Commit message: jbd2: clear BH_Delay & BH_Unwritten in journal_unmap_buffer

journal_unmap_buffer()'s zap_buffer: code clears a lot of buffer head
state ala discard_buffer(), but does not touch _Delay or _Unwritten as
discard_buffer() does.

This can be problematic in some areas of the ext4 code which assume
that if they have found a buffer marked unwritten or delay, then it's
a live one.  Perhaps those spots should check whether it is mapped
as well, but if jbd2 is going to tear down a buffer, let's really
tear it down completely.

Without this I get some fsx failures on sub-page-block filesystems
up until v3.2, at which point 4e96b2dbbf1d7e81f22047a50f862555a6cb87cb
and 189e868fa8fdca702eb9db9d8afc46b5cb9144c9 make the failures go
away, because buried within that large change is some more flag
clearing.  I still think it's worth doing in jbd2, since
->invalidatepage leads here directly, and it's the right place
to clear away these flags.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
CVE: CVE-2011-4086
CWE: CWE-119
Vulnerability description: The journal_unmap_buffer function in fs/jbd2/transaction.c in the Linux kernel before 3.3.1 does not properly handle the _Delay and _Unwritten buffer head states, which allows local users to cause a denial of service (system crash) by leveraging the presence of an ext4 filesystem that was mounted with a journal.

Project: linux
File: transaction.c

__blist_add_buffer(struct journal_head **list, struct journal_head *jh)
{
	if (!*list) {
		jh->b_tnext = jh->b_tprev = jh;
		*list = jh;
	} else {
		/* Insert at the tail of the list to preserve order */
		struct journal_head *first = *list, *last = first->b_tprev;
		jh->b_tprev = last;
		jh->b_tnext = first;
		last->b_tnext = first->b_tprev = jh;
	}
}

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);
	}
	return may_free;
}

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);

	J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
	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_IO:
		list = &transaction->t_iobuf_list;
		break;
	case BJ_Shadow:
		list = &transaction->t_shadow_list;
		break;
	case BJ_LogCtl:
		list = &transaction->t_log_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_refile_buffer(struct journal_head *jh)
{
	int was_dirty, jlist;
	struct buffer_head *bh = jh2bh(jh);

	J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
	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;
	}

	/*
	 * 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);
	/*
	 * 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.
	 */
	jh->b_transaction = jh->b_next_transaction;
	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);
}

Project: linux
File: transaction.c

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

	J_ASSERT_JH(jh, jbd_is_locked_bh_state(bh));
	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_IO:
		list = &transaction->t_iobuf_list;
		break;
	case BJ_Shadow:
		list = &transaction->t_shadow_list;
		break;
	case BJ_LogCtl:
		list = &transaction->t_log_list;
		break;
	case BJ_Reserved:
		list = &transaction->t_reserved_list;
		break;
	}

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

Project: linux
File: transaction.c

static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
{
	__jbd2_journal_temp_unlink_buffer(jh);
	jh->b_transaction = NULL;
	jbd2_journal_put_journal_head(jh);
}

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)
		goto out;

	spin_lock(&journal->j_list_lock);
	if (jh->b_cp_transaction != NULL && jh->b_transaction == NULL) {
		/* written-back checkpointed metadata buffer */
		if (jh->b_jlist == BJ_None) {
			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

do_get_write_access(handle_t *handle, struct journal_head *jh,
			int force_copy)
{
	struct buffer_head *bh;
	transaction_t *transaction;
	journal_t *journal;
	int error;
	char *frozen_buffer = NULL;
	int need_copy = 0;

	if (is_handle_aborted(handle))
		return -EROFS;

	transaction = handle->h_transaction;
	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. */

	lock_buffer(bh);
	jbd_lock_bh_state(bh);

	/* 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)) {
		jbd_unlock_bh_state(bh);
		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 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);
		jh->b_next_transaction = transaction;
		goto done;
	}

	/* Is there data here we need to preserve? */

	if (jh->b_transaction && jh->b_transaction != transaction) {
		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 (jh->b_jlist == BJ_Shadow) {
			DEFINE_WAIT_BIT(wait, &bh->b_state, BH_Unshadow);
			wait_queue_head_t *wqh;

			wqh = bit_waitqueue(&bh->b_state, BH_Unshadow);

