smb: client: fix creating symlinks under POSIX mounts

JIRA: https://issues.redhat.com/browse/RHEL-109507

commit 5b432ae
Author: Paulo Alcantara <pc@manguebit.org>
Date:   Thu Jul 31 20:46:43 2025 -0300

    smb: client: fix creating symlinks under POSIX mounts

    SMB3.1.1 POSIX mounts support native symlinks that are created with
    IO_REPARSE_TAG_SYMLINK reparse points, so skip the checking of
    FILE_SUPPORTS_REPARSE_POINTS as some servers might not have it set.

    Cc: linux-cifs@vger.kernel.org
    Cc: Ralph Boehme <slow@samba.org>
    Cc: David Howells <dhowells@redhat.com>
    Cc: <stable@vger.kernel.org>
    Reported-by: Matthew Richardson <m.richardson@ed.ac.uk>
    Closes: https://marc.info/?i=1124e7cd-6a46-40a6-9f44-b7664a66654b@ed.ac.uk
    Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.org>
    Signed-off-by: Steve French <stfrench@microsoft.com>

Signed-off-by: Paulo Alcantara <paalcant@redhat.com>

Author: pcacjr

fs/smb/client/cifsglob.h

@@ -2412,4 +2412,9 @@ static inline bool cifs_netbios_name(const char *name, size_t namelen)
 	return ret;
 }
 
+#define CIFS_REPARSE_SUPPORT(tcon) \
+	((tcon)->posix_extensions || \
+	 (le32_to_cpu((tcon)->fsAttrInfo.Attributes) & \
+	  FILE_SUPPORTS_REPARSE_POINTS))
+
 #endif	/* _CIFS_GLOB_H */

fs/smb/client/cifssmb.c

@@ -2692,7 +2692,7 @@ int cifs_query_reparse_point(const unsigned int xid,
 	if (cap_unix(tcon->ses))
 		return -EOPNOTSUPP;
 
-	if (!(le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS))
+	if (!CIFS_REPARSE_SUPPORT(tcon))
 		return -EOPNOTSUPP;
 
 	oparms = (struct cifs_open_parms) {
@@ -2820,7 +2820,7 @@ struct inode *cifs_create_reparse_inode(struct cifs_open_info_data *data,
 	 * attempt to create reparse point. This will prevent creating unusable
 	 * empty object on the server.
 	 */
-	if (!(le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS))
+	if (!CIFS_REPARSE_SUPPORT(tcon))
 		return ERR_PTR(-EOPNOTSUPP);
 
 #ifndef CONFIG_CIFS_XATTR

fs/smb/client/link.c

@@ -635,7 +635,7 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
 	case CIFS_SYMLINK_TYPE_NATIVE:
 	case CIFS_SYMLINK_TYPE_NFS:
 	case CIFS_SYMLINK_TYPE_WSL:
-		if (le32_to_cpu(pTcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS) {
+		if (CIFS_REPARSE_SUPPORT(pTcon)) {
 			rc = create_reparse_symlink(xid, inode, direntry, pTcon,
 						    full_path, symname);
 			goto symlink_exit;

fs/smb/client/smb1ops.c

@@ -1272,7 +1272,7 @@ cifs_make_node(unsigned int xid, struct inode *inode,
 		 */
 		return cifs_sfu_make_node(xid, inode, dentry, tcon,
 					  full_path, mode, dev);
-	} else if (le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS) {
+	} else if (CIFS_REPARSE_SUPPORT(tcon)) {
 		/*
 		 * mknod via reparse points requires server support for
 		 * storing reparse points, which is available since

fs/smb/client/smb2inode.c

@@ -1346,9 +1346,8 @@ struct inode *smb2_create_reparse_inode(struct cifs_open_info_data *data,
 	 * attempt to create reparse point. This will prevent creating unusable
 	 * empty object on the server.
 	 */
-	if (!(le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS))
-		if (!tcon->posix_extensions)
-			return ERR_PTR(-EOPNOTSUPP);
+	if (!CIFS_REPARSE_SUPPORT(tcon))
+		return ERR_PTR(-EOPNOTSUPP);
 
 	oparms = CIFS_OPARMS(cifs_sb, tcon, full_path,
 			     SYNCHRONIZE | DELETE |

fs/smb/client/smb2ops.c

@@ -5203,10 +5203,9 @@ static int smb2_make_node(unsigned int xid, struct inode *inode,
 	if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_UNX_EMUL) {
 		rc = cifs_sfu_make_node(xid, inode, dentry, tcon,
 					full_path, mode, dev);
-	} else if ((le32_to_cpu(tcon->fsAttrInfo.Attributes) & FILE_SUPPORTS_REPARSE_POINTS)
-		|| (tcon->posix_extensions)) {
+	} else if (CIFS_REPARSE_SUPPORT(tcon)) {
 		rc = mknod_reparse(xid, inode, dentry, tcon,
-					full_path, mode, dev);
+				   full_path, mode, dev);
 	}
 	return rc;
 }