Add TuxOnIce support adapted for the 4.5-gnu kernel versionpck-4.5-gnu

4 files changed, 596 insertions, 1 deletions

diff --git a/block/Makefile b/block/Makefile
index 4a3668393..37afa486e 100644
--- a/block/Makefile
+++ b/block/Makefile
@@ -7,7 +7,7 @@ obj-$(CONFIG_BLOCK) := bio.o elevator.o blk-core.o blk-tag.o blk-sysfs.o \
 			blk-exec.o blk-merge.o blk-softirq.o blk-timeout.o \
 			blk-lib.o blk-mq.o blk-mq-tag.o \
 			blk-mq-sysfs.o blk-mq-cpu.o blk-mq-cpumap.o ioctl.o \
-			genhd.o scsi_ioctl.o partition-generic.o ioprio.o \
+			uuid.o genhd.o scsi_ioctl.o partition-generic.o ioprio.o \
 			badblocks.o partitions/
 
 obj-$(CONFIG_BOUNCE)	+= bounce.o
diff --git a/block/blk-core.c b/block/blk-core.c
index b83d29755..64d137b04 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -48,6 +48,8 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
 
 DEFINE_IDA(blk_queue_ida);
 
+int trap_non_toi_io;
+
 /*
  * For the allocated request tables
  */
@@ -2104,6 +2106,9 @@ blk_qc_t submit_bio(int rw, struct bio *bio)
 {
 	bio->bi_rw |= rw;
 
+	if (unlikely(trap_non_toi_io))
+		BUG_ON(!bio_flagged(bio, BIO_TOI));
+
 	/*
 	 * If it's a regular read/write or a barrier with data attached,
 	 * go through the normal accounting stuff before submission.
diff --git a/block/genhd.c b/block/genhd.c
index 9f42526b4..7a6a655d8 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -18,6 +18,8 @@
 #include <linux/kobj_map.h>
 #include <linux/mutex.h>
 #include <linux/idr.h>
+#include <linux/ctype.h>
+#include <linux/fs_uuid.h>
 #include <linux/log2.h>
 #include <linux/pm_runtime.h>
 #include <linux/badblocks.h>
@@ -1417,6 +1419,85 @@ int invalidate_partition(struct gendisk *disk, int partno)
 
 EXPORT_SYMBOL(invalidate_partition);
 
+dev_t blk_lookup_fs_info(struct fs_info *seek)
+{
+	dev_t devt = MKDEV(0, 0);
+	struct class_dev_iter iter;
+	struct device *dev;
+	int best_score = 0;
+
+	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
+	while (best_score < 3 && (dev = class_dev_iter_next(&iter))) {
+		struct gendisk *disk = dev_to_disk(dev);
+		struct disk_part_iter piter;
+		struct hd_struct *part;
+
+		disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
+
+		while (best_score < 3 && (part = disk_part_iter_next(&piter))) {
+			int score = part_matches_fs_info(part, seek);
+			if (score > best_score) {
+				devt = part_devt(part);
+				best_score = score;
+			}
+		}
+		disk_part_iter_exit(&piter);
+	}
+	class_dev_iter_exit(&iter);
+	return devt;
+}
+
+/* Caller uses NULL, key to start. For each match found, we return a bdev on
+ * which we have done blkdev_get, and we do the blkdev_put on block devices
+ * that are passed to us. When no more matches are found, we return NULL.
