patch-2.3.3 linux/drivers/block/blkpg.c

• Lines: 289
• Date: Sat May 15 23:43:04 1999
• Orig file: v2.3.2/linux/drivers/block/blkpg.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.2/linux/drivers/block/blkpg.c linux/drivers/block/blkpg.c
@@ -0,0 +1,288 @@
+/*
+ * Partition table and disk geometry handling
+ *
+ * This obsoletes the partition-handling code in genhd.c:
+ * Userspace can look at a disk in arbitrary format and tell
+ * the kernel what partitions there are on the disk, and how
+ * these should be numbered.
+ * It also allows one to repartition a disk that is being used.
+ *
+ * A single ioctl with lots of subfunctions:
+ *
+ * Device number stuff:
+ *    get_whole_disk()          (given the device number of a partition, find
+ *                               the device number of the encompassing disk)
+ *    get_all_partitions()      (given the device number of a disk, return the
+ *                               device numbers of all its known partitions)
+ *
+ * Partition stuff:
+ *    add_partition()
+ *    delete_partition()
+ *    test_partition_in_use()   (also for test_disk_in_use)
+ *
+ * Geometry stuff:
+ *    get_geometry()
+ *    set_geometry()
+ *    get_bios_drivedata()
+ *
+ * For today, only the partition stuff - aeb, 990515
+ */
+
+#include <linux/errno.h>
+#include <linux/fs.h>			/* for BLKRASET, ... */
+#include <linux/sched.h>		/* for capable() */
+#include <linux/blk.h>			/* for set_device_ro() */
+#include <linux/blkpg.h>
+#include <linux/genhd.h>
+#include <linux/swap.h>			/* for is_swap_partition() */
+
+#include <asm/uaccess.h>
+
+/*
+ * What is the data describing a partition?
+ *
+ * 1. a device number (kdev_t)
+ * 2. a starting sector and number of sectors (hd_struct)
+ *    given in the part[] array of the gendisk structure for the drive.
+ *
+ * The number of sectors is replicated in the sizes[] array of
+ * the gendisk structure for the major, which again is copied to
+ * the blk_size[][] array.
+ * (However, hd_struct has the number of 512-byte sectors,
+ *  g->sizes[] and blk_size[][] have the number of 1024-byte blocks.)
+ * Note that several drives may have the same major.
+ */
+
+/* a linear search, superfluous when dev is a pointer */
+static struct gendisk *get_gendisk(kdev_t dev) {
+	struct gendisk *g;
+	int m = MAJOR(dev);
+
+	for (g = gendisk_head; g; g = g->next)
+		if (g->major == m)
+			break;
+	return g;
+}
+
+/* moved here from md.c - will be discarded later */
+char *partition_name (kdev_t dev) {
+	static char name[40];		/* kdevname returns 32 bytes */
+					/* disk_name requires 32 bytes */
+	struct gendisk *hd = get_gendisk (dev);
+
+	if (!hd) {
+		sprintf (name, "[dev %s]", kdevname(dev));
+		return (name);
+	}
+
+	return disk_name (hd, MINOR(dev), name);  /* routine in genhd.c */
+}
+
+/*
+ * Add a partition.
+ *
+ * returns: EINVAL: bad parameters
+ *          ENXIO: cannot find drive
+ *          EBUSY: proposed partition overlaps an existing one
+ *                 or has the same number as an existing one
+ *          0: all OK.
+ */
+int add_partition(kdev_t dev, struct blkpg_partition *p) {
+	struct gendisk *g;
+	long long ppstart, pplength;
+	long pstart, plength;
+	int i, drive, first_minor, end_minor, minor;
+
+	/* convert bytes to sectors, check for fit in a hd_struct */
+	ppstart = (p->start >> 9);
+	pplength = (p->length >> 9);
+	pstart = ppstart;
+	plength = pplength;
+	if (pstart != ppstart || plength != pplength
+	    || pstart < 0 || plength < 0)
+		return -EINVAL;
+
+	/* find the drive major */
+	g = get_gendisk(dev);
+	if (!g)
+		return -ENXIO;
+
+	/* existing drive? */
+	drive = (MINOR(dev) >> g->minor_shift);
+	first_minor = (drive << g->minor_shift);
+	end_minor   = first_minor + g->max_p;
+	if (drive >= g->nr_real)
+		return -ENXIO;
+
+	/* drive and partition number OK? */
+	if (first_minor != MINOR(dev) || p->pno <= 0 || p->pno >= g->max_p)
+		return -EINVAL;
+
+	/* partition number in use? */
+	minor = first_minor + p->pno;
+	if (g->part[minor].nr_sects != 0)
+		return -EBUSY;
+
+	/* overlap? */
+	for (i=first_minor+1; i<end_minor; i++)
+		if (!(pstart+plength <= g->part[i].start_sect ||
+		      pstart >= g->part[i].start_sect + g->part[i].nr_sects))
+			return -EBUSY;
+
+	/* all seems OK */
+	g->part[minor].start_sect = pstart;
+	g->part[minor].nr_sects = plength;
+	if (g->sizes)
+		g->sizes[minor] = (plength >> (BLOCK_SIZE_BITS - 9));
+	return 0;
+}
+
+/*
+ * Delete a partition given by partition number
+ *
+ * returns: EINVAL: bad parameters
+ *          ENXIO: cannot find partition
+ *          EBUSY: partition is busy
+ *          0: all OK.
