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Commit 3caa487f authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
Browse files

jbd2: checksum descriptor blocks 



Calculate and verify a checksum of each descriptor block.

Signed-off-by: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 42a7106d

fs/jbd2/commit.c

+24 −1
Original line number Diff line number Diff line
@@ -301,6 +301,24 @@ static void write_tag_block(int tag_bytes, journal_block_tag_t *tag, 
		tag->t_blocknr_high = cpu_to_be32((block >> 31) >> 1);

}



static void jbd2_descr_block_csum_set(journal_t *j,

				      struct journal_head *descriptor)

{

	struct jbd2_journal_block_tail *tail;

	__u32 csum;



	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))

		return;



	tail = (struct jbd2_journal_block_tail *)

			(jh2bh(descriptor)->b_data + j->j_blocksize -

			sizeof(struct jbd2_journal_block_tail));

	tail->t_checksum = 0;

	csum = jbd2_chksum(j, j->j_csum_seed, jh2bh(descriptor)->b_data,

			   j->j_blocksize);

	tail->t_checksum = cpu_to_be32(csum);

}



/*

 * jbd2_journal_commit_transaction

 *
@@ -334,6 +352,10 @@ void jbd2_journal_commit_transaction(journal_t *journal) 
	unsigned long first_block;

	tid_t first_tid;

	int update_tail;

	int csum_size = 0;



	if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))

		csum_size = sizeof(struct jbd2_journal_block_tail);



	/*

	 * First job: lock down the current transaction and wait for
@@ -643,7 +665,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) 


		if (bufs == journal->j_wbufsize ||

		    commit_transaction->t_buffers == NULL ||

		    space_left < tag_bytes + 16) {

		    space_left < tag_bytes + 16 + csum_size) {



			jbd_debug(4, "JBD2: Submit %d IOs\n", bufs);
@@ -653,6 +675,7 @@ void jbd2_journal_commit_transaction(journal_t *journal) 


			tag->t_flags |= cpu_to_be16(JBD2_FLAG_LAST_TAG);



			jbd2_descr_block_csum_set(journal, descriptor);

start_journal_io:

			for (i = 0; i < bufs; i++) {

				struct buffer_head *bh = wbuf[i];

fs/jbd2/recovery.c

+36 −1
Original line number Diff line number Diff line
@@ -174,6 +174,25 @@ static int jread(struct buffer_head **bhp, journal_t *journal, 
	return 0;

}



static int jbd2_descr_block_csum_verify(journal_t *j,

					void *buf)

{

	struct jbd2_journal_block_tail *tail;

	__u32 provided, calculated;



	if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2))

		return 1;



	tail = (struct jbd2_journal_block_tail *)(buf + j->j_blocksize -

			sizeof(struct jbd2_journal_block_tail));

	provided = tail->t_checksum;

	tail->t_checksum = 0;

	calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);

	tail->t_checksum = provided;



	provided = be32_to_cpu(provided);

	return provided == calculated;

}



/*

 * Count the number of in-use tags in a journal descriptor block.
@@ -186,6 +205,9 @@ static int count_tags(journal_t *journal, struct buffer_head *bh) 
	int			nr = 0, size = journal->j_blocksize;

	int			tag_bytes = journal_tag_bytes(journal);



	if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2))

		size -= sizeof(struct jbd2_journal_block_tail);



	tagp = &bh->b_data[sizeof(journal_header_t)];



	while ((tagp - bh->b_data + tag_bytes) <= size) {
@@ -366,6 +388,7 @@ static int do_one_pass(journal_t *journal, 
	int			blocktype;

	int			tag_bytes = journal_tag_bytes(journal);

	__u32			crc32_sum = ~0; /* Transactional Checksums */

	int			descr_csum_size = 0;



	/*

	 * First thing is to establish what we expect to find in the log
@@ -451,6 +474,18 @@ static int do_one_pass(journal_t *journal, 


		switch(blocktype) {

		case JBD2_DESCRIPTOR_BLOCK:

			/* Verify checksum first */

			if (JBD2_HAS_INCOMPAT_FEATURE(journal,

					JBD2_FEATURE_INCOMPAT_CSUM_V2))

				descr_csum_size =

					sizeof(struct jbd2_journal_block_tail);

			if (descr_csum_size > 0 &&

			    !jbd2_descr_block_csum_verify(journal,

							  bh->b_data)) {

				err = -EIO;

				goto failed;

			}



			/* If it is a valid descriptor block, replay it

			 * in pass REPLAY; if journal_checksums enabled, then

			 * calculate checksums in PASS_SCAN, otherwise,
@@ -481,7 +516,7 @@ static int do_one_pass(journal_t *journal, 


			tagp = &bh->b_data[sizeof(journal_header_t)];

			while ((tagp - bh->b_data + tag_bytes)

			       <= journal->j_blocksize) {

			       <= journal->j_blocksize - descr_csum_size) {

				unsigned long io_block;



				tag = (journal_block_tag_t *) tagp;