Commit message: jbd2: fix use-after-free of transaction_t race

jbd2_journal_wait_updates() is called with j_state_lock held. But if
there is a commit in progress, then this transaction might get committed
and freed via jbd2_journal_commit_transaction() ->
jbd2_journal_free_transaction(), when we release j_state_lock.
So check for journal->j_running_transaction everytime we release and
acquire j_state_lock to avoid use-after-free issue.

Link: https://lore.kernel.org/r/948c2fed518ae739db6a8f7f83f1d58b504f87d0.1644497105.git.ritesh.list@gmail.com
Fixes: 4f98186848707f53 ("jbd2: refactor wait logic for transaction updates into a common function")
Cc: stable@kernel.org
Reported-and-tested-by: syzbot+afa2ca5171d93e44b348@syzkaller.appspotmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
CVE: CVE-2022-28796
CWE: CWE-416
Vulnerability description: jbd2_journal_wait_updates in fs/jbd2/transaction.c in the Linux kernel before 5.17.1 has a use-after-free caused by a transaction_t race condition.

Project: linux
File: transaction.c

handle_t *jbd2__journal_start(journal_t *journal, int nblocks, int rsv_blocks,
			      int revoke_records, gfp_t gfp_mask,
			      unsigned int type, unsigned int line_no)
{
	handle_t *handle = journal_current_handle();
	int err;

	if (!journal)
		return ERR_PTR(-EROFS);

	if (handle) {
		J_ASSERT(handle->h_transaction->t_journal == journal);
		handle->h_ref++;
		return handle;
	}

	nblocks += DIV_ROUND_UP(revoke_records,
				journal->j_revoke_records_per_block);
	handle = new_handle(nblocks);
	if (!handle)
		return ERR_PTR(-ENOMEM);
	if (rsv_blocks) {
		handle_t *rsv_handle;

		rsv_handle = new_handle(rsv_blocks);
		if (!rsv_handle) {
			jbd2_free_handle(handle);
			return ERR_PTR(-ENOMEM);
		}
		rsv_handle->h_reserved = 1;
		rsv_handle->h_journal = journal;
		handle->h_rsv_handle = rsv_handle;
	}
	handle->h_revoke_credits = revoke_records;

	err = start_this_handle(journal, handle, gfp_mask);
	if (err < 0) {
		if (handle->h_rsv_handle)
			jbd2_free_handle(handle->h_rsv_handle);
		jbd2_free_handle(handle);
		return ERR_PTR(err);
	}
	handle->h_type = type;
	handle->h_line_no = line_no;
	trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
				handle->h_transaction->t_tid, type,
				line_no, nblocks);

	return handle;
}

Project: linux
File: transaction.c

static void __jbd2_journal_unreserve_handle(handle_t *handle, transaction_t *t)
{
	journal_t *journal = handle->h_journal;

	WARN_ON(!handle->h_reserved);
	sub_reserved_credits(journal, handle->h_total_credits);
	if (t)
		atomic_sub(handle->h_total_credits, &t->t_outstanding_credits);
}

Project: linux
File: transaction.c

int __init jbd2_journal_init_transaction_cache(void)
{
	J_ASSERT(!transaction_cache);
	transaction_cache = kmem_cache_create("jbd2_transaction_s",
					sizeof(transaction_t),
					0,
					SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY,
					NULL);
	if (!transaction_cache) {
		pr_emerg("JBD2: failed to create transaction cache\n");
		return -ENOMEM;
	}
	return 0;
}

Project: linux
File: transaction.c

int jbd2_journal_get_undo_access(handle_t *handle, struct buffer_head *bh)
{
	int err;
	struct journal_head *jh;
	char *committed_data = NULL;

	if (is_handle_aborted(handle))
		return -EROFS;

	if (jbd2_write_access_granted(handle, bh, true))
		return 0;

	jh = jbd2_journal_add_journal_head(bh);
	JBUFFER_TRACE(jh, "entry");

	/*
	 * Do this first --- it can drop the journal lock, so we want to
	 * make sure that obtaining the committed_data is done
	 * atomically wrt. completion of any outstanding commits.
	 */
	err = do_get_write_access(handle, jh, 1);
	if (err)
		goto out;

repeat:
	if (!jh->b_committed_data)
		committed_data = jbd2_alloc(jh2bh(jh)->b_size,
					    GFP_NOFS|__GFP_NOFAIL);

	spin_lock(&jh->b_state_lock);
	if (!jh->b_committed_data) {
		/* Copy out the current buffer contents into the
		 * preserved, committed copy. */
		JBUFFER_TRACE(jh, "generate b_committed data");
		if (!committed_data) {
			spin_unlock(&jh->b_state_lock);
			goto repeat;
		}

		jh->b_committed_data = committed_data;
		committed_data = NULL;
		memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
	}
	spin_unlock(&jh->b_state_lock);
out:
	jbd2_journal_put_journal_head(jh);
	if (unlikely(committed_data))
		jbd2_free(committed_data, bh->b_size);
	return err;
}

Project: linux
File: transaction.c

static int jbd2_descriptor_blocks_per_trans(journal_t *journal)
{
	int tag_space = journal->j_blocksize - sizeof(journal_header_t);
	int tags_per_block;

	/* Subtract UUID */
	tag_space -= 16;
	if (jbd2_journal_has_csum_v2or3(journal))
		tag_space -= sizeof(struct jbd2_journal_block_tail);
	/* Commit code leaves a slack space of 16 bytes at the end of block */
	tags_per_block = (tag_space - 16) / journal_tag_bytes(journal);
	/*
	 * Revoke descriptors are accounted separately so we need to reserve
	 * space for commit block and normal transaction descriptor blocks.
	 */
	return 1 + DIV_ROUND_UP(journal->j_max_transaction_buffers,
				tags_per_block);
}

Project: linux
File: transaction.c

static int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode,
		unsigned long flags, loff_t start_byte, loff_t end_byte)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal;

	if (is_handle_aborted(handle))
		return -EROFS;
	journal = transaction->t_journal;

	jbd_debug(4, "Adding inode %lu, tid:%d\n", jinode->i_vfs_inode->i_ino,
			transaction->t_tid);

	spin_lock(&journal->j_list_lock);
	jinode->i_flags |= flags;

	if (jinode->i_dirty_end) {
		jinode->i_dirty_start = min(jinode->i_dirty_start, start_byte);
		jinode->i_dirty_end = max(jinode->i_dirty_end, end_byte);
	} else {
		jinode->i_dirty_start = start_byte;
		jinode->i_dirty_end = end_byte;
	}

	/* Is inode already attached where we need it? */
	if (jinode->i_transaction == transaction ||
	    jinode->i_next_transaction == transaction)
		goto done;

	/*
	 * We only ever set this variable to 1 so the test is safe. Since
	 * t_need_data_flush is likely to be set, we do the test to save some
	 * cacheline bouncing
	 */
	if (!transaction->t_need_data_flush)
		transaction->t_need_data_flush = 1;
	/* On some different transaction's list - should be
	 * the committing one */
	if (jinode->i_transaction) {
		J_ASSERT(jinode->i_next_transaction == NULL);
		J_ASSERT(jinode->i_transaction ==
					journal->j_committing_transaction);
		jinode->i_next_transaction = transaction;
		goto done;
	}
	/* Not on any transaction list... */
	J_ASSERT(!jinode->i_next_transaction);
	jinode->i_transaction = transaction;
	list_add(&jinode->i_list, &transaction->t_inode_list);
done:
	spin_unlock(&journal->j_list_lock);

	return 0;
}

Project: linux
File: transaction.c

static bool jbd2_write_access_granted(handle_t *handle, struct buffer_head *bh,
							bool undo)
{
	struct journal_head *jh;
	bool ret = false;

	/* Dirty buffers require special handling... */
	if (buffer_dirty(bh))
		return false;

	/*
	 * RCU protects us from dereferencing freed pages. So the checks we do
	 * are guaranteed not to oops. However the jh slab object can get freed
	 * & reallocated while we work with it. So we have to be careful. When
	 * we see jh attached to the running transaction, we know it must stay
	 * so until the transaction is committed. Thus jh won't be freed and
	 * will be attached to the same bh while we run.  However it can
	 * happen jh gets freed, reallocated, and attached to the transaction
	 * just after we get pointer to it from bh. So we have to be careful
	 * and recheck jh still belongs to our bh before we return success.
	 */
	rcu_read_lock();
	if (!buffer_jbd(bh))
		goto out;
	/* This should be bh2jh() but that doesn't work with inline functions */
	jh = READ_ONCE(bh->b_private);
	if (!jh)
		goto out;
	/* For undo access buffer must have data copied */
	if (undo && !jh->b_committed_data)
		goto out;
	if (READ_ONCE(jh->b_transaction) != handle->h_transaction &&
	    READ_ONCE(jh->b_next_transaction) != handle->h_transaction)
		goto out;
	/*
	 * There are two reasons for the barrier here:
	 * 1) Make sure to fetch b_bh after we did previous checks so that we
	 * detect when jh went through free, realloc, attach to transaction
	 * while we were checking. Paired with implicit barrier in that path.
	 * 2) So that access to bh done after jbd2_write_access_granted()
	 * doesn't get reordered and see inconsistent state of concurrent
	 * do_get_write_access().
	 */
	smp_mb();
	if (unlikely(jh->b_bh != bh))
		goto out;
	ret = true;
out:
	rcu_read_unlock();
	return ret;
}

