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Btrfs: do not set subvolume flags in readonly mode

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$ 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@cn.fujitsu.com>
This commit is contained in:
Liu Bo 2012-06-29 03:58:49 -06:00 committed by Chris Mason
parent e54bfa3104
commit b9ca0664dc
1 changed files with 28 additions and 14 deletions
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42
fs/btrfs/ioctl.c
View File

@ -1521,29 +1521,40 @@ 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;
if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID)
return -EINVAL;
if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) {
ret = -EINVAL;
goto out_drop_write;
}
if (copy_from_user(&flags, arg, sizeof(flags)))
return -EFAULT;
if (copy_from_user(&flags, arg, sizeof(flags))) {
ret = -EFAULT;
goto out_drop_write;
}
if (flags & BTRFS_SUBVOL_CREATE_ASYNC)
return -EINVAL;
if (flags & BTRFS_SUBVOL_CREATE_ASYNC) {
ret = -EINVAL;
goto out_drop_write;
}
if (flags & ~BTRFS_SUBVOL_RDONLY)
return -EOPNOTSUPP;
if (flags & ~BTRFS_SUBVOL_RDONLY) {
ret = -EOPNOTSUPP;
goto out_drop_write;
}
if (!inode_owner_or_capable(inode))
return -EACCES;
if (!inode_owner_or_capable(inode)) {
ret = -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)
@ -1566,8 +1577,11 @@ 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;
}