block, partition: add partition_meta_info to hd_struct

I'm reposting this patch series as v4 since there have been no additional
comments, and I cleaned up one extra bit of unneeded code (in 3/3). The patches
are against Linus's tree: 2bfc96a1
(2.6.36-rc3).

Would this patchset be suitable for inclusion in an mm branch?

This changes adds a partition_meta_info struct which itself contains a
union of structures that provide partition table specific metadata.

This change leaves the union empty. The subsequent patch includes an
implementation for CONFIG_EFI_PARTITION-based metadata.
Signed-off-by: Will Drewry <wad@chromium.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

block/genhd.c

@@ -1004,6 +1004,7 @@ static void disk_release(struct device *dev)
 	kfree(disk->random);
 	disk_replace_part_tbl(disk, NULL);
 	free_part_stats(&disk->part0);
+	free_part_info(&disk->part0);
 	kfree(disk);
 }
 struct class block_class = {

block/ioctl.c

@@ -62,7 +62,7 @@ static int blkpg_ioctl(struct block_device *bdev, struct blkpg_ioctl_arg __user
 
 			/* all seems OK */
 			part = add_partition(disk, partno, start, length,
-					     ADDPART_FLAG_NONE);
+					     ADDPART_FLAG_NONE, NULL);
 			mutex_unlock(&bdev->bd_mutex);
 			return IS_ERR(part) ? PTR_ERR(part) : 0;
 		case BLKPG_DEL_PARTITION:

fs/partitions/check.c

@@ -352,6 +352,7 @@ static void part_release(struct device *dev)
 {
 	struct hd_struct *p = dev_to_part(dev);
 	free_part_stats(p);
+	free_part_info(p);
 	kfree(p);
 }
 
@@ -401,7 +402,8 @@ static DEVICE_ATTR(whole_disk, S_IRUSR | S_IRGRP | S_IROTH,
 		   whole_disk_show, NULL);
 
 struct hd_struct *add_partition(struct gendisk *disk, int partno,
-				sector_t start, sector_t len, int flags)
+				sector_t start, sector_t len, int flags,
+				struct partition_meta_info *info)
 {
 	struct hd_struct *p;
 	dev_t devt = MKDEV(0, 0);
@@ -438,6 +440,14 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
 	p->partno = partno;
 	p->policy = get_disk_ro(disk);
 
+	if (info) {
+		struct partition_meta_info *pinfo = alloc_part_info(disk);
+		if (!pinfo)
+			goto out_free_stats;
+		memcpy(pinfo, info, sizeof(*info));
+		p->info = pinfo;
+	}
+
 	dname = dev_name(ddev);
 	if (isdigit(dname[strlen(dname) - 1]))
 		dev_set_name(pdev, "%sp%d", dname, partno);
@@ -451,7 +461,7 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
 
 	err = blk_alloc_devt(p, &devt);
 	if (err)
-		goto out_free_stats;
+		goto out_free_info;
 	pdev->devt = devt;
 
 	/* delay uevent until 'holders' subdir is created */
@@ -481,6 +491,8 @@ struct hd_struct *add_partition(struct gendisk *disk, int partno,
 
 	return p;
 
+out_free_info:
+	free_part_info(p);
 out_free_stats:
 	free_part_stats(p);
 out_free:
@@ -642,6 +654,7 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
 	/* add partitions */
 	for (p = 1; p < state->limit; p++) {
 		sector_t size, from;
+		struct partition_meta_info *info = NULL;
 
 		size = state->parts[p].size;
 		if (!size)
@@ -675,8 +688,12 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
 				size = get_capacity(disk) - from;
 			}
 		}
+
+		if (state->parts[p].has_info)
+			info = &state->parts[p].info;
 		part = add_partition(disk, p, from, size,
-				     state->parts[p].flags);
+				     state->parts[p].flags,
+				     &state->parts[p].info);
 		if (IS_ERR(part)) {
 			printk(KERN_ERR " %s: p%d could not be added: %ld\n",
 			       disk->disk_name, p, -PTR_ERR(part));