Project: linux
File: transaction.c

int jbd2_journal_extend(handle_t *handle, int nblocks, int revoke_records)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal;
	int result;
	int wanted;

	if (is_handle_aborted(handle))
		return -EROFS;
	journal = transaction->t_journal;

	result = 1;

	read_lock(&journal->j_state_lock);

	/* Don't extend a locked-down transaction! */
	if (transaction->t_state != T_RUNNING) {
		jbd_debug(3, "denied handle %p %d blocks: "
			  "transaction not running\n", handle, nblocks);
		goto error_out;
	}

	nblocks += DIV_ROUND_UP(
			handle->h_revoke_credits_requested + revoke_records,
			journal->j_revoke_records_per_block) -
		DIV_ROUND_UP(
			handle->h_revoke_credits_requested,
			journal->j_revoke_records_per_block);
	spin_lock(&transaction->t_handle_lock);
	wanted = atomic_add_return(nblocks,
				   &transaction->t_outstanding_credits);

	if (wanted > journal->j_max_transaction_buffers) {
		jbd_debug(3, "denied handle %p %d blocks: "
			  "transaction too large\n", handle, nblocks);
		atomic_sub(nblocks, &transaction->t_outstanding_credits);
		goto unlock;
	}

	trace_jbd2_handle_extend(journal->j_fs_dev->bd_dev,
				 transaction->t_tid,
				 handle->h_type, handle->h_line_no,
				 handle->h_total_credits,
				 nblocks);

	handle->h_total_credits += nblocks;
	handle->h_requested_credits += nblocks;
	handle->h_revoke_credits += revoke_records;
	handle->h_revoke_credits_requested += revoke_records;
	result = 0;

	jbd_debug(3, "extended handle %p by %d\n", handle, nblocks);
unlock:
	spin_unlock(&transaction->t_handle_lock);
error_out:
	read_unlock(&journal->j_state_lock);
	return result;
}

Project: linux
File: transaction.c

static int start_this_handle(journal_t *journal, handle_t *handle,
			     gfp_t gfp_mask)
{
	transaction_t	*transaction, *new_transaction = NULL;
	int		blocks = handle->h_total_credits;
	int		rsv_blocks = 0;
	unsigned long ts = jiffies;

	if (handle->h_rsv_handle)
		rsv_blocks = handle->h_rsv_handle->h_total_credits;

	/*
	 * Limit the number of reserved credits to 1/2 of maximum transaction
	 * size and limit the number of total credits to not exceed maximum
	 * transaction size per operation.
	 */
	if ((rsv_blocks > journal->j_max_transaction_buffers / 2) ||
	    (rsv_blocks + blocks > journal->j_max_transaction_buffers)) {
		printk(KERN_ERR "JBD2: %s wants too many credits "
		       "credits:%d rsv_credits:%d max:%d\n",
		       current->comm, blocks, rsv_blocks,
		       journal->j_max_transaction_buffers);
		WARN_ON(1);
		return -ENOSPC;
	}

alloc_transaction:
	/*
	 * This check is racy but it is just an optimization of allocating new
	 * transaction early if there are high chances we'll need it. If we
	 * guess wrong, we'll retry or free unused transaction.
	 */
	if (!data_race(journal->j_running_transaction)) {
		/*
		 * If __GFP_FS is not present, then we may be being called from
		 * inside the fs writeback layer, so we MUST NOT fail.
		 */
		if ((gfp_mask & __GFP_FS) == 0)
			gfp_mask |= __GFP_NOFAIL;
		new_transaction = kmem_cache_zalloc(transaction_cache,
						    gfp_mask);
		if (!new_transaction)
			return -ENOMEM;
	}

	jbd_debug(3, "New handle %p going live.\n", handle);

	/*
	 * We need to hold j_state_lock until t_updates has been incremented,
	 * for proper journal barrier handling
	 */
repeat:
	read_lock(&journal->j_state_lock);
	BUG_ON(journal->j_flags & JBD2_UNMOUNT);
	if (is_journal_aborted(journal) ||
	    (journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
		read_unlock(&journal->j_state_lock);
		jbd2_journal_free_transaction(new_transaction);
		return -EROFS;
	}

	/*
	 * Wait on the journal's transaction barrier if necessary. Specifically
	 * we allow reserved handles to proceed because otherwise commit could
	 * deadlock on page writeback not being able to complete.
	 */
	if (!handle->h_reserved && journal->j_barrier_count) {
		read_unlock(&journal->j_state_lock);
		wait_event(journal->j_wait_transaction_locked,
				journal->j_barrier_count == 0);
		goto repeat;
	}

	if (!journal->j_running_transaction) {
		read_unlock(&journal->j_state_lock);
		if (!new_transaction)
			goto alloc_transaction;
		write_lock(&journal->j_state_lock);
		if (!journal->j_running_transaction &&
		    (handle->h_reserved || !journal->j_barrier_count)) {
			jbd2_get_transaction(journal, new_transaction);
			new_transaction = NULL;
		}
		write_unlock(&journal->j_state_lock);
		goto repeat;
	}

	transaction = journal->j_running_transaction;

	if (!handle->h_reserved) {
		/* We may have dropped j_state_lock - restart in that case */
		if (add_transaction_credits(journal, blocks, rsv_blocks)) {
			/*
			 * add_transaction_credits releases
			 * j_state_lock on a non-zero return
			 */
			__release(&journal->j_state_lock);
			goto repeat;
		}
	} else {
		/*
		 * We have handle reserved so we are allowed to join T_LOCKED
		 * transaction and we don't have to check for transaction size
		 * and journal space. But we still have to wait while running
		 * transaction is being switched to a committing one as it
		 * won't wait for any handles anymore.
		 */
		if (transaction->t_state == T_SWITCH) {
			wait_transaction_switching(journal);
			goto repeat;
		}
		sub_reserved_credits(journal, blocks);
		handle->h_reserved = 0;
	}

	/* OK, account for the buffers that this operation expects to
	 * use and add the handle to the running transaction.
	 */
	update_t_max_wait(transaction, ts);
	handle->h_transaction = transaction;
	handle->h_requested_credits = blocks;
	handle->h_revoke_credits_requested = handle->h_revoke_credits;
	handle->h_start_jiffies = jiffies;
	atomic_inc(&transaction->t_updates);
	atomic_inc(&transaction->t_handle_count);
	jbd_debug(4, "Handle %p given %d credits (total %d, free %lu)\n",
		  handle, blocks,
		  atomic_read(&transaction->t_outstanding_credits),
		  jbd2_log_space_left(journal));
	read_unlock(&journal->j_state_lock);
	current->journal_info = handle;

	rwsem_acquire_read(&journal->j_trans_commit_map, 0, 0, _THIS_IP_);
	jbd2_journal_free_transaction(new_transaction);
	/*
	 * Ensure that no allocations done while the transaction is open are
	 * going to recurse back to the fs layer.
	 */
	handle->saved_alloc_context = memalloc_nofs_save();
	return 0;
}

Project: linux
File: transaction.c

void jbd2_journal_free_transaction(transaction_t *transaction)
{
	if (unlikely(ZERO_OR_NULL_PTR(transaction)))
		return;
	kmem_cache_free(transaction_cache, transaction);
}

Project: linux
File: transaction.c

int jbd2_journal_invalidatepage(journal_t *journal,
				struct page *page,
				unsigned int offset,
				unsigned int length)
{
	struct buffer_head *head, *bh, *next;
	unsigned int stop = offset + length;
	unsigned int curr_off = 0;
	int partial_page = (offset || length < PAGE_SIZE);
	int may_free = 1;
	int ret = 0;

	if (!PageLocked(page))
		BUG();
	if (!page_has_buffers(page))
		return 0;

	BUG_ON(stop > PAGE_SIZE || stop < length);

	/* We will potentially be playing with lists other than just the
	 * data lists (especially for journaled data mode), so be
	 * cautious in our locking. */

	head = bh = page_buffers(page);
	do {
		unsigned int next_off = curr_off + bh->b_size;
		next = bh->b_this_page;

		if (next_off > stop)
			return 0;

		if (offset <= curr_off) {
			/* This block is wholly outside the truncation point */
			lock_buffer(bh);
			ret = journal_unmap_buffer(journal, bh, partial_page);
			unlock_buffer(bh);
			if (ret < 0)
				return ret;
			may_free &= ret;
		}
		curr_off = next_off;
		bh = next;

	} while (bh != head);

	if (!partial_page) {
		if (may_free && try_to_free_buffers(page))
			J_ASSERT(!page_has_buffers(page));
	}
	return 0;
}

Project: linux
File: transaction.c

do_get_write_access(handle_t *handle, struct journal_head *jh,
			int force_copy)
{
	struct buffer_head *bh;
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal;
	int error;
	char *frozen_buffer = NULL;
	unsigned long start_lock, time_lock;

	journal = transaction->t_journal;

	jbd_debug(5, "journal_head %p, force_copy %d\n", jh, force_copy);

	JBUFFER_TRACE(jh, "entry");
repeat:
	bh = jh2bh(jh);

	/* @@@ Need to check for errors here at some point. */

 	start_lock = jiffies;
	lock_buffer(bh);
	spin_lock(&jh->b_state_lock);

