cifs: Recognize SFU socket type

SFU since its (first) version 3.0 supports AF_LOCAL sockets and stores them
on filesytem as system file with one zero byte. Add support for detecting
this SFU socket type into cifs_sfu_type() function.

With this change cifs_sfu_type() would correctly detect all special file
types created by SFU: fifo, socket, symlink, block and char.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: pali

fs/smb/client/inode.c

@@ -545,7 +545,7 @@ cifs_sfu_type(struct cifs_fattr *fattr, const char *path,
 		fattr->cf_mode |= S_IFIFO;
 		fattr->cf_dtype = DT_FIFO;
 		return 0;
-	} else if (fattr->cf_eof < 8) {
+	} else if (fattr->cf_eof > 1 && fattr->cf_eof < 8) {
 		fattr->cf_mode |= S_IFREG;
 		fattr->cf_dtype = DT_REG;
 		return -EINVAL;	 /* EOPNOTSUPP? */
@@ -655,6 +655,10 @@ cifs_sfu_type(struct cifs_fattr *fattr, const char *path,
 			fattr->cf_dtype = DT_REG;
 			rc = -EOPNOTSUPP;
 		}
+	} else if ((rc == 0) && (bytes_read == 1) && (pbuf[0] == '\0')) {
+		cifs_dbg(FYI, "Socket\n");
+		fattr->cf_mode |= S_IFSOCK;
+		fattr->cf_dtype = DT_SOCK;
 	} else {
 		fattr->cf_mode |= S_IFREG; /* then it is a file */
 		fattr->cf_dtype = DT_REG;