On 6/12/26 19:58, Yongpeng Yang wrote:
> 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;
Previously, we can split largest extent node to two if we punched it, now
we can not? IIUC.
Thanks,
> skip:
> /* Let's drop, if checkpoint got corrupted. */
> if (f2fs_cp_error(sbi)) {
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