ext2: convert to the new mount API

Convert ext2 to the new mount API.

Note that this makes the sb= option more accepting than it was before;
previosly, sb= was only accepted if it was the first specified option.
Now it can exist anywhere, and if respecified, the last specified value
is used.

Parse-time messages here are sent to ext2_msg with a NULL sb, and
ext2_msg is adjusted to accept that, as ext4 does today as well.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250223201014.7541-2-sandeen@redhat.com

fs/ext2/ext2.h

@@ -368,6 +368,7 @@ struct ext2_inode {
 #define EXT2_MOUNT_ERRORS_CONT		0x000010  /* Continue on errors */
 #define EXT2_MOUNT_ERRORS_RO		0x000020  /* Remount fs ro on errors */
 #define EXT2_MOUNT_ERRORS_PANIC		0x000040  /* Panic on errors */
+#define EXT2_MOUNT_ERRORS_MASK		0x000070
 #define EXT2_MOUNT_MINIX_DF		0x000080  /* Mimics the Minix statfs */
 #define EXT2_MOUNT_NOBH			0x000100  /* No buffer_heads */
 #define EXT2_MOUNT_NO_UID32		0x000200  /* Disable 32-bit UIDs */