On 19 Nov 2021 at 04:43, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> 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.
>
Looks good.
Reviewed-by: Chandan Babu R <chandan.babu@xxxxxxxxxx>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
> ---
> fs/xfs/xfs_log.c | 69 +++++++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 66 insertions(+), 3 deletions(-)
>
> diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
> index f26c85dbc765..6d93b2c96262 100644
> --- a/fs/xfs/xfs_log.c
> +++ b/fs/xfs/xfs_log.c
> @@ -2224,6 +2224,58 @@ 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,
> @@ -2388,8 +2440,8 @@ 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) {
> @@ -2409,7 +2461,6 @@ 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
> @@ -2421,10 +2472,22 @@ 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;
--
chandan