+ */
+struct block_device *next_bdev_of_type(struct block_device *last,
+	const char *key)
+{
+	dev_t devt = MKDEV(0, 0);
+	struct class_dev_iter iter;
+	struct device *dev;
+	struct block_device *next = NULL, *bdev;
+	int got_last = 0;
+
+	if (!key)
+		goto out;
+
+	class_dev_iter_init(&iter, &block_class, NULL, &disk_type);
+	while (!devt && (dev = class_dev_iter_next(&iter))) {
+		struct gendisk *disk = dev_to_disk(dev);
+		struct disk_part_iter piter;
+		struct hd_struct *part;
+
+		disk_part_iter_init(&piter, disk, DISK_PITER_INCL_PART0);
+
+		while ((part = disk_part_iter_next(&piter))) {
+			bdev = bdget(part_devt(part));
+			if (last && !got_last) {
+				if (last == bdev)
+					got_last = 1;
+				continue;
+			}
+
+			if (blkdev_get(bdev, FMODE_READ, 0))
+				continue;
+
+			if (bdev_matches_key(bdev, key)) {
+				next = bdev;
+				break;
+			}
+
+			blkdev_put(bdev, FMODE_READ);
+		}
+		disk_part_iter_exit(&piter);
+	}
+	class_dev_iter_exit(&iter);
+out:
+	if (last)
+		blkdev_put(last, FMODE_READ);
+	return next;
+}
+
 /*
  * Disk events - monitor disk events like media change and eject request.
  */
diff --git a/block/uuid.c b/block/uuid.c
new file mode 100644
index 000000000..4610d7b8f
--- /dev/null
+++ b/block/uuid.c
@@ -0,0 +1,509 @@
+#include <linux/blkdev.h>
+#include <linux/ctype.h>
+#include <linux/fs_uuid.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+
+static int debug_enabled;
+
+#define PRINTK(fmt, args...) do {					\
+	if (debug_enabled)						\
+		printk(KERN_DEBUG fmt, ## args);			\
+	} while(0)
+
+#define PRINT_HEX_DUMP(v1, v2, v3, v4, v5, v6, v7, v8)			\
+	do {								\
+		if (debug_enabled)					\
+			print_hex_dump(v1, v2, v3, v4, v5, v6, v7, v8);	\
+	} while(0)
+
+/*
+ * Simple UUID translation
+ */
+
+struct uuid_info {
+	const char *key;
+	const char *name;
+	long bkoff;
+	unsigned sboff;
+	unsigned sig_len;
+	const char *magic;
+	int uuid_offset;
+	int last_mount_offset;
+	int last_mount_size;
+};
+
+/*
+ * Based on libuuid's blkid_magic array. Note that I don't
+ * have uuid offsets for all of these yet - mssing ones are 0x0.
+ * Further information welcome.
+ *
+ * Rearranged by page of fs signature for optimisation.
+ */
+static struct uuid_info uuid_list[] = {
+ { NULL, "oracleasm", 0, 32, 8, "ORCLDISK", 0x0, 0, 0 },
+ { "ntfs", "ntfs", 0, 3, 8, "NTFS    ", 0x0, 0, 0 },
+ { "vfat", "vfat", 0, 0x52, 5, "MSWIN", 0x0, 0, 0 },
+ { "vfat", "vfat", 0, 0x52, 8, "FAT32   ", 0x0, 0, 0 },
+ { "vfat", "vfat", 0, 0x36, 5, "MSDOS", 0x0, 0, 0 },
+ { "vfat", "vfat", 0, 0x36, 8, "FAT16   ", 0x0, 0, 0 },
+ { "vfat", "vfat", 0, 0x36, 8, "FAT12   ", 0x0, 0, 0 },
+ { "vfat", "vfat", 0, 0, 1, "\353", 0x0, 0, 0 },
