Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 852 insertions, 0 deletions

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
new file mode 100644
index 000000000..a4967b27f
--- /dev/null
+++ b/fs/jbd2/recovery.c
@@ -0,0 +1,852 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * linux/fs/jbd2/recovery.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
+ *
+ * Copyright 1999-2000 Red Hat Software --- All Rights Reserved
+ *
+ * Journal recovery routines for the generic filesystem journaling code;
+ * part of the ext2fs journaling system.
+ */
+
+#ifndef __KERNEL__
+#include "jfs_user.h"
+#else
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd2.h>
+#include <linux/errno.h>
+#include <linux/crc32.h>
+#include <linux/blkdev.h>
+#endif
+
+/*
+ * Maintain information about the progress of the recovery job, so that
+ * the different passes can carry information between them.
+ */
+struct recovery_info
+{
+	tid_t		start_transaction;
+	tid_t		end_transaction;
+
+	int		nr_replays;
+	int		nr_revokes;
+	int		nr_revoke_hits;
+};
+
+enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY};
+static int do_one_pass(journal_t *journal,
+				struct recovery_info *info, enum passtype pass);
+static int scan_revoke_records(journal_t *, struct buffer_head *,
+				tid_t, struct recovery_info *);
+
+#ifdef __KERNEL__
+
+/* Release readahead buffers after use */
+static void journal_brelse_array(struct buffer_head *b[], int n)
+{
+	while (--n >= 0)
+		brelse (b[n]);
+}
+
+
+/*
+ * When reading from the journal, we are going through the block device
+ * layer directly and so there is no readahead being done for us.  We
+ * need to implement any readahead ourselves if we want it to happen at
+ * all.  Recovery is basically one long sequential read, so make sure we
+ * do the IO in reasonably large chunks.
+ *
+ * This is not so critical that we need to be enormously clever about
+ * the readahead size, though.  128K is a purely arbitrary, good-enough
+ * fixed value.
+ */
+
+#define MAXBUF 8
+static int do_readahead(journal_t *journal, unsigned int start)
+{
+	int err;
+	unsigned int max, nbufs, next;
+	unsigned long long blocknr;
+	struct buffer_head *bh;
+
+	struct buffer_head * bufs[MAXBUF];
+
+	/* Do up to 128K of readahead */
+	max = start + (128 * 1024 / journal->j_blocksize);
+	if (max > journal->j_maxlen)
+		max = journal->j_maxlen;
+
+	/* Do the readahead itself.  We'll submit MAXBUF buffer_heads at
+	 * a time to the block device IO layer. */
+
+	nbufs = 0;
+
+	for (next = start; next < max; next++) {
+		err = jbd2_journal_bmap(journal, next, &blocknr);
+
+		if (err) {
+			printk(KERN_ERR "JBD2: bad block at offset %u\n",
+				next);
+			goto failed;
+		}
+
+		bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
+		if (!bh) {
+			err = -ENOMEM;
+			goto failed;
+		}
+
+		if (!buffer_uptodate(bh) && !buffer_locked(bh)) {
+			bufs[nbufs++] = bh;
+			if (nbufs == MAXBUF) {
+				ll_rw_block(REQ_OP_READ, 0, nbufs, bufs);
+				journal_brelse_array(bufs, nbufs);
+				nbufs = 0;
+			}
+		} else
+			brelse(bh);
+	}
+
+	if (nbufs)
+		ll_rw_block(REQ_OP_READ, 0, nbufs, bufs);
+	err = 0;
+
+failed:
+	if (nbufs)
+		journal_brelse_array(bufs, nbufs);
+	return err;
+}
+
+#endif /* __KERNEL__ */
+
+
+/*
+ * Read a block from the journal
+ */
+
+static int jread(struct buffer_head **bhp, journal_t *journal,
+		 unsigned int offset)
+{
+	int err;
+	unsigned long long blocknr;
+	struct buffer_head *bh;
+
+	*bhp = NULL;
+
+	if (offset >= journal->j_maxlen) {
+		printk(KERN_ERR "JBD2: corrupted journal superblock\n");
+		return -EFSCORRUPTED;
+	}
+
+	err = jbd2_journal_bmap(journal, offset, &blocknr);
+
+	if (err) {
+		printk(KERN_ERR "JBD2: bad block at offset %u\n",
+			offset);
+		return err;
+	}
+
+	bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
+	if (!bh)
+		return -ENOMEM;
+
+	if (!buffer_uptodate(bh)) {
+		/* If this is a brand new buffer, start readahead.
