From b471eb99e64495a1f0e430da3f96b88f600d3bb5 Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 22 Apr 2019 17:33:53 +0800 Subject: f2fs: relocate chksum_offset for large_nat_bitmap feature For large_nat_bitmap feature, there is a design flaw: Previous: struct f2fs_checkpoint layout: +--------------------------+ 0x0000 | checkpoint_ver | | ...... | | checksum_offset |------+ | ...... | | | sit_nat_version_bitmap[] |<-----|-------+ | ...... | | | | checksum_value |<-----+ | +--------------------------+ 0x1000 | | | nat_bitmap + sit_bitmap | payload blocks | | | | | +--------------------------|<-------------+ Obviously, if nat_bitmap size + sit_bitmap size is larger than MAX_BITMAP_SIZE_IN_CKPT, nat_bitmap or sit_bitmap may overlap checkpoint checksum's position, once checkpoint() is triggered from kernel, nat or sit bitmap will be damaged by checksum field. In order to fix this, let's relocate checksum_value's position to the head of sit_nat_version_bitmap as below, then nat/sit bitmap and chksum value update will become safe. After: struct f2fs_checkpoint layout: +--------------------------+ 0x0000 | checkpoint_ver | | ...... | | checksum_offset |------+ | ...... | | | sit_nat_version_bitmap[] |<-----+ | ...... |<-------------+ | | | +--------------------------+ 0x1000 | | | nat_bitmap + sit_bitmap | payload blocks | | | | | +--------------------------|<-------------+ Related report and discussion: https://sourceforge.net/p/linux-f2fs/mailman/message/36642346/ Reported-by: Park Ju Hyung Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/checkpoint.c | 11 +++++++++++ fs/f2fs/f2fs.h | 6 +++++- 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c index af77655e65b2..d52a15799488 100644 --- a/fs/f2fs/checkpoint.c +++ b/fs/f2fs/checkpoint.c @@ -795,6 +795,17 @@ static int get_checkpoint_version(struct f2fs_sb_info *sbi, block_t cp_addr, return -EINVAL; } + if (__is_set_ckpt_flags(*cp_block, CP_LARGE_NAT_BITMAP_FLAG)) { + if (crc_offset != CP_MIN_CHKSUM_OFFSET) { + f2fs_put_page(*cp_page, 1); + f2fs_msg(sbi->sb, KERN_WARNING, + "layout of large_nat_bitmap is deprecated, " + "run fsck to repair, chksum_offset: %zu", + crc_offset); + return -EINVAL; + } + } + crc = f2fs_checkpoint_chksum(sbi, *cp_block); if (crc != cur_cp_crc(*cp_block)) { f2fs_put_page(*cp_page, 1); diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 9a9dc20e295b..97e4ef71de64 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -1910,7 +1910,11 @@ static inline void *__bitmap_ptr(struct f2fs_sb_info *sbi, int flag) if (is_set_ckpt_flags(sbi, CP_LARGE_NAT_BITMAP_FLAG)) { offset = (flag == SIT_BITMAP) ? le32_to_cpu(ckpt->nat_ver_bitmap_bytesize) : 0; - return &ckpt->sit_nat_version_bitmap + offset; + /* + * if large_nat_bitmap feature is enabled, leave checksum + * protection for all nat/sit bitmaps. + */ + return &ckpt->sit_nat_version_bitmap + offset + sizeof(__le32); } if (__cp_payload(sbi) > 0) { -- cgit v1.2.3