btrfs-progs: Remove extent_buffer::tree member

Commit Message

Qu Wenruo April 14, 2020, 1:34 a.m. UTC

This member can be fetched from eb::fs_info, and no caller really
depends on that member to determine if an eb is dummy. We have eb::flags
to determine that.

Kernel doesn't have such member either.

Signed-off-by: Qu Wenruo <[e-mail]>
---
NOTE: Another candidate to cleanup is eb::cache_node, in kernel we use
radix tree, thus no need for any structure in eb.

But in btrfs-progs, we also rely on extent_io_tree to do cache size
limitation, and for U-boot there is no radix tree implemented yet.

Thus eb::cache_node may live for a longer time.
---
 disk-io.c   |  7 ++++---
 extent_io.c | 14 +++++---------
 extent_io.h |  1 -
 3 files changed, 9 insertions(+), 13 deletions(-)

Comments

David Sterba April 14, 2020, 3:05 p.m. UTC | #1

On Tue, Apr 14, 2020 at 09:34:04AM +0800, Qu Wenruo wrote:
> This member can be fetched from eb::fs_info, and no caller really
> depends on that member to determine if an eb is dummy. We have eb::flags
> to determine that.
> 
> Kernel doesn't have such member either.
> 
> Signed-off-by: Qu Wenruo <[e-mail]>

Added to devel, thanks.

> NOTE: Another candidate to cleanup is eb::cache_node, in kernel we use
> radix tree, thus no need for any structure in eb.
> 
> But in btrfs-progs, we also rely on extent_io_tree to do cache size
> limitation, and for U-boot there is no radix tree implemented yet.
> 
> Thus eb::cache_node may live for a longer time.

Ok. There will be differences among the implementations, we might add
some thin API to hide the caching or underlying strcutres but for now I
don't have anything specific in mind.

Patch

diff --git a/disk-io.c b/disk-io.c
index c895bd277491..093a87cc9c48 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -371,8 +371,8 @@  struct extent_buffer* read_tree_block(struct btrfs_fs_info *fs_info, u64 bytenr,
 		ret = read_whole_eb(fs_info, eb, mirror_num);
 		if (ret == 0 && csum_tree_block(fs_info, eb, 1) == 0 &&
 		    check_tree_block(fs_info, eb) == 0 &&
-		    verify_parent_transid(eb->tree, eb, parent_transid, ignore)
-		    == 0) {
+		    verify_parent_transid(&fs_info->extent_cache, eb,
+					  parent_transid, ignore) == 0) {
 			if (eb->flags & EXTENT_BAD_TRANSID &&
 			    list_empty(&eb->recow)) {
 				list_add_tail(&eb->recow,
@@ -1951,7 +1951,8 @@  int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid)
 	if (!ret)
 		return ret;
 
-	ret = verify_parent_transid(buf->tree, buf, parent_transid, 1);
+	ret = verify_parent_transid(&buf->fs_info->extent_cache, buf,
+				    parent_transid, 1);
 	return !ret;
 }
 
diff --git a/extent_io.c b/extent_io.c
index 4b5acb1aabf0..5ec8f41de265 100644
--- a/extent_io.c
+++ b/extent_io.c
@@ -619,7 +619,6 @@  static struct extent_buffer *__alloc_extent_buffer(struct btrfs_fs_info *info,
 	eb->cache_node.start = bytenr;
 	eb->cache_node.size = blocksize;
 	eb->fs_info = info;
-	eb->tree = &info->extent_cache;
 	INIT_LIST_HEAD(&eb->recow);
 	INIT_LIST_HEAD(&eb->lru);
 	memset_extent_buffer(eb, 0, 0, blocksize);
@@ -634,8 +633,6 @@  struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
 	new = __alloc_extent_buffer(src->fs_info, src->start, src->len);
 	if (!new)
 		return NULL;
-	/* cloned eb is not linked into fs_info->extent_cache */
-	new->tree = NULL;
 
 	copy_extent_buffer(new, src, 0, 0, src->len);
 	new->flags |= EXTENT_BUFFER_DUMMY;
@@ -645,13 +642,13 @@  struct extent_buffer *btrfs_clone_extent_buffer(struct extent_buffer *src)
 
 static void free_extent_buffer_final(struct extent_buffer *eb)
 {
-	struct extent_io_tree *tree = eb->tree;
-
 	BUG_ON(eb->refs);
-	BUG_ON(tree && tree->cache_size < eb->len);
 	list_del_init(&eb->lru);
 	if (!(eb->flags & EXTENT_BUFFER_DUMMY)) {
+		struct extent_io_tree *tree = &eb->fs_info->extent_cache;
+
 		remove_cache_extent(&tree->cache, &eb->cache_node);
+		BUG_ON(tree->cache_size < eb->len);
 		tree->cache_size -= eb->len;
 	}
 	free(eb);
@@ -786,7 +783,6 @@  struct extent_buffer *alloc_dummy_extent_buffer(struct btrfs_fs_info *fs_info,
 	if (!ret)
 		return NULL;
 
-	ret->tree = NULL;
 	ret->flags |= EXTENT_BUFFER_DUMMY;
 
 	return ret;
@@ -970,7 +966,7 @@  out:
 
 int set_extent_buffer_dirty(struct extent_buffer *eb)
 {
-	struct extent_io_tree *tree = eb->tree;
+	struct extent_io_tree *tree = &eb->fs_info->extent_cache;
 	if (!(eb->flags & EXTENT_DIRTY)) {
 		eb->flags |= EXTENT_DIRTY;
 		set_extent_dirty(tree, eb->start, eb->start + eb->len - 1);
@@ -981,7 +977,7 @@  int set_extent_buffer_dirty(struct extent_buffer *eb)
 
 int clear_extent_buffer_dirty(struct extent_buffer *eb)
 {
-	struct extent_io_tree *tree = eb->tree;
+	struct extent_io_tree *tree = &eb->fs_info->extent_cache;
 	if (eb->flags & EXTENT_DIRTY) {
 		eb->flags &= ~EXTENT_DIRTY;
 		clear_extent_dirty(tree, eb->start, eb->start + eb->len - 1);
diff --git a/extent_io.h b/extent_io.h
index 8b65e2d2181b..bf934dfcbdf1 100644
--- a/extent_io.h
+++ b/extent_io.h
@@ -89,7 +89,6 @@  struct extent_buffer {
 	struct cache_extent cache_node;
 	u64 start;
 	u64 dev_bytenr;
-	struct extent_io_tree *tree;
 	struct list_head lru;
 	struct list_head recow;
 	u32 len;