From 52d98bc2c05a54fa8caefa18768258fb8edaae66 Mon Sep 17 00:00:00 2001
From: marcel <marcel@FreeBSD.org>
Date: Wed, 24 Sep 2014 22:45:03 +0000
Subject: [PATCH] Finish QCOW version 2 and stop making it conditional.

We have a different ordering for the RC block(s) and L2 tables.
This is expected to be a non-issue, because everything is found
through file offsets in the corresponding RC table and L1 table.
Files that grow organically have RC blocks and L2 tables scattered
all over the place anyway.

The reason for the difference is that mkimg needs to be able to
write to a pipe. We can't seek forward and backward to fill in
the bits in non-sequential order.
---
 usr.bin/mkimg/qcow.c | 112 ++++++++++++++++++++++++++-----------------
 1 file changed, 67 insertions(+), 45 deletions(-)

diff --git a/usr.bin/mkimg/qcow.c b/usr.bin/mkimg/qcow.c
index d86de7d0bdd9..5033286821b3 100644
--- a/usr.bin/mkimg/qcow.c
+++ b/usr.bin/mkimg/qcow.c
@@ -40,8 +40,6 @@ __FBSDID("$FreeBSD$");
 #include "format.h"
 #include "mkimg.h"
 
-#undef	QCOW_SUPPORT_QCOW2
-
 /* Default cluster sizes. */
 #define	QCOW1_CLSTR_LOG2SZ	12	/* 4KB */
 #define	QCOW2_CLSTR_LOG2SZ	16	/* 64KB */
@@ -123,21 +121,19 @@ qcow1_resize(lba_t imgsz)
 	return (qcow_resize(imgsz, QCOW_VERSION_1));
 }
 
-#ifdef QCOW_SUPPORT_QCOW2
 static int
 qcow2_resize(lba_t imgsz)
 {
 
 	return (qcow_resize(imgsz, QCOW_VERSION_2));
 }
-#endif
 
 static int
 qcow_write(int fd, u_int version)
 {
 	struct qcow_header *hdr;
-	uint64_t *l1tbl, *l2tbl;
-	uint16_t *rctbl;
+	uint64_t *l1tbl, *l2tbl, *rctbl;
+	uint16_t *rcblk;
 	uint64_t clstr_imgsz, clstr_l2tbls, clstr_l1tblsz;
 	uint64_t clstr_rcblks, clstr_rctblsz;
 	uint64_t n, imagesz, nclstrs, ofs, ofsflags;
@@ -170,13 +166,15 @@ qcow_write(int fd, u_int version)
 	 * 0 - header
 	 * 1 - L1 table
 	 * 2 - RC table (v2 only)
-	 * 3 - First RC block (v2 only)
-	 * 4 - L2 tables
-	 * n - data
+	 * 3 - L2 tables
+	 * 4 - RC block (v2 only)
+	 * 5 - data
 	 */
 
 	l1clno = 1;
 	rcclno = 0;
+	rctbl = l2tbl = l1tbl = NULL;
+	rcblk = NULL;
 
 	hdr = calloc(1, clstrsz);
 	if (hdr == NULL)
@@ -196,7 +194,7 @@ qcow_write(int fd, u_int version)
 	case QCOW_VERSION_2:
 		ofsflags = QCOW_CLSTR_COPIED;
 		rcclno = l1clno + clstr_l1tblsz;
-		l2clno = rcclno + clstr_rctblsz + 1;
+		l2clno = rcclno + clstr_rctblsz;
 		be32enc(&hdr->clstr_log2sz, clstr_log2sz);
 		be32enc(&hdr->u.v2.l1_entries, clstr_l2tbls);
 		be64enc(&hdr->u.v2.l1_offset, clstrsz * l1clno);
@@ -207,52 +205,62 @@ qcow_write(int fd, u_int version)
 		return (EDOOFUS);
 	}
 
