5 files changed, 344 insertions, 57 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index 9656139d2e99..219ec06a8c7e 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -236,6 +236,7 @@ config JBD_DEBUG
 
 config JBD2
         tristate
+        select CRC32
         help
           This is a generic journaling layer for block devices that support
           both 32-bit and 64-bit block numbers.  It is currently used by
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index c7305443e100..f7479d30735e 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -869,6 +869,7 @@ enum {
         Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl,
         Opt_reservation, Opt_noreservation, Opt_noload, Opt_nobh, Opt_bh,
         Opt_commit, Opt_journal_update, Opt_journal_inum, Opt_journal_dev,
+        Opt_journal_checksum, Opt_journal_async_commit,
         Opt_abort, Opt_data_journal, Opt_data_ordered, Opt_data_writeback,
         Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
         Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
@@ -908,6 +909,8 @@ static match_table_t tokens = {
         {Opt_journal_update, "journal=update"},
         {Opt_journal_inum, "journal=%u"},
         {Opt_journal_dev, "journal_dev=%u"},
+        {Opt_journal_checksum, "journal_checksum"},
+        {Opt_journal_async_commit, "journal_async_commit"},
         {Opt_abort, "abort"},
         {Opt_data_journal, "data=journal"},
         {Opt_data_ordered, "data=ordered"},
@@ -1095,6 +1098,13 @@ static int parse_options (char *options, struct super_block *sb,
                                 return 0;
                         *journal_devnum = option;
                         break;
+                case Opt_journal_checksum:
+                        set_opt(sbi->s_mount_opt, JOURNAL_CHECKSUM);
+                        break;
+                case Opt_journal_async_commit:
+                        set_opt(sbi->s_mount_opt, JOURNAL_ASYNC_COMMIT);
+                        set_opt(sbi->s_mount_opt, JOURNAL_CHECKSUM);
+                        break;
                 case Opt_noload:
                         set_opt (sbi->s_mount_opt, NOLOAD);
                         break;
@@ -2114,6 +2124,21 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
                 goto failed_mount4;
         }
 
+        if (test_opt(sb, JOURNAL_ASYNC_COMMIT)) {
+                jbd2_journal_set_features(sbi->s_journal,
+                                JBD2_FEATURE_COMPAT_CHECKSUM, 0,
+                                JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT);
+        } else if (test_opt(sb, JOURNAL_CHECKSUM)) {
+                jbd2_journal_set_features(sbi->s_journal,
+                                JBD2_FEATURE_COMPAT_CHECKSUM, 0, 0);
+                jbd2_journal_clear_features(sbi->s_journal, 0, 0,
+                                JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT);
+        } else {
+                jbd2_journal_clear_features(sbi->s_journal,
+                                JBD2_FEATURE_COMPAT_CHECKSUM, 0,
+                                JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT);
+        }
+
         /* We have now updated the journal if required, so we can
          * validate the data journaling mode. */
         switch (test_opt(sb, DATA_FLAGS)) {
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c
index 8749a86f4175..da8d0eb3b7b9 100644
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -21,6 +21,7 @@
 #include <linux/mm.h>
 #include <linux/pagemap.h>
 #include <linux/jiffies.h>
+#include <linux/crc32.h>
 
 /*
  * Default IO end handler for temporary BJ_IO buffer_heads.
@@ -93,19 +94,23 @@ static int inverted_lock(journal_t *journal, struct buffer_head *bh)
         return 1;
 }
 
-/* Done it all: now write the commit record.  We should have
+/*
+ * Done it all: now submit the commit record.  We should have
  * cleaned up our previous buffers by now, so if we are in abort
  * mode we can now just skip the rest of the journal write
  * entirely.
  *
  * Returns 1 if the journal needs to be aborted or 0 on success
  */
-static int journal_write_commit_record(journal_t *journal,
-                                        transaction_t *commit_transaction)
+static int journal_submit_commit_record(journal_t *journal,
+                                        transaction_t *commit_transaction,
+                                        struct buffer_head **cbh,
+                                        __u32 crc32_sum)
 {
         struct journal_head *descriptor;
+        struct commit_header *tmp;
         struct buffer_head *bh;
-        int i, ret;
+        int ret;
         int barrier_done = 0;
 
         if (is_journal_aborted(journal))
@@ -117,21 +122,33 @@ static int journal_write_commit_record(journal_t *journal,
 
         bh = jh2bh(descriptor);
 
