Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 729 insertions, 0 deletions

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
new file mode 100644
index 000000000..f033ac807
--- /dev/null
+++ b/fs/jbd2/checkpoint.c
@@ -0,0 +1,729 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * linux/fs/jbd2/checkpoint.c
+ *
+ * Written by Stephen C. Tweedie <sct@redhat.com>, 1999
+ *
+ * Copyright 1999 Red Hat Software --- All Rights Reserved
+ *
+ * Checkpoint routines for the generic filesystem journaling code.
+ * Part of the ext2fs journaling system.
+ *
+ * Checkpointing is the process of ensuring that a section of the log is
+ * committed fully to disk, so that that portion of the log can be
+ * reused.
+ */
+
+#include <linux/time.h>
+#include <linux/fs.h>
+#include <linux/jbd2.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/blkdev.h>
+#include <trace/events/jbd2.h>
+
+/*
+ * Unlink a buffer from a transaction checkpoint list.
+ *
+ * Called with j_list_lock held.
+ */
+static inline void __buffer_unlink(struct journal_head *jh)
+{
+	transaction_t *transaction = jh->b_cp_transaction;
+
+	jh->b_cpnext->b_cpprev = jh->b_cpprev;
+	jh->b_cpprev->b_cpnext = jh->b_cpnext;
+	if (transaction->t_checkpoint_list == jh) {
+		transaction->t_checkpoint_list = jh->b_cpnext;
+		if (transaction->t_checkpoint_list == jh)
+			transaction->t_checkpoint_list = NULL;
+	}
+}
+
+/*
+ * Check a checkpoint buffer could be release or not.
+ *
+ * Requires j_list_lock
+ */
+static inline bool __cp_buffer_busy(struct journal_head *jh)
+{
+	struct buffer_head *bh = jh2bh(jh);
+
+	return (jh->b_transaction || buffer_locked(bh) || buffer_dirty(bh));
+}
+
+/*
+ * __jbd2_log_wait_for_space: wait until there is space in the journal.
+ *
+ * Called under j-state_lock *only*.  It will be unlocked if we have to wait
+ * for a checkpoint to free up some space in the log.
+ */
+void __jbd2_log_wait_for_space(journal_t *journal)
+__acquires(&journal->j_state_lock)
+__releases(&journal->j_state_lock)
+{
+	int nblocks, space_left;
+	/* assert_spin_locked(&journal->j_state_lock); */
+
+	nblocks = journal->j_max_transaction_buffers;
+	while (jbd2_log_space_left(journal) < nblocks) {
+		write_unlock(&journal->j_state_lock);
+		mutex_lock_io(&journal->j_checkpoint_mutex);
+
+		/*
+		 * Test again, another process may have checkpointed while we
+		 * were waiting for the checkpoint lock. If there are no
+		 * transactions ready to be checkpointed, try to recover
+		 * journal space by calling cleanup_journal_tail(), and if
+		 * that doesn't work, by waiting for the currently committing
+		 * transaction to complete.  If there is absolutely no way
+		 * to make progress, this is either a BUG or corrupted
+		 * filesystem, so abort the journal and leave a stack
+		 * trace for forensic evidence.
+		 */
+		write_lock(&journal->j_state_lock);
+		if (journal->j_flags & JBD2_ABORT) {
+			mutex_unlock(&journal->j_checkpoint_mutex);
+			return;
+		}
+		spin_lock(&journal->j_list_lock);
+		space_left = jbd2_log_space_left(journal);
+		if (space_left < nblocks) {
+			int chkpt = journal->j_checkpoint_transactions != NULL;
+			tid_t tid = 0;
+
+			if (journal->j_committing_transaction)
+				tid = journal->j_committing_transaction->t_tid;
+			spin_unlock(&journal->j_list_lock);
+			write_unlock(&journal->j_state_lock);
+			if (chkpt) {
+				jbd2_log_do_checkpoint(journal);
+			} else if (jbd2_cleanup_journal_tail(journal) == 0) {
+				/* We were able to recover space; yay! */
+				;
+			} else if (tid) {
+				/*
+				 * jbd2_journal_commit_transaction() may want
+				 * to take the checkpoint_mutex if JBD2_FLUSHED
+				 * is set.  So we need to temporarily drop it.
