From 7abf5c1e2ba038e0e8327a477271334269016676 Mon Sep 17 00:00:00 2001
From: Zach Brown <zab@versity.com>
Date: Thu, 16 Aug 2018 13:57:01 -0700
Subject: [PATCH] scoutfs-utils: calculate segment crc in mkfs

Signed-off-by: Zach Brown <zab@versity.com>
---
 utils/src/crc.c    | 9 +++++++++
 utils/src/crc.h    | 1 +
 utils/src/format.h | 3 +++
 utils/src/mkfs.c   | 1 +
 4 files changed, 14 insertions(+)

diff --git a/utils/src/crc.c b/utils/src/crc.c
index 38640fbc..714afa90 100644
--- a/utils/src/crc.c
+++ b/utils/src/crc.c
@@ -37,3 +37,12 @@ u32 crc_block(struct scoutfs_block_header *hdr)
 	return crc32c(~0, (char *)hdr + sizeof(hdr->crc),
 		      SCOUTFS_BLOCK_SIZE - sizeof(hdr->crc));
 }
+
+u32 crc_segment(struct scoutfs_segment_block *sblk)
+{
+	u32 off = offsetof(struct scoutfs_segment_block, _padding) +
+		  sizeof(sblk->_padding);
+
+	return crc32c(~0, (char *)sblk + off,
+		      le32_to_cpu(sblk->total_bytes) - off);
+}
diff --git a/utils/src/crc.h b/utils/src/crc.h
index 6878bf2f..a928bf0a 100644
--- a/utils/src/crc.h
+++ b/utils/src/crc.h
@@ -8,5 +8,6 @@
 u32 crc32c(u32 crc, const void *data, unsigned int len);
 u64 crc32c_64(u32 crc, const void *data, unsigned int len);
 u32 crc_block(struct scoutfs_block_header *hdr);
+u32 crc_segment(struct scoutfs_segment_block *seg);
 
 #endif
diff --git a/utils/src/format.h b/utils/src/format.h
index 6f2d46f8..5a01f57b 100644
--- a/utils/src/format.h
+++ b/utils/src/format.h
@@ -271,6 +271,9 @@ struct scoutfs_segment_item {
 /*
  * Each large segment starts with a segment block that describes the
  * rest of the blocks that make up the segment.
+ *
+ * The crc covers the initial total_bytes of the segment but starts
+ * after the padding.
  */
 struct scoutfs_segment_block {
 	__le32 crc;
diff --git a/utils/src/mkfs.c b/utils/src/mkfs.c
index c0dfcbf5..678114ef 100644
--- a/utils/src/mkfs.c
+++ b/utils/src/mkfs.c
@@ -377,6 +377,7 @@ static int write_new_fs(char *path, int fd)
 
 	item = (void *)(inode + 1);
 	sblk->total_bytes = cpu_to_le32((long)item - (long)sblk);
+	sblk->crc = cpu_to_le32(crc_segment(sblk));
 
 	ret = pwrite(fd, sblk, SCOUTFS_SEGMENT_SIZE,
 		     first_segno << SCOUTFS_SEGMENT_SHIFT);