Commit 7ec94921 authored by Dave Chinner's avatar Dave Chinner Committed by Darrick J. Wong
Browse files

xfs: don't try to write a start record into every iclog 



The xlog_write() function iterates over iclogs until it completes
writing all the log vectors passed in. The ticket tracks whether
a start record has been written or not, so only the first iclog gets
a start record. We only ever pass single use tickets to
xlog_write() so we only ever need to write a start record once per
xlog_write() call.

Hence we don't need to store whether we should write a start record
in the ticket as the callers provide all the information we need to
determine if a start record should be written. For the moment, we
have to ensure that we clear the XLOG_TIC_INITED appropriately so
the code in xfs_log_done() still works correctly for committing
transactions.

(darrick: Note the slight behavior change that we always deduct the
size of the op header from the ticket, even for unmount records)

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
[hch: pass an explicit need_start_rec argument]
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent f8e566c0

fs/xfs/xfs_log.c

+37 −40
Original line number Diff line number Diff line
@@ -921,7 +921,7 @@ xfs_log_write_unmount_record( 
	/* remove inited flag, and account for space used */

	tic->t_flags = 0;

	tic->t_curr_res -= sizeof(magic);

	error = xlog_write(log, &vec, tic, &lsn, NULL, flags);

	error = xlog_write(log, &vec, tic, &lsn, NULL, flags, false);

	/*

	 * At this point, we're umounting anyway, so there's no point in

	 * transitioning log state to IOERROR. Just continue...
@@ -1541,7 +1541,7 @@ xlog_commit_record( 


	ASSERT_ALWAYS(iclog);

	error = xlog_write(log, &vec, ticket, commitlsnp, iclog,

					XLOG_COMMIT_TRANS);

					XLOG_COMMIT_TRANS, false);

	if (error)

		xfs_force_shutdown(mp, SHUTDOWN_LOG_IO_ERROR);

	return error;
@@ -2118,23 +2118,21 @@ xlog_print_trans( 
}



/*

 * Calculate the potential space needed by the log vector.  Each region gets

 * its own xlog_op_header_t and may need to be double word aligned.

 * Calculate the potential space needed by the log vector.  We may need a start

 * record, and each region gets its own struct xlog_op_header and may need to be

 * double word aligned.

 */

static int

xlog_write_calc_vec_length(

	struct xlog_ticket	*ticket,

	struct xfs_log_vec	*log_vector)

	struct xfs_log_vec	*log_vector,

	bool			need_start_rec)

{

	struct xfs_log_vec	*lv;

	int			headers = 0;

	int			headers = need_start_rec ? 1 : 0;

	int			len = 0;

	int			i;



	/* acct for start rec of xact */

	if (ticket->t_flags & XLOG_TIC_INITED)

		headers++;



	for (lv = log_vector; lv; lv = lv->lv_next) {

		/* we don't write ordered log vectors */

		if (lv->lv_buf_len == XFS_LOG_VEC_ORDERED)
@@ -2156,27 +2154,16 @@ xlog_write_calc_vec_length( 
	return len;

}



/*

 * If first write for transaction, insert start record  We can't be trying to

 * commit if we are inited.  We can't have any "partial_copy" if we are inited.

 */

static int

static void

xlog_write_start_rec(

	struct xlog_op_header	*ophdr,

	struct xlog_ticket	*ticket)

{

	if (!(ticket->t_flags & XLOG_TIC_INITED))

		return 0;



	ophdr->oh_tid	= cpu_to_be32(ticket->t_tid);

	ophdr->oh_clientid = ticket->t_clientid;

	ophdr->oh_len = 0;

	ophdr->oh_flags = XLOG_START_TRANS;

	ophdr->oh_res2 = 0;



	ticket->t_flags &= ~XLOG_TIC_INITED;



	return sizeof(struct xlog_op_header);

}



static xlog_op_header_t *
@@ -2365,7 +2352,8 @@ xlog_write( 
	struct xlog_ticket	*ticket,

	xfs_lsn_t		*start_lsn,

	struct xlog_in_core	**commit_iclog,

	uint			flags)

	uint			flags,

	bool			need_start_rec)

{

	struct xlog_in_core	*iclog = NULL;

	struct xfs_log_iovec	*vecp;
@@ -2381,23 +2369,22 @@ xlog_write( 


	*start_lsn = 0;



	len = xlog_write_calc_vec_length(ticket, log_vector);



	/*

	 * Region headers and bytes are already accounted for.

