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Btrfs: do not set subvolume flags in readonly mode
$ 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>
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parent
e54bfa3104
commit
b9ca0664dc
@ -1521,29 +1521,40 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
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u64 flags;
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int ret = 0;
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if (root->fs_info->sb->s_flags & MS_RDONLY)
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return -EROFS;
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ret = mnt_want_write_file(file);
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if (ret)
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goto out;
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if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID)
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return -EINVAL;
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if (btrfs_ino(inode) != BTRFS_FIRST_FREE_OBJECTID) {
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ret = -EINVAL;
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goto out_drop_write;
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}
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if (copy_from_user(&flags, arg, sizeof(flags)))
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return -EFAULT;
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if (copy_from_user(&flags, arg, sizeof(flags))) {
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ret = -EFAULT;
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goto out_drop_write;
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}
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if (flags & BTRFS_SUBVOL_CREATE_ASYNC)
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return -EINVAL;
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if (flags & BTRFS_SUBVOL_CREATE_ASYNC) {
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ret = -EINVAL;
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goto out_drop_write;
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}
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if (flags & ~BTRFS_SUBVOL_RDONLY)
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return -EOPNOTSUPP;
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if (flags & ~BTRFS_SUBVOL_RDONLY) {
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ret = -EOPNOTSUPP;
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goto out_drop_write;
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}
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if (!inode_owner_or_capable(inode))
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return -EACCES;
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if (!inode_owner_or_capable(inode)) {
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ret = -EACCES;
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goto out_drop_write;
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}
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down_write(&root->fs_info->subvol_sem);
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/* nothing to do */
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if (!!(flags & BTRFS_SUBVOL_RDONLY) == btrfs_root_readonly(root))
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goto out;
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goto out_drop_sem;
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root_flags = btrfs_root_flags(&root->root_item);
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if (flags & BTRFS_SUBVOL_RDONLY)
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@ -1566,8 +1577,11 @@ static noinline int btrfs_ioctl_subvol_setflags(struct file *file,
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out_reset:
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if (ret)
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btrfs_set_root_flags(&root->root_item, root_flags);
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out:
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out_drop_sem:
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up_write(&root->fs_info->subvol_sem);
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out_drop_write:
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mnt_drop_write_file(file);
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out:
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return ret;
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}
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