$ mkfs.btrfs /dev/sdb7 $ btrfstune -S1 /dev/sdb7 $ mount /dev/sdb7 /mnt/btrfs mount: block device /dev/sdb7 is write-protected, mounting read-only $ btrfs dev add /dev/sdb8 /mnt/btrfs/ Now we get a btrfs in which mnt flags has readonly but sb flags does not. So for those ioctls that only check sb flags with MS_RDONLY, it is going to be a problem. Setting subvolume flags is such an ioctl, we should use mnt_want_write_file() to check RO flags. Signed-off-by: Liu Bo <liubo2009@xxxxxxxxxxxxxx> --- fs/btrfs/ioctl.c | 27 ++++++++++++++++++--------- 1 files changed, 18 insertions(+), 9 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index df4c04d..ae29737 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1519,29 +1519,35 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file, u64 flags; int ret = 0; - if (root->fs_info->sb->s_flags & MS_RDONLY) - return -EROFS; + ret = mnt_want_write_file(file); + if (ret) + goto out; + ret = -EINVAL; if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) - return -EINVAL; + goto out_drop_write; + ret = -EFAULT; if (copy_from_user(&flags, arg, sizeof(flags))) - return -EFAULT; + goto out_drop_write; + ret = -EINVAL; if (flags & BTRFS_SUBVOL_CREATE_ASYNC) - return -EINVAL; + goto out_drop_write; + ret = -EOPNOTSUPP; if (flags & ~BTRFS_SUBVOL_RDONLY) - return -EOPNOTSUPP; + goto out_drop_write; + ret = -EACCES; if (!inode_owner_or_capable(inode)) - return -EACCES; + goto out_drop_write; down_write(&root->fs_info->subvol_sem); /* nothing to do */ if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root)) - goto out; + goto out_drop_sem; root_flags = btrfs_root_flags(&root->root_item); if (flags & BTRFS_SUBVOL_RDONLY) @@ -1564,8 +1570,11 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file, out_reset: if (ret) btrfs_set_root_flags(&root->root_item, root_flags); -out: +out_drop_sem: up_write(&root->fs_info->subvol_sem); +out_drop_write: + mnt_drop_write_file(file); +out: return ret; } -- 1.6.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
