let the UUID code correctly load sectors from disc using BIO

Signed-off-by: Thorsten Glaser <tg@mirbsd.org>

target/linux/patches/2.6.36/uuid.patch

@@ -1,6 +1,7 @@
 # DP: Add support for specifying the root device using UUIDs on the
 # DP: kernel command line like this without the need for an initrd:
 # DP: linux ... root=UUID=ce40d6b2-18eb-4a75-aefe-7ddb0995ce63
+# DP: Note: debugging code is kept in, commented out “//” style.
 # DP:
 # DP: Written © 2010 by Thorsten Glaser <tg@debian.org>
 # DP: Idea from 1999 by David Balazic <david.balazic@uni-mb.si>
@@ -25,24 +26,24 @@
  	.name		= "disk",
  	.groups		= disk_attr_groups,
  	.release	= disk_release,
---- linux-2.6.36/init/do_mounts.c~	Wed Oct 20 22:30:22 2010
-+++ linux-2.6.36/init/do_mounts.c	Sat Nov 20 23:16:07 2010
-@@ -32,6 +32,84 @@ static int __initdata root_wait;
+--- linux-2.6.36/init/do_mounts.c~	Wed Oct 20 20:29:58 2010
++++ linux-2.6.36/init/do_mounts.c	Sun Nov 21 18:37:36 2010
+@@ -32,6 +32,132 @@ static int __initdata root_wait;
  
  dev_t ROOT_DEV;
  
 +#ifdef CONFIG_EXT2_FS
 +/* support for root=UUID=ce40d6b2-18eb-4a75-aefe-7ddb0995ce63 bootargs */
 +
-+#include <linux/buffer_head.h>
 +#include <linux/ext2_fs.h>
 +
-+__u8 root_dev_label[16];
++__u8 root_dev_uuid[16];
 +int root_dev_type;	/* 0 = normal (/dev/hda1, 0301); 1 = UUID; 3 = bad */
 +
 +/* imported from block/genhd.c after removing its static qualifier */
 +extern struct device_type disk_type;
 +
++/* helper function */
 +static __u8 __init fromhex(char c)
 +{
 +	if (c >= '0' && c <= '9')
@@ -68,7 +69,7 @@
 +		k = fromhex(*s++);
 +		if (j == 0xFF || k == 0xFF)
 +			goto bad_uuid;
-+		root_dev_label[i] = (j << 4) | k;
++		root_dev_uuid[i] = (j << 4) | k;
 +	}
 +	return;
 + bad_uuid:
@@ -76,19 +77,54 @@
 +	root_dev_type = 3;
 +}
 +
-+static int __init check_dev(dev_t devt, int blocksize)
++/* from drivers/md/md.c */
++static void __init initcode_bi_complete(struct bio *bio, int error)
 +{
-+	/* most of this taken from fs/ext2/super.c */
++	complete((struct completion*)bio->bi_private);
++}
++
++static int __init initcode_sync_page_read(struct block_device *bdev,
++    sector_t sector, int size, struct page *page)
++{
++	struct bio *bio = bio_alloc(GFP_NOIO, 1);
++	struct completion event;
++	int ret, rw = READ;
++
++	rw |= REQ_SYNC | REQ_UNPLUG;
++
++	bio->bi_bdev = bdev;
++	bio->bi_sector = sector;
++	bio_add_page(bio, page, size, 0);
++	init_completion(&event);
++	bio->bi_private = &event;
++	bio->bi_end_io = initcode_bi_complete;
++	submit_bio(rw, bio);
++	wait_for_completion(&event);
 +
-+	struct buffer_head * bh;
++	ret = test_bit(BIO_UPTODATE, &bio->bi_flags);
++	bio_put(bio);
++	/* 0 = failure */
++	return ret;
++}
++
++/* most of this taken from fs/ext2/super.c */
++static int __init check_dev(struct gendisk *thedisk, dev_t devt,
++    int blocksize, struct page *page)
++{
 +	struct ext2_super_block * es;
 +	struct block_device *bdev;
 +	unsigned long sb_block = 1;
 +	unsigned long logic_sb_block;
 +	unsigned long offset = 0;
-+	int rv = 0;
++	int rv = /* not found */ 0;
++	char bff[22];
 +
 +	bdev = bdget(devt);
++	if (blkdev_get(bdev, FMODE_READ)) {
++		printk(KERN_ERR "VFS: opening block device %s failed!\n",
++		    format_dev_t(bff, devt));
++		return (0);
++	}
 +
 +	if (blocksize != BLOCK_SIZE) {
 +		logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
@@ -97,14 +133,27 @@
 +		logic_sb_block = sb_block;
 +	}
 +
-+	if (!(bh = __bread(bdev, logic_sb_block, blocksize)))
-+		return (0);
-+	es = (struct ext2_super_block *)(((char *)bh->b_data) + offset);
++//	printk(KERN_ERR "D: attempting to read %d @%lu from "
++//	    "bdev %p devt %08X %s\n", blocksize, logic_sb_block,
++//	    bdev, devt, format_dev_t(bff, devt));
++	if (!initcode_sync_page_read(bdev, logic_sb_block, blocksize, page)) {
++//		printk(KERN_ERR "D: failed!\n");
++		goto out;
++	}
++	es = (struct ext2_super_block *)(((char *)page_address(page)) + offset);
 +	if (le16_to_cpu(es->s_magic) == EXT2_SUPER_MAGIC) {
-+		if (!memcmp(es->s_uuid, root_dev_label, 16))
-+			rv = 1;
++//		printk(KERN_ERR "D: has uuid "
++//		    "%02X%02X%02X%02X-%02X%02X-%02X%02X-%02X%02X-%02X%02X%02X%02X%02X%02X\n",
++//		    es->s_uuid[0], es->s_uuid[1], es->s_uuid[2], es->s_uuid[3],
++//		    es->s_uuid[4], es->s_uuid[5], es->s_uuid[6], es->s_uuid[7],
++//		    es->s_uuid[8], es->s_uuid[9], es->s_uuid[10], es->s_uuid[11],
++//		    es->s_uuid[12], es->s_uuid[13], es->s_uuid[14], es->s_uuid[15]);
++		if (!memcmp(es->s_uuid, root_dev_uuid, 16))
++			rv = /* found */ 1;
 +	}
-+	brelse(bh);
++//	  else printk(KERN_ERR "D: bad ext2fs magic\n");
++ out:
++	blkdev_put(bdev, FMODE_READ);
 +	return (rv);
 +}
 +#endif /* CONFIG_EXT2_FS for UUID support */
@@ -112,7 +161,7 @@
  static int __init load_ramdisk(char *str)
  {
  	rd_doload = simple_strtol(str,NULL,0) & 3;
-@@ -148,6 +226,13 @@ done:
+@@ -148,6 +274,13 @@ done:
  static int __init root_dev_setup(char *line)
  {
  	strlcpy(saved_root_name, line, sizeof(saved_root_name));
@@ -126,12 +175,13 @@
  	return 1;
  }
  
