cifs: Rename struct reparse_posix_data to reparse_nfs_data_buffer and move to common/smb2pdu.h

Function parse_reparse_posix() parses NFS-style reparse points, which are
used only by Windows NFS server since Windows Server 2012 version. This
style is not understood by Microsoft POSIX/Interix/SFU/SUA subsystems.

So make it clear that parse_reparse_posix() function and reparse_posix_data
structure are not POSIX general, but rather NFS specific.

All reparse buffer structures are defined in common/smb2pdu.h and have
_buffer suffix. So move struct reparse_posix_data from client/cifspdu.h to
common/smb2pdu.h and rename it to reparse_nfs_data_buffer for consistency.
Note that also SMB specification in [MS-FSCC] document, section 2.1.2.6
defines it under name "Network File System (NFS) Reparse Data Buffer".
So use this name for consistency.

Having this structure in common/smb2pdu.h can be useful for ksmbd server
code as NFS-style reparse points is the preferred way for implementing
support for special files.

Signed-off-by: Pali Rohár <pali@kernel.org>
Acked-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: pali

fs/smb/client/cifspdu.h

@@ -1484,20 +1484,6 @@ struct file_notify_information {
 	__u8  FileName[];
 } __attribute__((packed));
 
-/* For IO_REPARSE_TAG_NFS */
-#define NFS_SPECFILE_LNK	0x00000000014B4E4C
-#define NFS_SPECFILE_CHR	0x0000000000524843
-#define NFS_SPECFILE_BLK	0x00000000004B4C42
-#define NFS_SPECFILE_FIFO	0x000000004F464946
-#define NFS_SPECFILE_SOCK	0x000000004B434F53
-struct reparse_posix_data {
-	__le32	ReparseTag;
-	__le16	ReparseDataLength;
-	__u16	Reserved;
-	__le64	InodeType; /* LNK, FIFO, CHR etc. */
-	__u8	DataBuffer[];
-} __attribute__((packed));
-
 struct cifs_quota_data {
 	__u32	rsrvd1;  /* 0 */
 	__u32	sid_size;

fs/smb/client/reparse.c

@@ -242,7 +242,7 @@ static int detect_directory_symlink_target(struct cifs_sb_info *cifs_sb,
 	return 0;
 }
 
-static int nfs_set_reparse_buf(struct reparse_posix_data *buf,
+static int nfs_set_reparse_buf(struct reparse_nfs_data_buffer *buf,
 			       mode_t mode, dev_t dev,
 			       struct kvec *iov)
 {
@@ -281,13 +281,13 @@ static int mknod_nfs(unsigned int xid, struct inode *inode,
 		     const char *full_path, umode_t mode, dev_t dev)
 {
 	struct cifs_open_info_data data;
-	struct reparse_posix_data *p;
+	struct reparse_nfs_data_buffer *p;
 	struct inode *new;
 	struct kvec iov;
 	__u8 buf[sizeof(*p) + sizeof(__le64)];
 	int rc;
 
-	p = (struct reparse_posix_data *)buf;
+	p = (struct reparse_nfs_data_buffer *)buf;
 	rc = nfs_set_reparse_buf(p, mode, dev, &iov);
 	if (rc)
 		return rc;
@@ -474,7 +474,7 @@ int smb2_mknod_reparse(unsigned int xid, struct inode *inode,
 }
 
 /* See MS-FSCC 2.1.2.6 for the 'NFS' style reparse tags */
-static int parse_reparse_posix(struct reparse_posix_data *buf,
+static int parse_reparse_nfs(struct reparse_nfs_data_buffer *buf,
 			       struct cifs_sb_info *cifs_sb,
 			       struct cifs_open_info_data *data)
 {
@@ -702,7 +702,7 @@ int parse_reparse_point(struct reparse_data_buffer *buf,
 	/* See MS-FSCC 2.1.2 */
 	switch (le32_to_cpu(buf->ReparseTag)) {
 	case IO_REPARSE_TAG_NFS:
-		return parse_reparse_posix((struct reparse_posix_data *)buf,
+		return parse_reparse_nfs((struct reparse_nfs_data_buffer *)buf,
 					   cifs_sb, data);
 	case IO_REPARSE_TAG_SYMLINK:
 		return parse_reparse_symlink(
@@ -816,7 +816,7 @@ static bool posix_reparse_to_fattr(struct cifs_sb_info *cifs_sb,
 				   struct cifs_fattr *fattr,
 				   struct cifs_open_info_data *data)
 {
-	struct reparse_posix_data *buf = (struct reparse_posix_data *)data->reparse.buf;
+	struct reparse_nfs_data_buffer *buf = (struct reparse_nfs_data_buffer *)data->reparse.buf;
 
 	if (buf == NULL)
 		return true;

fs/smb/common/smb2pdu.h

@@ -1550,7 +1550,19 @@ struct reparse_symlink_data_buffer {
 	__u8	PathBuffer[]; /* Variable Length */
 } __packed;
 
-/* See MS-FSCC 2.1.2.6 and cifspdu.h for struct reparse_posix_data */
+/* For IO_REPARSE_TAG_NFS - see MS-FSCC 2.1.2.6 */
+#define NFS_SPECFILE_LNK	0x00000000014B4E4C
+#define NFS_SPECFILE_CHR	0x0000000000524843
+#define NFS_SPECFILE_BLK	0x00000000004B4C42
+#define NFS_SPECFILE_FIFO	0x000000004F464946
+#define NFS_SPECFILE_SOCK	0x000000004B434F53
+struct reparse_nfs_data_buffer {
+	__le32	ReparseTag;
+	__le16	ReparseDataLength;
+	__u16	Reserved;
+	__le64	InodeType; /* NFS_SPECFILE_* */
+	__u8	DataBuffer[];
+} __packed;
 
 /* For IO_REPARSE_TAG_LX_SYMLINK */
 struct reparse_wsl_symlink_data_buffer {