答复: [PATCH v4 4/4] f2fs: Optimize f2fs_truncate_data_blocks_range()

["孙毅 (Yi Sun)" <Yi.Sun@unisoc.com>]

> -----邮件原件-----
> 发件人: Chao Yu <chao@kernel.org>
> 发送时间: 2025年1月14日 12:29
> 收件人: 孙毅 (Yi Sun) <Yi.Sun@unisoc.com>; jaegeuk@kernel.org
> 抄送: chao@kernel.org; sunyibuaa@gmail.com; linux-f2fs-
> devel@lists.sourceforge.net; linux-kernel@vger.kernel.org;
> niuzhiguo84@gmail.com; 王皓 (Hao_hao Wang) <Hao_hao.Wang@unisoc.com>;
> 王科 (Ke Wang) <Ke.Wang@unisoc.com>
> 主题: Re: [PATCH v4 4/4] f2fs: Optimize f2fs_truncate_data_blocks_range()
> 
> On 12/23/24 16:10, Yi Sun wrote:
> > Function f2fs_invalidate_blocks() can process continuous
> > blocks at a time, so f2fs_truncate_data_blocks_range() is
> > optimized to use the new functionality of
> > f2fs_invalidate_blocks().
> >
> > Signed-off-by: Yi Sun <yi.sun@unisoc.com>
> > ---
> >   fs/f2fs/file.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++---
> >   1 file changed, 68 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 81764b10840b..9980d17ef9f5 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -612,6 +612,15 @@ static int f2fs_file_open(struct inode *inode, struct file
> *filp)
> >       return finish_preallocate_blocks(inode);
> >   }
> >
> > +static bool check_curr_block_is_consecutive(struct f2fs_sb_info *sbi,
> > +                                     block_t curr, block_t end)
> 
> static inline bool is_consecutive_blkaddrs(block_t cur, block_t end)
> {
>         return cur == end || cur == end + 1;
> }
> 
> But maybe we don't need to add this function, see below comments.
> 
> > +{
> > +     if (curr - end == 1 || curr == end)
> > +             return true;
> > +     else
> > +             return false;
> > +}
> > +
> >   void f2fs_truncate_data_blocks_range(struct dnode_of_data *dn, int count)
> >   {
> >       struct f2fs_sb_info *sbi = F2FS_I_SB(dn->inode);
> > @@ -621,8 +630,27 @@ void f2fs_truncate_data_blocks_range(struct
> dnode_of_data *dn, int count)
> >       int cluster_index = 0, valid_blocks = 0;
> >       int cluster_size = F2FS_I(dn->inode)->i_cluster_size;
> >       bool released = !atomic_read(&F2FS_I(dn->inode)->i_compr_blocks);
> > +     /*
> > +      * Temporary record location.
> > +      * When the current  @blkaddr and @blkaddr_end can be processed
> > +      * together, update the value of @blkaddr_end.
> > +      * When it is detected that current @blkaddr is not continues with
> > +      * @blkaddr_end, it is necessary to process continues blocks
> 
> I prefer not adding these comments into function, what about describing the
> details in commit message, instead, thoughts?
> 
> > +      * range [blkaddr_start, blkaddr_end].
> > +      */
> > +     block_t blkaddr_start, blkaddr_end;
> > +     /*.
> > +      * To avoid processing various invalid data blocks.
> > +      * Because @blkaddr_start and @blkaddr_end may be assigned
> > +      * NULL_ADDR or invalid data blocks, @last_valid is used to
> > +      * record this situation.
> > +      */
> 
> Ditto,
> 
> What about using blkstart & blklen to record last consecutive block addresses,
> and using blklen to identify whether we need to call f2fs_invalidate_blocks() or
> not?
> 
> > +     bool last_valid = false;
> > +     /* Process the last @blkaddr separately? */
> > +     bool last_one = true;
> >
> >       addr = get_dnode_addr(dn->inode, dn->node_page) + ofs;
> > +     blkaddr_start = blkaddr_end = le32_to_cpu(*addr);
> >
> >       /* Assumption: truncation starts with cluster */
> >       for (; count > 0; count--, addr++, dn->ofs_in_node++, cluster_index++) {
> > @@ -638,24 +666,60 @@ void f2fs_truncate_data_blocks_range(struct
> dnode_of_data *dn, int count)
> >               }
> >
> >               if (blkaddr == NULL_ADDR)
> > -                     continue;
> > +                     goto next;
> >
> >               f2fs_set_data_blkaddr(dn, NULL_ADDR);
> >
> >               if (__is_valid_data_blkaddr(blkaddr)) {
> >                       if (time_to_inject(sbi, FAULT_BLKADDR_CONSISTENCE))
> > -                             continue;
> > +                             goto next;
> >                       if (!f2fs_is_valid_blkaddr_raw(sbi, blkaddr,
> >                                               DATA_GENERIC_ENHANCE))
> > -                             continue;
> > +                             goto next;
> >                       if (compressed_cluster)
> >                               valid_blocks++;
> >               }
> >
> > -             f2fs_invalidate_blocks(sbi, blkaddr, 1);
> 
> How about this? Can you change based on it?
> 
>                 if (blkstart + blklen == blkaddr) {
>                         blklen++;
>                 } else {
>                         f2fs_invalidate_blocks(sbi, blkstart, blklen);
>                         blkstart = blkaddr;
>                         blklen = 1;
>                 }
> 
> > +
> > +             if (check_curr_block_is_consecutive(sbi, blkaddr, blkaddr_end)) {
> > +                     /*
> > +                      * The current block @blkaddr is continuous with
> > +                      * @blkaddr_end, so @blkaddr_end is updated.
> > +                      * And the f2fs_invalidate_blocks() is skipped
> > +                      * until @blkaddr that cannot be processed
> > +                      * together is encountered.
> > +                      */
> > +                     blkaddr_end = blkaddr;
> > +                     if (count == 1)
> > +                             last_one = false;
> > +                     else
> > +                             goto skip_invalid;
> > +             }
> > +
> > +             f2fs_invalidate_blocks(sbi, blkaddr_start,
> > +                                     blkaddr_end - blkaddr_start + 1);
> > +             blkaddr_start = blkaddr_end = blkaddr;
> > +
> > +             if (count == 1 && last_one)
> > +                     f2fs_invalidate_blocks(sbi, blkaddr, 1);
> > +
> > +skip_invalid:
> > +             last_valid = true;
> >
> >               if (!released || blkaddr != COMPRESS_ADDR)
> >                       nr_free++;
> > +
> > +             continue;
> > +
> > +next:
> 
> next:
> 
>                 if (blklen) {
>                         f2fs_invalidate_blocks(sbi, blkstart, blklen);
>                         blkstart = blkaddr;
>                         blklen = 1;
>                 }
> 
> > +             /* If consecutive blocks have been recorded, we need to process them.
> */
> > +             if (last_valid == true)
> > +                     f2fs_invalidate_blocks(sbi, blkaddr_start,
> > +                                     blkaddr_end - blkaddr_start + 1);
> > +
> > +             blkaddr_start = blkaddr_end = le32_to_cpu(*(addr + 1));
> > +             last_valid = false;
> > +
> >       }
> 
>         if (blklen)
>                 f2fs_invalidate_blocks(sbi, blkstart, blklen);
> 
> Thanks,
> 

Hi Chao,
Your suggestion looks great, I will modify it accordingly.

> >
> >       if (compressed_cluster)