---

yaml
---
r: 347831
b: refs/heads/master
c: 8c209ce
h: refs/heads/master
i:
  347829: be01844
  347827: 81dec8e
  347823: 5c60ad8
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8d76349d359064859217dc292dc8733e209705af
+refs/heads/master: 8c209ce721444a61b61d9e772746c721e4d8d1e8

trunk/fs/fscache/internal.h

@@ -200,6 +200,7 @@ extern atomic_t fscache_n_store_vmscan_not_storing;
 extern atomic_t fscache_n_store_vmscan_gone;
 extern atomic_t fscache_n_store_vmscan_busy;
 extern atomic_t fscache_n_store_vmscan_cancelled;
+extern atomic_t fscache_n_store_vmscan_wait;
 
 extern atomic_t fscache_n_marks;
 extern atomic_t fscache_n_uncaches;

trunk/fs/fscache/page.c

@@ -56,6 +56,7 @@ bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
 
 	_enter("%p,%p,%x", cookie, page, gfp);
 
+try_again:
 	rcu_read_lock();
 	val = radix_tree_lookup(&cookie->stores, page->index);
 	if (!val) {
@@ -104,11 +105,19 @@ bool __fscache_maybe_release_page(struct fscache_cookie *cookie,
 	return true;
 
 page_busy:
-	/* we might want to wait here, but that could deadlock the allocator as
-	 * the work threads writing to the cache may all end up sleeping
-	 * on memory allocation */
-	fscache_stat(&fscache_n_store_vmscan_busy);
-	return false;
+	/* We will wait here if we're allowed to, but that could deadlock the
+	 * allocator as the work threads writing to the cache may all end up
+	 * sleeping on memory allocation, so we may need to impose a timeout
+	 * too. */
+	if (!(gfp & __GFP_WAIT)) {
+		fscache_stat(&fscache_n_store_vmscan_busy);
+		return false;
+	}
+
+	fscache_stat(&fscache_n_store_vmscan_wait);
+	__fscache_wait_on_page_write(cookie, page);
+	gfp &= ~__GFP_WAIT;
+	goto try_again;
 }
 EXPORT_SYMBOL(__fscache_maybe_release_page);
 

trunk/fs/fscache/stats.c

@@ -69,6 +69,7 @@ atomic_t fscache_n_store_vmscan_not_storing;
 atomic_t fscache_n_store_vmscan_gone;
 atomic_t fscache_n_store_vmscan_busy;
 atomic_t fscache_n_store_vmscan_cancelled;
+atomic_t fscache_n_store_vmscan_wait;
 
 atomic_t fscache_n_marks;
 atomic_t fscache_n_uncaches;
@@ -232,11 +233,12 @@ static int fscache_stats_show(struct seq_file *m, void *v)
 		   atomic_read(&fscache_n_store_radix_deletes),
 		   atomic_read(&fscache_n_store_pages_over_limit));
 
-	seq_printf(m, "VmScan : nos=%u gon=%u bsy=%u can=%u\n",
+	seq_printf(m, "VmScan : nos=%u gon=%u bsy=%u can=%u wt=%u\n",
 		   atomic_read(&fscache_n_store_vmscan_not_storing),
 		   atomic_read(&fscache_n_store_vmscan_gone),
 		   atomic_read(&fscache_n_store_vmscan_busy),
-		   atomic_read(&fscache_n_store_vmscan_cancelled));
+		   atomic_read(&fscache_n_store_vmscan_cancelled),
+		   atomic_read(&fscache_n_store_vmscan_wait));
 
 	seq_printf(m, "Ops    : pend=%u run=%u enq=%u can=%u rej=%u\n",
 		   atomic_read(&fscache_n_op_pend),

trunk/fs/nfs/write.c

@@ -1794,7 +1794,8 @@ int nfs_migrate_page(struct address_space *mapping, struct page *newpage,
 	if (PagePrivate(page))
 		return -EBUSY;
 
-	nfs_fscache_release_page(page, GFP_KERNEL);
+	if (!nfs_fscache_release_page(page, GFP_KERNEL))
+		return -EBUSY;
 
 	return migrate_page(mapping, newpage, page, mode);
 }