	/* If it takes too long to lock the buffer, trace it */
	time_lock = jbd2_time_diff(start_lock, jiffies);
	if (time_lock > HZ/10)
		trace_jbd2_lock_buffer_stall(bh->b_bdev->bd_dev,
			jiffies_to_msecs(time_lock));

	/* We now hold the buffer lock so it is safe to query the buffer
	 * state.  Is the buffer dirty?
	 *
	 * If so, there are two possibilities.  The buffer may be
	 * non-journaled, and undergoing a quite legitimate writeback.
	 * Otherwise, it is journaled, and we don't expect dirty buffers
	 * in that state (the buffers should be marked JBD_Dirty
	 * instead.)  So either the IO is being done under our own
	 * control and this is a bug, or it's a third party IO such as
	 * dump(8) (which may leave the buffer scheduled for read ---
	 * ie. locked but not dirty) or tune2fs (which may actually have
	 * the buffer dirtied, ugh.)  */

	if (buffer_dirty(bh)) {
		/*
		 * First question: is this buffer already part of the current
		 * transaction or the existing committing transaction?
		 */
		if (jh->b_transaction) {
			J_ASSERT_JH(jh,
				jh->b_transaction == transaction ||
				jh->b_transaction ==
					journal->j_committing_transaction);
			if (jh->b_next_transaction)
				J_ASSERT_JH(jh, jh->b_next_transaction ==
							transaction);
			warn_dirty_buffer(bh);
		}
		/*
		 * In any case we need to clean the dirty flag and we must
		 * do it under the buffer lock to be sure we don't race
		 * with running write-out.
		 */
		JBUFFER_TRACE(jh, "Journalling dirty buffer");
		clear_buffer_dirty(bh);
		set_buffer_jbddirty(bh);
	}

	unlock_buffer(bh);

	error = -EROFS;
	if (is_handle_aborted(handle)) {
		spin_unlock(&jh->b_state_lock);
		goto out;
	}
	error = 0;

	/*
	 * The buffer is already part of this transaction if b_transaction or
	 * b_next_transaction points to it
	 */
	if (jh->b_transaction == transaction ||
	    jh->b_next_transaction == transaction)
		goto done;

	/*
	 * this is the first time this transaction is touching this buffer,
	 * reset the modified flag
	 */
	jh->b_modified = 0;

	/*
	 * If the buffer is not journaled right now, we need to make sure it
	 * doesn't get written to disk before the caller actually commits the
	 * new data
	 */
	if (!jh->b_transaction) {
		JBUFFER_TRACE(jh, "no transaction");
		J_ASSERT_JH(jh, !jh->b_next_transaction);
		JBUFFER_TRACE(jh, "file as BJ_Reserved");
		/*
		 * Make sure all stores to jh (b_modified, b_frozen_data) are
		 * visible before attaching it to the running transaction.
		 * Paired with barrier in jbd2_write_access_granted()
		 */
		smp_wmb();
		spin_lock(&journal->j_list_lock);
		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
		spin_unlock(&journal->j_list_lock);
		goto done;
	}
	/*
	 * If there is already a copy-out version of this buffer, then we don't
	 * need to make another one
	 */
	if (jh->b_frozen_data) {
		JBUFFER_TRACE(jh, "has frozen data");
		J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
		goto attach_next;
	}

	JBUFFER_TRACE(jh, "owned by older transaction");
	J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
	J_ASSERT_JH(jh, jh->b_transaction == journal->j_committing_transaction);

	/*
	 * There is one case we have to be very careful about.  If the
	 * committing transaction is currently writing this buffer out to disk
	 * and has NOT made a copy-out, then we cannot modify the buffer
	 * contents at all right now.  The essence of copy-out is that it is
	 * the extra copy, not the primary copy, which gets journaled.  If the
	 * primary copy is already going to disk then we cannot do copy-out
	 * here.
	 */
	if (buffer_shadow(bh)) {
		JBUFFER_TRACE(jh, "on shadow: sleep");
		spin_unlock(&jh->b_state_lock);
		wait_on_bit_io(&bh->b_state, BH_Shadow, TASK_UNINTERRUPTIBLE);
		goto repeat;
	}

	/*
	 * Only do the copy if the currently-owning transaction still needs it.
	 * If buffer isn't on BJ_Metadata list, the committing transaction is
	 * past that stage (here we use the fact that BH_Shadow is set under
	 * bh_state lock together with refiling to BJ_Shadow list and at this
	 * point we know the buffer doesn't have BH_Shadow set).
	 *
	 * Subtle point, though: if this is a get_undo_access, then we will be
	 * relying on the frozen_data to contain the new value of the
	 * committed_data record after the transaction, so we HAVE to force the
	 * frozen_data copy in that case.
	 */
	if (jh->b_jlist == BJ_Metadata || force_copy) {
		JBUFFER_TRACE(jh, "generate frozen data");
		if (!frozen_buffer) {
			JBUFFER_TRACE(jh, "allocate memory for buffer");
			spin_unlock(&jh->b_state_lock);
			frozen_buffer = jbd2_alloc(jh2bh(jh)->b_size,
						   GFP_NOFS | __GFP_NOFAIL);
			goto repeat;
		}
		jh->b_frozen_data = frozen_buffer;
		frozen_buffer = NULL;
		jbd2_freeze_jh_data(jh);
	}
attach_next:
	/*
	 * Make sure all stores to jh (b_modified, b_frozen_data) are visible
	 * before attaching it to the running transaction. Paired with barrier
	 * in jbd2_write_access_granted()
	 */
	smp_wmb();
	jh->b_next_transaction = transaction;

done:
	spin_unlock(&jh->b_state_lock);

	/*
	 * If we are about to journal a buffer, then any revoke pending on it is
	 * no longer valid
	 */
	jbd2_journal_cancel_revoke(handle, jh);

out:
	if (unlikely(frozen_buffer))	/* It's usually NULL */
		jbd2_free(frozen_buffer, bh->b_size);

	JBUFFER_TRACE(jh, "exit");
	return error;
}

Project: linux
File: transaction.c

static void jbd2_freeze_jh_data(struct journal_head *jh)
{
	struct page *page;
	int offset;
	char *source;
	struct buffer_head *bh = jh2bh(jh);

	J_EXPECT_JH(jh, buffer_uptodate(bh), "Possible IO failure.\n");
	page = bh->b_page;
	offset = offset_in_page(bh->b_data);
	source = kmap_atomic(page);
	/* Fire data frozen trigger just before we copy the data */
	jbd2_buffer_frozen_trigger(jh, source + offset, jh->b_triggers);
	memcpy(jh->b_frozen_data, source + offset, bh->b_size);
	kunmap_atomic(source);

	/*
	 * Now that the frozen data is saved off, we need to store any matching
	 * triggers.
	 */
	jh->b_frozen_triggers = jh->b_triggers;
}

Project: linux
File: transaction.c

void jbd2_journal_file_buffer(struct journal_head *jh,
				transaction_t *transaction, int jlist)
{
	spin_lock(&jh->b_state_lock);
	spin_lock(&transaction->t_journal->j_list_lock);
	__jbd2_journal_file_buffer(jh, transaction, jlist);
	spin_unlock(&transaction->t_journal->j_list_lock);
	spin_unlock(&jh->b_state_lock);
}

Project: linux
File: transaction.c

static void warn_dirty_buffer(struct buffer_head *bh)
{
	printk(KERN_WARNING
	       "JBD2: Spotted dirty metadata buffer (dev = %pg, blocknr = %llu). "
	       "There's a risk of filesystem corruption in case of system "
	       "crash.\n",
	       bh->b_bdev, (unsigned long long)bh->b_blocknr);
}

Project: linux
File: transaction.c

int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal;
	struct journal_head *jh;
	int ret = 0;

	if (is_handle_aborted(handle))
		return -EROFS;
	if (!buffer_jbd(bh))
		return -EUCLEAN;

	/*
	 * We don't grab jh reference here since the buffer must be part
	 * of the running transaction.
	 */
	jh = bh2jh(bh);
	jbd_debug(5, "journal_head %p\n", jh);
	JBUFFER_TRACE(jh, "entry");

	/*
	 * This and the following assertions are unreliable since we may see jh
	 * in inconsistent state unless we grab bh_state lock. But this is
	 * crucial to catch bugs so let's do a reliable check until the
	 * lockless handling is fully proven.
	 */
	if (data_race(jh->b_transaction != transaction &&
	    jh->b_next_transaction != transaction)) {
		spin_lock(&jh->b_state_lock);
		J_ASSERT_JH(jh, jh->b_transaction == transaction ||
				jh->b_next_transaction == transaction);
		spin_unlock(&jh->b_state_lock);
	}
	if (jh->b_modified == 1) {
		/* If it's in our transaction it must be in BJ_Metadata list. */
		if (data_race(jh->b_transaction == transaction &&
		    jh->b_jlist != BJ_Metadata)) {
			spin_lock(&jh->b_state_lock);
			if (jh->b_transaction == transaction &&
			    jh->b_jlist != BJ_Metadata)
				pr_err("JBD2: assertion failure: h_type=%u "
				       "h_line_no=%u block_no=%llu jlist=%u\n",
				       handle->h_type, handle->h_line_no,
				       (unsigned long long) bh->b_blocknr,
				       jh->b_jlist);
			J_ASSERT_JH(jh, jh->b_transaction != transaction ||
					jh->b_jlist == BJ_Metadata);
			spin_unlock(&jh->b_state_lock);
		}
		goto out;
	}

	journal = transaction->t_journal;
	spin_lock(&jh->b_state_lock);

	if (jh->b_modified == 0) {
		/*
		 * This buffer's got modified and becoming part
		 * of the transaction. This needs to be done
		 * once a transaction -bzzz
		 */
		if (WARN_ON_ONCE(jbd2_handle_buffer_credits(handle) <= 0)) {
			ret = -ENOSPC;
			goto out_unlock_bh;
		}
		jh->b_modified = 1;
		handle->h_total_credits--;
	}

