* [PATCH 2/2] Btrfs: avoid unnecessary bitmap search for cluster setup
2011-11-16 5:17 [PATCH 1/2] Btrfs: fix to search one more bitmap for cluster setup Li Zefan
@ 2011-11-16 5:17 ` Li Zefan
2011-11-17 7:04 ` [PATCH v2 1/2] Btrfs: fix to search one more bitmap " Li Zefan
1 sibling, 0 replies; 3+ messages in thread
From: Li Zefan @ 2011-11-16 5:17 UTC (permalink / raw)
To: linux-btrfs@vger.kernel.org
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>
---
fs/btrfs/free-space-cache.c | 42 ++++--------------------------------------
1 files changed, 4 insertions(+), 38 deletions(-)
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index df3bc22..584ef14 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -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)
-- 1.7.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* [PATCH v2 1/2] Btrfs: fix to search one more bitmap for cluster setup
2011-11-16 5:17 [PATCH 1/2] Btrfs: fix to search one more bitmap for cluster setup Li Zefan
2011-11-16 5:17 ` [PATCH 2/2] Btrfs: avoid unnecessary bitmap search " Li Zefan
@ 2011-11-17 7:04 ` Li Zefan
1 sibling, 0 replies; 3+ messages in thread
From: Li Zefan @ 2011-11-17 7:04 UTC (permalink / raw)
To: linux-btrfs@vger.kernel.org
Suppose there are two bitmaps [0, 256], [256, 512] and one extent
[100, 120] in the free space cache, and we want to setup a cluster
with offset=100, bytes=50.
In this case, there will be only one bitmap [256, 512] in the temporary
bitmaps list, and then setup_cluster_bitmap() won't search bitmap [0, 256].
The cause is, the list is constructed in setup_cluster_no_bitmap(),
and only bitmaps with bitmap_entry->offset >= offset will be added
into the list, and the very bitmap that convers offset has
bitmap_entry->offset <= offset.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
---
v2: fix a NULL pointer deref.
---
fs/btrfs/free-space-cache.c | 12 ++++++++++++
1 files changed, 12 insertions(+), 0 deletions(-)
diff --git a/fs/btrfs/free-space-cache.c b/fs/btrfs/free-space-cache.c
index 181760f..8f792f4 100644
--- a/fs/btrfs/free-space-cache.c
+++ b/fs/btrfs/free-space-cache.c
@@ -2453,11 +2453,23 @@ setup_cluster_bitmap(struct btrfs_block_group_cache *block_group,
struct btrfs_free_space *entry;
struct rb_node *node;
int ret = -ENOSPC;
+ u64 bitmap_offset = offset_to_bitmap(ctl, offset);
if (ctl->total_bitmaps == 0)
return -ENOSPC;
/*
+ * The bitmap that covers offset won't be in the list unless offset
+ * is just its start offset.
+ */
+ entry = list_first_entry(bitmaps, struct btrfs_free_space, list);
+ if (entry->offset != bitmap_offset) {
+ entry = tree_search_offset(ctl, bitmap_offset, 1, 0);
+ if (entry && list_empty(&entry->list))
+ list_add(&entry->list, bitmaps);
+ }
+
+ /*
* First check our cached list of bitmaps and see if there is an entry
* here that will work.
*/
--
1.7.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread