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: Chris Mason <chris.mason@xxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/btrfs/extent_io.c | 21 ++++++---------------
1 file changed, 6 insertions(+), 15 deletions(-)
--- linux.orig/fs/btrfs/extent_io.c 2009-10-06 23:37:49.000000000 +0800
+++ linux/fs/btrfs/extent_io.c 2009-10-06 23:38:32.000000000 +0800
@@ -2402,10 +2402,9 @@ static int extent_write_cache_pages(stru
int done = 0;
int nr_to_write_done = 0;
struct pagevec pvec;
- int nr_pages;
+ int nr_pages = 1;
pgoff_t index;
pgoff_t end; /* Inclusive */
- int scanned = 0;
int range_whole = 0;
pagevec_init(&pvec, 0);
@@ -2417,16 +2416,14 @@ static int extent_write_cache_pages(stru
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 && !nr_to_write_done && (index <= end) &&
(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
PAGECACHE_TAG_DIRTY, min(end - index,
(pgoff_t)PAGEVEC_SIZE-1) + 1))) {
unsigned i;
- scanned = 1;
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
@@ -2447,7 +2444,7 @@ retry:
continue;
}
- if (!wbc->range_cyclic && page->index > end) {
+ if (page->index > end) {
done = 1;
unlock_page(page);
continue;
@@ -2484,15 +2481,9 @@ retry:
pagevec_release(&pvec);
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;
- index = 0;
- goto retry;
- }
+ if (!nr_pages)
+ mapping->writeback_index = 0;
+
return ret;
}
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