	/*
	 * fastpath, to avoid expensive locking.  If this buffer is already
	 * on the running transaction's metadata list there is nothing to do.
	 * Nobody can take it off again because there is a handle open.
	 * I _think_ we're OK here with SMP barriers - a mistaken decision will
	 * result in this test being false, so we go in and take the locks.
	 */
	if (jh->b_transaction == transaction && jh->b_jlist == BJ_Metadata) {
		JBUFFER_TRACE(jh, "fastpath");
		if (unlikely(jh->b_transaction !=
			     journal->j_running_transaction)) {
			printk(KERN_ERR "JBD2: %s: "
			       "jh->b_transaction (%llu, %p, %u) != "
			       "journal->j_running_transaction (%p, %u)\n",
			       journal->j_devname,
			       (unsigned long long) bh->b_blocknr,
			       jh->b_transaction,
			       jh->b_transaction ? jh->b_transaction->t_tid : 0,
			       journal->j_running_transaction,
			       journal->j_running_transaction ?
			       journal->j_running_transaction->t_tid : 0);
			ret = -EINVAL;
		}
		goto out_unlock_bh;
	}

	set_buffer_jbddirty(bh);

	/*
	 * Metadata already on the current transaction list doesn't
	 * need to be filed.  Metadata on another transaction's list must
	 * be committing, and will be refiled once the commit completes:
	 * leave it alone for now.
	 */
	if (jh->b_transaction != transaction) {
		JBUFFER_TRACE(jh, "already on other transaction");
		if (unlikely(((jh->b_transaction !=
			       journal->j_committing_transaction)) ||
			     (jh->b_next_transaction != transaction))) {
			printk(KERN_ERR "jbd2_journal_dirty_metadata: %s: "
			       "bad jh for block %llu: "
			       "transaction (%p, %u), "
			       "jh->b_transaction (%p, %u), "
			       "jh->b_next_transaction (%p, %u), jlist %u\n",
			       journal->j_devname,
			       (unsigned long long) bh->b_blocknr,
			       transaction, transaction->t_tid,
			       jh->b_transaction,
			       jh->b_transaction ?
			       jh->b_transaction->t_tid : 0,
			       jh->b_next_transaction,
			       jh->b_next_transaction ?
			       jh->b_next_transaction->t_tid : 0,
			       jh->b_jlist);
			WARN_ON(1);
			ret = -EINVAL;
		}
		/* And this case is illegal: we can't reuse another
		 * transaction's data buffer, ever. */
		goto out_unlock_bh;
	}

	/* That test should have eliminated the following case: */
	J_ASSERT_JH(jh, jh->b_frozen_data == NULL);

	JBUFFER_TRACE(jh, "file as BJ_Metadata");
	spin_lock(&journal->j_list_lock);
	__jbd2_journal_file_buffer(jh, transaction, BJ_Metadata);
	spin_unlock(&journal->j_list_lock);
out_unlock_bh:
	spin_unlock(&jh->b_state_lock);
out:
	JBUFFER_TRACE(jh, "exit");
	return ret;
}

Project: linux
File: transaction.c

__journal_try_to_free_buffer(journal_t *journal, struct buffer_head *bh)
{
	struct journal_head *jh;

	jh = bh2jh(bh);

	if (buffer_locked(bh) || buffer_dirty(bh))
		goto out;

	if (jh->b_next_transaction != NULL || jh->b_transaction != NULL)
		goto out;

	spin_lock(&journal->j_list_lock);
	if (jh->b_cp_transaction != NULL) {
		/* written-back checkpointed metadata buffer */
		JBUFFER_TRACE(jh, "remove from checkpoint list");
		__jbd2_journal_remove_checkpoint(jh);
	}
	spin_unlock(&journal->j_list_lock);
out:
	return;
}

Project: linux
File: transaction.c

static int journal_unmap_buffer(journal_t *journal, struct buffer_head *bh,
				int partial_page)
{
	transaction_t *transaction;
	struct journal_head *jh;
	int may_free = 1;

	BUFFER_TRACE(bh, "entry");

	/*
	 * It is safe to proceed here without the j_list_lock because the
	 * buffers cannot be stolen by try_to_free_buffers as long as we are
	 * holding the page lock. --sct
	 */

	jh = jbd2_journal_grab_journal_head(bh);
	if (!jh)
		goto zap_buffer_unlocked;

	/* OK, we have data buffer in journaled mode */
	write_lock(&journal->j_state_lock);
	spin_lock(&jh->b_state_lock);
	spin_lock(&journal->j_list_lock);

	/*
	 * We cannot remove the buffer from checkpoint lists until the
	 * transaction adding inode to orphan list (let's call it T)
	 * is committed.  Otherwise if the transaction changing the
	 * buffer would be cleaned from the journal before T is
	 * committed, a crash will cause that the correct contents of
	 * the buffer will be lost.  On the other hand we have to
	 * clear the buffer dirty bit at latest at the moment when the
	 * transaction marking the buffer as freed in the filesystem
	 * structures is committed because from that moment on the
	 * block can be reallocated and used by a different page.
	 * Since the block hasn't been freed yet but the inode has
	 * already been added to orphan list, it is safe for us to add
	 * the buffer to BJ_Forget list of the newest transaction.
	 *
	 * Also we have to clear buffer_mapped flag of a truncated buffer
	 * because the buffer_head may be attached to the page straddling
	 * i_size (can happen only when blocksize < pagesize) and thus the
	 * buffer_head can be reused when the file is extended again. So we end
	 * up keeping around invalidated buffers attached to transactions'
	 * BJ_Forget list just to stop checkpointing code from cleaning up
	 * the transaction this buffer was modified in.
	 */
	transaction = jh->b_transaction;
	if (transaction == NULL) {
		/* First case: not on any transaction.  If it
		 * has no checkpoint link, then we can zap it:
		 * it's a writeback-mode buffer so we don't care
		 * if it hits disk safely. */
		if (!jh->b_cp_transaction) {
			JBUFFER_TRACE(jh, "not on any transaction: zap");
			goto zap_buffer;
		}

		if (!buffer_dirty(bh)) {
			/* bdflush has written it.  We can drop it now */
			__jbd2_journal_remove_checkpoint(jh);
			goto zap_buffer;
		}

		/* OK, it must be in the journal but still not
		 * written fully to disk: it's metadata or
		 * journaled data... */

		if (journal->j_running_transaction) {
			/* ... and once the current transaction has
			 * committed, the buffer won't be needed any
			 * longer. */
			JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
			may_free = __dispose_buffer(jh,
					journal->j_running_transaction);
			goto zap_buffer;
		} else {
			/* There is no currently-running transaction. So the
			 * orphan record which we wrote for this file must have
			 * passed into commit.  We must attach this buffer to
			 * the committing transaction, if it exists. */
			if (journal->j_committing_transaction) {
				JBUFFER_TRACE(jh, "give to committing trans");
				may_free = __dispose_buffer(jh,
					journal->j_committing_transaction);
				goto zap_buffer;
			} else {
				/* The orphan record's transaction has
				 * committed.  We can cleanse this buffer */
				clear_buffer_jbddirty(bh);
				__jbd2_journal_remove_checkpoint(jh);
				goto zap_buffer;
			}
		}
	} else if (transaction == journal->j_committing_transaction) {
		JBUFFER_TRACE(jh, "on committing transaction");
		/*
		 * The buffer is committing, we simply cannot touch
		 * it. If the page is straddling i_size we have to wait
		 * for commit and try again.
		 */
		if (partial_page) {
			spin_unlock(&journal->j_list_lock);
			spin_unlock(&jh->b_state_lock);
			write_unlock(&journal->j_state_lock);
			jbd2_journal_put_journal_head(jh);
			return -EBUSY;
		}
		/*
		 * OK, buffer won't be reachable after truncate. We just clear
		 * b_modified to not confuse transaction credit accounting, and
		 * set j_next_transaction to the running transaction (if there
		 * is one) and mark buffer as freed so that commit code knows
		 * it should clear dirty bits when it is done with the buffer.
		 */
		set_buffer_freed(bh);
		if (journal->j_running_transaction && buffer_jbddirty(bh))
			jh->b_next_transaction = journal->j_running_transaction;
		jh->b_modified = 0;
		spin_unlock(&journal->j_list_lock);
		spin_unlock(&jh->b_state_lock);
		write_unlock(&journal->j_state_lock);
		jbd2_journal_put_journal_head(jh);
		return 0;
	} else {
		/* Good, the buffer belongs to the running transaction.
		 * We are writing our own transaction's data, not any
		 * previous one's, so it is safe to throw it away
		 * (remember that we expect the filesystem to have set
		 * i_size already for this truncate so recovery will not
		 * expose the disk blocks we are discarding here.) */
		J_ASSERT_JH(jh, transaction == journal->j_running_transaction);
		JBUFFER_TRACE(jh, "on running transaction");
		may_free = __dispose_buffer(jh, transaction);
	}

zap_buffer:
	/*
	 * This is tricky. Although the buffer is truncated, it may be reused
	 * if blocksize < pagesize and it is attached to the page straddling
	 * EOF. Since the buffer might have been added to BJ_Forget list of the
	 * running transaction, journal_get_write_access() won't clear
	 * b_modified and credit accounting gets confused. So clear b_modified
	 * here.
	 */
	jh->b_modified = 0;
	spin_unlock(&journal->j_list_lock);
	spin_unlock(&jh->b_state_lock);
	write_unlock(&journal->j_state_lock);
	jbd2_journal_put_journal_head(jh);
zap_buffer_unlocked:
	clear_buffer_dirty(bh);
	J_ASSERT_BH(bh, !buffer_jbddirty(bh));
	clear_buffer_mapped(bh);
	clear_buffer_req(bh);
	clear_buffer_new(bh);
	clear_buffer_delay(bh);
	clear_buffer_unwritten(bh);
	bh->b_bdev = NULL;
	return may_free;
}

