UBUNTU: Ubuntu-4.13.0-45.50

[mirror_ubuntu-artful-kernel.git] / fs / buffer.c

diff --git a/fs/buffer.c b/fs/buffer.c
index ea0e05ec29169328756875115f61a4e4640fcd9d..5715dac7821fe1c49a1c1ecd8f6b12192f3f1d1c 100644 (file)
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1281,44 +1281,31 @@ static inline void check_irqs_on(void)
 }
 
 /*
- * The LRU management algorithm is dopey-but-simple.  Sorry.
+ * Install a buffer_head into this cpu's LRU.  If not already in the LRU, it is
+ * inserted at the front, and the buffer_head at the back if any is evicted.
+ * Or, if already in the LRU it is moved to the front.
  */
 static void bh_lru_install(struct buffer_head *bh)
 {
-       struct buffer_head *evictee = NULL;
+       struct buffer_head *evictee = bh;
+       struct bh_lru *b;
+       int i;
 
        check_irqs_on();
        bh_lru_lock();
-       if (__this_cpu_read(bh_lrus.bhs[0]) != bh) {
-               struct buffer_head *bhs[BH_LRU_SIZE];
-               int in;
-               int out = 0;
-
-               get_bh(bh);
-               bhs[out++] = bh;
-               for (in = 0; in < BH_LRU_SIZE; in++) {
-                       struct buffer_head *bh2 =
-                               __this_cpu_read(bh_lrus.bhs[in]);
 
-                       if (bh2 == bh) {
-                               __brelse(bh2);
-                       } else {
-                               if (out >= BH_LRU_SIZE) {
-                                       BUG_ON(evictee != NULL);
-                                       evictee = bh2;
-                               } else {
-                                       bhs[out++] = bh2;
-                               }
-                       }
+       b = this_cpu_ptr(&bh_lrus);
+       for (i = 0; i < BH_LRU_SIZE; i++) {
+               swap(evictee, b->bhs[i]);
+               if (evictee == bh) {
+                       bh_lru_unlock();
+                       return;
                }
-               while (out < BH_LRU_SIZE)
-                       bhs[out++] = NULL;
-               memcpy(this_cpu_ptr(&bh_lrus.bhs), bhs, sizeof(bhs));
        }
-       bh_lru_unlock();
 
-       if (evictee)
-               __brelse(evictee);
+       get_bh(bh);
+       bh_lru_unlock();
+       brelse(evictee);
 }
 
 /*