[PATCH 11/14] hfsplus: implement functionality of transaction's block check

[PATCH 11/14] hfsplus: implement functionality of transaction's block check

[Vyacheslav Dubeyko]

From: Vyacheslav Dubeyko <slava@dubeyko.com>
Subject: [PATCH 11/14] hfsplus: implement functionality of transaction's block check

A group of related changes is called a transaction. When all of the
changes of a transaction have been written to their normal locations
on disk, that transaction has been committed, and is removed from the
journal. The journal may contain several transactions. Copying changes
from all transactions to their normal locations on disk is called
replaying the journal.

A single transaction consists of several blocks, including both the data
to be written, and the location where that data is to be written. This is
represented on disk by a block list header, which describes the number
and sizes of the blocks, immediately followed by the contents of those
blocks.

This patch implements method of checking description of
transaction's block before replaying of it.

Signed-off-by: Vyacheslav Dubeyko <slava@dubeyko.com>
CC: Al Viro <viro@zeniv.linux.org.uk>
CC: Christoph Hellwig <hch@infradead.org>
CC: Hin-Tak Leung <htl10@users.sourceforge.net>
---
 fs/hfsplus/journal.c |  100 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 100 insertions(+)

diff --git a/fs/hfsplus/journal.c b/fs/hfsplus/journal.c
index fc88d2b..d061c7f 100644
--- a/fs/hfsplus/journal.c
+++ b/fs/hfsplus/journal.c
@@ -38,6 +38,11 @@
 	(be64_to_cpu(((struct hfsplus_journal *)(jnl))->jib->offset) >> \
 	 HFSPLUS_SB(sb)->alloc_blksz_shift)
 
+#define JOURNAL_OFF_TO_SEC(sb) \
+	(HFSPLUS_SB(sb)->blockoffset + \
+	 ((be64_to_cpu(HFSPLUS_SB(sb)->jnl->jib->offset) + \
+	   le64_to_cpu(HFSPLUS_SB(sb)->jnl->jh->start)) >> \
+	   HFSPLUS_SECTOR_SHIFT))
 #define BLOCK_TO_SEC(sb, blk) \
 	((sector_t)(blk) << \
 	 (HFSPLUS_SB(sb)->alloc_blksz_shift - HFSPLUS_SECTOR_SHIFT))
@@ -490,6 +495,101 @@ struct hfsplus_block_info *hfsplus_get_binfo(struct super_block *sb,
 	return &desc->binfo[diff];
 }
 
+static int hfsplus_check_transaction_block(struct super_block *sb, int i,
+					   struct hfsplus_blist_desc *desc)
+{
+	struct hfsplus_journal *jnl = HFSPLUS_SB(sb)->jnl;
+	struct hfsplus_journal_header *jh = jnl->jh;
+	struct hfsplus_blhdr *blhdr = &desc->blhdr;
+	struct hfsplus_block_info *binfo;
+	sector_t sec;
+	u32 size;
+	u32 checksum = 0;
+
+	hfs_dbg(JREPLAY, "check binfo[%u]\n", i);
+
+	binfo = hfsplus_get_binfo(sb, i, desc);
+	if (!binfo) {
+		pr_err("unable to get binfo[%u]\n", i);
+		return -EIO;
+	}
+
+	if (BNUM(binfo) == ~(u64)0) {
+		hfs_dbg(JREPLAY, "don't add *killed* block %llu\n",
+			BNUM(binfo));
+		return 0; /* don't add "killed" blocks */
+	}
+
+	BUG_ON(BSIZE(binfo) % HFSPLUS_SECTOR_SIZE);
+
+	if ((BSIZE(binfo) / HFSPLUS_SECTOR_SIZE) == 0) {
+		pr_warn("transaction block size is not aligned\n");
+		return -EINVAL;
+	}
+
+	sec = JOURNAL_OFF_TO_SEC(sb);
+	size = BSIZE(binfo);
+	while (size > 0) {
+		void *block_ptr;
+		size_t check_size = HFSPLUS_SECTOR_SIZE;
+		size_t rest_bytes;
+		int err;
+
+		if (need_to_wrap_journal(jh, TR_START(jh), check_size)) {
+			hfsplus_wrap_journal(sb, TR_START(jh), check_size);
+			sec = JOURNAL_OFF_TO_SEC(sb);
+		}
+
+		err = hfsplus_submit_bio(sb, sec, desc->src_buf,
+					 (void **)&block_ptr,
+					 READA, &rest_bytes);
+		if (err) {
+			pr_err("can't read sector %lu of block list\n", sec);
+			return err;
+		}
+
+		BUG_ON(rest_bytes < HFSPLUS_SECTOR_SIZE);
+
+		if (TR_START(jh) > LAST_TR_END(jh)) {
+			if ((TR_START(jh) + check_size) > JOURNAL_SIZE(jh))
+				err = -EIO;
+		} else if (TR_START(jh) < LAST_TR_END(jh)) {
+			if ((TR_START(jh) + check_size) > LAST_TR_END(jh))
+				err = -EIO;
+		} else /* start == end */
+			err = -EIO;
+
+		if (err) {
+			pr_err("invalid transaction: start %llu, end %llu, journal size %llu, bsize %zu\n",
+				TR_START(jh), LAST_TR_END(jh),
+				JOURNAL_SIZE(jh), check_size);
+			return err;
+		}
+
+		if (NEED_CHECK_CSUM(blhdr)) {
+			checksum = calc_internal_checksum(checksum,
+							  block_ptr,
+							  check_size);
+		}
+
+		size -= check_size;
+		le64_add_cpu(&jh->start, check_size);
+		sec = JOURNAL_OFF_TO_SEC(sb);
+	}
+
+	if (NEED_CHECK_CSUM(blhdr)) {
+		if (HFSPLUS_CHECKSUM(checksum) != binfo->block.checksum) {
+			pr_err("invalid transaction's checksum\n");
+			hfs_dbg(JREPLAY, "calc checksum: %#x, checksum: %#x\n",
+				le32_to_cpu(HFSPLUS_CHECKSUM(checksum)),
+				le32_to_cpu(binfo->block.checksum));
+			return -EIO;
+		}
+	}
+
+	return 0;
+}
+
 static inline
 bool hfsplus_journal_empty(struct hfsplus_journal_header *jh)
 {
-- 
1.7.9.5