			JBUFFER_TRACE(jh, "on shadow: sleep");
			jbd_unlock_bh_state(bh);
			/* commit wakes up all shadow buffers after IO */
			for ( ; ; ) {
				prepare_to_wait(wqh, &wait.wait,
						TASK_UNINTERRUPTIBLE);
				if (jh->b_jlist != BJ_Shadow)
					break;
				schedule();
			}
			finish_wait(wqh, &wait.wait);
			goto repeat;
		}

		/* Only do the copy if the currently-owning transaction
		 * still needs it.  If it is on the Forget list, the
		 * committing transaction is past that stage.  The
		 * buffer had better remain locked during the kmalloc,
		 * but that should be true --- we hold the journal lock
		 * still and the buffer is already on the BUF_JOURNAL
		 * list so won't be flushed.
		 *
		 * 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_Forget || force_copy) {
			JBUFFER_TRACE(jh, "generate frozen data");
			if (!frozen_buffer) {
				JBUFFER_TRACE(jh, "allocate memory for buffer");
				jbd_unlock_bh_state(bh);
				frozen_buffer =
					jbd2_alloc(jh2bh(jh)->b_size,
							 GFP_NOFS);
				if (!frozen_buffer) {
					printk(KERN_EMERG
					       "%s: OOM for frozen_buffer\n",
					       __func__);
					JBUFFER_TRACE(jh, "oom!");
					error = -ENOMEM;
					jbd_lock_bh_state(bh);
					goto done;
				}
				goto repeat;
			}
			jh->b_frozen_data = frozen_buffer;
			frozen_buffer = NULL;
			need_copy = 1;
		}
		jh->b_next_transaction = transaction;
	}


	/*
	 * Finally, 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");
		spin_lock(&journal->j_list_lock);
		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
		spin_unlock(&journal->j_list_lock);
	}

done:
	if (need_copy) {
		struct page *page;
		int offset;
		char *source;

		J_EXPECT_JH(jh, buffer_uptodate(jh2bh(jh)),
			    "Possible IO failure.\n");
		page = jh2bh(jh)->b_page;
		offset = offset_in_page(jh2bh(jh)->b_data);
		source = kmap_atomic(page, KM_USER0);
		/* 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, jh2bh(jh)->b_size);
		kunmap_atomic(source, KM_USER0);

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

	/*
	 * 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

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

	/*
	 * First unlink the handle from its current transaction, and start the
	 * commit on that.
	 */
	J_ASSERT(atomic_read(&transaction->t_updates) > 0);
	J_ASSERT(journal_current_handle() == handle);

	read_lock(&journal->j_state_lock);
	spin_lock(&transaction->t_handle_lock);
	atomic_sub(handle->h_buffer_credits,
		   &transaction->t_outstanding_credits);
	if (atomic_dec_and_test(&transaction->t_updates))
		wake_up(&journal->j_wait_updates);
	spin_unlock(&transaction->t_handle_lock);

	jbd_debug(2, "restarting handle %p\n", handle);
	tid = transaction->t_tid;
	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);

	lock_map_release(&handle->h_lockdep_map);
	handle->h_buffer_credits = nblocks;
	ret = start_this_handle(journal, handle, gfp_mask);
	return ret;
}

Project: linux
File: transaction.c

handle_t *jbd2__journal_start(journal_t *journal, int nblocks, gfp_t gfp_mask)
{
	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;
	}

	handle = new_handle(nblocks);
	if (!handle)
		return ERR_PTR(-ENOMEM);

	current->journal_info = handle;

	err = start_this_handle(journal, handle, gfp_mask);
	if (err < 0) {
		jbd2_free_handle(handle);
		current->journal_info = NULL;
		handle = ERR_PTR(err);
	}
	return handle;
}

Project: linux
File: transaction.c

void jbd2_buffer_frozen_trigger(struct journal_head *jh, void *mapped_data,
				struct jbd2_buffer_trigger_type *triggers)
{
	struct buffer_head *bh = jh2bh(jh);

	if (!triggers || !triggers->t_frozen)
		return;

	triggers->t_frozen(triggers, bh, mapped_data, bh->b_size);
}

Project: linux
File: transaction.c

int jbd2_journal_begin_ordered_truncate(journal_t *journal,
					struct jbd2_inode *jinode,
					loff_t new_size)
{
	transaction_t *inode_trans, *commit_trans;
	int ret = 0;

