xfs_trans.c

linux 内核源代码

	/*
	 * We need to pass the iclog buffer which was used for the
	 * transaction commit record into this function, and attach
	 * the callback to it. The callback must be attached before
	 * the items are unlocked to avoid racing with other threads
	 * waiting for an item to unlock.
	 */
	shutdown = xfs_log_notify(mp, commit_iclog, &(tp->t_logcb));

	/*
	 * Mark this thread as no longer being in a transaction
	 */
	current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);

	/*
	 * Once all the items of the transaction have been copied
	 * to the in core log and the callback is attached, the
	 * items can be unlocked.
	 *
	 * This will free descriptors pointing to items which were
	 * not logged since there is nothing more to do with them.
	 * For items which were logged, we will keep pointers to them
	 * so they can be unpinned after the transaction commits to disk.
	 * This will also stamp each modified meta-data item with
	 * the commit lsn of this transaction for dependency tracking
	 * purposes.
	 */
	xfs_trans_unlock_items(tp, commit_lsn);

	/*
	 * If we detected a log error earlier, finish committing
	 * the transaction now (unpin log items, etc).
	 *
	 * Order is critical here, to avoid using the transaction
	 * pointer after its been freed (by xfs_trans_committed
	 * either here now, or as a callback).  We cannot do this
	 * step inside xfs_log_notify as was done earlier because
	 * of this issue.
	 */
	if (shutdown)
		xfs_trans_committed(tp, XFS_LI_ABORTED);

	/*
	 * Now that the xfs_trans_committed callback has been attached,
	 * and the items are released we can finally allow the iclog to
	 * go to disk.
	 */
	error = xfs_log_release_iclog(mp, commit_iclog);

	/*
	 * If the transaction needs to be synchronous, then force the
	 * log out now and wait for it.
	 */
	if (sync) {
		if (!error) {
			error = _xfs_log_force(mp, commit_lsn,
				      XFS_LOG_FORCE | XFS_LOG_SYNC,
				      log_flushed);
		}
		XFS_STATS_INC(xs_trans_sync);
	} else {
		XFS_STATS_INC(xs_trans_async);
	}

	return (error);
}


/*
 * Total up the number of log iovecs needed to commit this
 * transaction.  The transaction itself needs one for the
 * transaction header.  Ask each dirty item in turn how many
 * it needs to get the total.
 */
STATIC uint
xfs_trans_count_vecs(
	xfs_trans_t	*tp)
{
	int			nvecs;
	xfs_log_item_desc_t	*lidp;

	nvecs = 1;
	lidp = xfs_trans_first_item(tp);
	ASSERT(lidp != NULL);

	/* In the non-debug case we need to start bailing out if we
	 * didn't find a log_item here, return zero and let trans_commit
	 * deal with it.
	 */
	if (lidp == NULL)
		return 0;

	while (lidp != NULL) {
		/*
		 * Skip items which aren't dirty in this transaction.
		 */
		if (!(lidp->lid_flags & XFS_LID_DIRTY)) {
			lidp = xfs_trans_next_item(tp, lidp);
			continue;
		}
		lidp->lid_size = IOP_SIZE(lidp->lid_item);
		nvecs += lidp->lid_size;
		lidp = xfs_trans_next_item(tp, lidp);
	}

	return nvecs;
}

/*
 * Called from the trans_commit code when we notice that
 * the filesystem is in the middle of a forced shutdown.
 */
STATIC void
xfs_trans_uncommit(
	xfs_trans_t	*tp,
	uint		flags)
{
	xfs_log_item_desc_t	*lidp;

	for (lidp = xfs_trans_first_item(tp);
	     lidp != NULL;
	     lidp = xfs_trans_next_item(tp, lidp)) {
		/*
		 * Unpin all but those that aren't dirty.
		 */
		if (lidp->lid_flags & XFS_LID_DIRTY)
			IOP_UNPIN_REMOVE(lidp->lid_item, tp);
	}

	xfs_trans_unreserve_and_mod_sb(tp);
	XFS_TRANS_UNRESERVE_AND_MOD_DQUOTS(tp->t_mountp, tp);

	xfs_trans_free_items(tp, flags);
	xfs_trans_free_busy(tp);
	xfs_trans_free(tp);
}

/*
 * Fill in the vector with pointers to data to be logged
 * by this transaction.  The transaction header takes
 * the first vector, and then each dirty item takes the
 * number of vectors it indicated it needed in xfs_trans_count_vecs().
 *
 * As each item fills in the entries it needs, also pin the item
 * so that it cannot be flushed out until the log write completes.
 */
STATIC void
xfs_trans_fill_vecs(
	xfs_trans_t		*tp,
	xfs_log_iovec_t		*log_vector)
{
	xfs_log_item_desc_t	*lidp;
	xfs_log_iovec_t		*vecp;
	uint			nitems;

