答复: 答复: 答复: [PATCH] jbd2: avoid transaction reuse after reformatting

[常凤楠 <changfengnan@hikvision.com>]

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The attachment is new patch.
I have fix the logic in JBD2_REVOKE_BLOCK and JBD2_COMMIT_BLOCK case.
If the revoke block is the first block after valid transaction, I set the flag like descriptor block ,and check it in commit block.
If the commit block is the first block after valid transaction, I use ri_commit_block to judge whether this commit block is next to another
commit block, if so it is illegal. I did't use time to judge commit block, because of the possibility of time calibration, I think use
ri_commit_block is more reliable.

-----邮件原件-----
发件人: Jan Kara <jack@suse.cz>
发送时间: 2020年9月18日 21:03
收件人: 常凤楠 <changfengnan@hikvision.com>
抄送: Jan Kara <jack@suse.cz>; changfengnan <changfengnan@qq.com>; adilger@dilger.ca; darrick.wong@oracle.com; jack@suse.com; linux-ext4@vger.kernel.org; tytso@mit.edu
主题: Re: 答复: 答复: [PATCH] jbd2: avoid transaction reuse after reformatting

Hello,

On Fri 18-09-20 01:49:09, 常凤楠 wrote:
> Sorry about my mailer, the patch is in the attachment.

Thanks for the patch. Functionally the patch looks mostly OK now. The only concern I have is that it handles checksum failures only in JBD2_DESCRIPTOR_BLOCK. This is the most likely case but it could also happen that JBD2_REVOKE_BLOCK or JBD2_COMMIT_BLOCK is the first one you see with mismatching checksum. So I think you need to handle these cases as well. I think your ri_commit_block logic below is an attempt to deal with these cases (but it's difficult to be sure because of complete lack of
comments) but it is not reliable. A valid transaction can begin both with a descriptor or with a revoke block.

A few other comments mostly about coding style below:

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c index a4967b27ffb6..f7702e14077f 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -417,7 +417,7 @@ static int do_one_pass(journal_t *journal,
 struct recovery_info *info, enum passtype pass)  {
 unsigned intfirst_commit_ID, next_commit_ID;
-unsigned longnext_log_block;
+unsigned longnext_log_block, ri_commit_block = 0;
 interr, success = 0;
 journal_superblock_t *sb;
 journal_header_t *tmp;
@@ -428,7 +428,9 @@ static int do_one_pass(journal_t *journal,
 __u32crc32_sum = ~0; /* Transactional Checksums */
 intdescr_csum_size = 0;
 intblock_error = 0;
-
+boolneed_check_commit_time = false;
+__be64last_trans_commit_time;

All variable names in this function seem to be indented by one more column. Please keep the indentation.

+

This empty line has whitespace on it. Please delete.

 /*
  * First thing is to establish what we expect to find in the log
  * (in terms of transaction IDs), and where (in terms of log @@ -514,18 +516,18 @@ static int do_one_pass(journal_t *journal,
 switch(blocktype) {
 case JBD2_DESCRIPTOR_BLOCK:
 /* Verify checksum first */
+if(pass == PASS_SCAN)
  ^ Coding style requires space before opening (.
You have this problem at multiple places.

+ri_commit_block = 0;
+
 if (jbd2_journal_has_csum_v2or3(journal))
 descr_csum_size =
 sizeof(struct jbd2_journal_block_tail);
 if (descr_csum_size > 0 &&
     !jbd2_descriptor_block_csum_verify(journal,
        bh->b_data)) {
-printk(KERN_ERR "JBD2: Invalid checksum "
-       "recovering block %lu in log\n",
-       next_log_block);
-err = -EFSBADCRC;
-brelse(bh);
-goto failed;
+need_check_commit_time = true;
+jbd_debug(1, "invalid descriptor block found in %lu, continue
+recovery first.\n",next_log_block);
+
 }

