}
+
+static __be32 nfsd4_encode_fattr4_case_preserving(struct xdr_stream *xdr,
+					const struct nfsd4_fattr_args *args)
+{
+	return nfsd4_encode_bool(xdr, args->case_preserving);
+}
+
 static __be32 nfsd4_encode_fattr4_filehandle(struct xdr_stream *xdr,
 					     const struct nfsd4_fattr_args *args)
 {
@@ -3487,8 +3501,8 @@ static const nfsd4_enc_attr nfsd4_enc_fattr4_encode_ops[] = {
 	[FATTR4_ACLSUPPORT]		= nfsd4_encode_fattr4_aclsupport,
 	[FATTR4_ARCHIVE]		= nfsd4_encode_fattr4__noop,
 	[FATTR4_CANSETTIME]		= nfsd4_encode_fattr4__true,
-	[FATTR4_CASE_INSENSITIVE]	= nfsd4_encode_fattr4__false,
-	[FATTR4_CASE_PRESERVING]	= nfsd4_encode_fattr4__true,
+	[FATTR4_CASE_INSENSITIVE]	= nfsd4_encode_fattr4_case_insensitive,
+	[FATTR4_CASE_PRESERVING]	= nfsd4_encode_fattr4_case_preserving,
 	[FATTR4_CHOWN_RESTRICTED]	= nfsd4_encode_fattr4__true,
 	[FATTR4_FILEHANDLE]		= nfsd4_encode_fattr4_filehandle,
 	[FATTR4_FILEID]			= nfsd4_encode_fattr4_fileid,
@@ -3674,8 +3688,9 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 		if (err)
 			goto out_nfserr;
 	}
-	if ((attrmask[0] & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID)) &&
-	    !fhp) {
+	if ((attrmask[0] & (FATTR4_WORD0_FILEHANDLE | FATTR4_WORD0_FSID |
+			    FATTR4_WORD0_CASE_INSENSITIVE |
+			    FATTR4_WORD0_CASE_PRESERVING)) && !fhp) {
 		tempfh = kmalloc(sizeof(struct svc_fh), GFP_KERNEL);
 		status = nfserr_jukebox;
 		if (!tempfh)
@@ -3687,6 +3702,14 @@ nfsd4_encode_fattr4(struct svc_rqst *rqstp, struct xdr_stream *xdr,
 		args.fhp = tempfh;
 	} else
 		args.fhp = fhp;
+	if (attrmask[0] & (FATTR4_WORD0_CASE_INSENSITIVE |
+			   FATTR4_WORD0_CASE_PRESERVING)) {
+		status = nfsd_get_case_info(args.fhp, &args.case_insensitive,
+					    &args.case_preserving);
+		if (status != nfs_ok)
+			attrmask[0] &= ~(FATTR4_WORD0_CASE_INSENSITIVE |
+					 FATTR4_WORD0_CASE_PRESERVING);
+	}
 
 	if (attrmask[0] & FATTR4_WORD0_ACL) {
 		err = nfsd4_get_nfs4_acl(rqstp, dentry, &args.acl);
-- 
2.52.0

[PATCH v7 16/16] ksmbd: Report filesystem case sensitivity via FS_ATTRIBUTE_INFORMATION

[Chuck Lever]

From: Chuck Lever <chuck.lever@oracle.com>

ksmbd hard-codes FILE_CASE_SENSITIVE_SEARCH and
FILE_CASE_PRESERVED_NAMES in FS_ATTRIBUTE_INFORMATION responses,
incorrectly indicating all exports are case-sensitive. This breaks
clients accessing case-insensitive filesystems like exFAT or
ext4/f2fs directories with casefold enabled.

Query actual case behavior via vfs_fileattr_get() and report accurate
attributes to SMB clients. Filesystems without ->fileattr_get continue
reporting default POSIX behavior (case-sensitive, case-preserving).

SMB's FS_ATTRIBUTE_INFORMATION reports per-share attributes from the
share root, not per-file. Shares mixing casefold and non-casefold
directories report the root directory's behavior.

Acked-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 fs/smb/server/smb2pdu.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/fs/smb/server/smb2pdu.c b/fs/smb/server/smb2pdu.c
index 2fcd0d4d1fb0..257da9282bcf 100644
--- a/fs/smb/server/smb2pdu.c
+++ b/fs/smb/server/smb2pdu.c
@@ -13,6 +13,7 @@
 #include <linux/falloc.h>
 #include <linux/mount.h>
 #include <linux/filelock.h>
+#include <linux/fileattr.h>
 
 #include "glob.h"
 #include "smbfsctl.h"
@@ -5486,16 +5487,28 @@ static int smb2_get_info_filesystem(struct ksmbd_work *work,
 	case FS_ATTRIBUTE_INFORMATION:
 	{
 		FILE_SYSTEM_ATTRIBUTE_INFO *info;
+		struct file_kattr fa = {};
 		size_t sz;
+		u32 attrs;
+		int err;
 
 		info = (FILE_SYSTEM_ATTRIBUTE_INFO *)rsp->Buffer;
-		info->Attributes = cpu_to_le32(FILE_SUPPORTS_OBJECT_IDS |
-					       FILE_PERSISTENT_ACLS |
-					       FILE_UNICODE_ON_DISK |
-					       FILE_CASE_PRESERVED_NAMES |
-					       FILE_CASE_SENSITIVE_SEARCH |
-					       FILE_SUPPORTS_BLOCK_REFCOUNTING);
+		attrs = FILE_SUPPORTS_OBJECT_IDS |
+			FILE_PERSISTENT_ACLS |
+			FILE_UNICODE_ON_DISK |
+			FILE_SUPPORTS_BLOCK_REFCOUNTING;
 
