[PATCH 7/8] xfs: attached iclog callbacks in xlog_cil_set_ctx_write_state()

Dave Chinner
2021-06-17T08:26:26Z

From: Dave Chinner <dchinner@redhat.com>

We currently attach iclog callbacks for the CIL when the commit
iclog is returned from xlog_write. Because
xlog_state_get_iclog_space() always guarantees that the commit
record will fit in the iclog it returns, we can move this IO
callback setting to xlog_cil_set_ctx_write_state(), record the
commit iclog in the context and remove the need for the commit iclog
to be returned by xlog_write() altogether.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_log.c | 8 ++----
fs/xfs/xfs_log_cil.c | 65 +++++++++++++++++++++++++------------------
fs/xfs/xfs_log_priv.h | 3 +-
3 files changed, 42 insertions(+), 34 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 1c214b395223..359246d54db7 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -871,7 +871,7 @@ xlog_write_unmount_record(
*/
if (log->l_targ != log->l_mp->m_ddev_targp)
blkdev_issue_flush(log->l_targ->bt_bdev);
- return xlog_write(log, NULL, &lv_chain, ticket, NULL, reg.i_len);
+ return xlog_write(log, NULL, &lv_chain, ticket, reg.i_len);
}

/*
@@ -2386,7 +2386,6 @@ xlog_write(
struct xfs_cil_ctx *ctx,
struct list_head *lv_chain,
struct xlog_ticket *ticket,
- struct xlog_in_core **commit_iclog,
uint32_t len)
{
struct xlog_in_core *iclog = NULL;
@@ -2436,10 +2435,7 @@ xlog_write(
*/
spin_lock(&log->l_icloglock);
xlog_state_finish_copy(log, iclog, record_cnt, 0);
- if (commit_iclog)
- *commit_iclog = iclog;
- else
- error = xlog_state_release_iclog(log, iclog, ticket);
+ error = xlog_state_release_iclog(log, iclog, ticket);
spin_unlock(&log->l_icloglock);

return error;
diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c
index 2d8d904ffb78..87e30917ce2e 100644
--- a/fs/xfs/xfs_log_cil.c
+++ b/fs/xfs/xfs_log_cil.c
@@ -799,11 +799,34 @@ xlog_cil_set_ctx_write_state(

ASSERT(!ctx->commit_lsn);
spin_lock(&cil->xc_push_lock);
- if (!ctx->start_lsn)
+ if (!ctx->start_lsn) {
ctx->start_lsn = lsn;
- else
- ctx->commit_lsn = lsn;
+ spin_unlock(&cil->xc_push_lock);
+ return;
+ }
+
+ /*
+ * Take a reference to the iclog for the context so that we still hold
+ * it when xlog_write is done and has released it. This means the
+ * context controls when the iclog is released for IO.
+ */
+ atomic_inc(&iclog->ic_refcnt);
+ ctx->commit_iclog = iclog;
+ ctx->commit_lsn = lsn;
spin_unlock(&cil->xc_push_lock);
+
+ /*
+ * xlog_state_get_iclog_space() guarantees there is enough space in the
+ * iclog for an entire commit record, so attach the context callbacks to
+ * the iclog at this time if we are not already in a shutdown state.
+ */
+ spin_lock(&iclog->ic_callback_lock);
+ if (iclog->ic_state == XLOG_STATE_IOERROR) {
+ spin_unlock(&iclog->ic_callback_lock);
+ return;
+ }
+ list_add_tail(&ctx->iclog_entry, &iclog->ic_callbacks);
+ spin_unlock(&iclog->ic_callback_lock);
}

/*
@@ -858,8 +881,7 @@ xlog_cil_order_write(
*/
int
xlog_cil_write_commit_record(
- struct xfs_cil_ctx *ctx,
- struct xlog_in_core **iclog)
+ struct xfs_cil_ctx *ctx)
{
struct xlog *log = ctx->cil->xc_log;
struct xlog_op_header ophdr = {
@@ -890,7 +912,7 @@ xlog_cil_write_commit_record(