+                   Otherwise, we assume we are already reading it.  */
+		if (!buffer_req(bh))
+			do_readahead(journal, offset);
+		wait_on_buffer(bh);
+	}
+
+	if (!buffer_uptodate(bh)) {
+		printk(KERN_ERR "JBD2: Failed to read block at offset %u\n",
+			offset);
+		brelse(bh);
+		return -EIO;
+	}
+
+	*bhp = bh;
+	return 0;
+}
+
+static int jbd2_descriptor_block_csum_verify(journal_t *j, void *buf)
+{
+	struct jbd2_journal_block_tail *tail;
+	__be32 provided;
+	__u32 calculated;
+
+	if (!jbd2_journal_has_csum_v2or3(j))
+		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;
+
+	return provided == cpu_to_be32(calculated);
+}
+
+/*
+ * Count the number of in-use tags in a journal descriptor block.
+ */
+
+static int count_tags(journal_t *journal, struct buffer_head *bh)
+{
+	char *			tagp;
+	journal_block_tag_t *	tag;
+	int			nr = 0, size = journal->j_blocksize;
+	int			tag_bytes = journal_tag_bytes(journal);
+
+	if (jbd2_journal_has_csum_v2or3(journal))
+		size -= sizeof(struct jbd2_journal_block_tail);
+
+	tagp = &bh->b_data[sizeof(journal_header_t)];
+
+	while ((tagp - bh->b_data + tag_bytes) <= size) {
+		tag = (journal_block_tag_t *) tagp;
+
+		nr++;
+		tagp += tag_bytes;
+		if (!(tag->t_flags & cpu_to_be16(JBD2_FLAG_SAME_UUID)))
+			tagp += 16;
+
+		if (tag->t_flags & cpu_to_be16(JBD2_FLAG_LAST_TAG))
+			break;
+	}
+
+	return nr;
+}
+
+
+/* Make sure we wrap around the log correctly! */
+#define wrap(journal, var)						\
+do {									\
+	if (var >= (journal)->j_last)					\
+		var -= ((journal)->j_last - (journal)->j_first);	\
+} while (0)
+
+/**
+ * jbd2_journal_recover - recovers a on-disk journal
+ * @journal: the journal to recover
+ *
+ * The primary function for recovering the log contents when mounting a
+ * journaled device.
+ *
+ * Recovery is done in three passes.  In the first pass, we look for the
+ * end of the log.  In the second, we assemble the list of revoke
+ * blocks.  In the third and final pass, we replay any un-revoked blocks
+ * in the log.
+ */
+int jbd2_journal_recover(journal_t *journal)
+{
+	int			err, err2;
+	journal_superblock_t *	sb;
+
+	struct recovery_info	info;
+
+	memset(&info, 0, sizeof(info));
+	sb = journal->j_superblock;
+
+	/*
+	 * The journal superblock's s_start field (the current log head)
+	 * is always zero if, and only if, the journal was cleanly
+	 * unmounted.
+	 */
+
+	if (!sb->s_start) {
+		jbd_debug(1, "No recovery required, last transaction %d\n",
+			  be32_to_cpu(sb->s_sequence));
+		journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1;
+		return 0;
+	}
+
+	err = do_one_pass(journal, &info, PASS_SCAN);
+	if (!err)
+		err = do_one_pass(journal, &info, PASS_REVOKE);
+	if (!err)
+		err = do_one_pass(journal, &info, PASS_REPLAY);
+
+	jbd_debug(1, "JBD2: recovery, exit status %d, "
+		  "recovered transactions %u to %u\n",
+		  err, info.start_transaction, info.end_transaction);
+	jbd_debug(1, "JBD2: Replayed %d and revoked %d/%d blocks\n",
+		  info.nr_replays, info.nr_revoke_hits, info.nr_revokes);
+
+	/* Restart the log at the next transaction ID, thus invalidating
+	 * any existing commit records in the log. */
+	journal->j_transaction_sequence = ++info.end_transaction;
+
+	jbd2_journal_clear_revoke(journal);
+	err2 = sync_blockdev(journal->j_fs_dev);
+	if (!err)
+		err = err2;
+	/* Make sure all replayed data is on permanent storage */
+	if (journal->j_flags & JBD2_BARRIER) {
+		err2 = blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
+		if (!err)
+			err = err2;
+	}
+	return err;
+}
+
+/**
+ * jbd2_journal_skip_recovery - Start journal and wipe exiting records
+ * @journal: journal to startup
+ *
+ * Locate any valid recovery information from the journal and set up the
+ * journal structures in memory to ignore it (presumably because the
+ * caller has evidence that it is out of date).