 /* If it is a valid descriptor block, replay it @@ -535,6 +537,7 @@ static int do_one_pass(journal_t *journal,
 if (pass != PASS_REPLAY) {
 if (pass == PASS_SCAN &&
     jbd2_has_feature_checksum(journal) &&
+    !need_check_commit_time &&
     !info->end_transaction) {
 if (calc_chksums(journal, bh,
 &next_log_block,
@@ -688,6 +691,36 @@ static int do_one_pass(journal_t *journal,
  * are present verify them in PASS_SCAN; else not
  * much to do other than move on to the next sequence
  * number. */
+if(pass == PASS_SCAN) {
+struct commit_header *cbh =
+(struct commit_header *)bh->b_data;
+if(need_check_commit_time) {
+__be64 commit_time = be64_to_cpu(cbh->h_commit_sec);
+if(commit_time >= last_trans_commit_time) {
+printk(KERN_ERR "JBD2: Invalid checksum found in log, %d\n",
+next_commit_ID);
+err = -EFSBADCRC;
+brelse(bh);
+goto failed;
+}
+else
+{
  Coding style requires to put opening { on the same line as 'else'. Like:
else {
+/*it's not belong to same journal, just end this recovery with success*/
+jbd_debug(1, "JBD2: Invalid checksum found in block in log, but not same journal %d\n",
+next_commit_ID);
+err = 0;
+brelse(bh);
+goto done;
+}
+}
+if(ri_commit_block) {
+jbd_debug(1, "invalid commit block found in %lu, stop here.\n",next_log_block);
+brelse(bh);
+goto done;
+}
+ri_commit_block = next_log_block;

Why does the ri_commit_block logic exist? I don't see it bringing any benefit...

+last_trans_commit_time = be64_to_cpu(cbh->h_commit_sec);
+}
 if (pass == PASS_SCAN &&
     jbd2_has_feature_checksum(journal)) {
 int chksum_err, chksum_seen;
@@ -755,6 +788,12 @@ static int do_one_pass(journal_t *journal,
 continue;

 case JBD2_REVOKE_BLOCK:
+if (pass == PASS_SCAN &&
+ri_commit_block) {
+jbd_debug(1, "invalid revoke block found in %lu, stop here.\n",next_log_block);
+brelse(bh);
+goto done;
+}

This is wrong. A valid transaction can start with a revoke block...

 /* If we aren't in the REVOKE pass, then we can
  * just skip over this block. */
 if (pass != PASS_REVOKE) {

Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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[-- Attachment #2: jbd2.patch --]
[-- Type: application/octet-stream, Size: 4579 bytes --]

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index a4967b27ffb6..631a42b50516 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -417,7 +417,7 @@ static int do_one_pass(journal_t *journal,
 			struct recovery_info *info, enum passtype pass)
 {
 	unsigned int		first_commit_ID, next_commit_ID;
-	unsigned long		next_log_block;
+	unsigned long		next_log_block, ri_commit_block = 0;
 	int			err, success = 0;
 	journal_superblock_t *	sb;
 	journal_header_t *	tmp;
@@ -428,6 +428,8 @@ static int do_one_pass(journal_t *journal,
 	__u32			crc32_sum = ~0; /* Transactional Checksums */
 	int			descr_csum_size = 0;
 	int			block_error = 0;
+	bool		need_check_commit_time = false;
+	__be64		last_trans_commit_time = 0;
 
 	/*
 	 * First thing is to establish what we expect to find in the log
@@ -514,18 +516,17 @@ static int do_one_pass(journal_t *journal,
 		switch(blocktype) {
 		case JBD2_DESCRIPTOR_BLOCK:
 			/* Verify checksum first */
+			if (pass == PASS_SCAN)
+				ri_commit_block = 0;
 			if (jbd2_journal_has_csum_v2or3(journal))
 				descr_csum_size =
 					sizeof(struct jbd2_journal_block_tail);
 			if (descr_csum_size > 0 &&
 			    !jbd2_descriptor_block_csum_verify(journal,
 							       bh->b_data)) {
-				printk(KERN_ERR "JBD2: Invalid checksum "
-				       "recovering block %lu in log\n",
-				       next_log_block);
-				err = -EFSBADCRC;
-				brelse(bh);
-				goto failed;
+				need_check_commit_time = true;
+				jbd_debug(1, "invalid descriptor block found in %lu, continue recovery first.\n",
+						next_log_block);
 			}
 
