[bug report] btrfs: zoned: enable relocation on a zoned filesystem

[bug report] btrfs: zoned: enable relocation on a zoned filesystem

[Dan Carpenter]

Hello Naohiro Aota,

The patch 32430c614844: "btrfs: zoned: enable relocation on a zoned
filesystem" from Feb 4, 2021, leads to the following static checker
warning:

	fs/btrfs/relocation.c:3777 __insert_orphan_inode()
	warn: was expecting a 64 bit value instead of '(1 << 4)'

fs/btrfs/relocation.c
    3767 static int __insert_orphan_inode(struct btrfs_trans_handle *trans,
    3768 				 struct btrfs_root *root, u64 objectid)
    3769 {
    3770 	struct btrfs_path *path;
    3771 	struct btrfs_inode_item *item;
    3772 	struct extent_buffer *leaf;
    3773 	u64 flags = BTRFS_INODE_NOCOMPRESS | BTRFS_INODE_PREALLOC;
    3774 	int ret;
    3775 
    3776 	if (btrfs_is_zoned(trans->fs_info))
--> 3777 		flags &= ~BTRFS_INODE_PREALLOC;

This code is supposed to clear out bit BTRFS_INODE_PREALLOC but it
actually clears out the top 32bits as well.  The works in the current
code because even though "flags" is declared as a u64, only the lower
u32 bits are used.

For correctness and future proofing then probably we should declare
BTRFS_INODE_PREALLOC and friends as "1ULL << 4".

    3778 
    3779 	path = btrfs_alloc_path();
    3780 	if (!path)
    3781 		return -ENOMEM;
    3782 
    3783 	ret = btrfs_insert_empty_inode(trans, root, path, objectid);
    3784 	if (ret)
    3785 		goto out;
    3786 
    3787 	leaf = path->nodes[0];
    3788 	item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_inode_item);
    3789 	memzero_extent_buffer(leaf, (unsigned long)item, sizeof(*item));
    3790 	btrfs_set_inode_generation(leaf, item, 1);
    3791 	btrfs_set_inode_size(leaf, item, 0);
    3792 	btrfs_set_inode_mode(leaf, item, S_IFREG | 0600);
    3793 	btrfs_set_inode_flags(leaf, item, flags);
                                                  ^^^^^
The btrfs_set_inode_flags() function takes a u64.

    3794 	btrfs_mark_buffer_dirty(leaf);
    3795 out:
    3796 	btrfs_free_path(path);
    3797 	return ret;
    3798 }

regards,
dan carpenter