+ erofs-convert-compressed-files-from-readpages-to-readahead.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: erofs: convert compressed files from readpages to readahead
has been added to the -mm tree.  Its filename is
     erofs-convert-compressed-files-from-readpages-to-readahead.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/erofs-convert-compressed-files-from-readpages-to-readahead.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/erofs-convert-compressed-files-from-readpages-to-readahead.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Subject: erofs: convert compressed files from readpages to readahead

Use the new readahead operation in erofs.

Link: http://lkml.kernel.org/r/20200414150233.24495-20-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/erofs/zdata.c |   29 +++++++++--------------------
 1 file changed, 9 insertions(+), 20 deletions(-)

--- a/fs/erofs/zdata.c~erofs-convert-compressed-files-from-readpages-to-readahead
+++ a/fs/erofs/zdata.c
@@ -1305,28 +1305,23 @@ static bool should_decompress_synchronou
 	return nr <= sbi->max_sync_decompress_pages;
 }
 
-static int z_erofs_readpages(struct file *filp, struct address_space *mapping,
-			     struct list_head *pages, unsigned int nr_pages)
+static void z_erofs_readahead(struct readahead_control *rac)
 {
-	struct inode *const inode = mapping->host;
+	struct inode *const inode = rac->mapping->host;
 	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 
-	bool sync = should_decompress_synchronously(sbi, nr_pages);
+	bool sync = should_decompress_synchronously(sbi, readahead_count(rac));
 	struct z_erofs_decompress_frontend f = DECOMPRESS_FRONTEND_INIT(inode);
-	gfp_t gfp = mapping_gfp_constraint(mapping, GFP_KERNEL);
-	struct page *head = NULL;
+	struct page *page, *head = NULL;
 	LIST_HEAD(pagepool);
 
-	trace_erofs_readpages(mapping->host, lru_to_page(pages)->index,
-			      nr_pages, false);
+	trace_erofs_readpages(inode, readahead_index(rac),
+			readahead_count(rac), false);
 
-	f.headoffset = (erofs_off_t)lru_to_page(pages)->index << PAGE_SHIFT;
-
-	for (; nr_pages; --nr_pages) {
-		struct page *page = lru_to_page(pages);
+	f.headoffset = readahead_pos(rac);
 
+	while ((page = readahead_page(rac))) {
 		prefetchw(&page->flags);
-		list_del(&page->lru);
 
 		/*
 		 * A pure asynchronous readahead is indicated if
@@ -1335,11 +1330,6 @@ static int z_erofs_readpages(struct file
 		 */
 		sync &= !(PageReadahead(page) && !head);
 
-		if (add_to_page_cache_lru(page, mapping, page->index, gfp)) {
-			list_add(&page->lru, &pagepool);
-			continue;
-		}
-
 		set_page_private(page, (unsigned long)head);
 		head = page;
 	}
@@ -1368,11 +1358,10 @@ static int z_erofs_readpages(struct file
 
 	/* clean up the remaining free pages */
 	put_pages_list(&pagepool);
-	return 0;
 }
 
 const struct address_space_operations z_erofs_aops = {
 	.readpage = z_erofs_readpage,
-	.readpages = z_erofs_readpages,
+	.readahead = z_erofs_readahead,
 };
 
_

Patches currently in -mm which might be from willy@infradead.org are

mm-move-readahead-prototypes-from-mmh.patch
mm-return-void-from-various-readahead-functions.patch
mm-ignore-return-value-of-readpages.patch
mm-move-readahead-nr_pages-check-into-read_pages.patch
mm-add-new-readahead_control-api.patch
mm-use-readahead_control-to-pass-arguments.patch
mm-rename-various-offset-parameters-to-index.patch
mm-rename-readahead-loop-variable-to-i.patch
mm-remove-page_offset-from-readahead-loop.patch
mm-put-readahead-pages-in-cache-earlier.patch
mm-add-readahead-address-space-operation.patch
mm-move-end_index-check-out-of-readahead-loop.patch
mm-add-page_cache_readahead_unbounded.patch
mm-document-why-we-dont-set-pagereadahead.patch
mm-use-memalloc_nofs_save-in-readahead-path.patch
fs-convert-mpage_readpages-to-mpage_readahead.patch
btrfs-convert-from-readpages-to-readahead.patch
erofs-convert-uncompressed-files-from-readpages-to-readahead.patch
erofs-convert-compressed-files-from-readpages-to-readahead.patch
ext4-convert-from-readpages-to-readahead.patch
ext4-pass-the-inode-to-ext4_mpage_readpages.patch
f2fs-convert-from-readpages-to-readahead.patch
f2fs-pass-the-inode-to-f2fs_mpage_readpages.patch
fuse-convert-from-readpages-to-readahead.patch
iomap-convert-from-readpages-to-readahead.patch