Convert wbc.range_cyclic to new behavior: when past EOF, abort writeback
of the inode, which instructs writeback_single_inode() to delay it for a
while if necessary.
It removes one inefficient .range_cyclic IO pattern when writeback_index
wraps:
submit [10000-10100], (wrap), submit [0-100]
In which the submitted pages may be consisted of two distant ranges.
It also prevents submitting pointless IO for busy overwriters.
CC: Steven Whitehouse <swhiteho@xxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/gfs2/aops.c | 16 ++--------------
1 file changed, 2 insertions(+), 14 deletions(-)
--- linux.orig/fs/gfs2/aops.c 2009-10-06 23:37:48.000000000 +0800
+++ linux/fs/gfs2/aops.c 2009-10-06 23:38:41.000000000 +0800
@@ -287,7 +287,7 @@ static int gfs2_write_jdata_pagevec(stru
continue;
}
- if (!wbc->range_cyclic && page->index > end) {
+ if (page->index > end) {
ret = 1;
unlock_page(page);
continue;
@@ -340,7 +340,6 @@ static int gfs2_write_cache_jdata(struct
int nr_pages;
pgoff_t index;
pgoff_t end;
- int scanned = 0;
int range_whole = 0;
pagevec_init(&pvec, 0);
@@ -352,15 +351,12 @@ static int gfs2_write_cache_jdata(struct
end = wbc->range_end >> PAGE_CACHE_SHIFT;
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
range_whole = 1;
- scanned = 1;
}
-retry:
while (!done && (index <= end) &&
(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
PAGECACHE_TAG_DIRTY,
min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
- scanned = 1;
ret = gfs2_write_jdata_pagevec(mapping, wbc, &pvec, nr_pages, end);
if (ret)
done = 1;
@@ -371,16 +367,8 @@ retry:
cond_resched();
}
- if (!scanned && !done) {
- /*
- * We hit the last page and there is more work to be done: wrap
- * back to the start of the file
- */
- scanned = 1;
+ if (!nr_pages)
index = 0;
- goto retry;
- }
-
if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
mapping->writeback_index = index;
return ret;
--
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