Btrfs: fix unnecessary while loop when search the free space, cache (de6c4115) · Commits · 戴 / test

When we find a bitmap free space entry, we may check the previous extent entry covers the offset or not. But if we find this entry is also a bitmap entry, we will continue to check the previous entry of the current one by a while loop. It is unnecessary because it is impossible that the extent entry which is in front of a bitmap entry can cover the offset of the entry after that bitmap entry. Signed-off-by:

Miao Xie <miaox@cn.fujitsu.com> Reviewed-by:

Liu Bo <bo.li.liu@oracle.com> Signed-off-by:

Chris Mason <chris.mason@fusionio.com>

fs/btrfs/free-space-cache.c

+10 −20

Original line number	Diff line number	Diff line
		@@ -1250,18 +1250,13 @@ tree_search_offset(struct btrfs_free_space_ctl *ctl,
		* if previous extent entry covers the offset,
		* we should return it instead of the bitmap entry
		*/
		n = &entry->offset_index;
		while (1) {
		n = rb_prev(n);
		if (!n)
		break;
		n = rb_prev(&entry->offset_index);
		if (n) {
		prev = rb_entry(n, struct btrfs_free_space,
		offset_index);
		if (!prev->bitmap) {
		if (prev->offset + prev->bytes > offset)
		if (!prev->bitmap &&
		prev->offset + prev->bytes > offset)
		entry = prev;
		break;
		}
		}
		}
		return entry;
		@@ -1287,18 +1282,13 @@ tree_search_offset(struct btrfs_free_space_ctl *ctl,
		}

		if (entry->bitmap) {
		n = &entry->offset_index;
		while (1) {
		n = rb_prev(n);
		if (!n)
		break;
		n = rb_prev(&entry->offset_index);
		if (n) {
		prev = rb_entry(n, struct btrfs_free_space,
		offset_index);
		if (!prev->bitmap) {
		if (prev->offset + prev->bytes > offset)
		if (!prev->bitmap &&
		prev->offset + prev->bytes > offset)
		return prev;
		break;
		}
		}
		if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
		return entry;

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