Commit a1a0dfd5 authored by NeilBrown's avatar NeilBrown Committed by Andrew Morton
Browse files

mm: handle THP in swap_*page_fs() 

Pages passed to swap_readpage()/swap_writepage() are not necessarily all
the same size - there may be transparent-huge-pages involves.

The BIO paths of swap_*page() handle this correctly, but the SWP_FS_OPS
path does not.

So we need to use thp_size() to find the size, not just assume PAGE_SIZE,
and we need to track the total length of the request, not just assume it
is "page * PAGE_SIZE".

Link: https://lkml.kernel.org/r/165119301488.15698.9457662928942765453.stgit@noble.brown


Signed-off-by: default avatarNeilBrown <neilb@suse.de>
Reported-by: default avatarMiaohe Lin <linmiaohe@huawei.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 2282679f

mm/page_io.c

+13 −10
Original line number Diff line number Diff line
@@ -239,6 +239,7 @@ struct swap_iocb { 
	struct kiocb		iocb;

	struct bio_vec		bvec[SWAP_CLUSTER_MAX];

	int			pages;

	int			len;

};

static mempool_t *sio_pool;
@@ -261,7 +262,7 @@ static void sio_write_complete(struct kiocb *iocb, long ret) 
	struct page *page = sio->bvec[0].bv_page;

	int p;



	if (ret != PAGE_SIZE * sio->pages) {

	if (ret != sio->len) {

		/*

		 * In the case of swap-over-nfs, this can be a

		 * temporary failure if the system has limited
@@ -301,7 +302,7 @@ static int swap_writepage_fs(struct page *page, struct writeback_control *wbc) 
		sio = *wbc->swap_plug;

	if (sio) {

		if (sio->iocb.ki_filp != swap_file ||

		    sio->iocb.ki_pos + sio->pages * PAGE_SIZE != pos) {

		    sio->iocb.ki_pos + sio->len != pos) {

			swap_write_unplug(sio);

			sio = NULL;

		}
@@ -312,10 +313,12 @@ static int swap_writepage_fs(struct page *page, struct writeback_control *wbc) 
		sio->iocb.ki_complete = sio_write_complete;

		sio->iocb.ki_pos = pos;

		sio->pages = 0;

		sio->len = 0;

	}

	sio->bvec[sio->pages].bv_page = page;

	sio->bvec[sio->pages].bv_len = PAGE_SIZE;

	sio->bvec[sio->pages].bv_len = thp_size(page);

	sio->bvec[sio->pages].bv_offset = 0;

	sio->len += thp_size(page);

	sio->pages += 1;

	if (sio->pages == ARRAY_SIZE(sio->bvec) || !wbc->swap_plug) {

		swap_write_unplug(sio);
@@ -371,8 +374,7 @@ void swap_write_unplug(struct swap_iocb *sio) 
	struct address_space *mapping = sio->iocb.ki_filp->f_mapping;

	int ret;



	iov_iter_bvec(&from, WRITE, sio->bvec, sio->pages,

		      PAGE_SIZE * sio->pages);

	iov_iter_bvec(&from, WRITE, sio->bvec, sio->pages, sio->len);

	ret = mapping->a_ops->swap_rw(&sio->iocb, &from);

	if (ret != -EIOCBQUEUED)

		sio_write_complete(&sio->iocb, ret);
@@ -383,7 +385,7 @@ static void sio_read_complete(struct kiocb *iocb, long ret) 
	struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb);

	int p;



	if (ret == PAGE_SIZE * sio->pages) {

	if (ret == sio->len) {

		for (p = 0; p < sio->pages; p++) {

			struct page *page = sio->bvec[p].bv_page;
@@ -415,7 +417,7 @@ static void swap_readpage_fs(struct page *page, 
		sio = *plug;

	if (sio) {

		if (sio->iocb.ki_filp != sis->swap_file ||

		    sio->iocb.ki_pos + sio->pages * PAGE_SIZE != pos) {

		    sio->iocb.ki_pos + sio->len != pos) {

			swap_read_unplug(sio);

			sio = NULL;

		}
@@ -426,10 +428,12 @@ static void swap_readpage_fs(struct page *page, 
		sio->iocb.ki_pos = pos;

		sio->iocb.ki_complete = sio_read_complete;

		sio->pages = 0;

		sio->len = 0;

	}

	sio->bvec[sio->pages].bv_page = page;

	sio->bvec[sio->pages].bv_len = PAGE_SIZE;

	sio->bvec[sio->pages].bv_len = thp_size(page);

	sio->bvec[sio->pages].bv_offset = 0;

	sio->len += thp_size(page);

	sio->pages += 1;

	if (sio->pages == ARRAY_SIZE(sio->bvec) || !plug) {

		swap_read_unplug(sio);
@@ -521,8 +525,7 @@ void __swap_read_unplug(struct swap_iocb *sio) 
	struct address_space *mapping = sio->iocb.ki_filp->f_mapping;

	int ret;



	iov_iter_bvec(&from, READ, sio->bvec, sio->pages,

		      PAGE_SIZE * sio->pages);

	iov_iter_bvec(&from, READ, sio->bvec, sio->pages, sio->len);

	ret = mapping->a_ops->swap_rw(&sio->iocb, &from);

	if (ret != -EIOCBQUEUED)

		sio_read_complete(&sio->iocb, ret);