Commit db357078 authored by Dave Chinner's avatar Dave Chinner Committed by Dave Chinner
Browse files

xfs: introduce xlog_write_full() 



Introduce an optimised version of xlog_write() that is used when the
entire write will fit in a single iclog. This greatly simplifies the
implementation of writing a log vector chain into an iclog, and sets
the ground work for a much more understandable xlog_write()
implementation.

This incorporates some factoring and simplifications proposed by
Christoph Hellwig.

Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChandan Babu R <chandan.babu@oracle.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent decb545f

fs/xfs/xfs_log.c

+66 −3
Original line number Diff line number Diff line
@@ -2210,6 +2210,58 @@ xlog_print_trans( 
	}

}



static inline void

xlog_write_iovec(

	struct xlog_in_core	*iclog,

	uint32_t		*log_offset,

	void			*data,

	uint32_t		write_len,

	int			*bytes_left,

	uint32_t		*record_cnt,

	uint32_t		*data_cnt)

{

	ASSERT(*log_offset % sizeof(int32_t) == 0);

	ASSERT(write_len % sizeof(int32_t) == 0);



	memcpy(iclog->ic_datap + *log_offset, data, write_len);

	*log_offset += write_len;

	*bytes_left -= write_len;

	(*record_cnt)++;

	*data_cnt += write_len;

}



/*

 * Write log vectors into a single iclog which is guaranteed by the caller

 * to have enough space to write the entire log vector into.

 */

static void

xlog_write_full(

	struct xfs_log_vec	*lv,

	struct xlog_ticket	*ticket,

	struct xlog_in_core	*iclog,

	uint32_t		*log_offset,

	uint32_t		*len,

	uint32_t		*record_cnt,

	uint32_t		*data_cnt)

{

	int			index;



	ASSERT(*log_offset + *len <= iclog->ic_size);



	/*

	 * Ordered log vectors have no regions to write so this

	 * loop will naturally skip them.

	 */

	for (index = 0; index < lv->lv_niovecs; index++) {

		struct xfs_log_iovec	*reg = &lv->lv_iovecp[index];

		struct xlog_op_header	*ophdr = reg->i_addr;



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

		xlog_write_iovec(iclog, log_offset, reg->i_addr,

				reg->i_len, len, record_cnt, data_cnt);

	}

}



static xlog_op_header_t *

xlog_write_setup_ophdr(

	struct xlog_op_header	*ophdr,
@@ -2374,8 +2426,8 @@ xlog_write( 
	int			partial_copy = 0;

	int			partial_copy_len = 0;

	int			contwr = 0;

	int			record_cnt = 0;

	int			data_cnt = 0;

	uint32_t		record_cnt = 0;

	uint32_t		data_cnt = 0;

	int			error = 0;



	if (ticket->t_curr_res < 0) {
@@ -2395,7 +2447,6 @@ xlog_write( 
			return error;



		ASSERT(log_offset <= iclog->ic_size - 1);

		ptr = iclog->ic_datap + log_offset;



		/*

		 * If we have a context pointer, pass it the first iclog we are
@@ -2407,10 +2458,22 @@ xlog_write( 
			ctx = NULL;

		}



		/* If this is a single iclog write, go fast... */

		if (!contwr && lv == log_vector) {

			while (lv) {

				xlog_write_full(lv, ticket, iclog, &log_offset,

						 &len, &record_cnt, &data_cnt);

				lv = lv->lv_next;

			}

			data_cnt = 0;

			break;

		}



		/*

		 * This loop writes out as many regions as can fit in the amount

		 * of space which was allocated by xlog_state_get_iclog_space().

		 */

		ptr = iclog->ic_datap + log_offset;

		while (lv && (!lv->lv_niovecs || index < lv->lv_niovecs)) {

			struct xfs_log_iovec	*reg;

			struct xlog_op_header	*ophdr;