Hi Chao,

How about changing the original patch slightly like below?

 o don't have to use index variable
 o should not skip the entire dnode indices, when one of them is -ENOENT

---
 fs/f2fs/file.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 180b838..e8536a8 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -739,33 +739,32 @@ static int fill_zero(struct inode *inode, pgoff_t index,
 
 int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end)
 {
-       pgoff_t count, index = pg_start;
+       pgoff_t count;
        int err;
 
-       while (index < pg_end) {
+       while (pg_start < pg_end) {
                struct dnode_of_data dn;
                pgoff_t end_offset;
 
                set_new_dnode(&dn, inode, NULL, NULL, 0);
-               err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
+               err = get_dnode_of_data(&dn, pg_start, LOOKUP_NODE);
                if (err) {
                        if (err == -ENOENT) {
-                               index = PGOFS_OF_NEXT_DNODE(index,
-                                                       F2FS_I(inode));
+                               pg_start++;
                                continue;
                        }
                        return err;
                }
 
                end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
-               count = min(end_offset - dn.ofs_in_node, pg_end - index);
+               count = min(end_offset - dn.ofs_in_node, pg_end - pg_start);
 
                f2fs_bug_on(F2FS_I_SB(inode), count == 0 || count > end_offset);
 
                truncate_data_blocks_range(&dn, count);
                f2fs_put_dnode(&dn);
 
-               index += count;
+               pg_start += count;
        }
        return 0;
 }
-- 
2.1.1

On Fri, Sep 11, 2015 at 02:38:05PM +0800, Chao Yu wrote:
> truncate_data_blocks_range can do in batches truncation which makes all
> changes in dnode page content, dnode page status, extent cache, block
> count updating together.
> 
> But previously, truncate_hole() always truncates one block in dnode page
> at a time by invoking truncate_data_blocks_range(,1), which make thing
> slow.
> 
> This patch changes truncate_hole() to do in batches truncation for all
> target blocks in one direct node inside truncate_data_blocks_range, which
> can make our punch hole operation in ->fallocate more efficent.
> 
> Signed-off-by: Chao Yu <chao2...@samsung.com>
> ---
>  fs/f2fs/file.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index b2fab9e..ac97f78 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -738,23 +738,33 @@ static int fill_zero(struct inode *inode, pgoff_t index,
>  
>  int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end)
>  {
> -     pgoff_t index;
> +     pgoff_t count, index = pg_start;
>       int err;
>  
> -     for (index = pg_start; index < pg_end; index++) {
> +     while (index < pg_end) {
>               struct dnode_of_data dn;
> +             pgoff_t end_offset;
>  
>               set_new_dnode(&dn, inode, NULL, NULL, 0);
>               err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
>               if (err) {
> -                     if (err == -ENOENT)
> +                     if (err == -ENOENT) {
> +                             index = PGOFS_OF_NEXT_DNODE(index,
> +                                                     F2FS_I(inode));
>                               continue;
> +                     }
>                       return err;
>               }
>  
> -             if (dn.data_blkaddr != NULL_ADDR)
> -                     truncate_data_blocks_range(&dn, 1);
> +             end_offset = ADDRS_PER_PAGE(dn.node_page, F2FS_I(inode));
> +             count = min(end_offset - dn.ofs_in_node, pg_end - index);
> +
> +             f2fs_bug_on(F2FS_I_SB(inode), count == 0 || count > end_offset);
> +
> +             truncate_data_blocks_range(&dn, count);
>               f2fs_put_dnode(&dn);
> +
> +             index += count;
>       }
>       return 0;
>  }
> -- 
> 2.4.2


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