+ * This function doesn't appear to be exported..
+ *
+ * We perform one pass over the journal to allow us to tell the user how
+ * much recovery information is being erased, and to let us initialise
+ * the journal transaction sequence numbers to the next unused ID.
+ */
+int jbd2_journal_skip_recovery(journal_t *journal)
+{
+	int			err;
+
+	struct recovery_info	info;
+
+	memset (&info, 0, sizeof(info));
+
+	err = do_one_pass(journal, &info, PASS_SCAN);
+
+	if (err) {
+		printk(KERN_ERR "JBD2: error %d scanning journal\n", err);
+		++journal->j_transaction_sequence;
+	} else {
+#ifdef CONFIG_JBD2_DEBUG
+		int dropped = info.end_transaction - 
+			be32_to_cpu(journal->j_superblock->s_sequence);
+		jbd_debug(1,
+			  "JBD2: ignoring %d transaction%s from the journal.\n",
+			  dropped, (dropped == 1) ? "" : "s");
+#endif
+		journal->j_transaction_sequence = ++info.end_transaction;
+	}
+
+	journal->j_tail = 0;
+	return err;
+}
+
+static inline unsigned long long read_tag_block(journal_t *journal,
+						journal_block_tag_t *tag)
+{
+	unsigned long long block = be32_to_cpu(tag->t_blocknr);
+	if (jbd2_has_feature_64bit(journal))
+		block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
+	return block;
+}
+
+/*
+ * calc_chksums calculates the checksums for the blocks described in the
+ * descriptor block.
+ */
+static int calc_chksums(journal_t *journal, struct buffer_head *bh,
+			unsigned long *next_log_block, __u32 *crc32_sum)
+{
+	int i, num_blks, err;
+	unsigned long io_block;
+	struct buffer_head *obh;
+
+	num_blks = count_tags(journal, bh);
+	/* Calculate checksum of the descriptor block. */
+	*crc32_sum = crc32_be(*crc32_sum, (void *)bh->b_data, bh->b_size);
+
+	for (i = 0; i < num_blks; i++) {
+		io_block = (*next_log_block)++;
+		wrap(journal, *next_log_block);
+		err = jread(&obh, journal, io_block);
+		if (err) {
+			printk(KERN_ERR "JBD2: IO error %d recovering block "
+				"%lu in log\n", err, io_block);
+			return 1;
+		} else {
+			*crc32_sum = crc32_be(*crc32_sum, (void *)obh->b_data,
+				     obh->b_size);
+		}
+		put_bh(obh);
+	}
+	return 0;
+}
+
+static int jbd2_commit_block_csum_verify(journal_t *j, void *buf)
+{
+	struct commit_header *h;
+	__be32 provided;
+	__u32 calculated;
+
+	if (!jbd2_journal_has_csum_v2or3(j))
+		return 1;
+
+	h = buf;
+	provided = h->h_chksum[0];
+	h->h_chksum[0] = 0;
+	calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
+	h->h_chksum[0] = provided;
+
+	return provided == cpu_to_be32(calculated);
+}
+
+static int jbd2_block_tag_csum_verify(journal_t *j, journal_block_tag_t *tag,
+				      void *buf, __u32 sequence)
+{
+	journal_block_tag3_t *tag3 = (journal_block_tag3_t *)tag;
+	__u32 csum32;
+	__be32 seq;
+
+	if (!jbd2_journal_has_csum_v2or3(j))
+		return 1;
+
+	seq = cpu_to_be32(sequence);
+	csum32 = jbd2_chksum(j, j->j_csum_seed, (__u8 *)&seq, sizeof(seq));
+	csum32 = jbd2_chksum(j, csum32, buf, j->j_blocksize);
+
+	if (jbd2_has_feature_csum3(j))
+		return tag3->t_checksum == cpu_to_be32(csum32);
+	else
+		return tag->t_checksum == cpu_to_be16(csum32);
+}
+
+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;
+	int			err, success = 0;
+	journal_superblock_t *	sb;
+	journal_header_t *	tmp;
+	struct buffer_head *	bh;
+	unsigned int		sequence;
+	int			blocktype;
+	int			tag_bytes = journal_tag_bytes(journal);
+	__u32			crc32_sum = ~0; /* Transactional Checksums */
+	int			descr_csum_size = 0;
+	int			block_error = 0;
+
+	/*
+	 * First thing is to establish what we expect to find in the log
+	 * (in terms of transaction IDs), and where (in terms of log
+	 * block offsets): query the superblock.
