STRLCPY/criu

vma: Do not open similar VMAs multiple times

On real apps it's typical to have sequences ov VMAs with
absolutely the same file mapped. We've seen this dump-time
and fixed multiple openings of map_files links with the
file_borrowed flag.

Restore situation is the same -- the vm_open() call in many
cases re-open the same path with the same flags. This slows
things down.

To fix this -- chain VMAs with mapped files to each other
and only the first one opens the file and only the last
one closes it.

✓ travis-ci: success for mem: Do not re-open files for mappings when not required
Signed-off-by: Pavel Emelyanov <[email protected]>

Pavel Emelyanov committed 7 years ago

a0738c75

1 parent 77e9c5d8

Total 6 files Show one by one

■ ■ ■ ■ ■ ■ ■

criu/files-reg.c

		skipped 1623 lines
1624	1624		return open_reg_fd(fd);
1625	1625		}
1626	1626
	1627	+	static int borrow_filemap(int pid, struct vma_area *vma)
	1628	+	{
	1629	+	struct vma_area *fvma = vma->fvma;
	1630	+
	1631	+	BUG_ON(!(fvma->e->status & VMA_NO_CLOSE));
	1632	+	vma->e->fd = fvma->e->fd;
	1633	+
	1634	+	return 0;
	1635	+	}
	1636	+
1627	1637		static int open_filemap(int pid, struct vma_area *vma)
1628	1638		{
1629	1639		u32 flags;
		skipped 16 lines
1646	1656		return 0;
1647	1657		}
1648	1658
1649		-	int collect_filemap(struct vma_area *vma)
	1659	+	int collect_filemap(struct vma_area vma, struct vma_file_ctx ctx)
1650	1660		{
1651	1661		struct file_desc *fd;
1652	1662
		skipped 12 lines
1665	1675		return -1;
1666	1676
1667	1677		vma->vmfd = fd;
1668		-	vma->vm_open = open_filemap;
	1678	+	if (ctx->vma && ctx->flags == vma->e->flags && ctx->fd == fd) {
	1679	+	vma->vm_open = borrow_filemap;
	1680	+	vma->fvma = ctx->vma;
	1681	+	ctx->vma->e->status \|= VMA_NO_CLOSE;
	1682	+	/* Change VMA so that next borrower sets NO_CLOSE on us */
	1683	+	ctx->vma = vma;
	1684	+	} else {
	1685	+	vma->vm_open = open_filemap;
	1686	+	ctx->flags = vma->e->fdflags;
	1687	+	ctx->fd = fd;
	1688	+	ctx->vma = vma;
	1689	+	}
	1690	+
1669	1691		return 0;
1670	1692		}
1671	1693
		skipped 83 lines

■ ■ ■ ■ ■ ■

criu/include/files-reg.h

		skipped 39 lines
40	40
41	41		extern struct file_desc *try_collect_special_file(u32 id, int optional);
42	42		#define collect_special_file(id) try_collect_special_file(id, 0)
43		-	extern int collect_filemap(struct vma_area *);
	43	+	struct vma_file_ctx {
	44	+	u32 flags;
	45	+	struct file_desc *fd;
	46	+	struct vma_area *vma;
	47	+	};
	48	+	extern int collect_filemap(struct vma_area , struct vma_file_ctx ctx);
44	49
45	50		extern int collect_remaps_and_regfiles(void);
46	51
		skipped 11 lines

■ ■ ■ ■ ■ ■

criu/include/image.h

		skipped 88 lines
89	89		#define VMA_AREA_VVAR (1 << 12)
90	90		#define VMA_AREA_AIORING (1 << 13)
91	91
	92	+	#define VMA_NO_CLOSE (1 << 28)
92	93		#define VMA_NO_PROT_WRITE (1 << 29)
93	94		#define VMA_PREMMAPED (1 << 30)
94	95		#define VMA_UNSUPP (1 << 31)
		skipped 78 lines

■ ■ ■ ■ ■ ■

criu/include/vma.h

		skipped 52 lines
53	53		int (vm_open)(int pid, struct vma_area vma);
54	54		struct file_desc *vmfd;
55	55		struct vma_area pvma; / parent for inherited VMAs */
	56	+	struct vma_area fvma; / vma from which to borrow a file */
56	57		unsigned long page_bitmap; / existent pages */
57	58		unsigned long premmaped_addr; /* restore only */
58	59
		skipped 69 lines

■ ■ ■ ■ ■ ■

criu/mem.c

		skipped 449 lines
450	450		int ret = -1, vn = 0;
451	451		struct cr_img *img;
452	452		struct rst_info *ri = rsti(i);
	453	+	struct vma_file_ctx ctx = {};
453	454
454	455		img = open_image(CR_FD_MM, O_RSTR, pid);
455	456		if (!img)
		skipped 53 lines
509	510		ret = collect_shmem(pid, vma);
510	511		else if (vma_area_is(vma, VMA_FILE_PRIVATE) \|\|
511	512		vma_area_is(vma, VMA_FILE_SHARED))
512		-	ret = collect_filemap(vma);
	513	+	ret = collect_filemap(vma, &ctx);
513	514		else if (vma_area_is(vma, VMA_AREA_SOCKET))
514	515		ret = collect_socket_map(vma);
515	516		else
		skipped 160 lines
676	677		return -1;
677	678		}
678	679
679		-	if (vma_area_is(vma, VMA_FILE_PRIVATE))
	680	+	if (vma_area_is(vma, VMA_FILE_PRIVATE) &&
	681	+	!vma_area_is(vma, VMA_NO_CLOSE))
680	682		close(vma->e->fd);
681	683		} else {
682	684		void *paddr;
		skipped 455 lines

■ ■ ■ ■ ■ ■

criu/pie/restorer.c

		skipped 617 lines
618	618		vma_entry->fd,
619	619		vma_entry->pgoff);
620	620
621		-	if (vma_entry->fd != -1)
	621	+	if ((vma_entry->fd != -1) &&
	622	+	!(vma_entry->status & VMA_NO_CLOSE))
622	623		sys_close(vma_entry->fd);
623	624
624	625		return addr;
		skipped 969 lines