Merge tag 'vfs-7.2-rc1.casefold' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs casefolding updates from Christian Brauner:
 "This exposes the case folding behavior of local filesystems so that
  file servers - nfsd, ksmbd, and user space file servers - can report
  the actual behavior to clients instead of guessing.

  Filesystems report case-insensitive and case-nonpreserving behavior
  via new file_kattr flags in their fileattr_get implementations. fat,
  exfat, ntfs3, hfs, hfsplus, xfs, cifs, nfs, vboxsf, and isofs are
  wired up. Local filesystems that are not explicitly handled default to
  the usual POSIX behavior of case-sensitive and case-preserving.

  nfsd uses this to report case folding via NFSv3 PATHCONF and to
  implement the NFSv4 FATTR4_CASE_INSENSITIVE and FATTR4_CASE_PRESERVING
  attributes - both have been part of the NFS protocols for decades to
  support clients on non-POSIX systems - and ksmbd reports it via
  FS_ATTRIBUTE_INFORMATION. Exposing the information through the
  fileattr uapi covers user space file servers.

  The immediate motivation is interoperability: Windows NFS clients
  hard-require servers to report case-insensitivity for Win32
  applications to work correctly, and a client that knows the server is
  case-insensitive can avoid issuing multiple LOOKUP/READDIR requests
  searching for case variants.

  The Linux NFS client already grew support for case-insensitive shares
  years ago in support of the Hammerspace NFS server - negative dentry
  caching must be disabled (a lookup for "FILE.TXT" failing must not
  cache a negative entry when "file.txt" exists) and directory change
  invalidation must drop cached case-folded name variants. Such servers
  often operate in multi-protocol environments where a single file
  service instance caters to both NFS and SMB clients, and nfsd needs to
  report case folding properly to participate as a first-class citizen
  there.

  A follow-up series brings fixes for the initial work: the nfsd
  case-info probe now uses kernel credentials, maps -ESTALE to
  NFS3ERR_STALE, and has its cost capped across READDIR entries; the nfs
  client avoids transiently zeroed case capability bits during the probe
  and skips the pathconf probe when neither field is consumed; the
  FS_CASEFOLD_FL semantics are clarified in the UAPI header; and the
  tools UAPI headers are synced"

* tag 'vfs-7.2-rc1.casefold' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (22 commits)
  nfsd: Cap case-folding probe cost across READDIR entries
  nfsd: Map -ESTALE from case probe to NFS3ERR_STALE
  nfsd: Use kernel credentials for case-info probe
  fs: Clarify FS_CASEFOLD_FL semantics in UAPI header
  nfs: Skip pathconf probe when neither field is consumed
  nfs: Avoid transient zeroed case capability bits during probe
  tools headers UAPI: Sync case-sensitivity flags from linux/fs.h
  ksmbd: Report filesystem case sensitivity via FS_ATTRIBUTE_INFORMATION
  nfsd: Implement NFSv4 FATTR4_CASE_INSENSITIVE and FATTR4_CASE_PRESERVING
  nfsd: Report export case-folding via NFSv3 PATHCONF
  isofs: Implement fileattr_get for case sensitivity
  vboxsf: Implement fileattr_get for case sensitivity
  nfs: Implement fileattr_get for case sensitivity
  cifs: Implement fileattr_get for case sensitivity
  xfs: Report case sensitivity in fileattr_get
  hfsplus: Report case sensitivity in fileattr_get
  hfs: Implement fileattr_get for case sensitivity
  ntfs3: Implement fileattr_get for case sensitivity
  exfat: Implement fileattr_get for case sensitivity
  fat: Implement fileattr_get for case sensitivity
  ...

3 files changed, 5 insertions, 2 deletions

diff --git a/include/linux/fileattr.h b/include/linux/fileattr.h
index 3780904a63a6..58044b598016 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_VERITY)
+	(FS_XFLAG_PREALLOC | FS_XFLAG_HASATTR | FS_XFLAG_VERITY | \
+	 FS_XFLAG_CASEFOLD | FS_XFLAG_CASENONPRESERVING)
 
 /* Flags to indicate valid value of fsx_ fields */
 #define FS_XFLAG_VALUES_MASK \
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 4daee27fa5eb..34d294774f8c 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -306,7 +306,7 @@ struct nfs_server {
 #define NFS_CAP_ATOMIC_OPEN	(1U << 4)
 #define NFS_CAP_LGOPEN		(1U << 5)
 #define NFS_CAP_CASE_INSENSITIVE	(1U << 6)
-#define NFS_CAP_CASE_PRESERVING	(1U << 7)
+#define NFS_CAP_CASE_NONPRESERVING	(1U << 7)
 #define NFS_CAP_REBOOT_LAYOUTRETURN	(1U << 8)
 #define NFS_CAP_OFFLOAD_STATUS	(1U << 9)
 #define NFS_CAP_ZERO_RANGE	(1U << 10)
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index fcbd21b5685f..83ee991cde2b 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 {