[PATCH 5/9] writeback: consolidate variable names in balance_dirty_pages()

Wu Fengguang
2011-06-29T15:09:08Z

[-- Attachment #1: writeback-cleanup-name-merge.patch --]
[-- Type: text/plain, Size: 2684 bytes --]

Introduce

nr_dirty = NR_FILE_DIRTY + NR_WRITEBACK + NR_UNSTABLE_NFS

in order to simplify many tests in the following patches.

balance_dirty_pages() will eventually care only about the dirty sums
besides nr_writeback.

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
---
mm/page-writeback.c | 21 +++++++++++----------
1 file changed, 11 insertions(+), 10 deletions(-)

--- linux-next.orig/mm/page-writeback.c 2011-06-20 00:16:58.000000000 +0800
+++ linux-next/mm/page-writeback.c 2011-06-20 00:17:06.000000000 +0800
@@ -560,8 +560,9 @@ static void bdi_update_bandwidth(struct
static void balance_dirty_pages(struct address_space *mapping,
unsigned long write_chunk)
{
- long nr_reclaimable, bdi_nr_reclaimable;
- long nr_writeback, bdi_nr_writeback;
+ unsigned long nr_reclaimable, bdi_nr_reclaimable;
+ unsigned long nr_dirty; /* = file_dirty + writeback + unstable_nfs */
+ unsigned long bdi_dirty;
unsigned long background_thresh;
unsigned long dirty_thresh;
unsigned long bdi_thresh;
@@ -574,7 +575,7 @@ static void balance_dirty_pages(struct a
for (;;) {
nr_reclaimable = global_page_state(NR_FILE_DIRTY) +
global_page_state(NR_UNSTABLE_NFS);
- nr_writeback = global_page_state(NR_WRITEBACK);
+ nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK);

global_dirty_limits(&background_thresh, &dirty_thresh);

@@ -583,8 +584,7 @@ static void balance_dirty_pages(struct a
* catch-up. This avoids (excessively) small writeouts
* when the bdi limits are ramping up.
*/
- if (nr_reclaimable + nr_writeback <=
- (background_thresh + dirty_thresh) / 2)
+ if (nr_dirty <= (background_thresh + dirty_thresh) / 2)
break;

bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
@@ -602,10 +602,12 @@ static void balance_dirty_pages(struct a
*/
if (bdi_thresh < 2*bdi_stat_error(bdi)) {
bdi_nr_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE);
- bdi_nr_writeback = bdi_stat_sum(bdi, BDI_WRITEBACK);
+ bdi_dirty = bdi_nr_reclaimable +
+ bdi_stat_sum(bdi, BDI_WRITEBACK);
} else {
bdi_nr_reclaimable = bdi_stat(bdi, BDI_RECLAIMABLE);
- bdi_nr_writeback = bdi_stat(bdi, BDI_WRITEBACK);
+ bdi_dirty = bdi_nr_reclaimable +
+ bdi_stat(bdi, BDI_WRITEBACK);
}

/*
@@ -614,9 +616,8 @@ static void balance_dirty_pages(struct a
* bdi or process from holding back light ones; The latter is
* the last resort safeguard.
*/
- dirty_exceeded =
- (bdi_nr_reclaimable + bdi_nr_writeback > bdi_thresh)
- || (nr_reclaimable + nr_writeback > dirty_thresh);
+ dirty_exceeded = (bdi_dirty > bdi_thresh) ||
+ (nr_dirty > dirty_thresh);

if (!dirty_exceeded)
break;