On Fri, Oct 10, 2008 at 10:08:29AM -0400, Christoph Hellwig wrote:
> On Fri, Oct 10, 2008 at 10:05:35AM -0400, Theodore Tso wrote:
> > 3) A version which (optionally via a flag in the wbc structure)
> > instructs write_cache_pages() to not pursue those updates. This has
> > not been written yet.
>
> This one sounds best to me (although we'd have to actualy see it..)
something like the below ?
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index bd91987..7599af2 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -63,6 +63,8 @@ struct writeback_control {
unsigned for_writepages:1; /* This is a writepages() call */
unsigned range_cyclic:1; /* range_start is cyclic */
unsigned more_io:1; /* more io to be dispatched */
+ /* flags which control the write_cache_pages behaviour */
+ int writeback_flags;
};
/*
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 718efa6..c198ead 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -876,11 +876,18 @@ int write_cache_pages(struct address_space *mapping,
pgoff_t end; /* Inclusive */
int scanned = 0;
int range_whole = 0;
+ int flags = wbc->writeback_flags;
+ long *nr_to_write, count;
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
return 0;
}
+ if (flags & WB_NO_NRWRITE_UPDATE) {
+ count = wbc->nr_to_write;
+ nr_to_write = &count;
+ } else
+ nr_to_write = &wbc->nr_to_write;
pagevec_init(&pvec, 0);
if (wbc->range_cyclic) {
@@ -939,7 +946,7 @@ int write_cache_pages(struct address_space *mapping,
unlock_page(page);
ret = 0;
}
- if (ret || (--(wbc->nr_to_write) <= 0))
+ if (ret || (--(*nr_to_write) <= 0))
done = 1;
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
@@ -958,8 +965,11 @@ int write_cache_pages(struct address_space *mapping,
index = 0;
goto retry;
}
- if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
+ if ((wbc->range_cyclic ||
+ (range_whole && wbc->nr_to_write > 0)) &&
+ (flags & ~WB_NO_INDEX_UPDATE)) {
mapping->writeback_index = index;
+ }
return ret;
}
--
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