+				 */
+				mutex_unlock(&journal->j_checkpoint_mutex);
+				jbd2_log_wait_commit(journal, tid);
+				write_lock(&journal->j_state_lock);
+				continue;
+			} else {
+				printk(KERN_ERR "%s: needed %d blocks and "
+				       "only had %d space available\n",
+				       __func__, nblocks, space_left);
+				printk(KERN_ERR "%s: no way to get more "
+				       "journal space in %s\n", __func__,
+				       journal->j_devname);
+				WARN_ON(1);
+				jbd2_journal_abort(journal, -EIO);
+			}
+			write_lock(&journal->j_state_lock);
+		} else {
+			spin_unlock(&journal->j_list_lock);
+		}
+		mutex_unlock(&journal->j_checkpoint_mutex);
+	}
+}
+
+static void
+__flush_batch(journal_t *journal, int *batch_count)
+{
+	int i;
+	struct blk_plug plug;
+
+	blk_start_plug(&plug);
+	for (i = 0; i < *batch_count; i++)
+		write_dirty_buffer(journal->j_chkpt_bhs[i], REQ_SYNC);
+	blk_finish_plug(&plug);
+
+	for (i = 0; i < *batch_count; i++) {
+		struct buffer_head *bh = journal->j_chkpt_bhs[i];
+		BUFFER_TRACE(bh, "brelse");
+		__brelse(bh);
+		journal->j_chkpt_bhs[i] = NULL;
+	}
+	*batch_count = 0;
+}
+
+/*
+ * Perform an actual checkpoint. We take the first transaction on the
+ * list of transactions to be checkpointed and send all its buffers
+ * to disk. We submit larger chunks of data at once.
+ *
+ * The journal should be locked before calling this function.
+ * Called with j_checkpoint_mutex held.
+ */
+int jbd2_log_do_checkpoint(journal_t *journal)
+{
+	struct journal_head	*jh;
+	struct buffer_head	*bh;
+	transaction_t		*transaction;
+	tid_t			this_tid;
+	int			result, batch_count = 0;
+
+	jbd2_debug(1, "Start checkpoint\n");
+
+	/*
+	 * First thing: if there are any transactions in the log which
+	 * don't need checkpointing, just eliminate them from the
+	 * journal straight away.
+	 */
+	result = jbd2_cleanup_journal_tail(journal);
+	trace_jbd2_checkpoint(journal, result);
+	jbd2_debug(1, "cleanup_journal_tail returned %d\n", result);
+	if (result <= 0)
+		return result;
+
+	/*
+	 * OK, we need to start writing disk blocks.  Take one transaction
+	 * and write it.
+	 */
+	spin_lock(&journal->j_list_lock);
+	if (!journal->j_checkpoint_transactions)
+		goto out;
+	transaction = journal->j_checkpoint_transactions;
+	if (transaction->t_chp_stats.cs_chp_time == 0)
+		transaction->t_chp_stats.cs_chp_time = jiffies;
+	this_tid = transaction->t_tid;
+restart:
+	/*
+	 * If someone cleaned up this transaction while we slept, we're
+	 * done (maybe it's a new transaction, but it fell at the same
+	 * address).
+	 */
+	if (journal->j_checkpoint_transactions != transaction ||
+	    transaction->t_tid != this_tid)
+		goto out;
+
+	/* checkpoint all of the transaction's buffers */
+	while (transaction->t_checkpoint_list) {
+		jh = transaction->t_checkpoint_list;
+		bh = jh2bh(jh);
+
+		if (jh->b_transaction != NULL) {
+			transaction_t *t = jh->b_transaction;
+			tid_t tid = t->t_tid;
+
+			transaction->t_chp_stats.cs_forced_to_close++;
+			spin_unlock(&journal->j_list_lock);
+			if (unlikely(journal->j_flags & JBD2_UNMOUNT))
+				/*
+				 * The journal thread is dead; so
+				 * starting and waiting for a commit
+				 * to finish will cause us to wait for
+				 * a _very_ long time.
+				 */
+				printk(KERN_ERR
+		"JBD2: %s: Waiting for Godot: block %llu\n",
+		journal->j_devname, (unsigned long long) bh->b_blocknr);
+
+			if (batch_count)
+				__flush_batch(journal, &batch_count);
+			jbd2_log_start_commit(journal, tid);
+			/*
+			 * jbd2_journal_commit_transaction() may want
+			 * to take the checkpoint_mutex if JBD2_FLUSHED
+			 * is set, jbd2_update_log_tail() called by
+			 * jbd2_journal_commit_transaction() may also take
+			 * checkpoint_mutex.  So we need to temporarily
+			 * drop it.