+ { "vfat", "vfat", 0, 0, 1, "\351", 0x0, 0, 0 },
+ { "vfat", "vfat", 0, 0x1fe, 2, "\125\252", 0x0, 0, 0 },
+ { "xfs", "xfs", 0, 0, 4, "XFSB", 0x20, 0, 0 },
+ { "romfs", "romfs", 0, 0, 8, "-rom1fs-", 0x0, 0, 0 },
+ { "bfs", "bfs", 0, 0, 4, "\316\372\173\033", 0, 0, 0 },
+ { "cramfs", "cramfs", 0, 0, 4, "E=\315\050", 0x0, 0, 0 },
+ { "qnx4", "qnx4", 0, 4, 6, "QNX4FS", 0, 0, 0 },
+ { NULL, "crypt_LUKS", 0, 0, 6, "LUKS\xba\xbe", 0x0, 0, 0 },
+ { "squashfs", "squashfs", 0, 0, 4, "sqsh", 0, 0, 0 },
+ { "squashfs", "squashfs", 0, 0, 4, "hsqs", 0, 0, 0 },
+ { "ocfs", "ocfs", 0, 8, 9, "OracleCFS", 0x0, 0, 0 },
+ { "lvm2pv", "lvm2pv", 0, 0x018, 8, "LVM2 001", 0x0, 0, 0 },
+ { "sysv", "sysv", 0, 0x3f8, 4, "\020~\030\375", 0, 0, 0 },
+ { "ext", "ext", 1, 0x38, 2, "\123\357", 0x468, 0x42c, 4 },
+ { "minix", "minix", 1, 0x10, 2, "\177\023", 0, 0, 0 },
+ { "minix", "minix", 1, 0x10, 2, "\217\023", 0, 0, 0 },
+ { "minix", "minix", 1, 0x10, 2, "\150\044", 0, 0, 0 },
+ { "minix", "minix", 1, 0x10, 2, "\170\044", 0, 0, 0 },
+ { "lvm2pv", "lvm2pv", 1, 0x018, 8, "LVM2 001", 0x0, 0, 0 },
+ { "vxfs", "vxfs", 1, 0, 4, "\365\374\001\245", 0, 0, 0 },
+ { "hfsplus", "hfsplus", 1, 0, 2, "BD", 0x0, 0, 0 },
+ { "hfsplus", "hfsplus", 1, 0, 2, "H+", 0x0, 0, 0 },
+ { "hfsplus", "hfsplus", 1, 0, 2, "HX", 0x0, 0, 0 },
+ { "hfs", "hfs", 1, 0, 2, "BD", 0x0, 0, 0 },
+ { "ocfs2", "ocfs2", 1, 0, 6, "OCFSV2", 0x0, 0, 0 },
+ { "lvm2pv", "lvm2pv", 0, 0x218, 8, "LVM2 001", 0x0, 0, 0 },
+ { "lvm2pv", "lvm2pv", 1, 0x218, 8, "LVM2 001", 0x0, 0, 0 },
+ { "ocfs2", "ocfs2", 2, 0, 6, "OCFSV2", 0x0, 0, 0 },
+ { "swap", "swap", 0, 0xff6, 10, "SWAP-SPACE", 0x40c, 0, 0 },
+ { "swap", "swap", 0, 0xff6, 10, "SWAPSPACE2", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0xff6, 9, "S1SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0xff6, 9, "S2SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0xff6, 9, "ULSUSPEND", 0x40c, 0, 0 },
+ { "ocfs2", "ocfs2", 4, 0, 6, "OCFSV2", 0x0, 0, 0 },
+ { "ocfs2", "ocfs2", 8, 0, 6, "OCFSV2", 0x0, 0, 0 },
+ { "hpfs", "hpfs", 8, 0, 4, "I\350\225\371", 0, 0, 0 },
+ { "reiserfs", "reiserfs", 8, 0x34, 8, "ReIsErFs", 0x10054, 0, 0 },
+ { "reiserfs", "reiserfs", 8, 20, 8, "ReIsErFs", 0x10054, 0, 0 },
+ { "zfs", "zfs", 8, 0, 8, "\0\0\x02\xf5\xb0\x07\xb1\x0c", 0x0, 0, 0 },
+ { "zfs", "zfs", 8, 0, 8, "\x0c\xb1\x07\xb0\xf5\x02\0\0", 0x0, 0, 0 },
+ { "ufs", "ufs", 8, 0x55c, 4, "T\031\001\000", 0, 0, 0 },
+ { "swap", "swap", 0, 0x1ff6, 10, "SWAP-SPACE", 0x40c, 0, 0 },
+ { "swap", "swap", 0, 0x1ff6, 10, "SWAPSPACE2", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x1ff6, 9, "S1SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x1ff6, 9, "S2SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x1ff6, 9, "ULSUSPEND", 0x40c, 0, 0 },