-@@ -333,6 +418,45 @@ void __init change_floppy(char *fmt, ...)
+@@ -333,6 +466,83 @@ void __init change_floppy(char *fmt, ...
  
  void __init mount_root(void)
  {
 +#ifdef CONFIG_EXT2_FS
 +	/* UUID support */
++//	printk_all_partitions();
 +	if (root_dev_type == 1) {
 +		int blocksize;
 +
@@ -139,34 +189,71 @@
 +		struct class_dev_iter iter;
 +		struct device *dev;
 +
++		/* from drivers/md/md.c */
++		struct page *sb_page;
++
++		if (!(sb_page = alloc_page(GFP_KERNEL))) {
++			printk(KERN_ERR "VFS: no memory for bio page\n");
++			goto nomemforbio;
++		}
++
++//		printk(KERN_ERR "D: root is: "
++//		    "%02X%02X%02X%02X-%02X%02X-%02X%02X-%02X%02X-%02X%02X%02X%02X%02X%02X\n",
++//		    root_dev_uuid[0], root_dev_uuid[1], root_dev_uuid[2], root_dev_uuid[3],
++//		    root_dev_uuid[4], root_dev_uuid[5], root_dev_uuid[6], root_dev_uuid[7],
++//		    root_dev_uuid[8], root_dev_uuid[9], root_dev_uuid[10], root_dev_uuid[11],
++//		    root_dev_uuid[12], root_dev_uuid[13], root_dev_uuid[14], root_dev_uuid[15]);
++		/* from block/genhd.c printk_all_partitions */
++//		printk(KERN_ERR "D: begin iter\n");
 +		class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
 +		while (root_dev_type && (dev = class_dev_iter_next(&iter))) {
++//			char bff[22];
 +			struct gendisk *disk = dev_to_disk(dev);
 +			struct disk_part_iter piter;
 +			struct hd_struct *part;
 +			if (get_capacity(disk) == 0 ||
-+			    (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO))
++			    (disk->flags & GENHD_FL_SUPPRESS_PARTITION_INFO)) {
++//				printk(KERN_ERR "D: ignoring\n");
 +				continue;
++			}
 +			blocksize = queue_logical_block_size(disk->queue);
-+
++//			printk(KERN_ERR "D: gendisk, blocksize %d "
++//			    "name '%s' devt %08X %s #part %d\n", blocksize,
++//			    disk->disk_name, dev->devt,
++//			    format_dev_t(bff, dev->devt),
++//			    disk_max_parts(disk));
 +			disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
 +			while (root_dev_type && (part = disk_part_iter_next(&piter))) {
 +				/* avoid empty or too small partitions */
++//				printk(KERN_ERR "D: part #%d start %llu "
++//				    "nr %llu\n", part->partno,
++//				    (__u64)part->start_sect,
++//				    (__u64)part->nr_sects);
 +				if (part->nr_sects < 8)
 +					continue;
-+				if (check_dev(part_devt(part), blocksize)) {
++				if (check_dev(disk, MKDEV(MAJOR(dev->devt),
++				    MINOR(dev->devt) + part->partno),
++				    blocksize, sb_page)) {
 +					ROOT_DEV = part_devt(part);
++//					printk(KERN_ERR "D: got match!\n");
++					// comment out below for debugging
 +					root_dev_type = 0;
 +				}
 +			}
 +			disk_part_iter_exit(&piter);
 +		}
++//		printk(KERN_ERR "D: end iter\n");
 +		class_dev_iter_exit(&iter);
++		put_page(sb_page);
 +	}
++ nomemforbio:
 +	if (root_dev_type == 1)
-+		printk(KERN_ERR "VFS: Unable to find root by UUID %s.\n", saved_root_name + 5);
++		printk(KERN_ERR "VFS: Unable to find root by UUID %s.\n",
++		    saved_root_name + 5);
 +	else if (root_dev_type == 3)
-+		panic("Badly formatted UUID %s was supplied as kernel parameter root", saved_root_name + 5);
++		/* execute deferred panic from parse_uuid */
++		panic("Badly formatted UUID %s was supplied as kernel "
++		    "parameter root", saved_root_name + 5);
 +#endif /* CONFIG_EXT2_FS for UUID support */
 +
  #ifdef CONFIG_ROOT_NFS