Re: [PATCH] erofs: remove unneeded icur field from struct z_erofs_decompress_frontend

From: Gao Xiang
Date: Mon Apr 17 2023 - 03:12:45 EST




On 2023/4/17 15:15, Yue Hu wrote:
On Mon, 17 Apr 2023 15:00:25 +0800
Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> wrote:


..


Although please help refine the comment below:

/* scan & fill inplace I/O pages in the reverse order */

Ok, will refine it in v2.

I rethink this, I don't want to go far in this way, and this makes a
O(n) scan into O(n^2) when a single inplace I/O page is added.

So sorry, I don't think it's a good way, although I also don't think
`icur` is a good name and we might need to find a better name.

Thanks,
Gao Xiang



Thanks,
Gao Xiang

+    unsigned int icur = pcl->pclusterpages;
-    while (fe->icur > 0) {
-        if (!cmpxchg(&pcl->compressed_bvecs[--fe->icur].page,
+    while (icur > 0) {
+        if (!cmpxchg(&pcl->compressed_bvecs[--icur].page,
                   NULL, bvec->page)) {
-            pcl->compressed_bvecs[fe->icur] = *bvec;
+            pcl->compressed_bvecs[icur] = *bvec;
              return true;
          }
      }
@@ -877,8 +876,6 @@ static int z_erofs_collector_begin(struct z_erofs_decompress_frontend *fe)
      }
      z_erofs_bvec_iter_begin(&fe->biter, &fe->pcl->bvset,
                  Z_EROFS_INLINE_BVECS, fe->pcl->vcnt);
-    /* since file-backed online pages are traversed in reverse order */
-    fe->icur = z_erofs_pclusterpages(fe->pcl);
      return 0;
  }