	/* This is a quick check to avoid locking if not necessary */
	if (!jinode->i_transaction)
		goto out;
	/* Locks are here just to force reading of recent values, it is
	 * enough that the transaction was not committing before we started
	 * a transaction adding the inode to orphan list */
	read_lock(&journal->j_state_lock);
	commit_trans = journal->j_committing_transaction;
	read_unlock(&journal->j_state_lock);
	spin_lock(&journal->j_list_lock);
	inode_trans = jinode->i_transaction;
	spin_unlock(&journal->j_list_lock);
	if (inode_trans == commit_trans) {
		ret = filemap_fdatawrite_range(jinode->i_vfs_inode->i_mapping,
			new_size, LLONG_MAX);
		if (ret)
			jbd2_journal_abort(journal, ret);
	}
out:
	return ret;
}

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 = transaction->t_journal;
	struct journal_head *jh = bh2jh(bh);
	int ret = 0;

	jbd_debug(5, "journal_head %p\n", jh);
	JBUFFER_TRACE(jh, "entry");
	if (is_handle_aborted(handle))
		goto out;
	if (!buffer_jbd(bh)) {
		ret = -EUCLEAN;
		goto out;
	}

	jbd_lock_bh_state(bh);

	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
		 */
		jh->b_modified = 1;
		J_ASSERT_JH(jh, handle->h_buffer_credits > 0);
		handle->h_buffer_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_EMERG "JBD: %s: "
			       "jh->b_transaction (%llu, %p, %u) != "
			       "journal->j_running_transaction (%p, %u)",
			       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)) {
			printk(KERN_EMERG "JBD: %s: "
			       "jh->b_transaction (%llu, %p, %u) != "
			       "journal->j_committing_transaction (%p, %u)",
			       journal->j_devname,
			       (unsigned long long) bh->b_blocknr,
			       jh->b_transaction,
			       jh->b_transaction ? jh->b_transaction->t_tid : 0,
			       journal->j_committing_transaction,
			       journal->j_committing_transaction ?
			       journal->j_committing_transaction->t_tid : 0);
			ret = -EINVAL;
		}
		if (unlikely(jh->b_next_transaction != transaction)) {
			printk(KERN_EMERG "JBD: %s: "
			       "jh->b_next_transaction (%llu, %p, %u) != "
			       "transaction (%p, %u)",
			       journal->j_devname,
			       (unsigned long long) bh->b_blocknr,
			       jh->b_next_transaction,
			       jh->b_next_transaction ?
			       jh->b_next_transaction->t_tid : 0,
			       transaction, transaction->t_tid);
			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, handle->h_transaction, BJ_Metadata);
	spin_unlock(&journal->j_list_lock);
out_unlock_bh:
	jbd_unlock_bh_state(bh);
out:
	JBUFFER_TRACE(jh, "exit");
	WARN_ON(ret);	/* All errors are bugs, so dump the stack */
	return ret;
}

Project: linux
File: transaction.c

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

	result = -EIO;
	if (is_handle_aborted(handle))
		goto out;

	result = 1;

	read_lock(&journal->j_state_lock);

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

	spin_lock(&transaction->t_handle_lock);
	wanted = atomic_read(&transaction->t_outstanding_credits) + nblocks;

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

	if (wanted > __jbd2_log_space_left(journal)) {
		jbd_debug(3, "denied handle %p %d blocks: "
			  "insufficient log space\n", handle, nblocks);
		goto unlock;
	}

	handle->h_buffer_credits += nblocks;
	atomic_add(nblocks, &transaction->t_outstanding_credits);
	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);
out:
	return result;
}

Project: linux
File: transaction.c

void jbd2_journal_file_buffer(struct journal_head *jh,
				transaction_t *transaction, int jlist)
{
	jbd_lock_bh_state(jh2bh(jh));
	spin_lock(&transaction->t_journal->j_list_lock);
	__jbd2_journal_file_buffer(jh, transaction, jlist);
	spin_unlock(&transaction->t_journal->j_list_lock);
	jbd_unlock_bh_state(jh2bh(jh));
}

Project: linux
File: transaction.c

int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode)
{
	transaction_t *transaction = handle->h_transaction;
	journal_t *journal = transaction->t_journal;

	if (is_handle_aborted(handle))
		return -EIO;

