[PATCH] fix return value for mb_cache_shrink_fn when nr_to_scan > 0

[Wang Sheng-Hui <crosslonelyover@xxxxxxxxx>]

Sorry. regerated the patch, please check it.
I wrapped most code in single pair of spinlock ops for 2 reasons:
1) get spinlock 2 times seems time consuming
2) use single pair of spinlock ops can keep "count"
  consistent for the shrink operation. 2 pairs may
  get some new ces created by other processes. 



Signed-off-by: Wang Sheng-Hui <crosslonelyover@xxxxxxxxx>
---
fs/mbcache.c |   24 ++++++++++++------------
1 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/fs/mbcache.c b/fs/mbcache.c
index ec88ff3..ee57aa3 100644
--- a/fs/mbcache.c
+++ b/fs/mbcache.c
@@ -201,21 +201,15 @@ mb_cache_shrink_fn(int nr_to_scan, gfp_t gfp_mask)
{
	LIST_HEAD(free_list);
	struct list_head *l, *ltmp;
+	struct mb_cache *cache;
	int count = 0;

-	spin_lock(&mb_cache_spinlock);
-	list_for_each(l, &mb_cache_list) {
-		struct mb_cache *cache =
-			list_entry(l, struct mb_cache, c_cache_list);
-		mb_debug("cache %s (%d)", cache->c_name,
-			  atomic_read(&cache->c_entry_count));
-		count += atomic_read(&cache->c_entry_count);
-	}
	mb_debug("trying to free %d entries", nr_to_scan);
-	if (nr_to_scan == 0) {
-		spin_unlock(&mb_cache_spinlock);
+
+	spin_lock(&mb_cache_spinlock);
+	if (nr_to_scan == 0)
		goto out;
-	}
+
	while (nr_to_scan-- && !list_empty(&mb_cache_lru_list)) {
		struct mb_cache_entry *ce =
			list_entry(mb_cache_lru_list.next,
@@ -223,12 +217,18 @@ mb_cache_shrink_fn(int nr_to_scan, gfp_t gfp_mask)
		list_move_tail(&ce->e_lru_list, &free_list);
		__mb_cache_entry_unhash(ce);
	}
-	spin_unlock(&mb_cache_spinlock);
	list_for_each_safe(l, ltmp, &free_list) {
		__mb_cache_entry_forget(list_entry(l, struct mb_cache_entry,
						   e_lru_list), gfp_mask);
	}
out:
+	list_for_each_entry(cache, &mb_cache_list, c_cache_list) {
+		mb_debug("cache %s (%d)", cache->c_name,
+			  atomic_read(&cache->c_entry_count));
+		count += atomic_read(&cache->c_entry_count);
+	}
+	spin_unlock(&mb_cache_spinlock);
+
	return (count / 100) * sysctl_vfs_cache_pressure;
}

--
1.6.3.3

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