Btrfs: avoid unnecessary bitmap search for cluster setup
setup_cluster_no_bitmap() searches all the extents and bitmaps starting
from offset. Therefore if it returns -ENOSPC, all the bitmaps starting
from offset are in the bitmaps list, so it's sufficient to search from
this list in setup_cluser_bitmap().
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 8f792f4..8c32434 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2451,7 +2451,6 @@
{
struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
struct btrfs_free_space *entry;
- struct rb_node *node;
int ret = -ENOSPC;
u64 bitmap_offset = offset_to_bitmap(ctl, offset);
@@ -2469,10 +2468,6 @@
list_add(&entry->list, bitmaps);
}
- /*
- * First check our cached list of bitmaps and see if there is an entry
- * here that will work.
- */
list_for_each_entry(entry, bitmaps, list) {
if (entry->bytes < min_bytes)
continue;
@@ -2483,38 +2478,10 @@
}
/*
- * If we do have entries on our list and we are here then we didn't find
- * anything, so go ahead and get the next entry after the last entry in
- * this list and start the search from there.
+ * The bitmaps list has all the bitmaps that record free space
+ * starting after offset, so no more search is required.
*/
- if (!list_empty(bitmaps)) {
- entry = list_entry(bitmaps->prev, struct btrfs_free_space,
- list);
- node = rb_next(&entry->offset_index);
- if (!node)
- return -ENOSPC;
- entry = rb_entry(node, struct btrfs_free_space, offset_index);
- goto search;
- }
-
- entry = tree_search_offset(ctl, offset_to_bitmap(ctl, offset), 0, 1);
- if (!entry)
- return -ENOSPC;
-
-search:
- node = &entry->offset_index;
- do {
- entry = rb_entry(node, struct btrfs_free_space, offset_index);
- node = rb_next(&entry->offset_index);
- if (!entry->bitmap)
- continue;
- if (entry->bytes < min_bytes)
- continue;
- ret = btrfs_bitmap_cluster(block_group, entry, cluster, offset,
- bytes, min_bytes);
- } while (ret && node);
-
- return ret;
+ return -ENOSPC;
}
/*
@@ -2532,8 +2499,8 @@
u64 offset, u64 bytes, u64 empty_size)
{
struct btrfs_free_space_ctl *ctl = block_group->free_space_ctl;
- struct list_head bitmaps;
struct btrfs_free_space *entry, *tmp;
+ LIST_HEAD(bitmaps);
u64 min_bytes;
int ret;
@@ -2572,7 +2539,6 @@
goto out;
}
- INIT_LIST_HEAD(&bitmaps);
ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
bytes, min_bytes);
if (ret)