Re: [PATCH] f2fs: fix null reference error when checking end of zone

[Chao Yu <chao@kernel.org>]

On 2024/7/4 9:01, Daejun Park wrote:
> This patch fixes a potentially null pointer being accessed by
> is_end_zone_blkaddr() that checks the last block of a zone
> when f2fs is mounted as a single device.

blkzoned feature depends on multiple device feature? One regular
device and one seq-zone device?

Thanks,

> 
> Fixes: e067dc3c6b9c ("f2fs: maintain six open zones for zoned devices")
> Signed-off-by: Daejun Park <daejun7.park@samsung.com>
> ---
>   fs/f2fs/data.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index b6dcb3bcaef7..1aa7eefa659c 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -925,6 +925,7 @@ int f2fs_merge_page_bio(struct f2fs_io_info *fio)
>   #ifdef CONFIG_BLK_DEV_ZONED
>   static bool is_end_zone_blkaddr(struct f2fs_sb_info *sbi, block_t blkaddr)
>   {
> +	struct block_device *bdev = sbi->sb->s_bdev;
>   	int devi = 0;
>   
>   	if (f2fs_is_multi_device(sbi)) {
> @@ -935,8 +936,9 @@ static bool is_end_zone_blkaddr(struct f2fs_sb_info *sbi, block_t blkaddr)
>   			return false;
>   		}
>   		blkaddr -= FDEV(devi).start_blk;
> +		bdev = FDEV(devi).bdev;
>   	}
> -	return bdev_is_zoned(FDEV(devi).bdev) &&
> +	return bdev_is_zoned(bdev) &&
>   		f2fs_blkz_is_seq(sbi, devi, blkaddr) &&
>   		(blkaddr % sbi->blocks_per_blkz == sbi->blocks_per_blkz - 1);
>   }