isofs: Do not return EACCES for unknown filesystems

When isofs_mount() is called to mount a device read-write, it returns
EACCES even before it checks that the device actually contains an isofs
filesystem. This may confuse mount(8) which then tries to mount all
subsequent filesystem types in read-only mode.

Fix the problem by returning EACCES only once we verify that the device
indeed contains an iso9660 filesystem.

CC: stable@vger.kernel.org
Fixes: 17b7f7cf58926844e1dd40f5eb5348d481deca6a
Reported-by: Kent Overstreet <kent.overstreet@gmail.com>
Reported-by: Karel Zak <kzak@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/isofs/inode.c b/fs/isofs/inode.c
index ad0c745ebad72e89fd987e0f67de5e61f525ff2a..871c8b39209913d95708398688df19ca31b0eba7 100644 (file)
--- a/fs/isofs/inode.c
+++ b/fs/isofs/inode.c
@@ -687,6 +687,11 @@ static int isofs_fill_super(struct super_block *s, void *data, int silent)
        pri_bh = NULL;
 
 root_found:
+       /* We don't support read-write mounts */
+       if (!(s->s_flags & MS_RDONLY)) {
+               error = -EACCES;
+               goto out_freebh;
+       }
 
        if (joliet_level && (pri == NULL || !opt.rock)) {
                /* This is the case of Joliet with the norock mount flag.
@@ -1501,9 +1506,6 @@ struct inode *__isofs_iget(struct super_block *sb,
 static struct dentry *isofs_mount(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *data)
 {
-       /* We don't support read-write mounts */
-       if (!(flags & MS_RDONLY))
-               return ERR_PTR(-EACCES);
        return mount_bdev(fs_type, flags, dev_name, data, isofs_fill_super);
 }