-        /* AKPM: buglet - add `i' to tmp! */
-        for (i = 0; i < bh->b_size; i += 512) {
-                journal_header_t *tmp = (journal_header_t*)bh->b_data;
-                tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
-                tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK);
-                tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
+        tmp = (struct commit_header *)bh->b_data;
+        tmp->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER);
+        tmp->h_blocktype = cpu_to_be32(JBD2_COMMIT_BLOCK);
+        tmp->h_sequence = cpu_to_be32(commit_transaction->t_tid);
+
+        if (JBD2_HAS_COMPAT_FEATURE(journal,
+                                    JBD2_FEATURE_COMPAT_CHECKSUM)) {
+                tmp->h_chksum_type      = JBD2_CRC32_CHKSUM;
+                tmp->h_chksum_size      = JBD2_CRC32_CHKSUM_SIZE;
+                tmp->h_chksum[0]        = cpu_to_be32(crc32_sum);
         }
 
-        JBUFFER_TRACE(descriptor, "write commit block");
+        JBUFFER_TRACE(descriptor, "submit commit block");
+        lock_buffer(bh);
+
         set_buffer_dirty(bh);
-        if (journal->j_flags & JBD2_BARRIER) {
+        set_buffer_uptodate(bh);
+        bh->b_end_io = journal_end_buffer_io_sync;
+
+        if (journal->j_flags & JBD2_BARRIER &&
+                !JBD2_HAS_COMPAT_FEATURE(journal,
+                                         JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
                 set_buffer_ordered(bh);
                 barrier_done = 1;
         }
-        ret = sync_dirty_buffer(bh);
+        ret = submit_bh(WRITE, bh);
+
         /* is it possible for another commit to fail at roughly
          * the same time as this one?  If so, we don't want to
          * trust the barrier flag in the super, but instead want
@@ -152,14 +169,72 @@ static int journal_write_commit_record(journal_t *journal,
                 clear_buffer_ordered(bh);
                 set_buffer_uptodate(bh);
                 set_buffer_dirty(bh);
-                ret = sync_dirty_buffer(bh);
+                ret = submit_bh(WRITE, bh);
         }
-        put_bh(bh);             /* One for getblk() */
-        jbd2_journal_put_journal_head(descriptor);
+        *cbh = bh;
+        return ret;
+}
+
+/*
+ * This function along with journal_submit_commit_record
+ * allows to write the commit record asynchronously.
+ */
+static int journal_wait_on_commit_record(struct buffer_head *bh)
+{
+        int ret = 0;
+
+        clear_buffer_dirty(bh);
+        wait_on_buffer(bh);
 
-        return (ret == -EIO);
+        if (unlikely(!buffer_uptodate(bh)))
+                ret = -EIO;
+        put_bh(bh);            /* One for getblk() */
+        jbd2_journal_put_journal_head(bh2jh(bh));
+
+        return ret;
 }
 
+/*
+ * Wait for all submitted IO to complete.
+ */
+static int journal_wait_on_locked_list(journal_t *journal,
+                                       transaction_t *commit_transaction)
+{
+        int ret = 0;
+        struct journal_head *jh;
+
+        while (commit_transaction->t_locked_list) {
+                struct buffer_head *bh;
+
+                jh = commit_transaction->t_locked_list->b_tprev;
+                bh = jh2bh(jh);
+                get_bh(bh);
+                if (buffer_locked(bh)) {
+                        spin_unlock(&journal->j_list_lock);
+                        wait_on_buffer(bh);
+                        if (unlikely(!buffer_uptodate(bh)))
+                                ret = -EIO;
+                        spin_lock(&journal->j_list_lock);
+                }
+                if (!inverted_lock(journal, bh)) {
+                        put_bh(bh);
+                        spin_lock(&journal->j_list_lock);
+                        continue;
+                }
+                if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) {
+                        __jbd2_journal_unfile_buffer(jh);
+                        jbd_unlock_bh_state(bh);
+                        jbd2_journal_remove_journal_head(bh);
+                        put_bh(bh);
+                } else {
+                        jbd_unlock_bh_state(bh);
+                }
+                put_bh(bh);
+                cond_resched_lock(&journal->j_list_lock);
+        }
+        return ret;
+  }
+
 static void journal_do_submit_data(struct buffer_head **wbuf, int bufs)
 {
         int i;
@@ -275,7 +350,21 @@ write_out_data:
         journal_do_submit_data(wbuf, bufs);
 }
 