+		err = vfs_fileattr_get(path.dentry, &fa);
+		if (err && err != -ENOIOCTLCMD) {
+			path_put(&path);
+			return err;
+		}
+		if (!(fa.fsx_xflags & FS_XFLAG_CASEFOLD))
+			attrs |= FILE_CASE_SENSITIVE_SEARCH;
+		if (!(fa.fsx_xflags & FS_XFLAG_CASENONPRESERVING))
+			attrs |= FILE_CASE_PRESERVED_NAMES;
+
+		info->Attributes = cpu_to_le32(attrs);
 		info->Attributes |= cpu_to_le32(server_conf.share_fake_fscaps);
 
 		if (test_share_config_flag(work->tcon->share_conf,
-- 
2.52.0

Re: [PATCH v7 01/16] fs: Add case sensitivity flags to file_kattr

[Darrick J. Wong]

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

> ---
>  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
> 
> 

Re: [PATCH v7 07/16] ext4: Report case sensitivity in fileattr_get

[Darrick J. Wong]

On Thu, Jan 22, 2026 at 11:03:02AM -0500, Chuck Lever wrote:
> From: Chuck Lever <chuck.lever@oracle.com>
> 
> Report ext4's case sensitivity behavior via the FS_XFLAG_CASEFOLD
> flag. ext4 always preserves case at rest.
> 
> Case sensitivity is a per-directory setting in ext4. If the queried
> inode is a casefolded directory, report case-insensitive; otherwise
> report case-sensitive (standard POSIX behavior).
> 
> Reviewed-by: Jan Kara <jack@suse.cz>
> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
> ---
>  fs/ext4/ioctl.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
> index 7ce0fc40aec2..462da7aadc80 100644
> --- a/fs/ext4/ioctl.c
> +++ b/fs/ext4/ioctl.c
> @@ -996,6 +996,13 @@ int ext4_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
>  	if (ext4_has_feature_project(inode->i_sb))
>  		fa->fsx_projid = from_kprojid(&init_user_ns, ei->i_projid);
>  
> +	/*
> +	 * Case folding is a directory attribute in ext4. Set FS_XFLAG_CASEFOLD
> +	 * for directories with the casefold attribute; all other inodes use
> +	 * standard case-sensitive semantics.
> +	 */
> +	if (IS_CASEFOLDED(inode))
> +		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;

Curious.  Shouldn't the VFS set FS_XFLAG_CASEFOLD if the VFS casefolding
flag is set?

OTOH, there are more filesystems that apparently support casefolding
(given the size of this patchset) than actually set S_CASEFOLD.  I think
I'm ignorant of something here...

--D

>  	return 0;
>  }
>  
> -- 
> 2.52.0
> 
> 

Re: [PATCH v7 01/16] fs: Add case sensitivity flags to file_kattr

[Chuck Lever]

On Thu, Jan 22, 2026, at 7:26 PM, Darrick J. Wong wrote:
> 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.

If I’m asked to post another revision of this series, I’ll look at splitting
1/16 into two patches.


>> 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>


-- 
Chuck Lever

Re: [PATCH v7 01/16] fs: Add case sensitivity flags to file_kattr

[Jan Kara]

On Thu 22-01-26 11:02:56, 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.
> 
> 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>

This scheme looks good. But AFAICT declared 'fa' needs to be zeroed-out
also in file_getattr()? Otherwise the patch looks good to me.

								Honza

> @@ -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
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

Re: [PATCH v7 07/16] ext4: Report case sensitivity in fileattr_get

[Chuck Lever]

On Thu, Jan 22, 2026, at 7:29 PM, Darrick J. Wong wrote:
> On Thu, Jan 22, 2026 at 11:03:02AM -0500, Chuck Lever wrote:
>> From: Chuck Lever <chuck.lever@oracle.com>
>> 
>> Report ext4's case sensitivity behavior via the FS_XFLAG_CASEFOLD
>> flag. ext4 always preserves case at rest.
>> 
>> Case sensitivity is a per-directory setting in ext4. If the queried
>> inode is a casefolded directory, report case-insensitive; otherwise
>> report case-sensitive (standard POSIX behavior).
>> 
>> Reviewed-by: Jan Kara <jack@suse.cz>
>> Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
>> ---
>>  fs/ext4/ioctl.c | 7 +++++++
>>  1 file changed, 7 insertions(+)
>> 
>> diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
>> index 7ce0fc40aec2..462da7aadc80 100644
>> --- a/fs/ext4/ioctl.c
>> +++ b/fs/ext4/ioctl.c
>> @@ -996,6 +996,13 @@ int ext4_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
>>  	if (ext4_has_feature_project(inode->i_sb))
>>  		fa->fsx_projid = from_kprojid(&init_user_ns, ei->i_projid);
>>  
>> +	/*
>> +	 * Case folding is a directory attribute in ext4. Set FS_XFLAG_CASEFOLD
>> +	 * for directories with the casefold attribute; all other inodes use
>> +	 * standard case-sensitive semantics.
>> +	 */
>> +	if (IS_CASEFOLDED(inode))
>> +		fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
>
> Curious.  Shouldn't the VFS set FS_XFLAG_CASEFOLD if the VFS casefolding
> flag is set?
>
> OTOH, there are more filesystems that apparently support casefolding
> (given the size of this patchset) than actually set S_CASEFOLD.  I think
> I'm ignorant of something here...

I'm not clear if there's a review action needed. Help?


-- 
Chuck Lever