+			 */
+			mutex_unlock(&journal->j_checkpoint_mutex);
+			jbd2_log_wait_commit(journal, tid);
+			mutex_lock_io(&journal->j_checkpoint_mutex);
+			spin_lock(&journal->j_list_lock);
+			goto restart;
+		}
+		if (!trylock_buffer(bh)) {
+			/*
+			 * The buffer is locked, it may be writing back, or
+			 * flushing out in the last couple of cycles, or
+			 * re-adding into a new transaction, need to check
+			 * it again until it's unlocked.
+			 */
+			get_bh(bh);
+			spin_unlock(&journal->j_list_lock);
+			wait_on_buffer(bh);
+			/* the journal_head may have gone by now */
+			BUFFER_TRACE(bh, "brelse");
+			__brelse(bh);
+			goto retry;
+		} else if (!buffer_dirty(bh)) {
+			unlock_buffer(bh);
+			BUFFER_TRACE(bh, "remove from checkpoint");
+			/*
+			 * If the transaction was released or the checkpoint
+			 * list was empty, we're done.
+			 */
+			if (__jbd2_journal_remove_checkpoint(jh) ||
+			    !transaction->t_checkpoint_list)
+				goto out;
+		} else {
+			unlock_buffer(bh);
+			/*
+			 * We are about to write the buffer, it could be
+			 * raced by some other transaction shrink or buffer
+			 * re-log logic once we release the j_list_lock,
+			 * leave it on the checkpoint list and check status
+			 * again to make sure it's clean.
+			 */
+			BUFFER_TRACE(bh, "queue");
+			get_bh(bh);
+			J_ASSERT_BH(bh, !buffer_jwrite(bh));
+			journal->j_chkpt_bhs[batch_count++] = bh;
+			transaction->t_chp_stats.cs_written++;
+			transaction->t_checkpoint_list = jh->b_cpnext;
+		}
+
+		if ((batch_count == JBD2_NR_BATCH) ||
+		    need_resched() || spin_needbreak(&journal->j_list_lock) ||
+		    jh2bh(transaction->t_checkpoint_list) == journal->j_chkpt_bhs[0])
+			goto unlock_and_flush;
+	}
+
+	if (batch_count) {
+		unlock_and_flush:
+			spin_unlock(&journal->j_list_lock);
+		retry:
+			if (batch_count)
+				__flush_batch(journal, &batch_count);
+			spin_lock(&journal->j_list_lock);
+			goto restart;
+	}
+
+out:
+	spin_unlock(&journal->j_list_lock);
+	result = jbd2_cleanup_journal_tail(journal);
+
+	return (result < 0) ? result : 0;
+}
+
+/*
+ * Check the list of checkpoint transactions for the journal to see if
+ * we have already got rid of any since the last update of the log tail
+ * in the journal superblock.  If so, we can instantly roll the
+ * superblock forward to remove those transactions from the log.
+ *
+ * Return <0 on error, 0 on success, 1 if there was nothing to clean up.
+ *
+ * Called with the journal lock held.
+ *
+ * This is the only part of the journaling code which really needs to be
+ * aware of transaction aborts.  Checkpointing involves writing to the
+ * main filesystem area rather than to the journal, so it can proceed
+ * even in abort state, but we must not update the super block if
+ * checkpointing may have failed.  Otherwise, we would lose some metadata
+ * buffers which should be written-back to the filesystem.
+ */
+
+int jbd2_cleanup_journal_tail(journal_t *journal)
+{
+	tid_t		first_tid;
+	unsigned long	blocknr;
+
+	if (is_journal_aborted(journal))
+		return -EIO;
+
+	if (!jbd2_journal_get_log_tail(journal, &first_tid, &blocknr))
+		return 1;
+	J_ASSERT(blocknr != 0);
+
+	/*
+	 * We need to make sure that any blocks that were recently written out
+	 * --- perhaps by jbd2_log_do_checkpoint() --- are flushed out before
+	 * we drop the transactions from the journal. It's unlikely this will
+	 * be necessary, especially with an appropriately sized journal, but we
+	 * need this to guarantee correctness.  Fortunately
+	 * jbd2_cleanup_journal_tail() doesn't get called all that often.