	/*
	 * Skip over the entry for the transaction header, we'll
	 * fill that in at the end.
	 */
	vecp = log_vector + 1;		/* pointer arithmetic */

	nitems = 0;
	lidp = xfs_trans_first_item(tp);
	ASSERT(lidp != NULL);
	while (lidp != NULL) {
		/*
		 * Skip items which aren't dirty in this transaction.
		 */
		if (!(lidp->lid_flags & XFS_LID_DIRTY)) {
			lidp = xfs_trans_next_item(tp, lidp);
			continue;
		}
		/*
		 * The item may be marked dirty but not log anything.
		 * This can be used to get called when a transaction
		 * is committed.
		 */
		if (lidp->lid_size) {
			nitems++;
		}
		IOP_FORMAT(lidp->lid_item, vecp);
		vecp += lidp->lid_size;		/* pointer arithmetic */
		IOP_PIN(lidp->lid_item);
		lidp = xfs_trans_next_item(tp, lidp);
	}

	/*
	 * Now that we've counted the number of items in this
	 * transaction, fill in the transaction header.
	 */
	tp->t_header.th_magic = XFS_TRANS_HEADER_MAGIC;
	tp->t_header.th_type = tp->t_type;
	tp->t_header.th_num_items = nitems;
	log_vector->i_addr = (xfs_caddr_t)&tp->t_header;
	log_vector->i_len = sizeof(xfs_trans_header_t);
	XLOG_VEC_SET_TYPE(log_vector, XLOG_REG_TYPE_TRANSHDR);
}


/*
 * Unlock all of the transaction's items and free the transaction.
 * The transaction must not have modified any of its items, because
 * there is no way to restore them to their previous state.
 *
 * If the transaction has made a log reservation, make sure to release
 * it as well.
 */
void
xfs_trans_cancel(
	xfs_trans_t		*tp,
	int			flags)
{
	int			log_flags;
#ifdef DEBUG
	xfs_log_item_chunk_t	*licp;
	xfs_log_item_desc_t	*lidp;
	xfs_log_item_t		*lip;
	int			i;
#endif
	xfs_mount_t		*mp = tp->t_mountp;

	/*
	 * See if the caller is being too lazy to figure out if
	 * the transaction really needs an abort.
	 */
	if ((flags & XFS_TRANS_ABORT) && !(tp->t_flags & XFS_TRANS_DIRTY))
		flags &= ~XFS_TRANS_ABORT;
	/*
	 * See if the caller is relying on us to shut down the
	 * filesystem.  This happens in paths where we detect
	 * corruption and decide to give up.
	 */
	if ((tp->t_flags & XFS_TRANS_DIRTY) && !XFS_FORCED_SHUTDOWN(mp)) {
		XFS_ERROR_REPORT("xfs_trans_cancel", XFS_ERRLEVEL_LOW, mp);
		xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
	}
#ifdef DEBUG
	if (!(flags & XFS_TRANS_ABORT)) {
		licp = &(tp->t_items);
		while (licp != NULL) {
			lidp = licp->lic_descs;
			for (i = 0; i < licp->lic_unused; i++, lidp++) {
				if (XFS_LIC_ISFREE(licp, i)) {
					continue;
				}

				lip = lidp->lid_item;
				if (!XFS_FORCED_SHUTDOWN(mp))
					ASSERT(!(lip->li_type == XFS_LI_EFD));
			}
			licp = licp->lic_next;
		}
	}
#endif
	xfs_trans_unreserve_and_mod_sb(tp);
	XFS_TRANS_UNRESERVE_AND_MOD_DQUOTS(mp, tp);

	if (tp->t_ticket) {
		if (flags & XFS_TRANS_RELEASE_LOG_RES) {
			ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
			log_flags = XFS_LOG_REL_PERM_RESERV;
		} else {
			log_flags = 0;
		}
		xfs_log_done(mp, tp->t_ticket, NULL, log_flags);
	}

	/* mark this thread as no longer being in a transaction */
	current_restore_flags_nested(&tp->t_pflags, PF_FSTRANS);

	xfs_trans_free_items(tp, flags);
	xfs_trans_free_busy(tp);
	xfs_trans_free(tp);
}


/*
 * Free the transaction structure.  If there is more clean up
 * to do when the structure is freed, add it here.
 */
STATIC void
xfs_trans_free(
	xfs_trans_t	*tp)
{
	atomic_dec(&tp->t_mountp->m_active_trans);
	XFS_TRANS_FREE_DQINFO(tp->t_mountp, tp);
	kmem_zone_free(xfs_trans_zone, tp);
}


/*
 * THIS SHOULD BE REWRITTEN TO USE xfs_trans_next_item().
 *
 * This is typically called by the LM when a transaction has been fully
 * committed to disk.  It needs to unpin the items which have
 * been logged by the transaction and update their positions
 * in the AIL if necessary.
 * This also gets called when the transactions didn't get written out
 * because of an I/O error. Abortflag & XFS_LI_ABORTED is set then.
 *
 * Call xfs_trans_chunk_committed() to process the items in
 * each chunk.
 */
STATIC void
xfs_trans_committed(
	xfs_trans_t	*tp,
	int		abortflag)
{
	xfs_log_item_chunk_t	*licp;
	xfs_log_item_chunk_t	*next_licp;
	xfs_log_busy_chunk_t	*lbcp;
	xfs_log_busy_slot_t	*lbsp;
	int			i;

