File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
new file mode 100644
index 0000000..7f277e4
--- /dev/null
+++ b/fs/jbd2/recovery.c
@@ -0,0 +1,876 @@
+/*
+ * linux/fs/jbd2/recovery.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
+ *
+ * Copyright 1999-2000 Red Hat Software --- All Rights Reserved
+ *
+ * This file is part of the Linux kernel and is made available under
+ * the terms of the GNU General Public License, version 2, or at your
+ * option, any later version, incorporated herein by reference.
+ *
+ * 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(READ, nbufs, bufs);
+ journal_brelse_array(bufs, nbufs);
+ nbufs = 0;
+ }
+ } else
+ brelse(bh);
+ }
+
+ if (nbufs)
+ ll_rw_block(READ, 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_descr_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 does'nt appear to be exorted..
+ *
+ * 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_descr_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 "
+ "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;
+}
+
+static int jbd2_revoke_block_csum_verify(journal_t *j,
+ void *buf)
+{
+ struct jbd2_journal_revoke_tail *tail;
+ __be32 provided;
+ __u32 calculated;
+
+ if (!jbd2_journal_has_csum_v2or3(j))
+ return 1;
+
+ tail = (struct jbd2_journal_revoke_tail *)(buf + j->j_blocksize -
+ sizeof(struct jbd2_journal_revoke_tail));
+ provided = tail->r_checksum;
+ tail->r_checksum = 0;
+ calculated = jbd2_chksum(j, j->j_csum_seed, buf, j->j_blocksize);
+ tail->r_checksum = provided;
+
+ return provided == cpu_to_be32(calculated);
+}
+
+/* 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_revoke_block_csum_verify(journal, header))
+ return -EFSBADCRC;
+
+ if (jbd2_journal_has_csum_v2or3(journal))
+ csum_size = sizeof(struct jbd2_journal_revoke_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;
+}