[PATCH 8/8] xfs: simplify the list iteration in xlog_write

Christoph Hellwig
2021-06-16T16:35:10Z

Just use a single list_for_each_entry in xlog_write which then
dispatches to the simple or partial cases instead of using nested
loops.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/xfs_log.c | 73 +++++++++++-------------------------------------
1 file changed, 17 insertions(+), 56 deletions(-)

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index f8df09f37c3b84..365914c25ff0f0 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -2175,47 +2175,6 @@ xlog_write_full(
}
}

-/*
- * Write whole log vectors into a single iclog which is guaranteed to have
- * either sufficient space for the entire log vector chain to be written or
- * exclusive access to the remaining space in the iclog.
- *
- * Return the number of iovecs and data written into the iclog, as well as
- * a pointer to the logvec that doesn't fit in the log (or NULL if we hit the
- * end of the chain.
- */
-static struct xfs_log_vec *
-xlog_write_single(
- struct list_head *lv_chain,
- struct xfs_log_vec *log_vector,
- struct xlog_ticket *ticket,
- struct xlog_in_core *iclog,
- uint32_t *log_offset,
- uint32_t *len,
- uint32_t *record_cnt,
- uint32_t *data_cnt)
-{
- struct xfs_log_vec *lv;
-
- for (lv = log_vector;
- !list_entry_is_head(lv, lv_chain, lv_list);
- lv = list_next_entry(lv, lv_list)) {
- /*
- * If the entire log vec does not fit in the iclog, punt it to
- * the partial copy loop which can handle this case.
- */
- if (lv->lv_niovecs &&
- lv->lv_bytes > iclog->ic_size - *log_offset)
- break;
- xlog_write_full(lv, ticket, iclog, log_offset, len, record_cnt,
- data_cnt);
- }
- if (list_entry_is_head(lv, lv_chain, lv_list))
- lv = NULL;
- ASSERT(*len == 0 || lv);
- return lv;
-}
-
static int
xlog_write_get_more_iclog_space(
struct xlog *log,
@@ -2454,22 +2413,24 @@ xlog_write(
if (start_lsn)
*start_lsn = be64_to_cpu(iclog->ic_header.h_lsn);

- lv = list_first_entry_or_null(lv_chain, struct xfs_log_vec, lv_list);
- while (lv) {
- lv = xlog_write_single(lv_chain, lv, ticket, iclog, &log_offset,
- &len, &record_cnt, &data_cnt);
- if (!lv)
- break;
-
- error = xlog_write_partial(lv, ticket, &iclog, &log_offset,
- &len, &record_cnt, &data_cnt);
- if (error)
- break;
- lv = list_next_entry(lv, lv_list);
- if (list_entry_is_head(lv, lv_chain, lv_list))
- break;
+ list_for_each_entry(lv, lv_chain, lv_list) {
+ /*
+ * If the entire log vec does not fit in the iclog, punt it to
+ * the partial copy loop which can handle this case.
+ */
+ if (lv->lv_niovecs &&
+ lv->lv_bytes > iclog->ic_size - log_offset) {
+ error = xlog_write_partial(lv, ticket, &iclog,
+ &log_offset, &len,
+ &record_cnt, &data_cnt);
+ if (error)
+ break;
+ } else {
+ xlog_write_full(lv, ticket, iclog, &log_offset, &len,
+ &record_cnt, &data_cnt);
+ }
}
- ASSERT((len == 0 && !lv) || error);
+ ASSERT(len == 0 || error);

/*
* We've already been guaranteed that the last writes will fit inside
--
2.30.2