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Date: Wed, 2 Aug 2023 22:41:51 +0800
From: Chao Yu <chao@...nel.org>
To: Chao Liu <chaoliu719@...il.com>
Cc: Jaegeuk Kim <jaegeuk@...nel.org>,
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 2023/7/26 14:16, Chao Liu wrote:
> On 7月 26 09:24, Chao Yu wrote:
>> 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?
>>
>
> Sorry for not explaining this earlier.
>
> It's just a hint and has nothing to do with the code below. It
So, it should be near to related code..., otherwise, IMO, it makes the code
more confused.
Thanks,
> simply explains that we don't need to disable the largest here, which
> makes the whole code logic of the largest more clear. :)
>
> If it's not fitting, please let me know, and I'll drop them.
>
>>> 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);
>> }
>>
>
> Thank you. I feel it matches better with the existing code
> organization style. Let me apply it in v3.
>
>>> 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.
>
> Ok, I will drop these changes in v3. Ditto for __drop_extent_tree().
>
>>
>>> 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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