Project: linux
File: transaction.c

	__releases(journal->j_state_lock)
{
	DEFINE_WAIT(wait);
	int need_to_start;
	tid_t tid = journal->j_running_transaction->t_tid;

	prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
			TASK_UNINTERRUPTIBLE);
	need_to_start = !tid_geq(journal->j_commit_request, tid);
	read_unlock(&journal->j_state_lock);
	if (need_to_start)
		jbd2_log_start_commit(journal, tid);
	jbd2_might_wait_for_commit(journal);
	schedule();
	finish_wait(&journal->j_wait_transaction_locked, &wait);
}

Project: linux
File: transaction.c

int jbd2_journal_inode_ranged_write(handle_t *handle,
		struct jbd2_inode *jinode, loff_t start_byte, loff_t length)
{
	return jbd2_journal_file_inode(handle, jinode,
			JI_WRITE_DATA | JI_WAIT_DATA, start_byte,
			start_byte + length - 1);
}

Project: linux
File: transaction.c

void jbd2_journal_wait_updates(journal_t *journal)
{
	DEFINE_WAIT(wait);

	while (1) {
		/*
		 * Note that the running transaction can get freed under us if
		 * this transaction is getting committed in
		 * jbd2_journal_commit_transaction() ->
		 * jbd2_journal_free_transaction(). This can only happen when we
		 * release j_state_lock -> schedule() -> acquire j_state_lock.
		 * Hence we should everytime retrieve new j_running_transaction
		 * value (after j_state_lock release acquire cycle), else it may
		 * lead to use-after-free of old freed transaction.
		 */
		transaction_t *transaction = journal->j_running_transaction;

		if (!transaction)
			break;

		spin_lock(&transaction->t_handle_lock);
		prepare_to_wait(&journal->j_wait_updates, &wait,
				TASK_UNINTERRUPTIBLE);
		if (!atomic_read(&transaction->t_updates)) {
			spin_unlock(&transaction->t_handle_lock);
			finish_wait(&journal->j_wait_updates, &wait);
			break;
		}
		spin_unlock(&transaction->t_handle_lock);
		write_unlock(&journal->j_state_lock);
		schedule();
		finish_wait(&journal->j_wait_updates, &wait);
		write_lock(&journal->j_state_lock);
	}
}

Project: linux
File: transaction.c

int jbd2_journal_start_reserved(handle_t *handle, unsigned int type,
				unsigned int line_no)
{
	journal_t *journal = handle->h_journal;
	int ret = -EIO;

	if (WARN_ON(!handle->h_reserved)) {
		/* Someone passed in normal handle? Just stop it. */
		jbd2_journal_stop(handle);
		return ret;
	}
	/*
	 * Usefulness of mixing of reserved and unreserved handles is
	 * questionable. So far nobody seems to need it so just error out.
	 */
	if (WARN_ON(current->journal_info)) {
		jbd2_journal_free_reserved(handle);
		return ret;
	}

	handle->h_journal = NULL;
	/*
	 * GFP_NOFS is here because callers are likely from writeback or
	 * similarly constrained call sites
	 */
	ret = start_this_handle(journal, handle, GFP_NOFS);
	if (ret < 0) {
		handle->h_journal = journal;
		jbd2_journal_free_reserved(handle);
		return ret;
	}
	handle->h_type = type;
	handle->h_line_no = line_no;
	trace_jbd2_handle_start(journal->j_fs_dev->bd_dev,
				handle->h_transaction->t_tid, type,
				line_no, handle->h_total_credits);
	return 0;
}

Project: linux
File: transaction.c

static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
{
	J_ASSERT_JH(jh, jh->b_transaction != NULL);
	J_ASSERT_JH(jh, jh->b_next_transaction == NULL);

	__jbd2_journal_temp_unlink_buffer(jh);
	jh->b_transaction = NULL;
}

Project: linux
File: transaction.c

void jbd2_journal_set_triggers(struct buffer_head *bh,
			       struct jbd2_buffer_trigger_type *type)
{
	struct journal_head *jh = jbd2_journal_grab_journal_head(bh);

	if (WARN_ON_ONCE(!jh))
		return;
	jh->b_triggers = type;
	jbd2_journal_put_journal_head(jh);
}

Project: linux
File: transaction.c

__must_hold(&journal->j_state_lock)
{
	transaction_t *t = journal->j_running_transaction;
	int needed;
	int total = blocks + rsv_blocks;

	/*
	 * If the current transaction is locked down for commit, wait
	 * for the lock to be released.
	 */
	if (t->t_state != T_RUNNING) {
		WARN_ON_ONCE(t->t_state >= T_FLUSH);
		wait_transaction_locked(journal);
		__acquire(&journal->j_state_lock); /* fake out sparse */
		return 1;
	}

	/*
	 * If there is not enough space left in the log to write all
	 * potential buffers requested by this operation, we need to
	 * stall pending a log checkpoint to free some more log space.
	 */
	needed = atomic_add_return(total, &t->t_outstanding_credits);
	if (needed > journal->j_max_transaction_buffers) {
		/*
		 * If the current transaction is already too large,
		 * then start to commit it: we can then go back and
		 * attach this handle to a new transaction.
		 */
		atomic_sub(total, &t->t_outstanding_credits);

		/*
		 * Is the number of reserved credits in the current transaction too
		 * big to fit this handle? Wait until reserved credits are freed.
		 */
		if (atomic_read(&journal->j_reserved_credits) + total >
		    journal->j_max_transaction_buffers) {
			read_unlock(&journal->j_state_lock);
			jbd2_might_wait_for_commit(journal);
			wait_event(journal->j_wait_reserved,
				   atomic_read(&journal->j_reserved_credits) + total <=
				   journal->j_max_transaction_buffers);
			__acquire(&journal->j_state_lock); /* fake out sparse */
			return 1;
		}

		wait_transaction_locked(journal);
		__acquire(&journal->j_state_lock); /* fake out sparse */
		return 1;
	}

	/*
	 * The commit code assumes that it can get enough log space
	 * without forcing a checkpoint.  This is *critical* for
	 * correctness: a checkpoint of a buffer which is also
	 * associated with a committing transaction creates a deadlock,
	 * so commit simply cannot force through checkpoints.
	 *
	 * We must therefore ensure the necessary space in the journal
	 * *before* starting to dirty potentially checkpointed buffers
	 * in the new transaction.
	 */
	if (jbd2_log_space_left(journal) < journal->j_max_transaction_buffers) {
		atomic_sub(total, &t->t_outstanding_credits);
		read_unlock(&journal->j_state_lock);
		jbd2_might_wait_for_commit(journal);
		write_lock(&journal->j_state_lock);
		if (jbd2_log_space_left(journal) <
					journal->j_max_transaction_buffers)
			__jbd2_log_wait_for_space(journal);
		write_unlock(&journal->j_state_lock);
		__acquire(&journal->j_state_lock); /* fake out sparse */
		return 1;
	}

	/* No reservation? We are done... */
	if (!rsv_blocks)
		return 0;

	needed = atomic_add_return(rsv_blocks, &journal->j_reserved_credits);
	/* We allow at most half of a transaction to be reserved */
	if (needed > journal->j_max_transaction_buffers / 2) {
		sub_reserved_credits(journal, rsv_blocks);
		atomic_sub(total, &t->t_outstanding_credits);
		read_unlock(&journal->j_state_lock);
		jbd2_might_wait_for_commit(journal);
		wait_event(journal->j_wait_reserved,
			 atomic_read(&journal->j_reserved_credits) + rsv_blocks
			 <= journal->j_max_transaction_buffers / 2);
		__acquire(&journal->j_state_lock); /* fake out sparse */
		return 1;
	}
	return 0;
}

Project: linux
File: transaction.c

int jbd2_journal_get_create_access(handle_t *handle, struct buffer_head *bh)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal;
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
	int err;

	jbd_debug(5, "journal_head %p\n", jh);
	err = -EROFS;
	if (is_handle_aborted(handle))
		goto out;
	journal = transaction->t_journal;
	err = 0;

	JBUFFER_TRACE(jh, "entry");
	/*
	 * The buffer may already belong to this transaction due to pre-zeroing
	 * in the filesystem's new_block code.  It may also be on the previous,
	 * committing transaction's lists, but it HAS to be in Forget state in
	 * that case: the transaction must have deleted the buffer for it to be
	 * reused here.
	 */
	spin_lock(&jh->b_state_lock);
	J_ASSERT_JH(jh, (jh->b_transaction == transaction ||
		jh->b_transaction == NULL ||
		(jh->b_transaction == journal->j_committing_transaction &&
			  jh->b_jlist == BJ_Forget)));

