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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
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@ -1521,29 +1521,40 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
u64 flags; u64 flags;
int ret = 0; int ret = 0;
if (root->fs_info->sb->s_flags & MS_RDONLY) ret = mnt_want_write_file(file);
return -EROFS; if (ret)
goto out;
if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) {
return -EINVAL; ret = -EINVAL;
goto out_drop_write;
}
if (copy_from_user(&flags, arg, sizeof(flags))) if (copy_from_user(&flags, arg, sizeof(flags))) {
return -EFAULT; ret = -EFAULT;
goto out_drop_write;
}
if (flags & BTRFS_SUBVOL_CREATE_ASYNC) if (flags & BTRFS_SUBVOL_CREATE_ASYNC) {
return -EINVAL; ret = -EINVAL;
goto out_drop_write;
}
if (flags & ~BTRFS_SUBVOL_RDONLY) if (flags & ~BTRFS_SUBVOL_RDONLY) {
return -EOPNOTSUPP; ret = -EOPNOTSUPP;
goto out_drop_write;
}
if (!inode_owner_or_capable(inode)) if (!inode_owner_or_capable(inode)) {
return -EACCES; ret = -EACCES;
goto out_drop_write;
}
down_write(&root->fs_info->subvol_sem); down_write(&root->fs_info->subvol_sem);
/* nothing to do */ /* nothing to do */
if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root)) if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root))
goto out; goto out_drop_sem;
root_flags = btrfs_root_flags(&root->root_item); root_flags = btrfs_root_flags(&root->root_item);
if (flags & BTRFS_SUBVOL_RDONLY) if (flags & BTRFS_SUBVOL_RDONLY)
@ -1566,8 +1577,11 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
out_reset: out_reset:
if (ret) if (ret)
btrfs_set_root_flags(&root->root_item, root_flags); btrfs_set_root_flags(&root->root_item, root_flags);
out: out_drop_sem:
up_write(&root->fs_info->subvol_sem); up_write(&root->fs_info->subvol_sem);
out_drop_write:
mnt_drop_write_file(file);
out:
return ret; return ret;
} }