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| author | Chao Yu <yuchao0@huawei.com> | 2019-04-22 17:33:53 +0800 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2019-05-08 21:23:11 -0700 |
| commit | b471eb99e64495a1f0e430da3f96b88f600d3bb5 (patch) | |
| tree | 39a6ecf494e9fdde22a5947ef36d1ea6c077e2ca /fs/f2fs/f2fs.h | |
| parent | d7eb8f1cdfaefcd41b716ef0ed1745b43c6c4fc9 (diff) | |
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 <qkrwngud825@gmail.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs/f2fs.h')
| -rw-r--r-- | fs/f2fs/f2fs.h | 6 |
1 files changed, 5 insertions, 1 deletions
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) { |