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: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/afs/write.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
--- linux.orig/fs/afs/write.c 2009-10-06 23:37:48.000000000 +0800
+++ linux/fs/afs/write.c 2009-10-06 23:38:42.000000000 +0800
@@ -477,8 +477,10 @@ static int afs_writepages_region(struct
do {
n = find_get_pages_tag(mapping, &index, PAGECACHE_TAG_DIRTY,
1, &page);
- if (!n)
+ if (!n) {
+ index = 0;
break;
+ }
_debug("wback %lx", page->index);
@@ -551,9 +553,6 @@ int afs_writepages(struct address_space
start = mapping->writeback_index;
end = -1;
ret = afs_writepages_region(mapping, wbc, start, end, &next);
- if (start > 0 && wbc->nr_to_write > 0 && ret == 0)
- ret = afs_writepages_region(mapping, wbc, 0, start,
- &next);
mapping->writeback_index = next;
} else if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX) {
end = (pgoff_t)(LLONG_MAX >> PAGE_CACHE_SHIFT);
--
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