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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>
This commit is contained in:
Li Zefan 2011-11-20 07:33:38 -05:00 committed by Chris Mason
parent 0f0fbf1d0e
commit 52621cb6ed
1 changed files with 4 additions and 38 deletions
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42
fs/btrfs/free-space-cache.c
View File

@ -2451,7 +2451,6 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
{
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 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
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 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
}
/*
* 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 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
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 @@ int btrfs_find_space_cluster(struct btrfs_trans_handle *trans,
goto out;
}
INIT_LIST_HEAD(&bitmaps);
ret = setup_cluster_no_bitmap(block_group, cluster, &bitmaps, offset,
bytes, min_bytes);
if (ret)