+	 */
+
+	sb = journal->j_superblock;
+	next_commit_ID = be32_to_cpu(sb->s_sequence);
+	next_log_block = be32_to_cpu(sb->s_start);
+
+	first_commit_ID = next_commit_ID;
+	if (pass == PASS_SCAN)
+		info->start_transaction = first_commit_ID;
+
+	jbd_debug(1, "Starting recovery pass %d\n", pass);
+
+	/*
+	 * Now we walk through the log, transaction by transaction,
+	 * making sure that each transaction has a commit block in the
+	 * expected place.  Each complete transaction gets replayed back
+	 * into the main filesystem.
+	 */
+
+	while (1) {
+		int			flags;
+		char *			tagp;
+		journal_block_tag_t *	tag;
+		struct buffer_head *	obh;
+		struct buffer_head *	nbh;
+
+		cond_resched();
+
+		/* If we already know where to stop the log traversal,
+		 * check right now that we haven't gone past the end of
+		 * the log. */
+
+		if (pass != PASS_SCAN)
+			if (tid_geq(next_commit_ID, info->end_transaction))
+				break;
+
+		jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n",
+			  next_commit_ID, next_log_block, journal->j_last);
+
+		/* Skip over each chunk of the transaction looking
+		 * either the next descriptor block or the final commit
+		 * record. */
+
+		jbd_debug(3, "JBD2: checking block %ld\n", next_log_block);
+		err = jread(&bh, journal, next_log_block);
+		if (err)
+			goto failed;
+
+		next_log_block++;
+		wrap(journal, next_log_block);
+
+		/* What kind of buffer is it?
+		 *
+		 * If it is a descriptor block, check that it has the
+		 * expected sequence number.  Otherwise, we're all done
+		 * here. */
+
+		tmp = (journal_header_t *)bh->b_data;
+
+		if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) {
+			brelse(bh);
+			break;
+		}
+
+		blocktype = be32_to_cpu(tmp->h_blocktype);
+		sequence = be32_to_cpu(tmp->h_sequence);
+		jbd_debug(3, "Found magic %d, sequence %d\n",
+			  blocktype, sequence);
+
+		if (sequence != next_commit_ID) {
+			brelse(bh);
+			break;
+		}
+
+		/* OK, we have a valid descriptor block which matches
+		 * all of the sequence number checks.  What are we going
+		 * to do with it?  That depends on the pass... */
+
+		switch(blocktype) {
+		case JBD2_DESCRIPTOR_BLOCK:
+			/* Verify checksum first */
+			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;
+			}
+
+			/* If it is a valid descriptor block, replay it
+			 * in pass REPLAY; if journal_checksums enabled, then
+			 * calculate checksums in PASS_SCAN, otherwise,
+			 * just skip over the blocks it describes. */
+			if (pass != PASS_REPLAY) {
+				if (pass == PASS_SCAN &&
+				    jbd2_has_feature_checksum(journal) &&
+				    !info->end_transaction) {
+					if (calc_chksums(journal, bh,
+							&next_log_block,
+							&crc32_sum)) {
+						put_bh(bh);
+						break;
+					}
+					put_bh(bh);
+					continue;
+				}
+				next_log_block += count_tags(journal, bh);
+				wrap(journal, next_log_block);
+				put_bh(bh);
+				continue;
+			}
+
+			/* A descriptor block: we can now write all of
+			 * the data blocks.  Yay, useful work is finally
+			 * getting done here! */
+
+			tagp = &bh->b_data[sizeof(journal_header_t)];
+			while ((tagp - bh->b_data + tag_bytes)
+			       <= journal->j_blocksize - descr_csum_size) {
+				unsigned long io_block;
+
