[f2fs-dev] [PATCH RESEND 2/5] f2fs: only initialize largest extent without extent_node at inode init

From: Yongpeng Yang <[email protected]>

The largest extent takes effect during both read mapping and write
mapping lookups, while read mapping does not need to access the
extent_node. For write mapping, the case where the largest extent is
not in the extent tree can already be handled by the merge logic, and
cases that cannot be merged do not require the largest extent to
participate either.

Therefore, the largest extent does not need to initialize a
corresponding extent_node, reducing memory footprint.

Signed-off-by: Yongpeng Yang <[email protected]>
---
 fs/f2fs/extent_cache.c | 18 +-----------------
 1 file changed, 1 insertion(+), 17 deletions(-)

diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index aa368a01b035..f8d94db60dc6 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -410,10 +410,8 @@ static void __drop_largest_extent(struct extent_tree *et,
 void f2fs_init_read_extent_tree(struct inode *inode, struct folio *ifolio)
 {
 	struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
-	struct extent_tree_info *eti = &sbi->extent_tree[EX_READ];
 	struct f2fs_extent *i_ext = &F2FS_INODE(ifolio)->i_ext;
 	struct extent_tree *et;
-	struct extent_node *en;
 	struct extent_info ei = {0};
 
 	if (!__may_extent_tree(inode, EX_READ)) {
@@ -435,21 +433,7 @@ void f2fs_init_read_extent_tree(struct inode *inode, struct folio *ifolio)
 	if (atomic_read(&et->node_cnt) || !ei.len)
 		goto skip;
 
-	if (IS_DEVICE_ALIASING(inode)) {
-		et->largest = ei;
-		goto skip;
-	}
-
-	en = __attach_extent_node(sbi, et, &ei, NULL,
-				&et->root.rb_root.rb_node, true);
-	if (en) {
-		et->largest = en->ei;
-		et->cached_en = en;
-
-		spin_lock(&eti->extent_lock);
-		list_add_tail(&en->list, &eti->extent_list);
-		spin_unlock(&eti->extent_lock);
-	}
+	et->largest = ei;
 skip:
 	/* Let's drop, if checkpoint got corrupted. */
 	if (f2fs_cp_error(sbi)) {
-- 
2.43.0



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