+ { "reiserfs", "reiserfs", 64, 0x34, 9, "ReIsEr2Fs", 0x10054, 0, 0 },
+ { "reiserfs", "reiserfs", 64, 0x34, 9, "ReIsEr3Fs", 0x10054, 0, 0 },
+ { "reiserfs", "reiserfs", 64, 0x34, 8, "ReIsErFs", 0x10054, 0, 0 },
+ { "reiser4", "reiser4", 64, 0, 7, "ReIsEr4", 0x100544, 0, 0 },
+ { "gfs2", "gfs2", 64, 0, 4, "\x01\x16\x19\x70", 0x0, 0, 0 },
+ { "gfs", "gfs", 64, 0, 4, "\x01\x16\x19\x70", 0x0, 0, 0 },
+ { "btrfs", "btrfs", 64, 0x40, 8, "_BHRfS_M", 0x0, 0, 0 },
+ { "swap", "swap", 0, 0x3ff6, 10, "SWAP-SPACE", 0x40c, 0, 0 },
+ { "swap", "swap", 0, 0x3ff6, 10, "SWAPSPACE2", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x3ff6, 9, "S1SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x3ff6, 9, "S2SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x3ff6, 9, "ULSUSPEND", 0x40c, 0, 0 },
+ { "udf", "udf", 32, 1, 5, "BEA01", 0x0, 0, 0 },
+ { "udf", "udf", 32, 1, 5, "BOOT2", 0x0, 0, 0 },
+ { "udf", "udf", 32, 1, 5, "CD001", 0x0, 0, 0 },
+ { "udf", "udf", 32, 1, 5, "CDW02", 0x0, 0, 0 },
+ { "udf", "udf", 32, 1, 5, "NSR02", 0x0, 0, 0 },
+ { "udf", "udf", 32, 1, 5, "NSR03", 0x0, 0, 0 },
+ { "udf", "udf", 32, 1, 5, "TEA01", 0x0, 0, 0 },
+ { "iso9660", "iso9660", 32, 1, 5, "CD001", 0x0, 0, 0 },
+ { "iso9660", "iso9660", 32, 9, 5, "CDROM", 0x0, 0, 0 },
+ { "jfs", "jfs", 32, 0, 4, "JFS1", 0x88, 0, 0 },
+ { "swap", "swap", 0, 0x7ff6, 10, "SWAP-SPACE", 0x40c, 0, 0 },
+ { "swap", "swap", 0, 0x7ff6, 10, "SWAPSPACE2", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x7ff6, 9, "S1SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x7ff6, 9, "S2SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0x7ff6, 9, "ULSUSPEND", 0x40c, 0, 0 },
+ { "swap", "swap", 0, 0xfff6, 10, "SWAP-SPACE", 0x40c, 0, 0 },
+ { "swap", "swap", 0, 0xfff6, 10, "SWAPSPACE2", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0xfff6, 9, "S1SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0xfff6, 9, "S2SUSPEND", 0x40c, 0, 0 },
+ { "swap", "swsuspend", 0, 0xfff6, 9, "ULSUSPEND", 0x40c, 0, 0 },
+ { "zfs", "zfs", 264, 0, 8, "\0\0\x02\xf5\xb0\x07\xb1\x0c", 0x0, 0, 0 },
+ { "zfs", "zfs", 264, 0, 8, "\x0c\xb1\x07\xb0\xf5\x02\0\0", 0x0, 0, 0 },
+ { NULL, NULL, 0, 0, 0, NULL, 0x0, 0, 0 }
+};
+
+static int null_uuid(const char *uuid)
+{
+	int i;
+
+	for (i = 0; i < 16 && !uuid[i]; i++);
+
+	return (i == 16);
+}
+
+
+static void uuid_end_bio(struct bio *bio)
+{
+	struct page *page = bio->bi_io_vec[0].bv_page;
+
+        if (bio->bi_error)
+            SetPageError(page);
+
+	unlock_page(page);
+	bio_put(bio);
+}
+
+
+/**
+ * submit - submit BIO request
+ * @dev: The block device we're using.
