cifs: don't pass superblock to cifs_mount()

To close sget() races we'll need to be able to set cifs_sb up before
we get the superblock, so we'll want to be able to do cifs_mount()
earlier.  Fortunately, it's easy to do - setting ->s_maxbytes can
be done in cifs_read_super(), ditto for ->s_time_gran and as for
putting MS_POSIXACL into ->s_flags, we can mirror it in ->mnt_cifs_flags
until cifs_read_super() is called.  Kill unused 'devname' argument,
while we are at it...

Acked-by: Pavel Shilovsky <piastryyy@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/cifs/cifs_fs_sb.h

@@ -42,6 +42,7 @@
 #define CIFS_MOUNT_MULTIUSER	0x20000 /* multiuser mount */
 #define CIFS_MOUNT_STRICT_IO	0x40000 /* strict cache mode */
 #define CIFS_MOUNT_RWPIDFORWARD	0x80000 /* use pid forwarding for rw */
+#define CIFS_MOUNT_POSIXACL	0x100000 /* mirror of MS_POSIXACL in mnt_cifs_flags */
 
 struct cifs_sb_info {
 	struct rb_root tlink_tree;

fs/cifs/cifsfs.c

@@ -116,7 +116,7 @@ cifs_read_super(struct super_block *sb, struct smb_vol *volume_info,
 	spin_lock_init(&cifs_sb->tlink_tree_lock);
 	cifs_sb->tlink_tree = RB_ROOT;
 
-	rc = cifs_mount(sb, cifs_sb, volume_info, devname);
+	rc = cifs_mount(cifs_sb, volume_info);
 
 	if (rc) {
 		if (!silent)
@@ -124,6 +124,17 @@ cifs_read_super(struct super_block *sb, struct smb_vol *volume_info,
 		return rc;
 	}
 
+	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIXACL)
+		sb->s_flags |= MS_POSIXACL;
+
+	if (cifs_sb_master_tcon(cifs_sb)->ses->capabilities & CAP_LARGE_FILES)
+		sb->s_maxbytes = MAX_LFS_FILESIZE;
+	else
+		sb->s_maxbytes = MAX_NON_LFS;
+
+	/* BB FIXME fix time_gran to be larger for LANMAN sessions */
+	sb->s_time_gran = 100;
+
 	sb->s_magic = CIFS_MAGIC_NUMBER;
 	sb->s_op = &cifs_super_ops;
 	sb->s_bdi = &cifs_sb->bdi;

fs/cifs/cifsproto.h

@@ -157,8 +157,7 @@ extern int cifs_match_super(struct super_block *, void *);
 extern void cifs_cleanup_volume_info(struct smb_vol **pvolume_info);
 extern int cifs_setup_volume_info(struct smb_vol **pvolume_info,
 				  char *mount_data, const char *devname);
-extern int cifs_mount(struct super_block *, struct cifs_sb_info *,
-		      struct smb_vol *, const char *);
+extern int cifs_mount(struct cifs_sb_info *, struct smb_vol *);
 extern int cifs_umount(struct super_block *, struct cifs_sb_info *);
 extern void cifs_dfs_release_automount_timer(void);
 void cifs_proc_init(void);
@@ -218,7 +217,8 @@ extern int get_dfs_path(int xid, struct cifs_ses *pSesInfo,
 			struct dfs_info3_param **preferrals,
 			int remap);
 extern void reset_cifs_unix_caps(int xid, struct cifs_tcon *tcon,
-				 struct super_block *sb, struct smb_vol *vol);
+				 struct cifs_sb_info *cifs_sb,
+				 struct smb_vol *vol);
 extern int CIFSSMBQFSInfo(const int xid, struct cifs_tcon *tcon,
 			struct kstatfs *FSData);
 extern int SMBOldQFSInfo(const int xid, struct cifs_tcon *tcon,

fs/cifs/connect.c

@@ -2546,7 +2546,7 @@ ip_connect(struct TCP_Server_Info *server)
 }
 
 void reset_cifs_unix_caps(int xid, struct cifs_tcon *tcon,
-			  struct super_block *sb, struct smb_vol *vol_info)
+			  struct cifs_sb_info *cifs_sb, struct smb_vol *vol_info)
 {
 	/* if we are reconnecting then should we check to see if
 	 * any requested capabilities changed locally e.g. via
@@ -2600,22 +2600,23 @@ void reset_cifs_unix_caps(int xid, struct cifs_tcon *tcon,
 			cap &= ~CIFS_UNIX_POSIX_ACL_CAP;
 		else if (CIFS_UNIX_POSIX_ACL_CAP & cap) {
 			cFYI(1, "negotiated posix acl support");
-			if (sb)
-				sb->s_flags |= MS_POSIXACL;
+			if (cifs_sb)
+				cifs_sb->mnt_cifs_flags |=
+					CIFS_MOUNT_POSIXACL;
 		}
 
 		if (vol_info && vol_info->posix_paths == 0)
 			cap &= ~CIFS_UNIX_POSIX_PATHNAMES_CAP;
 		else if (cap & CIFS_UNIX_POSIX_PATHNAMES_CAP) {
 			cFYI(1, "negotiate posix pathnames");
-			if (sb)
-				CIFS_SB(sb)->mnt_cifs_flags |=
+			if (cifs_sb)
+				cifs_sb->mnt_cifs_flags |=
 					CIFS_MOUNT_POSIX_PATHS;
 		}
 
-		if (sb && (CIFS_SB(sb)->rsize > 127 * 1024)) {
+		if (cifs_sb && (cifs_sb->rsize > 127 * 1024)) {
 			if ((cap & CIFS_UNIX_LARGE_READ_CAP) == 0) {
-				CIFS_SB(sb)->rsize = 127 * 1024;
+				cifs_sb->rsize = 127 * 1024;
 				cFYI(DBG2, "larger reads not supported by srv");
 			}
 		}
@@ -2971,8 +2972,7 @@ out:
 }
 
 int
-cifs_mount(struct super_block *sb, struct cifs_sb_info *cifs_sb,
-	   struct smb_vol *volume_info, const char *devname)
+cifs_mount(struct cifs_sb_info *cifs_sb, struct smb_vol *volume_info)
 {
 	int rc = 0;
 	int xid;
@@ -3026,14 +3026,6 @@ try_mount_again:
 		goto mount_fail_check;
 	}
 
-	if (pSesInfo->capabilities & CAP_LARGE_FILES)
-		sb->s_maxbytes = MAX_LFS_FILESIZE;
-	else
-		sb->s_maxbytes = MAX_NON_LFS;
-
-	/* BB FIXME fix time_gran to be larger for LANMAN sessions */
-	sb->s_time_gran = 100;
-
 	/* search for existing tcon to this server share */
 	tcon = cifs_get_tcon(pSesInfo, volume_info);
 	if (IS_ERR(tcon)) {
@@ -3046,7 +3038,7 @@ try_mount_again:
 	if (tcon->ses->capabilities & CAP_UNIX) {
 		/* reset of caps checks mount to see if unix extensions
 		   disabled for just this mount */
-		reset_cifs_unix_caps(xid, tcon, sb, volume_info);
+		reset_cifs_unix_caps(xid, tcon, cifs_sb, volume_info);
 		if ((tcon->ses->server->tcpStatus == CifsNeedReconnect) &&
 		    (le64_to_cpu(tcon->fsUnixInfo.Capability) &
 		     CIFS_UNIX_TRANSPORT_ENCRYPTION_MANDATORY_CAP)) {