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Date:      Thu, 2 Nov 2017 08:47:03 +0000 (UTC)
From:      Toomas Soome <tsoome@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r325310 - head/sys/boot/zfs
Message-ID:  <201711020847.vA28l3o6015415@repo.freebsd.org>
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Author: tsoome
Date: Thu Nov  2 08:47:03 2017
New Revision: 325310
URL: https://svnweb.freebsd.org/changeset/base/325310

Log:
  zfs.c:vdev_read() needs to be careful about large sectors
  
  Using the same implementation as done in efi/boot1. We must handle smaller
  than sector size IO etc.
  
  Differential Revision:	https://reviews.freebsd.org/D12850

Modified:
  head/sys/boot/zfs/zfs.c

Modified: head/sys/boot/zfs/zfs.c
==============================================================================
--- head/sys/boot/zfs/zfs.c	Thu Nov  2 07:25:59 2017	(r325309)
+++ head/sys/boot/zfs/zfs.c	Thu Nov  2 08:47:03 2017	(r325310)
@@ -368,17 +368,61 @@ zfs_readdir(struct open_file *f, struct dirent *d)
 }
 
 static int
-vdev_read(vdev_t *vdev, void *priv, off_t offset, void *buf, size_t size)
+vdev_read(vdev_t *vdev, void *priv, off_t offset, void *buf, size_t bytes)
 {
-	int fd;
+	int fd, ret;
+	size_t res, size, remainder, rb_size, blksz;
+	unsigned secsz;
+	off_t off;
+	char *bouncebuf, *rb_buf;
 
 	fd = (uintptr_t) priv;
-	lseek(fd, offset, SEEK_SET);
-	if (read(fd, buf, size) == size) {
-		return 0;
-	} else {
-		return (EIO);
+	bouncebuf = NULL;
+
+	ret = ioctl(fd, DIOCGSECTORSIZE, &secsz);
+	if (ret != 0)
+		return (ret);
+
+	off = offset / secsz;
+	remainder = offset % secsz;
+	if (lseek(fd, off * secsz, SEEK_SET) == -1)
+		return (errno);
+
+	rb_buf = buf;
+	rb_size = bytes;
+	size = roundup2(bytes + remainder, secsz);
+	blksz = size;
+	if (remainder != 0 || size != bytes) {
+		bouncebuf = zfs_alloc(secsz);
+		if (bouncebuf == NULL) {
+			printf("vdev_read: out of memory\n");
+			return (ENOMEM);
+		}
+		rb_buf = bouncebuf;
+		blksz = rb_size - remainder;
 	}
+
+	while (bytes > 0) {
+		res = read(fd, rb_buf, rb_size);
+		if (res != rb_size) {
+			ret = EIO;
+			goto error;
+		}
+		if (bytes < blksz)
+			blksz = bytes;
+		if (bouncebuf != NULL)
+			memcpy(buf, rb_buf + remainder, blksz);
+		buf = (void *)((uintptr_t)buf + blksz);
+		bytes -= blksz;
+		remainder = 0;
+		blksz = rb_size;
+	}
+
+	ret = 0;
+error:
+	if (bouncebuf != NULL)
+		zfs_free(bouncebuf, secsz);
+	return (ret);
 }
 
 static int

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