+ * @page_num: The page we're reading.
+ *
+ * Based on Patrick Mochell's pmdisk code from long ago: "Straight from the
+ * textbook - allocate and initialize the bio. If we're writing, make sure
+ * the page is marked as dirty. Then submit it and carry on."
+ **/
+static struct page *read_bdev_page(struct block_device *dev, int page_num)
+{
+	struct bio *bio = NULL;
+	struct page *page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+
+	if (!page) {
+		printk(KERN_ERR "Failed to allocate a page for reading data "
+				"in UUID checks.");
+		return NULL;
+	}
+
+	bio = bio_alloc(GFP_NOFS, 1);
+	bio->bi_bdev = dev;
+	bio->bi_iter.bi_sector = page_num << 3;
+	bio->bi_end_io = uuid_end_bio;
+	bio->bi_flags |= (1 << BIO_TOI);
+
+	PRINTK("Submitting bio on device %lx, page %d using bio %p and page %p.\n",
+			(unsigned long) dev->bd_dev, page_num, bio, page);
+
+	if (bio_add_page(bio, page, PAGE_SIZE, 0) < PAGE_SIZE) {
+		printk(KERN_DEBUG "ERROR: adding page to bio at %d\n",
+				page_num);
+		bio_put(bio);
+		__free_page(page);
+		printk(KERN_DEBUG "read_bdev_page freed page %p (in error "
+				"path).\n", page);
+		return NULL;
+	}
+
+	lock_page(page);
+	submit_bio(READ | REQ_SYNC, bio);
+
+	wait_on_page_locked(page);
+	if (PageError(page)) {
+		__free_page(page);
+		page = NULL;
+	}
+	return page;
+}
+
+int bdev_matches_key(struct block_device *bdev, const char *key)
+{
+	unsigned char *data = NULL;
+	struct page *data_page = NULL;
+
+	int dev_offset, pg_num, pg_off, i;
+	int last_pg_num = -1;
+	int result = 0;
+	char buf[50];
+
+	if (null_uuid(key)) {
+		PRINTK("Refusing to find a NULL key.\n");
+		return 0;
+	}
+
+	if (!bdev->bd_disk) {
+		bdevname(bdev, buf);
+		PRINTK("bdev %s has no bd_disk.\n", buf);
+		return 0;
+	}
+
+	if (!bdev->bd_disk->queue) {
+		bdevname(bdev, buf);
+		PRINTK("bdev %s has no queue.\n", buf);
+		return 0;
+	}
+
+	for (i = 0; uuid_list[i].name; i++) {
+		struct uuid_info *dat = &uuid_list[i];
+
+		if (!dat->key || strcmp(dat->key, key))
+			continue;
+
+		dev_offset = (dat->bkoff << 10) + dat->sboff;
+		pg_num = dev_offset >> 12;
+		pg_off = dev_offset & 0xfff;
+
+		if ((((pg_num + 1) << 3) - 1) > bdev->bd_part->nr_sects >> 1)
+			continue;
+
+		if (pg_num != last_pg_num) {
+			if (data_page) {
+				kunmap(data_page);
+				__free_page(data_page);
+			}
+			data_page = read_bdev_page(bdev, pg_num);
+			if (!data_page)
+				continue;
+			data = kmap(data_page);
+		}
+
+		last_pg_num = pg_num;
+
+		if (strncmp(&data[pg_off], dat->magic, dat->sig_len))
+			continue;
+
+		result = 1;
+		break;
+	}
+
+	if (data_page) {
+		kunmap(data_page);
+		__free_page(data_page);
+	}
+
+	return result;
+}
+
+/* 
+ * part_matches_fs_info - Does the given partition match the details given?
