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xfs: refactor xlog_cil_insert_items() to facilitate transaction dump 

Transaction reservation overrun detection currently occurs too late
to print useful information about the offending transaction.
Ideally, the transaction data is printed before the associated log
items are moved from the transaction to the CIL, which occurs in
xlog_cil_insert_items(), such that details of the items logged by
the transaction are available for analysis.

Refactor xlog_cil_insert_items() to facilitate moving tx overrun
detection to this function. Update the function to track each bit of
extra log reservation stolen from the transaction (i.e., such as for
the CIL context ticket) and perform the log item migration as the
last operation before the CIL lock is released. This creates a
context where the transaction reservation consumption has been fully
calculated when the log items are moved to the CIL. This patch makes
no functional changes.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Brian Foster 2017-06-14 21:29:49 -07:00 committed by Darrick J. Wong
parent 7d2d565346
commit e2f2342639
1 changed files with 40 additions and 38 deletions
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78
fs/xfs/xfs_log_cil.c
View File

@ -410,6 +410,7 @@ xlog_cil_insert_items(
int len = 0;
int diff_iovecs = 0;
int iclog_space;
int iovhdr_res = 0, split_res = 0, ctx_res = 0;
ASSERT(tp);
@ -419,12 +420,50 @@ xlog_cil_insert_items(
*/
xlog_cil_insert_format_items(log, tp, &len, &diff_iovecs);
spin_lock(&cil->xc_cil_lock);
/* account for space used by new iovec headers */
iovhdr_res = diff_iovecs * sizeof(xlog_op_header_t);
len += iovhdr_res;
ctx->nvecs += diff_iovecs;
/* attach the transaction to the CIL if it has any busy extents */
if (!list_empty(&tp->t_busy))
list_splice_init(&tp->t_busy, &ctx->busy_extents);
/*
* Now transfer enough transaction reservation to the context ticket
* for the checkpoint. The context ticket is special - the unit
* reservation has to grow as well as the current reservation as we
* steal from tickets so we can correctly determine the space used
* during the transaction commit.
*/
if (ctx->ticket->t_curr_res == 0) {
ctx_res = ctx->ticket->t_unit_res;
ctx->ticket->t_curr_res = ctx_res;
tp->t_ticket->t_curr_res -= ctx_res;
}
/* do we need space for more log record headers? */
iclog_space = log->l_iclog_size - log->l_iclog_hsize;
if (len > 0 && (ctx->space_used / iclog_space !=
(ctx->space_used + len) / iclog_space)) {
split_res = (len + iclog_space - 1) / iclog_space;
/* need to take into account split region headers, too */
split_res *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
ctx->ticket->t_unit_res += split_res;
ctx->ticket->t_curr_res += split_res;
tp->t_ticket->t_curr_res -= split_res;
ASSERT(tp->t_ticket->t_curr_res >= len);
}
tp->t_ticket->t_curr_res -= len;
ctx->space_used += len;
/*
* Now (re-)position everything modified at the tail of the CIL.
* We do this here so we only need to take the CIL lock once during
* the transaction commit.
*/
spin_lock(&cil->xc_cil_lock);
list_for_each_entry(lidp, &tp->t_items, lid_trans) {
struct xfs_log_item *lip = lidp->lid_item;
@ -441,43 +480,6 @@ xlog_cil_insert_items(
list_move_tail(&lip->li_cil, &cil->xc_cil);
}
/* account for space used by new iovec headers */
len += diff_iovecs * sizeof(xlog_op_header_t);
ctx->nvecs += diff_iovecs;
/* attach the transaction to the CIL if it has any busy extents */
if (!list_empty(&tp->t_busy))
list_splice_init(&tp->t_busy, &ctx->busy_extents);
/*
* Now transfer enough transaction reservation to the context ticket
* for the checkpoint. The context ticket is special - the unit
* reservation has to grow as well as the current reservation as we
* steal from tickets so we can correctly determine the space used
* during the transaction commit.
*/
if (ctx->ticket->t_curr_res == 0) {
ctx->ticket->t_curr_res = ctx->ticket->t_unit_res;
tp->t_ticket->t_curr_res -= ctx->ticket->t_unit_res;
}
/* do we need space for more log record headers? */
iclog_space = log->l_iclog_size - log->l_iclog_hsize;
if (len > 0 && (ctx->space_used / iclog_space !=
(ctx->space_used + len) / iclog_space)) {
int hdrs;
hdrs = (len + iclog_space - 1) / iclog_space;
/* need to take into account split region headers, too */
hdrs *= log->l_iclog_hsize + sizeof(struct xlog_op_header);
ctx->ticket->t_unit_res += hdrs;
ctx->ticket->t_curr_res += hdrs;
tp->t_ticket->t_curr_res -= hdrs;
ASSERT(tp->t_ticket->t_curr_res >= len);
}
tp->t_ticket->t_curr_res -= len;
ctx->space_used += len;
spin_unlock(&cil->xc_cil_lock);
}