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Message-ID: <16625fbb-3dc0-34d5-ee75-fe010aa0d9ec@kernel.org>
Date: Wed, 26 Jul 2023 09:24:44 +0800
From: Chao Yu <chao@...nel.org>
To: Chao Liu <chaoliu719@...il.com>, Jaegeuk Kim <jaegeuk@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, Chao Liu <liuchao@...lpad.com>
Subject: Re: [PATCH v2] f2fs: introduce two helper functions for the largest
cached extent
On 2023/7/25 9:36, Chao Liu wrote:
> From: Chao Liu <liuchao@...lpad.com>
>
> This patch is a cleanup:
> 1. Merge __drop_largest_extent() since it has only one caller.
> 2. Introduce __unlock_tree_with_checking_largest() and
> __drop_largest_extent() to help manage largest and largest_update
> in extent_tree.
>
> Signed-off-by: Chao Liu <liuchao@...lpad.com>
> ---
> v2: Make sure et->largest_updated gets updated within &et->lock.
> Thanks to Chao Yu for pointing out.
> ---
> fs/f2fs/extent_cache.c | 66 ++++++++++++++++++++----------------------
> fs/f2fs/f2fs.h | 4 +--
> 2 files changed, 33 insertions(+), 37 deletions(-)
>
> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
> index 0e2d49140c07f..cfc69621a8a26 100644
> --- a/fs/f2fs/extent_cache.c
> +++ b/fs/f2fs/extent_cache.c
> @@ -19,6 +19,12 @@
> #include "node.h"
> #include <trace/events/f2fs.h>
>
> +static void __drop_largest_extent(struct extent_tree *et)
> +{
> + et->largest.len = 0;
> + et->largest_updated = true;
> +}
> +
> bool sanity_check_extent_cache(struct inode *inode)
> {
> struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> @@ -35,8 +41,7 @@ bool sanity_check_extent_cache(struct inode *inode)
>
> /* Let's drop, if checkpoint got corrupted. */
> if (is_set_ckpt_flags(sbi, CP_ERROR_FLAG)) {
> - ei->len = 0;
> - et->largest_updated = true;
> + __drop_largest_extent(et);
__drop_largest_extent_force(et);
> return true;
> }
>
> @@ -310,6 +315,8 @@ static void __detach_extent_node(struct f2fs_sb_info *sbi,
>
> if (et->cached_en == en)
> et->cached_en = NULL;
> +
> + /* keep the largest as we can still use it */
The comments doesn't match below code?
> kmem_cache_free(extent_node_slab, en);
> }
>
> @@ -385,15 +392,6 @@ static unsigned int __free_extent_tree(struct f2fs_sb_info *sbi,
> return count - atomic_read(&et->node_cnt);
> }
>
> -static void __drop_largest_extent(struct extent_tree *et,
> - pgoff_t fofs, unsigned int len)
> -{
> - if (fofs < et->largest.fofs + et->largest.len &&
> - fofs + len > et->largest.fofs) {
> - et->largest.len = 0;
> - et->largest_updated = true;
> - }
> -}
What about:
static void __drop_largest_extent_cond(struct extent_tree *et,
pgoff_t fofs, unsigned int len,
bool force)
{
if (force || (fofs < et->largest.fofs + et->largest.len &&
fofs + len > et->largest.fofs)) {
et->largest.len = 0;
et->largest_updated = true;
}
}
static void __drop_largest_extent_force(struct extent_tree *et)
{
__drop_largest_extent_cond(et, 0, 0, true);
}
>
> void f2fs_init_read_extent_tree(struct inode *inode, struct page *ipage)
> {
> @@ -601,6 +599,19 @@ static struct extent_node *__insert_extent_tree(struct f2fs_sb_info *sbi,
> return en;
> }
>
> +static void __unlock_tree_with_checking_largest(struct extent_tree *et,
> + struct inode *inode)
> +{
> + if (et->type == EX_READ && et->largest_updated) {
> + et->largest_updated = false;
> + write_unlock(&et->lock);
> + f2fs_mark_inode_dirty_sync(inode, true);
> + return;
> + }
> +
> + write_unlock(&et->lock);
> +}
> +
> static void __update_extent_tree_range(struct inode *inode,
> struct extent_info *tei, enum extent_type type)
> {
> @@ -612,7 +623,6 @@ static void __update_extent_tree_range(struct inode *inode,
> struct rb_node **insert_p = NULL, *insert_parent = NULL;