+				tag = (journal_block_tag_t *) tagp;
+				flags = be16_to_cpu(tag->t_flags);
+
+				io_block = next_log_block++;
+				wrap(journal, next_log_block);
+				err = jread(&obh, journal, io_block);
+				if (err) {
+					/* Recover what we can, but
+					 * report failure at the end. */
+					success = err;
+					printk(KERN_ERR
+						"JBD2: IO error %d recovering "
+						"block %ld in log\n",
+						err, io_block);
+				} else {
+					unsigned long long blocknr;
+
+					J_ASSERT(obh != NULL);
+					blocknr = read_tag_block(journal,
+								 tag);
+
+					/* If the block has been
+					 * revoked, then we're all done
+					 * here. */
+					if (jbd2_journal_test_revoke
+					    (journal, blocknr,
+					     next_commit_ID)) {
+						brelse(obh);
+						++info->nr_revoke_hits;
+						goto skip_write;
+					}
+
+					/* Look for block corruption */
+					if (!jbd2_block_tag_csum_verify(
+						journal, tag, obh->b_data,
+						be32_to_cpu(tmp->h_sequence))) {
+						brelse(obh);
+						success = -EFSBADCRC;
+						printk(KERN_ERR "JBD2: Invalid "
+						       "checksum recovering "
+						       "data block %llu in "
+						       "log\n", blocknr);
+						block_error = 1;
+						goto skip_write;
+					}
+
+					/* Find a buffer for the new
+					 * data being restored */
+					nbh = __getblk(journal->j_fs_dev,
+							blocknr,
+							journal->j_blocksize);
+					if (nbh == NULL) {
+						printk(KERN_ERR
+						       "JBD2: Out of memory "
+						       "during recovery.\n");
+						err = -ENOMEM;
+						brelse(bh);
+						brelse(obh);
+						goto failed;
+					}
+
+					lock_buffer(nbh);
+					memcpy(nbh->b_data, obh->b_data,
+							journal->j_blocksize);
+					if (flags & JBD2_FLAG_ESCAPE) {
+						*((__be32 *)nbh->b_data) =
+						cpu_to_be32(JBD2_MAGIC_NUMBER);
+					}
+
+					BUFFER_TRACE(nbh, "marking dirty");
+					set_buffer_uptodate(nbh);
+					mark_buffer_dirty(nbh);
+					BUFFER_TRACE(nbh, "marking uptodate");
+					++info->nr_replays;
+					/* ll_rw_block(WRITE, 1, &nbh); */
+					unlock_buffer(nbh);
+					brelse(obh);
+					brelse(nbh);
+				}
+
+			skip_write:
+				tagp += tag_bytes;
+				if (!(flags & JBD2_FLAG_SAME_UUID))
+					tagp += 16;
+
+				if (flags & JBD2_FLAG_LAST_TAG)
+					break;
+			}
+
+			brelse(bh);
+			continue;
+
+		case JBD2_COMMIT_BLOCK:
+			/*     How to differentiate between interrupted commit
+			 *               and journal corruption ?
+			 *
+			 * {nth transaction}
+			 *        Checksum Verification Failed
+			 *			 |
+			 *		 ____________________
+			 *		|		     |
+			 * 	async_commit             sync_commit
+			 *     		|                    |
+			 *		| GO TO NEXT    "Journal Corruption"
+			 *		| TRANSACTION
+			 *		|
+			 * {(n+1)th transanction}
+			 *		|
+			 * 	 _______|______________
+			 * 	|	 	      |
+			 * Commit block found	Commit block not found
+			 *      |		      |
+			 * "Journal Corruption"       |
+			 *		 _____________|_________
+			 *     		|	           	|
+			 *	nth trans corrupt	OR   nth trans
+			 *	and (n+1)th interrupted     interrupted
+			 *	before commit block
+			 *      could reach the disk.
+			 *	(Cannot find the difference in above
+			 *	 mentioned conditions. Hence assume
+			 *	 "Interrupted Commit".)