	J_ASSERT_JH(jh, jh->b_next_transaction == NULL);
	J_ASSERT_JH(jh, buffer_locked(jh2bh(jh)));

	if (jh->b_transaction == NULL) {
		/*
		 * Previous jbd2_journal_forget() could have left the buffer
		 * with jbddirty bit set because it was being committed. When
		 * the commit finished, we've filed the buffer for
		 * checkpointing and marked it dirty. Now we are reallocating
		 * the buffer so the transaction freeing it must have
		 * committed and so it's safe to clear the dirty bit.
		 */
		clear_buffer_dirty(jh2bh(jh));
		/* first access by this transaction */
		jh->b_modified = 0;

		JBUFFER_TRACE(jh, "file as BJ_Reserved");
		spin_lock(&journal->j_list_lock);
		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
		spin_unlock(&journal->j_list_lock);
	} else if (jh->b_transaction == journal->j_committing_transaction) {
		/* first access by this transaction */
		jh->b_modified = 0;

		JBUFFER_TRACE(jh, "set next transaction");
		spin_lock(&journal->j_list_lock);
		jh->b_next_transaction = transaction;
		spin_unlock(&journal->j_list_lock);
	}
	spin_unlock(&jh->b_state_lock);

	/*
	 * akpm: I added this.  ext3_alloc_branch can pick up new indirect
	 * blocks which contain freed but then revoked metadata.  We need
	 * to cancel the revoke in case we end up freeing it yet again
	 * and the reallocating as data - this would cause a second revoke,
	 * which hits an assertion error.
	 */
	JBUFFER_TRACE(jh, "cancelling revoke");
	jbd2_journal_cancel_revoke(handle, jh);
out:
	jbd2_journal_put_journal_head(jh);
	return err;
}

Project: linux
File: transaction.c

int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
{
	struct journal_head *jh;
	int rc;

	if (is_handle_aborted(handle))
		return -EROFS;

	if (jbd2_write_access_granted(handle, bh, false))
		return 0;

	jh = jbd2_journal_add_journal_head(bh);
	/* We do not want to get caught playing with fields which the
	 * log thread also manipulates.  Make sure that the buffer
	 * completes any outstanding IO before proceeding. */
	rc = do_get_write_access(handle, jh, 0);
	jbd2_journal_put_journal_head(jh);
	return rc;
}

Project: linux
File: transaction.c

int jbd2_journal_try_to_free_buffers(journal_t *journal, struct page *page)
{
	struct buffer_head *head;
	struct buffer_head *bh;
	int ret = 0;

	J_ASSERT(PageLocked(page));

	head = page_buffers(page);
	bh = head;
	do {
		struct journal_head *jh;

		/*
		 * We take our own ref against the journal_head here to avoid
		 * having to add tons of locking around each instance of
		 * jbd2_journal_put_journal_head().
		 */
		jh = jbd2_journal_grab_journal_head(bh);
		if (!jh)
			continue;

		spin_lock(&jh->b_state_lock);
		__journal_try_to_free_buffer(journal, bh);
		spin_unlock(&jh->b_state_lock);
		jbd2_journal_put_journal_head(jh);
		if (buffer_jbd(bh))
			goto busy;
	} while ((bh = bh->b_this_page) != head);

	ret = try_to_free_buffers(page);
busy:
	return ret;
}

Project: linux
File: transaction.c

static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
{
	struct journal_head **list = NULL;
	transaction_t *transaction;
	struct buffer_head *bh = jh2bh(jh);

	lockdep_assert_held(&jh->b_state_lock);
	transaction = jh->b_transaction;
	if (transaction)
		assert_spin_locked(&transaction->t_journal->j_list_lock);

	J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
	if (jh->b_jlist != BJ_None)
		J_ASSERT_JH(jh, transaction != NULL);

	switch (jh->b_jlist) {
	case BJ_None:
		return;
	case BJ_Metadata:
		transaction->t_nr_buffers--;
		J_ASSERT_JH(jh, transaction->t_nr_buffers >= 0);
		list = &transaction->t_buffers;
		break;
	case BJ_Forget:
		list = &transaction->t_forget;
		break;
	case BJ_Shadow:
		list = &transaction->t_shadow_list;
		break;
	case BJ_Reserved:
		list = &transaction->t_reserved_list;
		break;
	}

	__blist_del_buffer(list, jh);
	jh->b_jlist = BJ_None;
	if (transaction && is_journal_aborted(transaction->t_journal))
		clear_buffer_jbddirty(bh);
	else if (test_clear_buffer_jbddirty(bh))
		mark_buffer_dirty(bh);	/* Expose it to the VM */
}

Project: linux
File: transaction.c

	__releases(journal->j_state_lock)
{
	DEFINE_WAIT(wait);

	if (WARN_ON(!journal->j_running_transaction ||
		    journal->j_running_transaction->t_state != T_SWITCH)) {
		read_unlock(&journal->j_state_lock);
		return;
	}
	prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
			TASK_UNINTERRUPTIBLE);
	read_unlock(&journal->j_state_lock);
	/*
	 * We don't call jbd2_might_wait_for_commit() here as there's no
	 * waiting for outstanding handles happening anymore in T_SWITCH state
	 * and handling of reserved handles actually relies on that for
	 * correctness.
	 */
	schedule();
	finish_wait(&journal->j_wait_transaction_locked, &wait);
}

Project: linux
File: transaction.c

int jbd2_journal_restart(handle_t *handle, int nblocks)
{
	return jbd2__journal_restart(handle, nblocks, 0, GFP_NOFS);
}

Project: linux
File: transaction.c

int jbd2_journal_stop(handle_t *handle)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal;
	int err = 0, wait_for_commit = 0;
	tid_t tid;
	pid_t pid;

	if (--handle->h_ref > 0) {
		jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
						 handle->h_ref);
		if (is_handle_aborted(handle))
			return -EIO;
		return 0;
	}
	if (!transaction) {
		/*
		 * Handle is already detached from the transaction so there is
		 * nothing to do other than free the handle.
		 */
		memalloc_nofs_restore(handle->saved_alloc_context);
		goto free_and_exit;
	}
	journal = transaction->t_journal;
	tid = transaction->t_tid;

	if (is_handle_aborted(handle))
		err = -EIO;

	jbd_debug(4, "Handle %p going down\n", handle);
	trace_jbd2_handle_stats(journal->j_fs_dev->bd_dev,
				tid, handle->h_type, handle->h_line_no,
				jiffies - handle->h_start_jiffies,
				handle->h_sync, handle->h_requested_credits,
				(handle->h_requested_credits -
				 handle->h_total_credits));

	/*
	 * Implement synchronous transaction batching.  If the handle
	 * was synchronous, don't force a commit immediately.  Let's
	 * yield and let another thread piggyback onto this
	 * transaction.  Keep doing that while new threads continue to
	 * arrive.  It doesn't cost much - we're about to run a commit
	 * and sleep on IO anyway.  Speeds up many-threaded, many-dir
	 * operations by 30x or more...
	 *
	 * We try and optimize the sleep time against what the
	 * underlying disk can do, instead of having a static sleep
	 * time.  This is useful for the case where our storage is so
	 * fast that it is more optimal to go ahead and force a flush
	 * and wait for the transaction to be committed than it is to
	 * wait for an arbitrary amount of time for new writers to
	 * join the transaction.  We achieve this by measuring how
	 * long it takes to commit a transaction, and compare it with
	 * how long this transaction has been running, and if run time
	 * < commit time then we sleep for the delta and commit.  This
	 * greatly helps super fast disks that would see slowdowns as
	 * more threads started doing fsyncs.
	 *
	 * But don't do this if this process was the most recent one
	 * to perform a synchronous write.  We do this to detect the
	 * case where a single process is doing a stream of sync
	 * writes.  No point in waiting for joiners in that case.
	 *
	 * Setting max_batch_time to 0 disables this completely.
	 */
	pid = current->pid;
	if (handle->h_sync && journal->j_last_sync_writer != pid &&
	    journal->j_max_batch_time) {
		u64 commit_time, trans_time;

		journal->j_last_sync_writer = pid;

		read_lock(&journal->j_state_lock);
		commit_time = journal->j_average_commit_time;
		read_unlock(&journal->j_state_lock);

		trans_time = ktime_to_ns(ktime_sub(ktime_get(),
						   transaction->t_start_time));

		commit_time = max_t(u64, commit_time,
				    1000*journal->j_min_batch_time);
		commit_time = min_t(u64, commit_time,
				    1000*journal->j_max_batch_time);

		if (trans_time < commit_time) {
			ktime_t expires = ktime_add_ns(ktime_get(),
						       commit_time);
			set_current_state(TASK_UNINTERRUPTIBLE);
			schedule_hrtimeout(&expires, HRTIMER_MODE_ABS);
		}
	}

	if (handle->h_sync)
		transaction->t_synchronous_commit = 1;

