From: Wang Sheng-Hui Subject: [PATCH] fix return value for mb_cache_shrink_fn when nr_to_scan > 0 Date: Sun, 18 Jul 2010 09:01:39 +0800 Message-ID: <4C425273.5000702@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit To: linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, linux-mm@kvack.org, linux-ext4 , kernel-janitors , a.gruenbacher Return-path: Sender: owner-linux-mm@kvack.org List-Id: linux-ext4.vger.kernel.org Hi, The comment for struct shrinker in include/linux/mm.h says "shrink...It should return the number of objects which remain in the cache." Please notice the word "remain". In fs/mbcache.h, mb_cache_shrink_fn is used as the shrink function: static struct shrinker mb_cache_shrinker = { .shrink = mb_cache_shrink_fn, .seeks = DEFAULT_SEEKS, }; In mb_cache_shrink_fn, the return value for nr_to_scan > 0 is the number of mb_cache_entry before shrink operation. It may because the memory usage for mbcache is low, so the effect is not so obvious. I think we'd better fix the return value issue. Following patch is against 2.6.35-rc5. Please check it. Signed-off-by: Wang Sheng-Hui --- fs/mbcache.c | 10 ++++++++++ 1 files changed, 10 insertions(+), 0 deletions(-) diff --git a/fs/mbcache.c b/fs/mbcache.c index ec88ff3..412e7cc 100644 --- a/fs/mbcache.c +++ b/fs/mbcache.c @@ -228,6 +228,16 @@ mb_cache_shrink_fn(int nr_to_scan, gfp_t gfp_mask) __mb_cache_entry_forget(list_entry(l, struct mb_cache_entry, e_lru_list), gfp_mask); } + spin_lock(&mb_cache_spinlock); + count = 0; + 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); + } + spin_unlock(&mb_cache_spinlock); out: return (count / 100) * sysctl_vfs_cache_pressure; } -- 1.7.1.1 -- Thanks and Regards, shenghui -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org