Commit 05b63d2b authored by Gao Xiang's avatar Gao Xiang
Browse files

erofs: allocate extra bvec pages directly instead of retrying 



If non-bootstrap bvecs cannot be kept in place (very rarely), an extra
short-lived page is allocated.

Let's just allocate it immediately rather than do unnecessary -EAGAIN
return first and retry as a cleanup.  Also it's unnecessary to use
__GFP_NOFAIL here since we could gracefully fail out this case instead.

Signed-off-by: default avatarGao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: default avatarYue Hu <huyue2@coolpad.com>
Link: https://lore.kernel.org/r/20230526201459.128169-2-hsiangkao@linux.alibaba.com
parent 796e9149

fs/erofs/zdata.c

+12 −20
Original line number Diff line number Diff line
@@ -242,12 +242,17 @@ static int z_erofs_bvec_enqueue(struct z_erofs_bvec_iter *iter, 
				struct z_erofs_bvec *bvec,

				struct page **candidate_bvpage)

{

	if (iter->cur == iter->nr) {

		if (!*candidate_bvpage)

			return -EAGAIN;

	if (iter->cur >= iter->nr) {

		struct page *nextpage = *candidate_bvpage;



		if (!nextpage) {

			nextpage = alloc_page(GFP_NOFS);

			if (!nextpage)

				return -ENOMEM;

			set_page_private(nextpage, Z_EROFS_SHORTLIVED_PAGE);

		}

		DBG_BUGON(iter->bvset->nextpage);

		iter->bvset->nextpage = *candidate_bvpage;

		iter->bvset->nextpage = nextpage;

		z_erofs_bvset_flip(iter);



		iter->bvset->nextpage = NULL;
@@ -906,10 +911,8 @@ static bool z_erofs_collector_end(struct z_erofs_decompress_frontend *fe) 
	z_erofs_bvec_iter_end(&fe->biter);

	mutex_unlock(&pcl->lock);



	if (fe->candidate_bvpage) {

		DBG_BUGON(z_erofs_is_shortlived_page(fe->candidate_bvpage));

	if (fe->candidate_bvpage)

		fe->candidate_bvpage = NULL;

	}



	/*

	 * if all pending pages are added, don't hold its reference
@@ -1054,24 +1057,13 @@ static int z_erofs_do_read_page(struct z_erofs_decompress_frontend *fe, 
	if (cur)

		tight &= (fe->mode >= Z_EROFS_PCLUSTER_FOLLOWED);



retry:

	err = z_erofs_attach_page(fe, &((struct z_erofs_bvec) {

					.page = page,

					.offset = offset - map->m_la,

					.end = end,

				  }), exclusive);

	/* should allocate an additional short-lived page for bvset */

	if (err == -EAGAIN && !fe->candidate_bvpage) {

		fe->candidate_bvpage = alloc_page(GFP_NOFS | __GFP_NOFAIL);

		set_page_private(fe->candidate_bvpage,

				 Z_EROFS_SHORTLIVED_PAGE);

		goto retry;

	}



	if (err) {

		DBG_BUGON(err == -EAGAIN && fe->candidate_bvpage);

	if (err)

		goto out;

	}



	z_erofs_onlinepage_split(page);

	/* bump up the number of spiltted parts of a page */