/* account for space used by record data */
ctx->ticket->t_curr_res -= reg.i_len;
- error = xlog_write(log, ctx, &lv_chain, ctx->ticket, iclog, reg.i_len);
+ error = xlog_write(log, ctx, &lv_chain, ctx->ticket, reg.i_len);
if (error)
xfs_force_shutdown(log->l_mp, SHUTDOWN_LOG_IO_ERROR);
return error;
@@ -940,7 +962,6 @@ xlog_cil_push_work(
struct xlog *log = cil->xc_log;
struct xfs_log_vec *lv;
struct xfs_cil_ctx *new_ctx;
- struct xlog_in_core *commit_iclog;
int num_iovecs = 0;
int num_bytes = 0;
int error = 0;
@@ -1109,8 +1130,7 @@ xlog_cil_push_work(
* use the commit record lsn then we can move the tail beyond the grant
* write head.
*/
- error = xlog_write(log, ctx, &ctx->lv_chain, ctx->ticket,
- NULL, num_bytes);
+ error = xlog_write(log, ctx, &ctx->lv_chain, ctx->ticket, num_bytes);

/*
* Take the lvhdr back off the lv_chain as it should not be passed
@@ -1120,20 +1140,10 @@ xlog_cil_push_work(
if (error)
goto out_abort_free_ticket;

- error = xlog_cil_write_commit_record(ctx, &commit_iclog);
+ error = xlog_cil_write_commit_record(ctx);
if (error)
goto out_abort_free_ticket;

- spin_lock(&commit_iclog->ic_callback_lock);
- if (commit_iclog->ic_state == XLOG_STATE_IOERROR) {
- spin_unlock(&commit_iclog->ic_callback_lock);
- goto out_abort_free_ticket;
- }
- ASSERT_ALWAYS(commit_iclog->ic_state == XLOG_STATE_ACTIVE ||
- commit_iclog->ic_state == XLOG_STATE_WANT_SYNC);
- list_add_tail(&ctx->iclog_entry, &commit_iclog->ic_callbacks);
- spin_unlock(&commit_iclog->ic_callback_lock);
-
/*
* now the checkpoint commit is complete and we've attached the
* callbacks to the iclog we can assign the commit LSN to the context
@@ -1168,8 +1178,8 @@ xlog_cil_push_work(
if (ctx->start_lsn != commit_lsn) {
struct xlog_in_core *iclog;

- for (iclog = commit_iclog->ic_prev;
- iclog != commit_iclog;
+ for (iclog = ctx->commit_iclog->ic_prev;
+ iclog != ctx->commit_iclog;
iclog = iclog->ic_prev) {
xfs_lsn_t hlsn;

@@ -1201,7 +1211,7 @@ xlog_cil_push_work(
* ordering for this checkpoint is correctly preserved down to
* stable storage.
*/
- commit_iclog->ic_flags |= XLOG_ICL_NEED_FLUSH;
+ ctx->commit_iclog->ic_flags |= XLOG_ICL_NEED_FLUSH;
}

/*
@@ -1214,10 +1224,11 @@ xlog_cil_push_work(
* will be written when released, switch it's state to WANT_SYNC right
* now.
*/
- commit_iclog->ic_flags |= XLOG_ICL_NEED_FUA;
- if (push_commit_stable && commit_iclog->ic_state == XLOG_STATE_ACTIVE)
- xlog_state_switch_iclogs(log, commit_iclog, 0);
- xlog_state_release_iclog(log, commit_iclog, ticket);
+ ctx->commit_iclog->ic_flags |= XLOG_ICL_NEED_FUA;
+ if (push_commit_stable &&
+ ctx->commit_iclog->ic_state == XLOG_STATE_ACTIVE)
+ xlog_state_switch_iclogs(log, ctx->commit_iclog, 0);
+ xlog_state_release_iclog(log, ctx->commit_iclog, ticket);
spin_unlock(&log->l_icloglock);

xfs_log_ticket_ungrant(log, ticket);
diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h
index 849ba2eb3483..72dfa3b89513 100644
--- a/fs/xfs/xfs_log_priv.h
+++ b/fs/xfs/xfs_log_priv.h
@@ -237,6 +237,7 @@ struct xfs_cil_ctx {
struct work_struct discard_endio_work;
struct work_struct push_work;
atomic_t order_id;
+ struct xlog_in_core *commit_iclog;
};

/*
@@ -489,7 +490,7 @@ 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_cil_ctx *ctx,
struct list_head *lv_chain, struct xlog_ticket *tic,
- struct xlog_in_core **commit_iclog, uint32_t len);
+ uint32_t len);

void xfs_log_ticket_ungrant(struct xlog *log, struct xlog_ticket *ticket);
void xfs_log_ticket_regrant(struct xlog *log, struct xlog_ticket *ticket);
--
2.31.1