-static inline void write_tag_block(int tag_bytes, journal_block_tag_t *tag,
+static __u32 jbd2_checksum_data(__u32 crc32_sum, struct buffer_head *bh)
+{
+        struct page *page = bh->b_page;
+        char *addr;
+        __u32 checksum;
+
+        addr = kmap_atomic(page, KM_USER0);
+        checksum = crc32_be(crc32_sum,
+                (void *)(addr + offset_in_page(bh->b_data)), bh->b_size);
+        kunmap_atomic(addr, KM_USER0);
+
+        return checksum;
+}
+
+static void write_tag_block(int tag_bytes, journal_block_tag_t *tag,
                                    unsigned long long block)
 {
         tag->t_blocknr = cpu_to_be32(block & (u32)~0);
@@ -307,6 +396,8 @@ void jbd2_journal_commit_transaction(journal_t *journal)
         int tag_flag;
         int i;
         int tag_bytes = journal_tag_bytes(journal);
+        struct buffer_head *cbh = NULL; /* For transactional checksums */
+        __u32 crc32_sum = ~0;
 
         /*
          * First job: lock down the current transaction and wait for
@@ -451,38 +542,15 @@ void jbd2_journal_commit_transaction(journal_t *journal)
         journal_submit_data_buffers(journal, commit_transaction);
 
         /*
-         * Wait for all previously submitted IO to complete.
+         * Wait for all previously submitted IO to complete if commit
+         * record is to be written synchronously.
          */
         spin_lock(&journal->j_list_lock);
-        while (commit_transaction->t_locked_list) {
-                struct buffer_head *bh;
+        if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
+                JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT))
+                err = journal_wait_on_locked_list(journal,
+                                                commit_transaction);
 
-                jh = commit_transaction->t_locked_list->b_tprev;
-                bh = jh2bh(jh);
-                get_bh(bh);
-                if (buffer_locked(bh)) {
-                        spin_unlock(&journal->j_list_lock);
-                        wait_on_buffer(bh);
-                        if (unlikely(!buffer_uptodate(bh)))
-                                err = -EIO;
-                        spin_lock(&journal->j_list_lock);
-                }
-                if (!inverted_lock(journal, bh)) {
-                        put_bh(bh);
-                        spin_lock(&journal->j_list_lock);
-                        continue;
-                }
-                if (buffer_jbd(bh) && jh->b_jlist == BJ_Locked) {
-                        __jbd2_journal_unfile_buffer(jh);
-                        jbd_unlock_bh_state(bh);
-                        jbd2_journal_remove_journal_head(bh);
-                        put_bh(bh);
-                } else {
-                        jbd_unlock_bh_state(bh);
-                }
-                put_bh(bh);
-                cond_resched_lock(&journal->j_list_lock);
-        }
         spin_unlock(&journal->j_list_lock);
 
         if (err)
@@ -656,6 +724,15 @@ void jbd2_journal_commit_transaction(journal_t *journal)
 start_journal_io:
                         for (i = 0; i < bufs; i++) {
                                 struct buffer_head *bh = wbuf[i];
+                                /*
+                                 * Compute checksum.
+                                 */
+                                if (JBD2_HAS_COMPAT_FEATURE(journal,
+                                        JBD2_FEATURE_COMPAT_CHECKSUM)) {
+                                        crc32_sum =
+                                            jbd2_checksum_data(crc32_sum, bh);
+                                }
+
                                 lock_buffer(bh);
                                 clear_buffer_dirty(bh);
                                 set_buffer_uptodate(bh);
@@ -672,6 +749,23 @@ start_journal_io:
                 }
         }
 
+        /* Done it all: now write the commit record asynchronously. */
+
+        if (JBD2_HAS_INCOMPAT_FEATURE(journal,
+                JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
+                err = journal_submit_commit_record(journal, commit_transaction,
+                                                 &cbh, crc32_sum);
+                if (err)
+                        __jbd2_journal_abort_hard(journal);
+
+                spin_lock(&journal->j_list_lock);
+                err = journal_wait_on_locked_list(journal,
+                                                commit_transaction);
+                spin_unlock(&journal->j_list_lock);
+                if (err)
+                        __jbd2_journal_abort_hard(journal);
+        }
+
         /* Lo and behold: we have just managed to send a transaction to
            the log.  Before we can commit it, wait for the IO so far to
            complete.  Control buffers being written are on the
@@ -771,8 +865,14 @@ wait_for_iobuf:
 
         jbd_debug(3, "JBD: commit phase 6\n");
 