+	 */
+	if (journal->j_flags & JBD2_BARRIER)
+		blkdev_issue_flush(journal->j_fs_dev);
+
+	return __jbd2_update_log_tail(journal, first_tid, blocknr);
+}
+
+
+/* Checkpoint list management */
+
+enum shrink_type {SHRINK_DESTROY, SHRINK_BUSY_STOP, SHRINK_BUSY_SKIP};
+
+/*
+ * journal_shrink_one_cp_list
+ *
+ * Find all the written-back checkpoint buffers in the given list
+ * and try to release them. If the whole transaction is released, set
+ * the 'released' parameter. Return the number of released checkpointed
+ * buffers.
+ *
+ * Called with j_list_lock held.
+ */
+static unsigned long journal_shrink_one_cp_list(struct journal_head *jh,
+						enum shrink_type type,
+						bool *released)
+{
+	struct journal_head *last_jh;
+	struct journal_head *next_jh = jh;
+	unsigned long nr_freed = 0;
+	int ret;
+
+	*released = false;
+	if (!jh)
+		return 0;
+
+	last_jh = jh->b_cpprev;
+	do {
+		jh = next_jh;
+		next_jh = jh->b_cpnext;
+
+		if (type == SHRINK_DESTROY) {
+			ret = __jbd2_journal_remove_checkpoint(jh);
+		} else {
+			ret = jbd2_journal_try_remove_checkpoint(jh);
+			if (ret < 0) {
+				if (type == SHRINK_BUSY_SKIP)
+					continue;
+				break;
+			}
+		}
+
+		nr_freed++;
+		if (ret) {
+			*released = true;
+			break;
+		}
+
+		if (need_resched())
+			break;
+	} while (jh != last_jh);
+
+	return nr_freed;
+}
+
+/*
+ * jbd2_journal_shrink_checkpoint_list
+ *
+ * Find 'nr_to_scan' written-back checkpoint buffers in the journal
+ * and try to release them. Return the number of released checkpointed
+ * buffers.
+ *
+ * Called with j_list_lock held.
+ */
+unsigned long jbd2_journal_shrink_checkpoint_list(journal_t *journal,
+						  unsigned long *nr_to_scan)
+{
+	transaction_t *transaction, *last_transaction, *next_transaction;
+	bool __maybe_unused released;
+	tid_t first_tid = 0, last_tid = 0, next_tid = 0;
+	tid_t tid = 0;
+	unsigned long nr_freed = 0;
+	unsigned long freed;
+
+again:
+	spin_lock(&journal->j_list_lock);
+	if (!journal->j_checkpoint_transactions) {
+		spin_unlock(&journal->j_list_lock);
+		goto out;
+	}
+
+	/*
+	 * Get next shrink transaction, resume previous scan or start
+	 * over again. If some others do checkpoint and drop transaction
+	 * from the checkpoint list, we ignore saved j_shrink_transaction
+	 * and start over unconditionally.
+	 */
+	if (journal->j_shrink_transaction)
+		transaction = journal->j_shrink_transaction;
+	else
+		transaction = journal->j_checkpoint_transactions;
+
+	if (!first_tid)
+		first_tid = transaction->t_tid;
+	last_transaction = journal->j_checkpoint_transactions->t_cpprev;
+	next_transaction = transaction;
+	last_tid = last_transaction->t_tid;
+	do {
+		transaction = next_transaction;
+		next_transaction = transaction->t_cpnext;
+		tid = transaction->t_tid;
+
+		freed = journal_shrink_one_cp_list(transaction->t_checkpoint_list,
+						   SHRINK_BUSY_SKIP, &released);
+		nr_freed += freed;
+		(*nr_to_scan) -= min(*nr_to_scan, freed);
+		if (*nr_to_scan == 0)
+			break;
+		if (need_resched() || spin_needbreak(&journal->j_list_lock))
+			break;
+	} while (transaction != last_transaction);
+
+	if (transaction != last_transaction) {
+		journal->j_shrink_transaction = next_transaction;
+		next_tid = next_transaction->t_tid;
+	} else {
+		journal->j_shrink_transaction = NULL;
+		next_tid = 0;
+	}
+
+	spin_unlock(&journal->j_list_lock);
+	cond_resched();
+
+	if (*nr_to_scan && next_tid)
+		goto again;
+out:
+	trace_jbd2_shrink_checkpoint_list(journal, first_tid, tid, last_tid,
+					  nr_freed, next_tid);
+
+	return nr_freed;
+}
+
+/*
+ * journal_clean_checkpoint_list
+ *
+ * Find all the written-back checkpoint buffers in the journal and release them.
