Re: [f2fs-dev] [PATCH] f2fs: fix incorrect FI_NO_EXTENT handling in __destroy_extent_node()

[Chao Yu <chao@kernel.org>]

On 4/24/26 17:45, Yongpeng Yang wrote:
> 
> On 4/22/26 20:33, Chao Yu via Linux-f2fs-devel wrote:
>> On 4/22/2026 3:35 PM, Yongpeng Yang wrote:
>>> From: yangyongpeng <yangyongpeng@xiaomi.com>
>>>
>>> When __destroy_extent_node() sets the inode flag FI_NO_EXTENT, it does
>>> not reset the length of the largest extent to 0 and update the inode
>>> folio. Since modifications to the extent tree are disallowed afterward,
>>> the cached largest extent may become stale. This can trigger the
>>> following error in xfstests generic/388:
>>>
>>> F2FS-fs (dm-0): sanity_check_extent_cache: inode (ino=1761) extent
>>> info [220057, 57, 6] is incorrect, run fsck to fix
>>>
>>> In the f2fs_drop_inode path, __destroy_extent_node() does not need to
>>> guarantee that et->node_cnt is 0, because concurrency with writeback
>>> is expected in this path, and writeback may update the extent cache.
>>>
>>> This patch updates __destroy_extent_node() to avoid setting the inode
>>> flag FI_NO_EXTENT, and to remove the check zero of et->node_cnt.
>>>
>>> Fixes: ed78aeebef05 ("f2fs: fix node_cnt race between extent node
>>> destroy and writeback")
>>> Cc: stable@vger.kernel.org
>>> Reported-by: Chao Yu <chao@kernel.org>
>>> Suggested-by: Chao Yu <chao@kernel.org>
>>> Signed-off-by: yangyongpeng <yangyongpeng@xiaomi.com>
>>> ---
>>>    fs/f2fs/extent_cache.c | 4 ----
>>>    1 file changed, 4 deletions(-)
>>>
>>> diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
>>> index 87169fd29d89..3adbead27953 100644
>>> --- a/fs/f2fs/extent_cache.c
>>> +++ b/fs/f2fs/extent_cache.c
>>> @@ -645,14 +645,10 @@ static unsigned int __destroy_extent_node(struct
>>> inode *inode,
>>>          while (atomic_read(&et->node_cnt)) {
>>>            write_lock(&et->lock);
>>> -        if (!is_inode_flag_set(inode, FI_NO_EXTENT))
>>> -            set_inode_flag(inode, FI_NO_EXTENT);
>>
>> We'd better revert all change lines in "f2fs: fix node_cnt race between
>> extent node destroy and writeback"?
> 
> The others all check whether FI_NO_EXTENT is set. When it is set,
> inserting an age extent is disallowed, so nothing was removed.

diff --git a/fs/f2fs/extent_cache.c b/fs/f2fs/extent_cache.c
index 87169fd29d89..0ed84cc065a7 100644
--- a/fs/f2fs/extent_cache.c
+++ b/fs/f2fs/extent_cache.c
@@ -119,10 +119,9 @@ static bool __may_extent_tree(struct inode *inode, enum extent_type type)
         if (!__init_may_extent_tree(inode, type))
                 return false;

-       if (is_inode_flag_set(inode, FI_NO_EXTENT))
-               return false;
-
         if (type == EX_READ) {
+               if (is_inode_flag_set(inode, FI_NO_EXTENT))
+                       return false;
                 if (is_inode_flag_set(inode, FI_COMPRESSED_FILE) &&
                                  !f2fs_sb_has_readonly(F2FS_I_SB(inode)))
                         return false;

...

@@ -691,12 +688,12 @@ static void __update_extent_tree_range(struct inode *inode,

         write_lock(&et->lock);

-       if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
-               write_unlock(&et->lock);
-               return;
-       }
-
         if (type == EX_READ) {
+               if (is_inode_flag_set(inode, FI_NO_EXTENT)) {
+                       write_unlock(&et->lock);
+                       return;
+               }
+
                 prev = et->largest;
                 dei.len = 0;

Hmm, I'm not sure I understood you correctly, if you want to keep above codes, what
about changing in another patch w/ correct commit message?

Thanks,


> 
> Thanks
> Yongpeng,
> 
>>
>> Thanks,
>>
>>>            node_cnt += __free_extent_tree(sbi, et, nr_shrink);
>>>            write_unlock(&et->lock);
>>>        }
>>>    -    f2fs_bug_on(sbi, atomic_read(&et->node_cnt));
>>> -
>>>        return node_cnt;
>>>    }
>>>    
>>
>>
>>
>> _______________________________________________
>> Linux-f2fs-devel mailing list
>> Linux-f2fs-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
>