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

	/*
	 * First check whether inode isn't already on the transaction's
	 * lists without taking the lock. Note that this check is safe
	 * without the lock as we cannot race with somebody removing inode
	 * from the transaction. The reason is that we remove inode from the
	 * transaction only in journal_release_jbd_inode() and when we commit
	 * the transaction. We are guarded from the first case by holding
	 * a reference to the inode. We are safe against the second case
	 * because if jinode->i_transaction == transaction, commit code
	 * cannot touch the transaction because we hold reference to it,
	 * and if jinode->i_next_transaction == transaction, commit code
	 * will only file the inode where we want it.
	 */
	if (jinode->i_transaction == transaction ||
	    jinode->i_next_transaction == transaction)
		return 0;

	spin_lock(&journal->j_list_lock);

	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

int jbd2_journal_force_commit(journal_t *journal)
{
	handle_t *handle;
	int ret;

	handle = jbd2_journal_start(journal, 1);
	if (IS_ERR(handle)) {
		ret = PTR_ERR(handle);
	} else {
		handle->h_sync = 1;
		ret = jbd2_journal_stop(handle);
	}
	return ret;
}

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 = transaction->t_journal;
	struct journal_head *jh;
	int drop_reserve = 0;
	int err = 0;
	int was_modified = 0;

	BUFFER_TRACE(bh, "entry");

	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);

	if (!buffer_jbd(bh))
		goto not_jbd;
	jh = bh2jh(bh);

	/* 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 not_jbd;
	}

	/* keep track of wether 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 == handle->h_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.
		 */

		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);
			if (!buffer_jbd(bh)) {
				spin_unlock(&journal->j_list_lock);
				jbd_unlock_bh_state(bh);
				__bforget(bh);
				goto drop;
			}
		}
	} 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 if we
		 * have also modified it since the original commit. */

		if (jh->b_next_transaction) {
			J_ASSERT(jh->b_next_transaction == transaction);
			jh->b_next_transaction = NULL;

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

not_jbd:
	spin_unlock(&journal->j_list_lock);
	jbd_unlock_bh_state(bh);
	__brelse(bh);
drop:
	if (drop_reserve) {
		/* no need to reserve log space for this block -bzzz */
		handle->h_buffer_credits++;
	}
	return err;
}

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 = transaction->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;
	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.
	 */
	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_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");
		__jbd2_journal_file_buffer(jh, transaction, BJ_Reserved);
	} else if (jh->b_transaction == journal->j_committing_transaction) {
		/* first access by this transaction */
		jh->b_modified = 0;

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

	/*
	 * 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_undo_access(handle_t *handle, struct buffer_head *bh)
{
	int err;
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
	char *committed_data = NULL;

	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);
		if (!committed_data) {
			printk(KERN_EMERG "%s: No memory for committed data\n",
				__func__);
			err = -ENOMEM;
			goto out;
		}
	}

	jbd_lock_bh_state(bh);
	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) {
			jbd_unlock_bh_state(bh);
			goto repeat;
		}

		jh->b_committed_data = committed_data;
		committed_data = NULL;
		memcpy(jh->b_committed_data, bh->b_data, bh->b_size);
	}
	jbd_unlock_bh_state(bh);
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

int jbd2_journal_get_write_access(handle_t *handle, struct buffer_head *bh)
{
	struct journal_head *jh = jbd2_journal_add_journal_head(bh);
	int rc;

	/* 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

void jbd2_journal_invalidatepage(journal_t *journal,
		      struct page *page,
		      unsigned long offset)
{
	struct buffer_head *head, *bh, *next;
	unsigned int curr_off = 0;
	int may_free = 1;

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

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

	} while (bh != head);

	if (!offset) {
		if (may_free && try_to_free_buffers(page))
			J_ASSERT(!page_has_buffers(page));
	}
}

Project: linux
File: transaction.c

void jbd2_journal_refile_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);
	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);
	__jbd2_journal_refile_buffer(jh);
	jbd_unlock_bh_state(bh);
	spin_unlock(&journal->j_list_lock);
	__brelse(bh);
}

Project: linux
File: transaction.c

jbd2_journal_release_buffer(handle_t *handle, struct buffer_head *bh)
{
	BUFFER_TRACE(bh, "entry");
}