	/*
	 * If the handle is marked SYNC, we need to set another commit
	 * going!  We also want to force a commit if the transaction is too
	 * old now.
	 */
	if (handle->h_sync ||
	    time_after_eq(jiffies, transaction->t_expires)) {
		/* Do this even for aborted journals: an abort still
		 * completes the commit thread, it just doesn't write
		 * anything to disk. */

		jbd_debug(2, "transaction too old, requesting commit for "
					"handle %p\n", handle);
		/* This is non-blocking */
		jbd2_log_start_commit(journal, tid);

		/*
		 * Special case: JBD2_SYNC synchronous updates require us
		 * to wait for the commit to complete.
		 */
		if (handle->h_sync && !(current->flags & PF_MEMALLOC))
			wait_for_commit = 1;
	}

	/*
	 * Once stop_this_handle() drops t_updates, the transaction could start
	 * committing on us and eventually disappear.  So we must not
	 * dereference transaction pointer again after calling
	 * stop_this_handle().
	 */
	stop_this_handle(handle);

	if (wait_for_commit)
		err = jbd2_log_wait_commit(journal, tid);

free_and_exit:
	if (handle->h_rsv_handle)
		jbd2_free_handle(handle->h_rsv_handle);
	jbd2_free_handle(handle);
	return err;
}

Project: linux
File: transaction.c

void jbd2_journal_unfile_buffer(journal_t *journal, struct journal_head *jh)
{
	struct buffer_head *bh = jh2bh(jh);

	/* Get reference so that buffer cannot be freed before we unlock it */
	get_bh(bh);
	spin_lock(&jh->b_state_lock);
	spin_lock(&journal->j_list_lock);
	__jbd2_journal_unfile_buffer(jh);
	spin_unlock(&journal->j_list_lock);
	spin_unlock(&jh->b_state_lock);
	jbd2_journal_put_journal_head(jh);
	__brelse(bh);
}

Project: linux
File: transaction.c

static int __dispose_buffer(struct journal_head *jh, transaction_t *transaction)
{
	int may_free = 1;
	struct buffer_head *bh = jh2bh(jh);

	if (jh->b_cp_transaction) {
		JBUFFER_TRACE(jh, "on running+cp transaction");
		__jbd2_journal_temp_unlink_buffer(jh);
		/*
		 * We don't want to write the buffer anymore, clear the
		 * bit so that we don't confuse checks in
		 * __journal_file_buffer
		 */
		clear_buffer_dirty(bh);
		__jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
		may_free = 0;
	} else {
		JBUFFER_TRACE(jh, "on running transaction");
		__jbd2_journal_unfile_buffer(jh);
		jbd2_journal_put_journal_head(jh);
	}
	return may_free;
}

Project: linux
File: transaction.c

void jbd2_journal_refile_buffer(journal_t *journal, struct journal_head *jh)
{
	bool drop;

	spin_lock(&jh->b_state_lock);
	spin_lock(&journal->j_list_lock);
	drop = __jbd2_journal_refile_buffer(jh);
	spin_unlock(&jh->b_state_lock);
	spin_unlock(&journal->j_list_lock);
	if (drop)
		jbd2_journal_put_journal_head(jh);
}

Project: linux
File: transaction.c

int jbd2__journal_restart(handle_t *handle, int nblocks, int revoke_records,
			  gfp_t gfp_mask)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal;
	tid_t		tid;
	int		need_to_start;
	int		ret;

	/* If we've had an abort of any type, don't even think about
	 * actually doing the restart! */
	if (is_handle_aborted(handle))
		return 0;
	journal = transaction->t_journal;
	tid = transaction->t_tid;

	/*
	 * First unlink the handle from its current transaction, and start the
	 * commit on that.
	 */
	jbd_debug(2, "restarting handle %p\n", handle);
	stop_this_handle(handle);
	handle->h_transaction = NULL;

	/*
	 * TODO: If we use READ_ONCE / WRITE_ONCE for j_commit_request we can
 	 * get rid of pointless j_state_lock traffic like this.
	 */
	read_lock(&journal->j_state_lock);
	need_to_start = !tid_geq(journal->j_commit_request, tid);
	read_unlock(&journal->j_state_lock);
	if (need_to_start)
		jbd2_log_start_commit(journal, tid);
	handle->h_total_credits = nblocks +
		DIV_ROUND_UP(revoke_records,
			     journal->j_revoke_records_per_block);
	handle->h_revoke_credits = revoke_records;
	ret = start_this_handle(journal, handle, gfp_mask);
	trace_jbd2_handle_restart(journal->j_fs_dev->bd_dev,
				 ret ? 0 : handle->h_transaction->t_tid,
				 handle->h_type, handle->h_line_no,
				 handle->h_total_credits);
	return ret;
}

Project: linux
File: transaction.c

void __jbd2_journal_file_buffer(struct journal_head *jh,
			transaction_t *transaction, int jlist)
{
	struct journal_head **list = NULL;
	int was_dirty = 0;
	struct buffer_head *bh = jh2bh(jh);

	lockdep_assert_held(&jh->b_state_lock);
	assert_spin_locked(&transaction->t_journal->j_list_lock);

	J_ASSERT_JH(jh, jh->b_jlist < BJ_Types);
	J_ASSERT_JH(jh, jh->b_transaction == transaction ||
				jh->b_transaction == NULL);

	if (jh->b_transaction && jh->b_jlist == jlist)
		return;

	if (jlist == BJ_Metadata || jlist == BJ_Reserved ||
	    jlist == BJ_Shadow || jlist == BJ_Forget) {
		/*
		 * For metadata buffers, we track dirty bit in buffer_jbddirty
		 * instead of buffer_dirty. We should not see a dirty bit set
		 * here because we clear it in do_get_write_access but e.g.
		 * tune2fs can modify the sb and set the dirty bit at any time
		 * so we try to gracefully handle that.
		 */
		if (buffer_dirty(bh))
			warn_dirty_buffer(bh);
		if (test_clear_buffer_dirty(bh) ||
		    test_clear_buffer_jbddirty(bh))
			was_dirty = 1;
	}

	if (jh->b_transaction)
		__jbd2_journal_temp_unlink_buffer(jh);
	else
		jbd2_journal_grab_journal_head(bh);
	jh->b_transaction = transaction;

	switch (jlist) {
	case BJ_None:
		J_ASSERT_JH(jh, !jh->b_committed_data);
		J_ASSERT_JH(jh, !jh->b_frozen_data);
		return;
	case BJ_Metadata:
		transaction->t_nr_buffers++;
		list = &transaction->t_buffers;
		break;
	case BJ_Forget:
		list = &transaction->t_forget;
		break;
	case BJ_Shadow:
		list = &transaction->t_shadow_list;
		break;
	case BJ_Reserved:
		list = &transaction->t_reserved_list;
		break;
	}

	__blist_add_buffer(list, jh);
	jh->b_jlist = jlist;

	if (was_dirty)
		set_buffer_jbddirty(bh);
}

Project: linux
File: transaction.c

void jbd2_journal_lock_updates(journal_t *journal)
{
	jbd2_might_wait_for_commit(journal);

	write_lock(&journal->j_state_lock);
	++journal->j_barrier_count;

	/* Wait until there are no reserved handles */
	if (atomic_read(&journal->j_reserved_credits)) {
		write_unlock(&journal->j_state_lock);
		wait_event(journal->j_wait_reserved,
			   atomic_read(&journal->j_reserved_credits) == 0);
		write_lock(&journal->j_state_lock);
	}

	/* Wait until there are no running t_updates */
	jbd2_journal_wait_updates(journal);

	write_unlock(&journal->j_state_lock);

	/*
	 * We have now established a barrier against other normal updates, but
	 * we also need to barrier against other jbd2_journal_lock_updates() calls
	 * to make sure that we serialise special journal-locked operations
	 * too.
	 */
	mutex_lock(&journal->j_barrier);
}

Project: linux
File: transaction.c

static handle_t *new_handle(int nblocks)
{
	handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
	if (!handle)
		return NULL;
	handle->h_total_credits = nblocks;
	handle->h_ref = 1;

	return handle;
}

Project: linux
File: transaction.c

void jbd2_journal_free_reserved(handle_t *handle)
{
	journal_t *journal = handle->h_journal;

	/* Get j_state_lock to pin running transaction if it exists */
	read_lock(&journal->j_state_lock);
	__jbd2_journal_unreserve_handle(handle, journal->j_running_transaction);
	read_unlock(&journal->j_state_lock);
	jbd2_free_handle(handle);
}

Project: linux
File: transaction.c

int jbd2_journal_forget(handle_t *handle, struct buffer_head *bh)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal;
	struct journal_head *jh;
	int drop_reserve = 0;
	int err = 0;
	int was_modified = 0;

	if (is_handle_aborted(handle))
		return -EROFS;
	journal = transaction->t_journal;

	BUFFER_TRACE(bh, "entry");

	jh = jbd2_journal_grab_journal_head(bh);
	if (!jh) {
		__bforget(bh);
		return 0;
	}

	spin_lock(&jh->b_state_lock);

	/* Critical error: attempting to delete a bitmap buffer, maybe?
	 * Don't do any jbd operations, and return an error. */
	if (!J_EXPECT_JH(jh, !jh->b_committed_data,
			 "inconsistent data on disk")) {
		err = -EIO;
		goto drop;
	}

	/* keep track of whether or not this transaction modified us */
	was_modified = jh->b_modified;

	/*
	 * The buffer's going from the transaction, we must drop
	 * all references -bzzz
	 */
	jh->b_modified = 0;

	if (jh->b_transaction == transaction) {
		J_ASSERT_JH(jh, !jh->b_frozen_data);

