[PATCH 4/4] Btrfs: do not set subvolume flags in readonly mode
From: Liu Bo <hidden>
Date: 2012-06-21 11:39:57
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
$ 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 <redacted> --- 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