-	l2tbl = l1tbl = NULL;
-	rctbl = NULL;
+	if (sparse_write(fd, hdr, clstrsz) < 0) {
+                error = errno;
+		goto out;
+	}
+
+	free(hdr);
+	hdr = NULL;
+
+	ofs = clstrsz * l2clno;
+	nclstrs = 1 + clstr_l1tblsz + clstr_rctblsz;
 
 	l1tbl = calloc(1, clstrsz * clstr_l1tblsz);
 	if (l1tbl == NULL) {
 		error = ENOMEM;
 		goto out;
 	}
+
+	for (n = 0; n < clstr_imgsz; n++) {
+		blk = n * blk_clstrsz;
+		if (image_data(blk, blk_clstrsz)) {
+			nclstrs++;
+			l1idx = n >> (clstr_log2sz - 3);
+			if (l1tbl[l1idx] == 0) {
+				be64enc(l1tbl + l1idx, ofs + ofsflags);
+				ofs += clstrsz;
+				nclstrs++;
+			}
+		}
+	}
+
+	if (sparse_write(fd, l1tbl, clstrsz * clstr_l1tblsz) < 0) {
+		error = errno;
+		goto out;
+	}
+
+	clstr_rcblks = 0;
+	do {
+		n = clstr_rcblks;
+		clstr_rcblks = round_clstr((nclstrs + n) * 2) >> clstr_log2sz;
+	} while (n < clstr_rcblks);
+
 	if (rcclno > 0) {
 		rctbl = calloc(1, clstrsz * clstr_rctblsz);
 		if (rctbl == NULL) {
 			error = ENOMEM;
 			goto out;
 		}
-	}
-
-	ofs = clstrsz * l2clno;
-	for (n = 0; n < clstr_imgsz; n++) {
-		l1idx = n >> (clstr_log2sz - 3);
-		if (l1tbl[l1idx] != 0UL)
-			continue;
-		blk = n * blk_clstrsz;
-		if (image_data(blk, blk_clstrsz)) {
-			be64enc(l1tbl + l1idx, ofs + ofsflags);
+		for (n = 0; n < clstr_rcblks; n++) {
+			be64enc(rctbl + n, ofs);
 			ofs += clstrsz;
+			nclstrs++;
 		}
-	}
-
-	error = 0;
-	if (!error && sparse_write(fd, hdr, clstrsz) < 0)
-		error = errno;
-	if (!error && sparse_write(fd, l1tbl, clstrsz * clstr_l1tblsz) < 0)
-		error = errno;
-	if (rcclno > 0) {
-		if (!error &&
-		    sparse_write(fd, rctbl, clstrsz * clstr_rctblsz) < 0)
+		if (sparse_write(fd, rctbl, clstrsz * clstr_rctblsz) < 0) {
 			error = errno;
-		if (!error && sparse_write(fd, rctbl, clstrsz) < 0)
-			error = errno;
-	}
-	if (error)
-		goto out;
-
-	free(hdr);
-	hdr = NULL;
-	if (rctbl != NULL) {
+			goto out;
+		}
 		free(rctbl);
 		rctbl = NULL;
 	}
@@ -288,6 +296,22 @@ qcow_write(int fd, u_int version)
 	free(l1tbl);
 	l1tbl = NULL;
 
+	if (rcclno > 0) {
+		rcblk = calloc(1, clstrsz * clstr_rcblks);
+		if (rcblk == NULL) {
+			error = ENOMEM;
+			goto out;
+		}
+		for (n = 0; n < nclstrs; n++)
+			be16enc(rcblk + n, 1);
+		if (sparse_write(fd, rcblk, clstrsz * clstr_rcblks) < 0) {
+			error = errno;
+			goto out;
+		}
+		free(rcblk);
+		rcblk = NULL;
+	}
+
 	error = 0;
 	for (n = 0; n < clstr_imgsz; n++) {
 		blk = n * blk_clstrsz;
@@ -301,6 +325,8 @@ qcow_write(int fd, u_int version)
 		error = image_copyout_done(fd);
 
  out:
+	if (rcblk != NULL)
+		free(rcblk);
 	if (l2tbl != NULL)
 		free(l2tbl);
 	if (rctbl != NULL)
@@ -319,14 +345,12 @@ qcow1_write(int fd)
 	return (qcow_write(fd, QCOW_VERSION_1));
 }
 
-#ifdef QCOW_SUPPORT_QCOW2
 static int
 qcow2_write(int fd)
 {
 
 	return (qcow_write(fd, QCOW_VERSION_2));
 }
-#endif
 
 static struct mkimg_format qcow1_format = {
 	.name = "qcow",
@@ -336,7 +360,6 @@ static struct mkimg_format qcow1_format = {
 };
 FORMAT_DEFINE(qcow1_format);
 
-#ifdef QCOW_SUPPORT_QCOW2
 static struct mkimg_format qcow2_format = {
 	.name = "qcow2",
 	.description = "QEMU Copy-On-Write, version 2",
@@ -344,4 +367,3 @@ static struct mkimg_format qcow2_format = {
 	.write = qcow2_write,
 };
 FORMAT_DEFINE(qcow2_format);
-#endif