linux-kernel - Re: [PATCH] Revert "f2fs: stop allocating pinned sections if EAGAIN happens"

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Date: Mon, 5 Feb 2024 11:54:04 +0800
From: Chao Yu <chao@...nel.org>
To: Wu Bo <bo.wu@...o.com>, Jaegeuk Kim <jaegeuk@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org,
 Wu Bo <wubo.oduw@...il.com>, stable@...r.kernel.org
Subject: Re: [PATCH] Revert "f2fs: stop allocating pinned sections if EAGAIN
 happens"

On 2024/2/5 11:14, Wu Bo wrote:
> This reverts commit 2e42b7f817acd6e8d78226445eb6fe44fe79c12a.
> 
> If the GC victim section has a pinned block when fallocate() trigger
> FG_GC, the section is not able to be recycled. And this will return
> -EAGAIN cause fallocate() failed, even though there are much spare space
> as user see. As the GC policy prone to chose the same victim,
> fallocate() may not successed at a long period.
> 
> This scenario has been found during Android OTA.
> 
> Link: https://lore.kernel.org/linux-f2fs-devel/20231030094024.263707-1-bo.wu@vivo.com/t/#u
> 
> CC: stable@...r.kernel.org
> Signed-off-by: Wu Bo <bo.wu@...o.com>
> ---
>   fs/f2fs/file.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index b58ab1157b7e..19915faccee9 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1725,7 +1725,7 @@ static int f2fs_expand_inode_data(struct inode *inode, loff_t offset,
>   			f2fs_down_write(&sbi->gc_lock);
>   			stat_inc_gc_call_count(sbi, FOREGROUND);
>   			err = f2fs_gc(sbi, &gc_control);
> -			if (err && err != -ENODATA)
> +			if (err && err != -ENODATA && err != -EAGAIN)
>   				goto out_err;
>   		}

How about calling f2fs_balance_fs() to double check and make sure there is
enough free space for following allocation.

		if (has_not_enough_free_secs(sbi, 0,
			GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))) {
			f2fs_down_write(&sbi->gc_lock);
			stat_inc_gc_call_count(sbi, FOREGROUND);
			err = f2fs_gc(sbi, &gc_control);
			if (err == -EAGAIN)
				f2fs_balance_fs(sbi, true);
			if (err && err != -ENODATA)
				goto out_err;
		}

Thanks,

>