NFS: Use cond_resched_lock() to reduce latencies in the commit scans
Ensure that we conditionally drop the inode->i_lock when it is safe
to do so in the commit loops.
We do so after locking the nfs_page, but before removing it from the
commit list. We can then use list_safe_reset_next to recover the loop
after the lock is retaken.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 628d9a6..bd93d40 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -561,7 +561,8 @@
/* i_lock held by caller */
static int
-nfs_scan_commit_list(struct list_head *src, struct list_head *dst, int max)
+nfs_scan_commit_list(struct list_head *src, struct list_head *dst, int max,
+ spinlock_t *lock)
{
struct nfs_page *req, *tmp;
int ret = 0;
@@ -569,6 +570,8 @@
list_for_each_entry_safe(req, tmp, src, wb_list) {
if (!nfs_lock_request(req))
continue;
+ if (cond_resched_lock(lock))
+ list_safe_reset_next(req, tmp, wb_list);
nfs_request_remove_commit_list(req);
nfs_list_add_request(req, dst);
ret++;
@@ -596,8 +599,10 @@
if (nfsi->ncommit > 0) {
const int max = INT_MAX;
- ret = nfs_scan_commit_list(&nfsi->commit_list, dst, max);
- ret += pnfs_scan_commit_lists(inode, max - ret);
+ ret = nfs_scan_commit_list(&nfsi->commit_list, dst, max,
+ &inode->i_lock);
+ ret += pnfs_scan_commit_lists(inode, max - ret,
+ &inode->i_lock);
}
spin_unlock(&inode->i_lock);
return ret;