	 * We only need to take into account start records and

	 * split regions in this function.

	 * Region headers and bytes are already accounted for.  We only need to

	 * take into account start records and split regions in this function.

	 */

	if (ticket->t_flags & XLOG_TIC_INITED)

		ticket->t_curr_res -= sizeof(xlog_op_header_t);

	if (ticket->t_flags & XLOG_TIC_INITED) {

		ticket->t_curr_res -= sizeof(struct xlog_op_header);

		ticket->t_flags &= ~XLOG_TIC_INITED;

	}



	/*

	 * Commit record headers need to be accounted for. These

	 * come in as separate writes so are easy to detect.

	 * Commit record headers and unmount records need to be accounted for.

	 * These come in as separate writes so are easy to detect.

	 */

	if (flags & (XLOG_COMMIT_TRANS | XLOG_UNMOUNT_TRANS))

		ticket->t_curr_res -= sizeof(xlog_op_header_t);



	if (!need_start_rec)

		ticket->t_curr_res -= sizeof(struct xlog_op_header);

	if (ticket->t_curr_res < 0) {

		xfs_alert_tag(log->l_mp, XFS_PTAG_LOGRES,

		     "ctx ticket reservation ran out. Need to up reservation");
@@ -2405,6 +2392,8 @@ xlog_write( 
		xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);

	}



	len = xlog_write_calc_vec_length(ticket, log_vector, need_start_rec);



	index = 0;

	lv = log_vector;

	vecp = lv->lv_iovecp;
@@ -2431,7 +2420,6 @@ xlog_write( 
		while (lv && (!lv->lv_niovecs || index < lv->lv_niovecs)) {

			struct xfs_log_iovec	*reg;

			struct xlog_op_header	*ophdr;

			int			start_rec_copy;

			int			copy_len;

			int			copy_off;

			bool			ordered = false;
@@ -2447,11 +2435,15 @@ xlog_write( 
			ASSERT(reg->i_len % sizeof(int32_t) == 0);

			ASSERT((unsigned long)ptr % sizeof(int32_t) == 0);



			start_rec_copy = xlog_write_start_rec(ptr, ticket);

			if (start_rec_copy) {

				record_cnt++;

			/*

			 * Before we start formatting log vectors, we need to

			 * write a start record. Only do this for the first

			 * iclog we write to.

			 */

			if (need_start_rec) {

				xlog_write_start_rec(ptr, ticket);

				xlog_write_adv_cnt(&ptr, &len, &log_offset,

						   start_rec_copy);

						sizeof(struct xlog_op_header));

			}



			ophdr = xlog_write_setup_ophdr(log, ptr, ticket, flags);
@@ -2483,8 +2475,13 @@ xlog_write( 
				xlog_write_adv_cnt(&ptr, &len, &log_offset,

						   copy_len);

			}

			copy_len += start_rec_copy + sizeof(xlog_op_header_t);

			copy_len += sizeof(struct xlog_op_header);

			record_cnt++;

			if (need_start_rec) {

				copy_len += sizeof(struct xlog_op_header);

				record_cnt++;

				need_start_rec = false;

			}

			data_cnt += contwr ? copy_len : 0;



			error = xlog_write_copy_finish(log, iclog, flags,

fs/xfs/xfs_log_cil.c

+1 −1
Original line number Diff line number Diff line
@@ -801,7 +801,7 @@ xlog_cil_push_work( 
	lvhdr.lv_iovecp = &lhdr;

	lvhdr.lv_next = ctx->lv_chain;



	error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0);

	error = xlog_write(log, &lvhdr, tic, &ctx->start_lsn, NULL, 0, true);

	if (error)

		goto out_abort_free_ticket;

fs/xfs/xfs_log_priv.h

+4 −8
Original line number Diff line number Diff line
@@ -439,14 +439,10 @@ xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes) 


void	xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);

void	xlog_print_trans(struct xfs_trans *);

int

xlog_write(

	struct xlog		*log,

	struct xfs_log_vec	*log_vector,

	struct xlog_ticket	*tic,

	xfs_lsn_t		*start_lsn,

	struct xlog_in_core	**commit_iclog,

	uint			flags);

int	xlog_write(struct xlog *log, struct xfs_log_vec *log_vector,

		struct xlog_ticket *tic, xfs_lsn_t *start_lsn,

		struct xlog_in_core **commit_iclog, uint flags,

		bool need_start_rec);



/*

 * When we crack an atomic LSN, we sample it first so that the value will not

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