Btrfs: fix unnecessary while loop when search the free space, cache
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>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 1027b85..557502c 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -1250,18 +1250,13 @@
* 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)
- entry = prev;
- break;
- }
+ if (!prev->bitmap &&
+ prev->offset + prev->bytes > offset)
+ entry = prev;
}
}
return entry;
@@ -1287,18 +1282,13 @@
}
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)
- return prev;
- break;
- }
+ if (!prev->bitmap &&
+ prev->offset + prev->bytes > offset)
+ return prev;
}
if (entry->offset + BITS_PER_BITMAP * ctl->unit > offset)
return entry;