A background flush work may run for ever. So it's reasonable for it to
mimic the kupdate behavior of syncing old/expired inodes first.
The policy is
- enqueue all newly expired inodes at each queue_io() time
- retry with halfed expire interval until get some inodes to sync
CC: Jan Kara <jack@xxxxxxx>
Signed-off-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
fs/fs-writeback.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
--- linux-next.orig/fs/fs-writeback.c 2010-07-22 12:56:42.000000000 +0800
+++ linux-next/fs/fs-writeback.c 2010-07-22 13:07:51.000000000 +0800
@@ -217,14 +217,14 @@ static void move_expired_inodes(struct l
struct writeback_control *wbc)
{
unsigned long expire_interval = 0;
- unsigned long older_than_this;
+ unsigned long older_than_this = 0; /* reset to kill gcc warning */
LIST_HEAD(tmp);
struct list_head *pos, *node;
struct super_block *sb = NULL;
struct inode *inode;
int do_sb_sort = 0;
- if (wbc->for_kupdate) {
+ if (wbc->for_kupdate || wbc->for_background) {
expire_interval = msecs_to_jiffies(dirty_expire_interval * 10);
older_than_this = jiffies - expire_interval;
}
@@ -232,8 +232,15 @@ static void move_expired_inodes(struct l
while (!list_empty(delaying_queue)) {
inode = list_entry(delaying_queue->prev, struct inode, i_list);
if (expire_interval &&
- inode_dirtied_after(inode, older_than_this))
- break;
+ inode_dirtied_after(inode, older_than_this)) {
+ if (wbc->for_background &&
+ list_empty(dispatch_queue) && list_empty(&tmp)) {
+ expire_interval >>= 1;
+ older_than_this = jiffies - expire_interval;
+ continue;
+ } else
+ break;
+ }
if (sb && sb != inode->i_sb)
do_sb_sort = 1;
sb = inode->i_sb;
@@ -521,7 +528,8 @@ void writeback_inodes_wb(struct bdi_writ
wbc->wb_start = jiffies; /* livelock avoidance */
spin_lock(&inode_lock);
- if (!wbc->for_kupdate || list_empty(&wb->b_io))
+
+ if (!(wbc->for_kupdate || wbc->for_background) || list_empty(&wb->b_io))
queue_io(wb, wbc);
while (!list_empty(&wb->b_io)) {
@@ -550,7 +558,7 @@ static void __writeback_inodes_sb(struct
wbc->wb_start = jiffies; /* livelock avoidance */
spin_lock(&inode_lock);
- if (!wbc->for_kupdate || list_empty(&wb->b_io))
+ if (!(wbc->for_kupdate || wbc->for_background) || list_empty(&wb->b_io))
queue_io(wb, wbc);
writeback_sb_inodes(sb, wb, wbc, true);
spin_unlock(&inode_lock);
--
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