> unsigned int fofs = tei->fofs, len = tei->len;
> unsigned int end = fofs + len;
> - bool updated = false;
> bool leftmost = false;
>
> if (!et)
> @@ -636,11 +646,10 @@ static void __update_extent_tree_range(struct inode *inode,
> prev = et->largest;
> dei.len = 0;
>
> - /*
> - * drop largest extent before lookup, in case it's already
> - * been shrunk from extent tree
> - */
> - __drop_largest_extent(et, fofs, len);
__drop_largest_extent_cond(et, fofs, len, false);
> + /* updates may cause largest extent cache to become invalid */
> + if (fofs < et->largest.fofs + et->largest.len &&
> + fofs + len > et->largest.fofs)
> + __drop_largest_extent(et);
> }
>
> /* 1. lookup first extent node in range [fofs, fofs + len - 1] */
> @@ -733,8 +742,7 @@ static void __update_extent_tree_range(struct inode *inode,
> if (dei.len >= 1 &&
> prev.len < F2FS_MIN_EXTENT_LEN &&
> et->largest.len < F2FS_MIN_EXTENT_LEN) {
> - et->largest.len = 0;
> - et->largest_updated = true;
> + __drop_largest_extent(et);
__drop_largest_extent_force(et);
> set_inode_flag(inode, FI_NO_EXTENT);
> }
> }
> @@ -742,10 +750,6 @@ static void __update_extent_tree_range(struct inode *inode,
> if (is_inode_flag_set(inode, FI_NO_EXTENT))
> __free_extent_tree(sbi, et);
>
> - if (et->largest_updated) {
> - et->largest_updated = false;
> - updated = true;
> - }
I guess we'd better keep previous logic.
> goto out_read_extent_cache;
> update_age_extent_cache:
> if (!tei->last_blocks)
> @@ -757,10 +761,7 @@ static void __update_extent_tree_range(struct inode *inode,
> __insert_extent_tree(sbi, et, &ei,
> insert_p, insert_parent, leftmost);
> out_read_extent_cache:
> - write_unlock(&et->lock);
> -
> - if (updated)
> - f2fs_mark_inode_dirty_sync(inode, true);
Ditto,
> + __unlock_tree_with_checking_largest(et, inode);
> }
>
> #ifdef CONFIG_F2FS_FS_COMPRESSION
> @@ -1092,7 +1093,6 @@ static void __drop_extent_tree(struct inode *inode, enum extent_type type)
> {
> struct f2fs_sb_info *sbi = F2FS_I_SB(inode);
> struct extent_tree *et = F2FS_I(inode)->extent_tree[type];
> - bool updated = false;
>
> if (!__may_extent_tree(inode, type))
> return;
> @@ -1101,14 +1101,10 @@ static void __drop_extent_tree(struct inode *inode, enum extent_type type)
> __free_extent_tree(sbi, et);
> if (type == EX_READ) {
> set_inode_flag(inode, FI_NO_EXTENT);
> - if (et->largest.len) {
> - et->largest.len = 0;
> - updated = true;
> - }
> + if (et->largest.len)
> + __drop_largest_extent(et);
> }
> - write_unlock(&et->lock);
> - if (updated)
> - f2fs_mark_inode_dirty_sync(inode, true);
Ditto,
Thanks,
> + __unlock_tree_with_checking_largest(et, inode);
> }
>
> void f2fs_drop_extent_tree(struct inode *inode)
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index d372bedb0fe4e..da02e120e5ea6 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -665,7 +665,7 @@ struct extent_tree {
>
> struct extent_tree_info {
> struct radix_tree_root extent_tree_root;/* cache extent cache entries */
> - struct mutex extent_tree_lock; /* locking extent radix tree */
> + struct mutex extent_tree_lock; /* locking extent radix tree */
> struct list_head extent_list; /* lru list for shrinker */
> spinlock_t extent_lock; /* locking extent lru list */
> atomic_t total_ext_tree; /* extent tree count */
> @@ -766,7 +766,7 @@ enum {
> FI_ACL_MODE, /* indicate acl mode */
> FI_NO_ALLOC, /* should not allocate any blocks */
> FI_FREE_NID, /* free allocated nide */
> - FI_NO_EXTENT, /* not to use the extent cache */
> + FI_NO_EXTENT, /* not to use the read extent cache */
> FI_INLINE_XATTR, /* used for inline xattr */
> FI_INLINE_DATA, /* used for inline data*/
> FI_INLINE_DENTRY, /* used for inline dentry */
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