-        if (journal_write_commit_record(journal, commit_transaction))
-                err = -EIO;
+        if (!JBD2_HAS_INCOMPAT_FEATURE(journal,
+                JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)) {
+                err = journal_submit_commit_record(journal, commit_transaction,
+                                                &cbh, crc32_sum);
+                if (err)
+                        __jbd2_journal_abort_hard(journal);
+        }
+        err = journal_wait_on_commit_record(cbh);
 
         if (err)
                 jbd2_journal_abort(journal, err);
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 3667c91bc786..59ba2494dcaf 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1578,6 +1578,32 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat,
         return 1;
 }
 
+/*
+ * jbd2_journal_clear_features () - Clear a given journal feature in the
+ *                                  superblock
+ * @journal: Journal to act on.
+ * @compat: bitmask of compatible features
+ * @ro: bitmask of features that force read-only mount
+ * @incompat: bitmask of incompatible features
+ *
+ * Clear a given journal feature as present on the
+ * superblock.
+ */
+void jbd2_journal_clear_features(journal_t *journal, unsigned long compat,
+                                unsigned long ro, unsigned long incompat)
+{
+        journal_superblock_t *sb;
+
+        jbd_debug(1, "Clear features 0x%lx/0x%lx/0x%lx\n",
+                  compat, ro, incompat);
+
+        sb = journal->j_superblock;
+
+        sb->s_feature_compat    &= ~cpu_to_be32(compat);
+        sb->s_feature_ro_compat &= ~cpu_to_be32(ro);
+        sb->s_feature_incompat  &= ~cpu_to_be32(incompat);
+}
+EXPORT_SYMBOL(jbd2_journal_clear_features);
 
 /**
  * int jbd2_journal_update_format () - Update on-disk journal structure.
diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
index d0ce627539ef..921680663fa2 100644
--- a/fs/jbd2/recovery.c
+++ b/fs/jbd2/recovery.c
@@ -21,6 +21,7 @@
 #include <linux/jbd2.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
+#include <linux/crc32.h>
 #endif
 
 /*
@@ -316,6 +317,37 @@ static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag
         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 "JBD: 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);
+                }
+        }
+        return 0;
+}
+
 static int do_one_pass(journal_t *journal,
                         struct recovery_info *info, enum passtype pass)
 {
@@ -328,6 +360,7 @@ static int do_one_pass(journal_t *journal,
         unsigned int            sequence;
         int                     blocktype;
         int                     tag_bytes = journal_tag_bytes(journal);
+        __u32                   crc32_sum = ~0; /* Transactional Checksums */
 
         /* Precompute the maximum metadata descriptors in a descriptor block */
         int                     MAX_BLOCKS_PER_DESC;
@@ -419,12 +452,26 @@ static int do_one_pass(journal_t *journal,
                 switch(blocktype) {
                 case JBD2_DESCRIPTOR_BLOCK:
                         /* If it is a valid descriptor block, replay it
-                         * in pass REPLAY; otherwise, just skip over the
-                         * blocks it describes. */
+                         * 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_COMPAT_FEATURE(journal,
+                                            JBD2_FEATURE_COMPAT_CHECKSUM) &&
+                                    !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);
-                                brelse(bh);
+                                put_bh(bh);
                                 continue;
                         }
 
@@ -516,9 +563,96 @@ static int do_one_pass(journal_t *journal,
                         continue;
 
                 case JBD2_COMMIT_BLOCK:
-                        /* Found an expected commit block: not much to
-                         * do other than move on to the next sequence
+                        /*     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_COMPAT_FEATURE(journal,
+                                    JBD2_FEATURE_COMPAT_CHECKSUM)) {
+                                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) {
+                                        printk(KERN_ERR "JBD: Transaction %u "
+                                                "found to be corrupt.\n",
+                                                next_commit_ID - 1);
+                                        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_COMPAT_FEATURE(journal,
+                                           JBD2_FEATURE_INCOMPAT_ASYNC_COMMIT)){
+                                                printk(KERN_ERR
+                                                       "JBD: Transaction %u "
+                                                       "found to be corrupt.\n",
+                                                       next_commit_ID);
+                                                brelse(bh);
+                                                break;
+                                        }
+                                }
+                                crc32_sum = ~0;
+                        }
                         brelse(bh);
                         next_commit_ID++;
                         continue;
@@ -554,9 +688,10 @@ static int do_one_pass(journal_t *journal,
          * transaction marks the end of the valid log.
          */
 
-        if (pass == PASS_SCAN)
-                info->end_transaction = next_commit_ID;
-        else {
+        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) {