Re: [f2fs-dev] [PATCH] f2fs: do f2fs_zero_post_eof_page for all the time

[Chao Yu <chao@kernel.org>]

On 10/28/26 13:06, Jaegeuk Kim via Linux-f2fs-devel wrote:
> This fixes xfstests/generic/794, since the issue is not related to the
> posix=strict mode only.

Jaegeuk,

Actually, I fixed this only in fsync_mode=strict because I don't see such
scenario (described in original patch) in Android:

    Steps of generic/794:
    1. write 4096 bytes to file w/ 0x5a
    2. use fiemap to get PBA of first block in file
    3. truncate file to 4080
    4. umount; write 4096 bytes to file w/ 0x5a directly via PBA; mount
    5. extend filesize via
       a) append 4096 from offset 4096, or
       b) truncate 8192, or
       c) fallocate 4096 from offset 4096
    6. verify the gap is zeroed in memory [4080,4096)
    7. sync range 4096 from offset 4096; shutdown -f (flush meta before shutdown)
    8. umount; mount; verify [4080,4096) is zeroed or not.

Maybe we should only enable fsync_mode=strict for 794 to let it pass?

Thanks,

> 
> Cc: stable@kernel.org
> Fixes: 5eced87b7d19 ("f2fs: fix to zero post-EOF data when extending file size")
> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
> ---
>  fs/f2fs/file.c | 14 ++------------
>  1 file changed, 2 insertions(+), 12 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 8b4a7a9d7dbe..823df06ae0f2 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -74,15 +74,10 @@ static int f2fs_zero_post_eof_page(struct inode *inode,
>  					loff_t new_size, bool lock, bool writeback)
>  {
>  	loff_t old_size = i_size_read(inode);
> -	bool strict =
> -		F2FS_OPTION(F2FS_I_SB(inode)).fsync_mode == FSYNC_MODE_STRICT;
>  
>  	if (old_size >= new_size)
>  		return 0;
>  
> -	if (!strict && mapping_empty(inode->i_mapping))
> -		return 0;
> -
>  	if (lock)
>  		filemap_invalidate_lock(inode->i_mapping);
>  	/* zero or drop pages only in range of [old_size, new_size] */
> @@ -90,14 +85,9 @@ static int f2fs_zero_post_eof_page(struct inode *inode,
>  	if (lock)
>  		filemap_invalidate_unlock(inode->i_mapping);
>  
> -	if (!writeback || !strict)
> +	if (!writeback)
>  		return 0;
> -	/*
> -	 * In fsync_mode=strict, when we expand an unaligned EOF size, we
> -	 * should zero post EOF data and writeback the data immediately,
> -	 * so that it can avoid exposing stale data after metadata flush
> -	 * and POR.
> -	 */
> +
>  	return do_zero_post_eof_page(inode, new_size);
>  }
>