+ * If 'destroy' is set, release all buffers unconditionally.
+ *
+ * Called with j_list_lock held.
+ */
+void __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
+{
+	transaction_t *transaction, *last_transaction, *next_transaction;
+	enum shrink_type type;
+	bool released;
+
+	transaction = journal->j_checkpoint_transactions;
+	if (!transaction)
+		return;
+
+	type = destroy ? SHRINK_DESTROY : SHRINK_BUSY_STOP;
+	last_transaction = transaction->t_cpprev;
+	next_transaction = transaction;
+	do {
+		transaction = next_transaction;
+		next_transaction = transaction->t_cpnext;
+		journal_shrink_one_cp_list(transaction->t_checkpoint_list,
+					   type, &released);
+		/*
+		 * This function only frees up some memory if possible so we
+		 * dont have an obligation to finish processing. Bail out if
+		 * preemption requested:
+		 */
+		if (need_resched())
+			return;
+		/*
+		 * Stop scanning if we couldn't free the transaction. This
+		 * avoids pointless scanning of transactions which still
+		 * weren't checkpointed.
+		 */
+		if (!released)
+			return;
+	} while (transaction != last_transaction);
+}
+
+/*
+ * Remove buffers from all checkpoint lists as journal is aborted and we just
+ * need to free memory
+ */
+void jbd2_journal_destroy_checkpoint(journal_t *journal)
+{
+	/*
+	 * We loop because __jbd2_journal_clean_checkpoint_list() may abort
+	 * early due to a need of rescheduling.
+	 */
+	while (1) {
+		spin_lock(&journal->j_list_lock);
+		if (!journal->j_checkpoint_transactions) {
+			spin_unlock(&journal->j_list_lock);
+			break;
+		}
+		__jbd2_journal_clean_checkpoint_list(journal, true);
+		spin_unlock(&journal->j_list_lock);
+		cond_resched();
+	}
+}
+
+/*
+ * journal_remove_checkpoint: called after a buffer has been committed
+ * to disk (either by being write-back flushed to disk, or being
+ * committed to the log).
+ *
+ * We cannot safely clean a transaction out of the log until all of the
+ * buffer updates committed in that transaction have safely been stored
+ * elsewhere on disk.  To achieve this, all of the buffers in a
+ * transaction need to be maintained on the transaction's checkpoint
+ * lists until they have been rewritten, at which point this function is
+ * called to remove the buffer from the existing transaction's
+ * checkpoint lists.
+ *
+ * The function returns 1 if it frees the transaction, 0 otherwise.
+ * The function can free jh and bh.
+ *
+ * This function is called with j_list_lock held.
+ */
+int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
+{
+	struct transaction_chp_stats_s *stats;
+	transaction_t *transaction;
+	journal_t *journal;
+	struct buffer_head *bh = jh2bh(jh);
+
+	JBUFFER_TRACE(jh, "entry");
+
+	transaction = jh->b_cp_transaction;
+	if (!transaction) {
+		JBUFFER_TRACE(jh, "not on transaction");
+		return 0;
+	}
+	journal = transaction->t_journal;
+
+	JBUFFER_TRACE(jh, "removing from transaction");
+
+	/*
+	 * If we have failed to write the buffer out to disk, the filesystem
+	 * may become inconsistent. We cannot abort the journal here since
+	 * we hold j_list_lock and we have to be careful about races with
+	 * jbd2_journal_destroy(). So mark the writeback IO error in the
+	 * journal here and we abort the journal later from a better context.
+	 */
+	if (buffer_write_io_error(bh))
+		set_bit(JBD2_CHECKPOINT_IO_ERROR, &journal->j_atomic_flags);
+
+	__buffer_unlink(jh);
+	jh->b_cp_transaction = NULL;
+	percpu_counter_dec(&journal->j_checkpoint_jh_count);
+	jbd2_journal_put_journal_head(jh);
+
+	/* Is this transaction empty? */
+	if (transaction->t_checkpoint_list)
+		return 0;
+
+	/*
+	 * There is one special case to worry about: if we have just pulled the
+	 * buffer off a running or committing transaction's checkpoing list,
+	 * then even if the checkpoint list is empty, the transaction obviously
+	 * cannot be dropped!