+ *
+ * Note that the dev argument refers to the entire disk, not the partition.
+ */
+int del_partition(kdev_t dev, struct blkpg_partition *p) {
+	struct gendisk *g;
+	kdev_t devp;
+	int drive, first_minor, minor;
+
+	/* find the drive major */
+	g = get_gendisk(dev);
+	if (!g)
+		return -ENXIO;
+
+	/* drive and partition number OK? */
+	drive = (MINOR(dev) >> g->minor_shift);
+	first_minor = (drive << g->minor_shift);
+	if (first_minor != MINOR(dev) || p->pno <= 0 || p->pno >= g->max_p)
+		return -EINVAL;
+
+	/* existing drive and partition? */
+	minor = first_minor + p->pno;
+	if (drive >= g->nr_real || g->part[minor].nr_sects == 0)
+		return -ENXIO;
+
+	/* partition in use? Incomplete check for now. */
+	devp = MKDEV(MAJOR(dev), minor);
+	if (get_super(devp) ||		/* mounted? */
+	    is_swap_partition(devp))
+		return -EBUSY;
+
+	/* all seems OK */
+	fsync_dev(devp);
+	invalidate_buffers(devp);
+
+	g->part[minor].start_sect = 0;
+	g->part[minor].nr_sects = 0;
+	if (g->sizes)
+		g->sizes[minor] = 0;
+
+	return 0;
+}
+
+int blkpg_ioctl(kdev_t dev, struct blkpg_ioctl_arg *arg)
+{
+	struct blkpg_ioctl_arg a;
+	struct blkpg_partition p;
+	int len;
+
+	if (copy_from_user(&a, arg, sizeof(struct blkpg_ioctl_arg)))
+		return -EFAULT;
+
+	switch (a.op) {
+		case BLKPG_ADD_PARTITION:
+		case BLKPG_DEL_PARTITION:
+			len = a.datalen;
+			if (len < sizeof(struct blkpg_partition))
+				return -EINVAL;
+			if (copy_from_user(&p, a.data, sizeof(struct blkpg_partition)))
+				return -EFAULT;
+			if (!capable(CAP_SYS_ADMIN))
+				return -EACCES;
+			if (a.op == BLKPG_ADD_PARTITION)
+				return add_partition(dev, &p);
+			else
+				return del_partition(dev, &p);
+		default:
+			return -EINVAL;
+	}
+}
+
+/*
+ * Common ioctl's for block devices
+ */
+
+int blk_ioctl(kdev_t dev, unsigned int cmd, unsigned long arg)
+{
+	int intval;
+
+	switch (cmd) {
+		case BLKROSET:
+			if (!capable(CAP_SYS_ADMIN))
+				return -EACCES;
+			if (get_user(intval, (int *)(arg)))
+				return -EFAULT;
+			set_device_ro(dev, intval);
+			return 0;
+		case BLKROGET:
+			intval = (is_read_only(dev) != 0);
+			return put_user(intval, (int *)(arg));
+
+		case BLKRASET:
+			if(!capable(CAP_SYS_ADMIN))
+				return -EACCES;
+			if(!dev || arg > 0xff)
+				return -EINVAL;
+			read_ahead[MAJOR(dev)] = arg;
+			return 0;
+		case BLKRAGET:
+			if (!arg)
+				return -EINVAL;
+			return put_user(read_ahead[MAJOR(dev)], (long *) arg);
+
+		case BLKFLSBUF:
+			if(!capable(CAP_SYS_ADMIN))
+				return -EACCES;
+			if (!dev)
+				return -EINVAL;
+			fsync_dev(dev);
+			invalidate_buffers(dev);
+			return 0;
+
+		case BLKSSZGET:
+			/* get block device sector size as needed e.g. by fdisk */
+			intval = get_hardsect_size(dev);
+			return put_user(intval, (int *) arg);
+
+#if 0
+		case BLKGETSIZE:
+			/* Today get_gendisk() requires a linear scan;
+			   add this when dev has pointer type. */
+			g = get_gendisk(dev);
+			if (!g)
+				longval = 0;
+			else
+				longval = g->part[MINOR(dev)].nr_sects;
+			return put_user(longval, (long *) arg);
+#endif
+#if 0
+		case BLKRRPART: /* Re-read partition tables */
+			if (!capable(CAP_SYS_ADMIN)) 
+				return -EACCES;
+			return reread_partitions(dev, 1);
+#endif
+
+		case BLKPG:
+			return blkpg_ioctl(dev, (struct blkpg_ioctl_arg *) arg);
+			
+		default:
+			return -EINVAL;
+	}
+}
+