erofs: clean up z_erofs_pcluster_readmore()

`end` parameter is no needed since it's pointless for !backmost, we can
handle it with backmost internally.  And we only expand the trailing
edge, so the newstart can be replaced with ->headoffset.

Also, remove linux/prefetch.h inclusion since that is not used anymore
after commit 386292919c25 ("erofs: introduce readmore decompression
strategy").

Signed-off-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20230525072605.17857-1-zbestahu@gmail.com
[ Gao Xiang: update commit description. ]
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 4402c23..305426a 100644 (file)
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -5,7 +5,6 @@
  * Copyright (C) 2022 Alibaba Cloud
  */
 #include "compress.h"
-#include <linux/prefetch.h>
 #include <linux/psi.h>
 #include <linux/cpuhotplug.h>
 #include <trace/events/erofs.h>
@@ -1825,28 +1824,28 @@ static void z_erofs_runqueue(struct z_erofs_decompress_frontend *f,
  */
 static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
                                      struct readahead_control *rac,
-                                     erofs_off_t end,
-                                     struct page **pagepool,
-                                     bool backmost)
+                                     struct page **pagepool, bool backmost)
 {
        struct inode *inode = f->inode;
        struct erofs_map_blocks *map = &f->map;
-       erofs_off_t cur;
+       erofs_off_t cur, end, headoffset = f->headoffset;
        int err;
 
        if (backmost) {
+               if (rac)
+                       end = headoffset + readahead_length(rac) - 1;
+               else
+                       end = headoffset + PAGE_SIZE - 1;
                map->m_la = end;
                err = z_erofs_map_blocks_iter(inode, map,
                                              EROFS_GET_BLOCKS_READMORE);
                if (err)
                        return;
 
-               /* expend ra for the trailing edge if readahead */
+               /* expand ra for the trailing edge if readahead */
                if (rac) {
-                       loff_t newstart = readahead_pos(rac);
-
                        cur = round_up(map->m_la + map->m_llen, PAGE_SIZE);
-                       readahead_expand(rac, newstart, cur - newstart);
+                       readahead_expand(rac, headoffset, cur - headoffset);
                        return;
                }
                end = round_up(end, PAGE_SIZE);
@@ -1894,10 +1893,9 @@ static int z_erofs_read_folio(struct file *file, struct folio *folio)
        trace_erofs_readpage(page, false);
        f.headoffset = (erofs_off_t)page->index << PAGE_SHIFT;
 
-       z_erofs_pcluster_readmore(&f, NULL, f.headoffset + PAGE_SIZE - 1,
-                                 &pagepool, true);
+       z_erofs_pcluster_readmore(&f, NULL, &pagepool, true);
        err = z_erofs_do_read_page(&f, page, &pagepool);
-       z_erofs_pcluster_readmore(&f, NULL, 0, &pagepool, false);
+       z_erofs_pcluster_readmore(&f, NULL, &pagepool, false);
 
        (void)z_erofs_collector_end(&f);
 
@@ -1923,8 +1921,7 @@ static void z_erofs_readahead(struct readahead_control *rac)
 
        f.headoffset = readahead_pos(rac);
 
-       z_erofs_pcluster_readmore(&f, rac, f.headoffset +
-                                 readahead_length(rac) - 1, &pagepool, true);
+       z_erofs_pcluster_readmore(&f, rac, &pagepool, true);
        nr_pages = readahead_count(rac);
        trace_erofs_readpages(inode, readahead_index(rac), nr_pages, false);
 
@@ -1947,7 +1944,7 @@ static void z_erofs_readahead(struct readahead_control *rac)
                                  page->index, EROFS_I(inode)->nid);
                put_page(page);
        }
-       z_erofs_pcluster_readmore(&f, rac, 0, &pagepool, false);
+       z_erofs_pcluster_readmore(&f, rac, &pagepool, false);
        (void)z_erofs_collector_end(&f);
 
        z_erofs_runqueue(&f, &pagepool,