		/* If we are forgetting a buffer which is already part
		 * of this transaction, then we can just drop it from
		 * the transaction immediately. */
		clear_buffer_dirty(bh);
		clear_buffer_jbddirty(bh);

		JBUFFER_TRACE(jh, "belongs to current transaction: unfile");

		/*
		 * we only want to drop a reference if this transaction
		 * modified the buffer
		 */
		if (was_modified)
			drop_reserve = 1;

		/*
		 * We are no longer going to journal this buffer.
		 * However, the commit of this transaction is still
		 * important to the buffer: the delete that we are now
		 * processing might obsolete an old log entry, so by
		 * committing, we can satisfy the buffer's checkpoint.
		 *
		 * So, if we have a checkpoint on the buffer, we should
		 * now refile the buffer on our BJ_Forget list so that
		 * we know to remove the checkpoint after we commit.
		 */

		spin_lock(&journal->j_list_lock);
		if (jh->b_cp_transaction) {
			__jbd2_journal_temp_unlink_buffer(jh);
			__jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
		} else {
			__jbd2_journal_unfile_buffer(jh);
			jbd2_journal_put_journal_head(jh);
		}
		spin_unlock(&journal->j_list_lock);
	} else if (jh->b_transaction) {
		J_ASSERT_JH(jh, (jh->b_transaction ==
				 journal->j_committing_transaction));
		/* However, if the buffer is still owned by a prior
		 * (committing) transaction, we can't drop it yet... */
		JBUFFER_TRACE(jh, "belongs to older transaction");
		/* ... but we CAN drop it from the new transaction through
		 * marking the buffer as freed and set j_next_transaction to
		 * the new transaction, so that not only the commit code
		 * knows it should clear dirty bits when it is done with the
		 * buffer, but also the buffer can be checkpointed only
		 * after the new transaction commits. */

		set_buffer_freed(bh);

		if (!jh->b_next_transaction) {
			spin_lock(&journal->j_list_lock);
			jh->b_next_transaction = transaction;
			spin_unlock(&journal->j_list_lock);
		} else {
			J_ASSERT(jh->b_next_transaction == transaction);

			/*
			 * only drop a reference if this transaction modified
			 * the buffer
			 */
			if (was_modified)
				drop_reserve = 1;
		}
	} else {
		/*
		 * Finally, if the buffer is not belongs to any
		 * transaction, we can just drop it now if it has no
		 * checkpoint.
		 */
		spin_lock(&journal->j_list_lock);
		if (!jh->b_cp_transaction) {
			JBUFFER_TRACE(jh, "belongs to none transaction");
			spin_unlock(&journal->j_list_lock);
			goto drop;
		}

		/*
		 * Otherwise, if the buffer has been written to disk,
		 * it is safe to remove the checkpoint and drop it.
		 */
		if (!buffer_dirty(bh)) {
			__jbd2_journal_remove_checkpoint(jh);
			spin_unlock(&journal->j_list_lock);
			goto drop;
		}

		/*
		 * The buffer is still not written to disk, we should
		 * attach this buffer to current transaction so that the
		 * buffer can be checkpointed only after the current
		 * transaction commits.
		 */
		clear_buffer_dirty(bh);
		__jbd2_journal_file_buffer(jh, transaction, BJ_Forget);
		spin_unlock(&journal->j_list_lock);
	}
drop:
	__brelse(bh);
	spin_unlock(&jh->b_state_lock);
	jbd2_journal_put_journal_head(jh);
	if (drop_reserve) {
		/* no need to reserve log space for this block -bzzz */
		handle->h_total_credits++;
	}
	return err;
}

Project: linux
File: transaction.c

bool __jbd2_journal_refile_buffer(struct journal_head *jh)
{
	int was_dirty, jlist;
	struct buffer_head *bh = jh2bh(jh);

	lockdep_assert_held(&jh->b_state_lock);
	if (jh->b_transaction)
		assert_spin_locked(&jh->b_transaction->t_journal->j_list_lock);

	/* If the buffer is now unused, just drop it. */
	if (jh->b_next_transaction == NULL) {
		__jbd2_journal_unfile_buffer(jh);
		return true;
	}

	/*
	 * It has been modified by a later transaction: add it to the new
	 * transaction's metadata list.
	 */

	was_dirty = test_clear_buffer_jbddirty(bh);
	__jbd2_journal_temp_unlink_buffer(jh);

	/*
	 * b_transaction must be set, otherwise the new b_transaction won't
	 * be holding jh reference
	 */
	J_ASSERT_JH(jh, jh->b_transaction != NULL);

	/*
	 * We set b_transaction here because b_next_transaction will inherit
	 * our jh reference and thus __jbd2_journal_file_buffer() must not
	 * take a new one.
	 */
	WRITE_ONCE(jh->b_transaction, jh->b_next_transaction);
	WRITE_ONCE(jh->b_next_transaction, NULL);
	if (buffer_freed(bh))
		jlist = BJ_Forget;
	else if (jh->b_modified)
		jlist = BJ_Metadata;
	else
		jlist = BJ_Reserved;
	__jbd2_journal_file_buffer(jh, jh->b_transaction, jlist);
	J_ASSERT_JH(jh, jh->b_transaction->t_state == T_RUNNING);

	if (was_dirty)
		set_buffer_jbddirty(bh);
	return false;
}

Project: linux
File: transaction.c

void jbd2_journal_destroy_transaction_cache(void)
{
	kmem_cache_destroy(transaction_cache);
	transaction_cache = NULL;
}

Project: linux
File: transaction.c

static void sub_reserved_credits(journal_t *journal, int blocks)
{
	atomic_sub(blocks, &journal->j_reserved_credits);
	wake_up(&journal->j_wait_reserved);
}

Project: linux
File: transaction.c

int jbd2_journal_inode_ranged_wait(handle_t *handle, struct jbd2_inode *jinode,
		loff_t start_byte, loff_t length)
{
	return jbd2_journal_file_inode(handle, jinode, JI_WAIT_DATA,
			start_byte, start_byte + length - 1);
}

Project: linux
File: transaction.c

static void stop_this_handle(handle_t *handle)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;
	int revokes;

	J_ASSERT(journal_current_handle() == handle);
	J_ASSERT(atomic_read(&transaction->t_updates) > 0);
	current->journal_info = NULL;
	/*
	 * Subtract necessary revoke descriptor blocks from handle credits. We
	 * take care to account only for revoke descriptor blocks the
	 * transaction will really need as large sequences of transactions with
	 * small numbers of revokes are relatively common.
	 */
	revokes = handle->h_revoke_credits_requested - handle->h_revoke_credits;
	if (revokes) {
		int t_revokes, revoke_descriptors;
		int rr_per_blk = journal->j_revoke_records_per_block;

		WARN_ON_ONCE(DIV_ROUND_UP(revokes, rr_per_blk)
				> handle->h_total_credits);
		t_revokes = atomic_add_return(revokes,
				&transaction->t_outstanding_revokes);
		revoke_descriptors =
			DIV_ROUND_UP(t_revokes, rr_per_blk) -
			DIV_ROUND_UP(t_revokes - revokes, rr_per_blk);
		handle->h_total_credits -= revoke_descriptors;
	}
	atomic_sub(handle->h_total_credits,
		   &transaction->t_outstanding_credits);
	if (handle->h_rsv_handle)
		__jbd2_journal_unreserve_handle(handle->h_rsv_handle,
						transaction);
	if (atomic_dec_and_test(&transaction->t_updates))
		wake_up(&journal->j_wait_updates);

	rwsem_release(&journal->j_trans_commit_map, _THIS_IP_);
	/*
	 * Scope of the GFP_NOFS context is over here and so we can restore the
	 * original alloc context.
	 */
	memalloc_nofs_restore(handle->saved_alloc_context);
}

Project: linux
File: transaction.c

static void jbd2_get_transaction(journal_t *journal,
				transaction_t *transaction)
{
	transaction->t_journal = journal;
	transaction->t_state = T_RUNNING;
	transaction->t_start_time = ktime_get();
	transaction->t_tid = journal->j_transaction_sequence++;
	transaction->t_expires = jiffies + journal->j_commit_interval;
	spin_lock_init(&transaction->t_handle_lock);
	atomic_set(&transaction->t_updates, 0);
	atomic_set(&transaction->t_outstanding_credits,
		   jbd2_descriptor_blocks_per_trans(journal) +
		   atomic_read(&journal->j_reserved_credits));
	atomic_set(&transaction->t_outstanding_revokes, 0);
	atomic_set(&transaction->t_handle_count, 0);
	INIT_LIST_HEAD(&transaction->t_inode_list);
	INIT_LIST_HEAD(&transaction->t_private_list);

	/* Set up the commit timer for the new transaction. */
	journal->j_commit_timer.expires = round_jiffies_up(transaction->t_expires);
	add_timer(&journal->j_commit_timer);

	J_ASSERT(journal->j_running_transaction == NULL);
	journal->j_running_transaction = transaction;
	transaction->t_max_wait = 0;
	transaction->t_start = jiffies;
	transaction->t_requested = 0;
}

Project: linux
File: transaction.c

handle_t *jbd2_journal_start(journal_t *journal, int nblocks)
{
	return jbd2__journal_start(journal, nblocks, 0, 0, GFP_NOFS, 0, 0);
}