+			 */
+
+			/* Found an expected commit block: if checksums
+			 * 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 &&
+			    jbd2_has_feature_checksum(journal)) {
+				int chksum_err, chksum_seen;
+				struct commit_header *cbh =
+					(struct commit_header *)bh->b_data;
+				unsigned found_chksum =
+					be32_to_cpu(cbh->h_chksum[0]);
+
+				chksum_err = chksum_seen = 0;
+
+				if (info->end_transaction) {
+					journal->j_failed_commit =
+						info->end_transaction;
+					brelse(bh);
+					break;
+				}
+
+				if (crc32_sum == found_chksum &&
+				    cbh->h_chksum_type == JBD2_CRC32_CHKSUM &&
+				    cbh->h_chksum_size ==
+						JBD2_CRC32_CHKSUM_SIZE)
+				       chksum_seen = 1;
+				else if (!(cbh->h_chksum_type == 0 &&
+					     cbh->h_chksum_size == 0 &&
+					     found_chksum == 0 &&
+					     !chksum_seen))
+				/*
+				 * If fs is mounted using an old kernel and then
+				 * kernel with journal_chksum is used then we
+				 * get a situation where the journal flag has
+				 * checksum flag set but checksums are not
+				 * present i.e chksum = 0, in the individual
+				 * commit blocks.
+				 * Hence to avoid checksum failures, in this
+				 * situation, this extra check is added.
+				 */
+						chksum_err = 1;
+
+				if (chksum_err) {
+					info->end_transaction = next_commit_ID;
+
+					if (!jbd2_has_feature_async_commit(journal)) {
+						journal->j_failed_commit =
+							next_commit_ID;
+						brelse(bh);
+						break;
+					}
+				}
+				crc32_sum = ~0;
+			}
+			if (pass == PASS_SCAN &&
+			    !jbd2_commit_block_csum_verify(journal,
+							   bh->b_data)) {
+				info->end_transaction = next_commit_ID;
+
+				if (!jbd2_has_feature_async_commit(journal)) {
+					journal->j_failed_commit =
+						next_commit_ID;
+					brelse(bh);
+					break;
+				}
+			}
+			brelse(bh);
+			next_commit_ID++;
+			continue;
+
+		case JBD2_REVOKE_BLOCK:
+			/* If we aren't in the REVOKE pass, then we can
+			 * just skip over this block. */
+			if (pass != PASS_REVOKE) {
+				brelse(bh);
+				continue;
+			}
+
+			err = scan_revoke_records(journal, bh,
+						  next_commit_ID, info);
+			brelse(bh);
+			if (err)
+				goto failed;
+			continue;
+
+		default:
+			jbd_debug(3, "Unrecognised magic %d, end of scan.\n",
+				  blocktype);
+			brelse(bh);
+			goto done;
+		}
+	}
+
+ done:
+	/*
+	 * We broke out of the log scan loop: either we came to the
+	 * known end of the log or we found an unexpected block in the
+	 * log.  If the latter happened, then we know that the "current"
+	 * transaction marks the end of the valid log.
+	 */
+
+	if (pass == PASS_SCAN) {
+		if (!info->end_transaction)
+			info->end_transaction = next_commit_ID;
+	} else {
+		/* It's really bad news if different passes end up at
+		 * different places (but possible due to IO errors). */
+		if (info->end_transaction != next_commit_ID) {
+			printk(KERN_ERR "JBD2: recovery pass %d ended at "
+				"transaction %u, expected %u\n",
+				pass, next_commit_ID, info->end_transaction);
+			if (!success)
+				success = -EIO;
+		}
+	}
+	if (block_error && success == 0)
+		success = -EIO;
+	return success;
+
+ failed:
+	return err;
+}
+
+/* Scan a revoke record, marking all blocks mentioned as revoked. */
+
+static int scan_revoke_records(journal_t *journal, struct buffer_head *bh,
+			       tid_t sequence, struct recovery_info *info)
+{
+	jbd2_journal_revoke_header_t *header;
+	int offset, max;
+	int csum_size = 0;
+	__u32 rcount;
+	int record_len = 4;
+
+	header = (jbd2_journal_revoke_header_t *) bh->b_data;
+	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)
+		return -EINVAL;
+	max = rcount;
+
+	if (jbd2_has_feature_64bit(journal))
+		record_len = 8;
+
+	while (offset + record_len <= max) {
+		unsigned long long blocknr;
+		int err;
+
+		if (record_len == 4)
+			blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
+		else
+			blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
+		offset += record_len;
+		err = jbd2_journal_set_revoke(journal, blocknr, sequence);
+		if (err)
+			return err;
+		++info->nr_revokes;
+	}
+	return 0;
+}