+ *
+ * Returns a score saying how good the match is.
+ * 0 = no UUID match.
+ * 1 = UUID but last mount time differs.
+ * 2 = UUID, last mount time but not dev_t
+ * 3 = perfect match
+ *
+ * This lets us cope elegantly with probing resulting in dev_ts changing
+ * from boot to boot, and with the case where a user copies a partition
+ * (UUID is non unique), and we need to check the last mount time of the
+ * correct partition.
+ */
+int part_matches_fs_info(struct hd_struct *part, struct fs_info *seek)
+{
+	struct block_device *bdev;
+	struct fs_info *got;
+	int result = 0;
+	char buf[50];
+
+	if (null_uuid((char *) &seek->uuid)) {
+		PRINTK("Refusing to find a NULL uuid.\n");
+		return 0;
+	}
+
+	bdev = bdget(part_devt(part));
+
+	PRINTK("part_matches fs info considering %x.\n", part_devt(part));
+
+	if (blkdev_get(bdev, FMODE_READ, 0)) {
+		PRINTK("blkdev_get failed.\n");
+		return 0;
+	}
+
+	if (!bdev->bd_disk) {
+		bdevname(bdev, buf);
+		PRINTK("bdev %s has no bd_disk.\n", buf);
+		goto out;
+	}
+
+	if (!bdev->bd_disk->queue) {
+		bdevname(bdev, buf);
+		PRINTK("bdev %s has no queue.\n", buf);
+		goto out;
+	}
+
+	got = fs_info_from_block_dev(bdev);
+
+	if (got && !memcmp(got->uuid, seek->uuid, 16)) {
+		PRINTK(" Have matching UUID.\n");
+		PRINTK(" Got: LMS %d, LM %p.\n", got->last_mount_size, got->last_mount);
+		PRINTK(" Seek: LMS %d, LM %p.\n", seek->last_mount_size, seek->last_mount);
+		result = 1;
+
+		if (got->last_mount_size == seek->last_mount_size &&
+		    got->last_mount && seek->last_mount &&
+		    !memcmp(got->last_mount, seek->last_mount,
+			    got->last_mount_size)) {
+			result = 2;
+
+			PRINTK(" Matching last mount time.\n");
+
+			if (part_devt(part) == seek->dev_t) {
+				result = 3;
+				PRINTK(" Matching dev_t.\n");
+			} else
+				PRINTK("Dev_ts differ (%x vs %x).\n", part_devt(part), seek->dev_t);
+		}
+	}
+
+	PRINTK(" Score for %x is %d.\n", part_devt(part), result);
+	free_fs_info(got);
+out:
+	blkdev_put(bdev, FMODE_READ);
+	return result;
+}
+
+void free_fs_info(struct fs_info *fs_info)
+{
+	if (!fs_info || IS_ERR(fs_info))
+		return;
+
+	if (fs_info->last_mount)
+		kfree(fs_info->last_mount);
+
+	kfree(fs_info);
+}
+
+struct fs_info *fs_info_from_block_dev(struct block_device *bdev)
+{
+	unsigned char *data = NULL;
+	struct page *data_page = NULL;
+
+	int dev_offset, pg_num, pg_off;
+	int uuid_pg_num, uuid_pg_off, i;
+	unsigned char *uuid_data = NULL;
+	struct page *uuid_data_page = NULL;
+
+	int last_pg_num = -1, last_uuid_pg_num = 0;
+	char buf[50];
+	struct fs_info *fs_info = NULL;
+
+	bdevname(bdev, buf);
+
+	PRINTK("uuid_from_block_dev looking for partition type of %s.\n", buf);
+
+	for (i = 0; uuid_list[i].name; i++) {
+		struct uuid_info *dat = &uuid_list[i];
+		dev_offset = (dat->bkoff << 10) + dat->sboff;
+		pg_num = dev_offset >> 12;
+		pg_off = dev_offset & 0xfff;
