shithub: lwext4

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Better writeback cache operations.

--- a/lwext4/ext4_blockdev.c

+++ b/lwext4/ext4_blockdev.c

@@ -111,6 +111,10 @@

     /*If cache is full we have to flush it anyway :(*/

     if(ext4_bcache_is_full(bdev->bc) && bdev->cache_write_back){

+

+        uint32_t free_candidate = bdev->bc->cnt;

+        uint32_t min_lru = 0xFFFFFFFF;

+

         for (i = 0; i < bdev->bc->cnt; ++i) {

             /*Check if buffer free was delayed.*/

             if(!bdev->bc->free_delay[i])

@@ -120,15 +124,23 @@

             if(bdev->bc->refctr[i])

                 continue;

+            if(bdev->bc->lru_id[i] < min_lru){

+                min_lru = bdev->bc->lru_id[i];

+                free_candidate = i;

+                continue;

+            }

+        }

+

+        if(free_candidate < bdev->bc->cnt){

             /*Buffer free was delayed and have no reference. Flush it.*/

             r = ext4_blocks_set_direct(bdev,

-                    bdev->bc->data + bdev->bc->itemsize * i,

-                    bdev->bc->lba[i], 1);

+                    bdev->bc->data + bdev->bc->itemsize * free_candidate,

+                    bdev->bc->lba[free_candidate], 1);

             if(r != EOK)

                 return r;

             /*No delayed anymore*/

-            bdev->bc->free_delay[i] = 0;

+            bdev->bc->free_delay[free_candidate] = 0;

             /*Reduce refered block count*/

             bdev->bc->ref_blocks--;