	/*
	 * Call the transaction's completion callback if there
	 * is one.
	 */
	if (tp->t_callback != NULL) {
		tp->t_callback(tp, tp->t_callarg);
	}

	/*
	 * Special case the chunk embedded in the transaction.
	 */
	licp = &(tp->t_items);
	if (!(XFS_LIC_ARE_ALL_FREE(licp))) {
		xfs_trans_chunk_committed(licp, tp->t_lsn, abortflag);
	}

	/*
	 * Process the items in each chunk in turn.
	 */
	licp = licp->lic_next;
	while (licp != NULL) {
		ASSERT(!XFS_LIC_ARE_ALL_FREE(licp));
		xfs_trans_chunk_committed(licp, tp->t_lsn, abortflag);
		next_licp = licp->lic_next;
		kmem_free(licp, sizeof(xfs_log_item_chunk_t));
		licp = next_licp;
	}

	/*
	 * Clear all the per-AG busy list items listed in this transaction
	 */
	lbcp = &tp->t_busy;
	while (lbcp != NULL) {
		for (i = 0, lbsp = lbcp->lbc_busy; i < lbcp->lbc_unused; i++, lbsp++) {
			if (!XFS_LBC_ISFREE(lbcp, i)) {
				xfs_alloc_clear_busy(tp, lbsp->lbc_ag,
						     lbsp->lbc_idx);
			}
		}
		lbcp = lbcp->lbc_next;
	}
	xfs_trans_free_busy(tp);

	/*
	 * That's it for the transaction structure.  Free it.
	 */
	xfs_trans_free(tp);
}

/*
 * This is called to perform the commit processing for each
 * item described by the given chunk.
 *
 * The commit processing consists of unlocking items which were
 * held locked with the SYNC_UNLOCK attribute, calling the committed
 * routine of each logged item, updating the item's position in the AIL
 * if necessary, and unpinning each item.  If the committed routine
 * returns -1, then do nothing further with the item because it
 * may have been freed.
 *
 * Since items are unlocked when they are copied to the incore
 * log, it is possible for two transactions to be completing
 * and manipulating the same item simultaneously.  The AIL lock
 * will protect the lsn field of each item.  The value of this
 * field can never go backwards.
 *
 * We unpin the items after repositioning them in the AIL, because
 * otherwise they could be immediately flushed and we'd have to race
 * with the flusher trying to pull the item from the AIL as we add it.
 */
STATIC void
xfs_trans_chunk_committed(
	xfs_log_item_chunk_t	*licp,
	xfs_lsn_t		lsn,
	int			aborted)
{
	xfs_log_item_desc_t	*lidp;
	xfs_log_item_t		*lip;
	xfs_lsn_t		item_lsn;
	struct xfs_mount	*mp;
	int			i;
	SPLDECL(s);

	lidp = licp->lic_descs;
	for (i = 0; i < licp->lic_unused; i++, lidp++) {
		if (XFS_LIC_ISFREE(licp, i)) {
			continue;
		}

		lip = lidp->lid_item;
		if (aborted)
			lip->li_flags |= XFS_LI_ABORTED;

		/*
		 * Send in the ABORTED flag to the COMMITTED routine
		 * so that it knows whether the transaction was aborted
		 * or not.
		 */
		item_lsn = IOP_COMMITTED(lip, lsn);

		/*
		 * If the committed routine returns -1, make
		 * no more references to the item.
		 */
		if (XFS_LSN_CMP(item_lsn, (xfs_lsn_t)-1) == 0) {
			continue;
		}

		/*
		 * If the returned lsn is greater than what it
		 * contained before, update the location of the
		 * item in the AIL.  If it is not, then do nothing.
		 * Items can never move backwards in the AIL.
		 *
		 * While the new lsn should usually be greater, it
		 * is possible that a later transaction completing
		 * simultaneously with an earlier one using the
		 * same item could complete first with a higher lsn.
		 * This would cause the earlier transaction to fail
		 * the test below.
		 */
		mp = lip->li_mountp;
		AIL_LOCK(mp,s);
		if (XFS_LSN_CMP(item_lsn, lip->li_lsn) > 0) {
			/*
			 * This will set the item's lsn to item_lsn
			 * and update the position of the item in
			 * the AIL.
			 *
			 * xfs_trans_update_ail() drops the AIL lock.
			 */
			xfs_trans_update_ail(mp, lip, item_lsn, s);
		} else {
			AIL_UNLOCK(mp, s);
		}

		/*
		 * Now that we've repositioned the item in the AIL,
		 * unpin it so it can be flushed. Pass information
		 * about buffer stale state down from the log item
		 * flags, if anyone else stales the buffer we do not
		 * want to pay any attention to it.
		 */
		IOP_UNPIN(lip, lidp->lid_flags & XFS_LID_BUF_STALE);
	}
}