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SubjectRe: [PATCH 1/2] f2fs: allow unfixed f2fs_checkpoint.checksum_offset
On 04/22, Chao Yu wrote:
> Previously, f2fs_checkpoint.checksum_offset points fixed position of
> f2fs_checkpoint structure:
>
> "#define CP_CHKSUM_OFFSET 4092"
>
> It is unnecessary, and it breaks the consecutiveness of nat and sit
> bitmap stored across checkpoint park block and payload blocks.
>
> This patch allows f2fs to handle unfixed .checksum_offset.
>
> In addition, for the case checksum value is stored in the middle of
> checkpoint park, calculating checksum value with superposition method
> like we did for inode_checksum.
>
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
> fs/f2fs/checkpoint.c | 27 +++++++++++++++++++++------
> include/linux/f2fs_fs.h | 4 ++++
> 2 files changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index 441814607b13..a25556aef8cc 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -794,13 +794,27 @@ static void write_orphan_inodes(struct f2fs_sb_info *sbi, block_t start_blk)
> }
> }
>
> +static __u32 f2fs_checkpoint_chksum(struct f2fs_sb_info *sbi,
> + struct f2fs_checkpoint *ckpt)
> +{
> + unsigned int chksum_ofs = le32_to_cpu(ckpt->checksum_offset);
> + __u32 chksum;
> +
> + chksum = f2fs_crc32(sbi, ckpt, chksum_ofs);
> + if (chksum_ofs < CP_CHKSUM_OFFSET) {
> + chksum_ofs += sizeof(chksum);
> + chksum = f2fs_chksum(sbi, chksum, (__u8 *)ckpt + chksum_ofs,
> + F2FS_BLKSIZE - chksum_ofs);

Do we need to cover __cp_payload(sbi) * blksize - chksum_ofs?

> + }
> + return chksum;
> +}
> +
> static int get_checkpoint_version(struct f2fs_sb_info *sbi, block_t cp_addr,
> struct f2fs_checkpoint **cp_block, struct page **cp_page,
> unsigned long long *version)
> {
> - unsigned long blk_size = sbi->blocksize;
> size_t crc_offset = 0;
> - __u32 crc = 0;
> + __u32 crc;
>
> *cp_page = f2fs_get_meta_page(sbi, cp_addr);
> if (IS_ERR(*cp_page))
> @@ -809,15 +823,16 @@ static int get_checkpoint_version(struct f2fs_sb_info *sbi, block_t cp_addr,
> *cp_block = (struct f2fs_checkpoint *)page_address(*cp_page);
>
> crc_offset = le32_to_cpu((*cp_block)->checksum_offset);
> - if (crc_offset > (blk_size - sizeof(__le32))) {
> + if (crc_offset < CP_MIN_CHKSUM_OFFSET ||
> + crc_offset > CP_CHKSUM_OFFSET) {
> f2fs_put_page(*cp_page, 1);
> f2fs_msg(sbi->sb, KERN_WARNING,
> "invalid crc_offset: %zu", crc_offset);
> return -EINVAL;
> }
>
> - crc = cur_cp_crc(*cp_block);
> - if (!f2fs_crc_valid(sbi, crc, *cp_block, crc_offset)) {
> + crc = f2fs_checkpoint_chksum(sbi, *cp_block);
> + if (crc != cur_cp_crc(*cp_block)) {
> f2fs_put_page(*cp_page, 1);
> f2fs_msg(sbi->sb, KERN_WARNING, "invalid crc value");
> return -EINVAL;
> @@ -1425,7 +1440,7 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> get_sit_bitmap(sbi, __bitmap_ptr(sbi, SIT_BITMAP));
> get_nat_bitmap(sbi, __bitmap_ptr(sbi, NAT_BITMAP));
>
> - crc32 = f2fs_crc32(sbi, ckpt, le32_to_cpu(ckpt->checksum_offset));
> + crc32 = f2fs_checkpoint_chksum(sbi, ckpt);
> *((__le32 *)((unsigned char *)ckpt +
> le32_to_cpu(ckpt->checksum_offset)))
> = cpu_to_le32(crc32);
> diff --git a/include/linux/f2fs_fs.h b/include/linux/f2fs_fs.h
> index 55da9abed023..65559900d4d7 100644
> --- a/include/linux/f2fs_fs.h
> +++ b/include/linux/f2fs_fs.h
> @@ -164,6 +164,10 @@ struct f2fs_checkpoint {
> unsigned char sit_nat_version_bitmap[1];
> } __packed;
>
> +#define CP_CHKSUM_OFFSET 4092 /* default chksum offset in checkpoint */
> +#define CP_MIN_CHKSUM_OFFSET \
> + (offsetof(struct f2fs_checkpoint, sit_nat_version_bitmap))
> +
> /*
> * For orphan inode management
> */
> --
> 2.18.0.rc1

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