fs/partitions/check.h

 #include <linux/pagemap.h>
 #include <linux/blkdev.h>
+#include <linux/genhd.h>
 
 /*
  * add_gd_partition adds a partitions details to the devices partition
@@ -12,6 +13,8 @@ struct parsed_partitions {
 		sector_t from;
 		sector_t size;
 		int flags;
+		bool has_info;
+		struct partition_meta_info info;
 	} parts[DISK_MAX_PARTS];
 	int next;
 	int limit;

include/linux/genhd.h

@@ -12,6 +12,7 @@
 #include <linux/types.h>
 #include <linux/kdev_t.h>
 #include <linux/rcupdate.h>
+#include <linux/slab.h>
 
 #ifdef CONFIG_BLOCK
 
@@ -87,6 +88,14 @@ struct disk_stats {
 	unsigned long time_in_queue;
 };
 
+#define PARTITION_META_INFO_VOLNAMELTH	64
+#define PARTITION_META_INFO_UUIDLTH	16
+
+struct partition_meta_info {
+	u8 uuid[PARTITION_META_INFO_UUIDLTH];	/* always big endian */
+	u8 volname[PARTITION_META_INFO_VOLNAMELTH];
+};
+
 struct hd_struct {
 	sector_t start_sect;
 	sector_t nr_sects;
@@ -95,6 +104,7 @@ struct hd_struct {
 	struct device __dev;
 	struct kobject *holder_dir;
 	int policy, partno;
+	struct partition_meta_info *info;
 #ifdef CONFIG_FAIL_MAKE_REQUEST
 	int make_it_fail;
 #endif
@@ -181,6 +191,30 @@ static inline struct gendisk *part_to_disk(struct hd_struct *part)
 	return NULL;
 }
 
+static inline void part_pack_uuid(const u8 *uuid_str, u8 *to)
+{
+	int i;
+	for (i = 0; i < 16; ++i) {
+		*to++ = (hex_to_bin(*uuid_str) << 4) |
+			(hex_to_bin(*(uuid_str + 1)));
+		uuid_str += 2;
+		switch (i) {
+		case 3:
+		case 5:
+		case 7:
+		case 9:
+			uuid_str++;
+			continue;
+		}
+	}
+}
+
+static inline char *part_unpack_uuid(const u8 *uuid, char *out)
+{
+	sprintf(out, "%pU", uuid);
+	return out;
+}
+
 static inline int disk_max_parts(struct gendisk *disk)
 {
 	if (disk->flags & GENHD_FL_EXT_DEVT)
@@ -342,6 +376,19 @@ static inline int part_in_flight(struct hd_struct *part)
 	return part->in_flight[0] + part->in_flight[1];
 }
 
+static inline struct partition_meta_info *alloc_part_info(struct gendisk *disk)
+{
+	if (disk)
+		return kzalloc_node(sizeof(struct partition_meta_info),
+				    GFP_KERNEL, disk->node_id);
+	return kzalloc(sizeof(struct partition_meta_info), GFP_KERNEL);
+}
+
+static inline void free_part_info(struct hd_struct *part)
+{
+	kfree(part->info);
+}
+
 /* block/blk-core.c */
 extern void part_round_stats(int cpu, struct hd_struct *part);
 
@@ -533,7 +580,9 @@ extern int disk_expand_part_tbl(struct gendisk *disk, int target);
 extern int rescan_partitions(struct gendisk *disk, struct block_device *bdev);
 extern struct hd_struct * __must_check add_partition(struct gendisk *disk,
 						     int partno, sector_t start,
-						     sector_t len, int flags);
+						     sector_t len, int flags,
+						     struct partition_meta_info
+						       *info);
 extern void delete_partition(struct gendisk *, int);
 extern void printk_all_partitions(void);