 			/* If it is a valid descriptor block, replay it
@@ -535,6 +536,7 @@ static int do_one_pass(journal_t *journal,
 			if (pass != PASS_REPLAY) {
 				if (pass == PASS_SCAN &&
 				    jbd2_has_feature_checksum(journal) &&
+				    !need_check_commit_time &&
 				    !info->end_transaction) {
 					if (calc_chksums(journal, bh,
 							&next_log_block,
@@ -688,6 +690,47 @@ static int do_one_pass(journal_t *journal,
 			 * are present verify them in PASS_SCAN; else not
 			 * much to do other than move on to the next sequence
 			 * number. */
+			if (pass == PASS_SCAN) {
+				struct commit_header *cbh =
+					(struct commit_header *)bh->b_data;
+				/*
+				 * When need check commit time, it means csum
+				 * verify failed before, if commit time is
+				 * increasing, it's same journal, otherwise
+				 * not same journal, just end this recovery.
+				 */
+				if (need_check_commit_time) {
+					__be64 commit_time =
+						be64_to_cpu(cbh->h_commit_sec);
+
+					if (commit_time >= last_trans_commit_time) {
+						pr_err("JBD2: Invalid checksum found in log, %d\n",
+						next_commit_ID);
+						err = -EFSBADCRC;
+						brelse(bh);
+						goto failed;
+					} else {
+						/*
+						 * it's not belong to same journal, just
+						 * end this recovery with success.
+						 */
+						jbd_debug(1, "JBD2: Invalid checksum found in block in log, but not same journal %d\n",
+						next_commit_ID);
+						err = 0;
+						brelse(bh);
+						goto done;
+					}
+				}
+				if (ri_commit_block) {
+					jbd_debug(1, "invalid commit block found in %lu, stop here.\n",
+						next_log_block);
+					brelse(bh);
+					goto done;
+				}
+				ri_commit_block = next_log_block;
+				last_trans_commit_time =
+					be64_to_cpu(cbh->h_commit_sec);
+			}
 			if (pass == PASS_SCAN &&
 			    jbd2_has_feature_checksum(journal)) {
 				int chksum_err, chksum_seen;
@@ -755,6 +798,21 @@ static int do_one_pass(journal_t *journal,
 			continue;
 
 		case JBD2_REVOKE_BLOCK:
+			/*
+			 * Check revoke block crc in pass_scan, if csum verify
+			 * failed, check commit block time later.
+			 */
+			if (pass == PASS_SCAN) {
+				jbd2_journal_revoke_header_t *header =
+				(jbd2_journal_revoke_header_t *)bh->b_data;
+				ri_commit_block = 0;
+				if (!jbd2_descriptor_block_csum_verify(journal,
+						header)) {
+					jbd_debug(1, "invalid revoke block found in %lu, continue recovery first.\n",
+						next_log_block);
+					need_check_commit_time = true;
+				}
+			}
 			/* If we aren't in the REVOKE pass, then we can
 			 * just skip over this block. */
 			if (pass != PASS_REVOKE) {
@@ -822,9 +880,6 @@ static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
 	offset = sizeof(jbd2_journal_revoke_header_t);
 	rcount = be32_to_cpu(header->r_count);
 
-	if (!jbd2_descriptor_block_csum_verify(journal, header))
-		return -EFSBADCRC;
-
 	if (jbd2_journal_has_csum_v2or3(journal))
 		csum_size = sizeof(struct jbd2_journal_block_tail);
 	if (rcount > journal->j_blocksize - csum_size)