+	 *
+	 * The locking here around t_state is a bit sleazy.
+	 * See the comment at the end of jbd2_journal_commit_transaction().
+	 */
+	if (transaction->t_state != T_FINISHED)
+		return 0;
+
+	/*
+	 * OK, that was the last buffer for the transaction, we can now
+	 * safely remove this transaction from the log.
+	 */
+	stats = &transaction->t_chp_stats;
+	if (stats->cs_chp_time)
+		stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
+						    jiffies);
+	trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
+				    transaction->t_tid, stats);
+
+	__jbd2_journal_drop_transaction(journal, transaction);
+	jbd2_journal_free_transaction(transaction);
+	return 1;
+}
+
+/*
+ * Check the checkpoint buffer and try to remove it from the checkpoint
+ * list if it's clean. Returns -EBUSY if it is not clean, returns 1 if
+ * it frees the transaction, 0 otherwise.
+ *
+ * This function is called with j_list_lock held.
+ */
+int jbd2_journal_try_remove_checkpoint(struct journal_head *jh)
+{
+	struct buffer_head *bh = jh2bh(jh);
+
+	if (jh->b_transaction)
+		return -EBUSY;
+	if (!trylock_buffer(bh))
+		return -EBUSY;
+	if (buffer_dirty(bh)) {
+		unlock_buffer(bh);
+		return -EBUSY;
+	}
+	unlock_buffer(bh);
+
+	/*
+	 * Buffer is clean and the IO has finished (we held the buffer
+	 * lock) so the checkpoint is done. We can safely remove the
+	 * buffer from this transaction.
+	 */
+	JBUFFER_TRACE(jh, "remove from checkpoint list");
+	return __jbd2_journal_remove_checkpoint(jh);
+}
+
+/*
+ * journal_insert_checkpoint: put a committed buffer onto a checkpoint
+ * list so that we know when it is safe to clean the transaction out of
+ * the log.
+ *
+ * Called with the journal locked.
+ * Called with j_list_lock held.
+ */
+void __jbd2_journal_insert_checkpoint(struct journal_head *jh,
+			       transaction_t *transaction)
+{
+	JBUFFER_TRACE(jh, "entry");
+	J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
+	J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
+
+	/* Get reference for checkpointing transaction */
+	jbd2_journal_grab_journal_head(jh2bh(jh));
+	jh->b_cp_transaction = transaction;
+
+	if (!transaction->t_checkpoint_list) {
+		jh->b_cpnext = jh->b_cpprev = jh;
+	} else {
+		jh->b_cpnext = transaction->t_checkpoint_list;
+		jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
+		jh->b_cpprev->b_cpnext = jh;
+		jh->b_cpnext->b_cpprev = jh;
+	}
+	transaction->t_checkpoint_list = jh;
+	percpu_counter_inc(&transaction->t_journal->j_checkpoint_jh_count);
+}
+
+/*
+ * We've finished with this transaction structure: adios...
+ *
+ * The transaction must have no links except for the checkpoint by this
+ * point.
+ *
+ * Called with the journal locked.
+ * Called with j_list_lock held.
+ */
+
+void __jbd2_journal_drop_transaction(journal_t *journal, transaction_t *transaction)
+{
+	assert_spin_locked(&journal->j_list_lock);
+
+	journal->j_shrink_transaction = NULL;
+	if (transaction->t_cpnext) {
+		transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
+		transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
+		if (journal->j_checkpoint_transactions == transaction)
+			journal->j_checkpoint_transactions =
+				transaction->t_cpnext;
+		if (journal->j_checkpoint_transactions == transaction)
+			journal->j_checkpoint_transactions = NULL;
+	}
+
+	J_ASSERT(transaction->t_state == T_FINISHED);
+	J_ASSERT(transaction->t_buffers == NULL);
+	J_ASSERT(transaction->t_forget == NULL);
+	J_ASSERT(transaction->t_shadow_list == NULL);
+	J_ASSERT(transaction->t_checkpoint_list == NULL);
+	J_ASSERT(atomic_read(&transaction->t_updates) == 0);
+	J_ASSERT(journal->j_committing_transaction != transaction);
+	J_ASSERT(journal->j_running_transaction != transaction);
+
+	trace_jbd2_drop_transaction(journal, transaction);
+
+	jbd2_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
+}