Project: linux
File: transaction.c

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

Project: linux
File: transaction.c

void jbd2_journal_set_triggers(struct buffer_head *bh,
			       struct jbd2_buffer_trigger_type *type)
{
	struct journal_head *jh = bh2jh(bh);

	jh->b_triggers = type;
}

Project: linux
File: transaction.c

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

Project: linux
File: transaction.c

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

	J_ASSERT(journal_current_handle() == handle);

	if (is_handle_aborted(handle))
		err = -EIO;
	else {
		J_ASSERT(atomic_read(&transaction->t_updates) > 0);
		err = 0;
	}

	if (--handle->h_ref > 0) {
		jbd_debug(4, "h_ref %d -> %d\n", handle->h_ref + 1,
			  handle->h_ref);
		return err;
	}

	jbd_debug(4, "Handle %p going down\n", handle);

	/*
	 * 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.
	 */
	pid = current->pid;
	if (handle->h_sync && journal->j_last_sync_writer != pid) {
		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;
	current->journal_info = NULL;
	atomic_sub(handle->h_buffer_credits,
		   &transaction->t_outstanding_credits);

	/*
	 * If the handle is marked SYNC, we need to set another commit
	 * going!  We also want to force a commit if the current
	 * transaction is occupying too much of the log, or if the
	 * transaction is too old now.
	 */
	if (handle->h_sync ||
	    (atomic_read(&transaction->t_outstanding_credits) >
	     journal->j_max_transaction_buffers) ||
	    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, transaction->t_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 we drop t_updates, if it goes to zero the transaction
	 * could start committing on us and eventually disappear.  So
	 * once we do this, we must not dereference transaction
	 * pointer again.
	 */
	tid = transaction->t_tid;
	if (atomic_dec_and_test(&transaction->t_updates)) {
		wake_up(&journal->j_wait_updates);
		if (journal->j_barrier_count)
			wake_up(&journal->j_wait_transaction_locked);
	}

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

	lock_map_release(&handle->h_lockdep_map);

	jbd2_free_handle(handle);
	return err;
}

Project: linux
File: transaction.c

int jbd2_journal_try_to_free_buffers(journal_t *journal,
				struct page *page, gfp_t gfp_mask)
{
	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;

		jbd_lock_bh_state(bh);
		__journal_try_to_free_buffer(journal, bh);
		jbd2_journal_put_journal_head(jh);
		jbd_unlock_bh_state(bh);
		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

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);
	jbd_lock_bh_state(bh);
	spin_lock(&journal->j_list_lock);
	__jbd2_journal_unfile_buffer(jh);
	spin_unlock(&journal->j_list_lock);
	jbd_unlock_bh_state(bh);
	__brelse(bh);
}

Project: linux
File: transaction.c

void jbd2_journal_unlock_updates (journal_t *journal)
{
	J_ASSERT(journal->j_barrier_count != 0);

	mutex_unlock(&journal->j_barrier);
	write_lock(&journal->j_state_lock);
	--journal->j_barrier_count;
	write_unlock(&journal->j_state_lock);
	wake_up(&journal->j_wait_transaction_locked);
}

Project: linux
File: transaction.c

static handle_t *new_handle(int nblocks)
{
	handle_t *handle = jbd2_alloc_handle(GFP_NOFS);
	if (!handle)
		return NULL;
	memset(handle, 0, sizeof(*handle));
	handle->h_buffer_credits = nblocks;
	handle->h_ref = 1;

	lockdep_init_map(&handle->h_lockdep_map, "jbd2_handle",
						&jbd2_handle_key, 0);

	return handle;
}

Project: linux
File: transaction.c

static inline void update_t_max_wait(transaction_t *transaction,
				     unsigned long ts)
{
#ifdef CONFIG_JBD2_DEBUG
	if (jbd2_journal_enable_debug &&
	    time_after(transaction->t_start, ts)) {
		ts = jbd2_time_diff(ts, transaction->t_start);
		spin_lock(&transaction->t_handle_lock);
		if (ts > transaction->t_max_wait)
			transaction->t_max_wait = ts;
		spin_unlock(&transaction->t_handle_lock);
	}
#endif
}

Project: linux
File: transaction.c

static void warn_dirty_buffer(struct buffer_head *bh)
{
	char b[BDEVNAME_SIZE];

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