+		uuid_pg_num = dat->uuid_offset >> 12;
+		uuid_pg_off = dat->uuid_offset & 0xfff;
+
+		if ((((pg_num + 1) << 3) - 1) > bdev->bd_part->nr_sects >> 1)
+			continue;
+
+		/* Ignore partition types with no UUID offset */
+		if (!dat->uuid_offset)
+			continue;
+
+		if (pg_num != last_pg_num) {
+			if (data_page) {
+				kunmap(data_page);
+				__free_page(data_page);
+			}
+			data_page = read_bdev_page(bdev, pg_num);
+			if (!data_page)
+				continue;
+			data = kmap(data_page);
+		}
+
+		last_pg_num = pg_num;
+
+		if (strncmp(&data[pg_off], dat->magic, dat->sig_len))
+			continue;
+
+		PRINTK("This partition looks like %s.\n", dat->name);
+
+		fs_info = kzalloc(sizeof(struct fs_info), GFP_KERNEL);
+
+		if (!fs_info) {
+			PRINTK("Failed to allocate fs_info struct.");
+			fs_info = ERR_PTR(-ENOMEM);
+			break;
+		}
+
+		/* UUID can't be off the end of the disk */
+		if ((uuid_pg_num > bdev->bd_part->nr_sects >> 3) ||
+				!dat->uuid_offset)
+			goto no_uuid;
+
+		if (!uuid_data || uuid_pg_num != last_uuid_pg_num) {
+			/* No need to reread the page from above */
+			if (uuid_pg_num == pg_num && uuid_data)
+				memcpy(uuid_data, data, PAGE_SIZE);
+			else {
+				if (uuid_data_page) {
+					kunmap(uuid_data_page);
+					__free_page(uuid_data_page);
+				}
+				uuid_data_page = read_bdev_page(bdev, uuid_pg_num);
+				if (!uuid_data_page)
+					continue;
+				uuid_data = kmap(uuid_data_page);
+			}
+		}
+
+		last_uuid_pg_num = uuid_pg_num;
+		memcpy(&fs_info->uuid, &uuid_data[uuid_pg_off], 16);
+		fs_info->dev_t = bdev->bd_dev;
+
+no_uuid:
+		PRINT_HEX_DUMP(KERN_EMERG, "fs_info_from_block_dev "
+				"returning uuid ", DUMP_PREFIX_NONE, 16, 1,
+				fs_info->uuid, 16, 0);
+
+		if (dat->last_mount_size) {
+			int pg = dat->last_mount_offset >> 12, sz;
+			int off = dat->last_mount_offset & 0xfff;
+			struct page *last_mount = read_bdev_page(bdev, pg);
+			unsigned char *last_mount_data;
+			char *ptr;
+
+			if (!last_mount) {
+				fs_info = ERR_PTR(-ENOMEM);
+				break;
+			}
+			last_mount_data = kmap(last_mount);
+			sz = dat->last_mount_size;
+			ptr = kmalloc(sz, GFP_KERNEL);
+
+			if (!ptr) {
+				printk(KERN_EMERG "fs_info_from_block_dev "
+					"failed to get memory for last mount "
+					"timestamp.");
+				free_fs_info(fs_info);
+				fs_info = ERR_PTR(-ENOMEM);
+			} else {
+				fs_info->last_mount = ptr;
+				fs_info->last_mount_size = sz;
+				memcpy(ptr, &last_mount_data[off], sz);
+			}
+
+			kunmap(last_mount);
+			__free_page(last_mount);
+		}
+		break;
+	}
+
+	if (data_page) {
+		kunmap(data_page);
+		__free_page(data_page);
+	}
+
+	if (uuid_data_page) {
+		kunmap(uuid_data_page);
+		__free_page(uuid_data_page);
+	}
+
+	return fs_info;
+}
+
+static int __init uuid_debug_setup(char *str)
+{
+	int value;
+
+	if (sscanf(str, "=%d", &value))
+		debug_enabled = value;
+
+	return 1;
+}
+
+__setup("uuid_debug", uuid_debug_setup);