minix/lib/libblockdriver/drvlib.c
David van Moolenbroek b4d909d415 Split block/character protocols and libdriver
This patch separates the character and block driver communication
protocols. The old character protocol remains the same, but a new
block protocol is introduced. The libdriver library is replaced by
two new libraries: libchardriver and libblockdriver. Their exposed
API, and drivers that use them, have been updated accordingly.
Together, libbdev and libblockdriver now completely abstract away
the message format used by the block protocol. As the memory driver
is both a character and a block device driver, it now implements its
own message loop.

The most important semantic change made to the block protocol is that
it is no longer possible to return both partial results and an error
for a single transfer. This simplifies the interaction between the
caller and the driver, as the I/O vector no longer needs to be copied
back. Also, drivers are now no longer supposed to decide based on the
layout of the I/O vector when a transfer should be cut short. Put
simply, transfers are now supposed to either succeed completely, or
result in an error.

After this patch, the state of the various pieces is as follows:
- block protocol: stable
- libbdev API: stable for synchronous communication
- libblockdriver API: needs slight revision (the drvlib/partition API
  in particular; the threading API will also change shortly)
- character protocol: needs cleanup
- libchardriver API: needs cleanup accordingly
- driver restarts: largely unsupported until endpoint changes are
  reintroduced

As a side effect, this patch eliminates several bugs, hacks, and gcc
-Wall and -W warnings all over the place. It probably introduces a
few new ones, too.

Update warning: this patch changes the protocol between MFS and disk
drivers, so in order to use old/new images, the MFS from the ramdisk
must be used to mount all file systems.
2011-11-23 14:06:37 +01:00

229 lines
7.5 KiB
C

/* IBM device driver utility functions. Author: Kees J. Bot
* 7 Dec 1995
* Entry point:
* partition: partition a disk to the partition table(s) on it.
*/
#include <minix/blockdriver.h>
#include <minix/drvlib.h>
#include <unistd.h>
/* Extended partition? */
#define ext_part(s) ((s) == 0x05 || (s) == 0x0F)
FORWARD _PROTOTYPE( void parse_part_table, (struct blockdriver *bdp,
int device, int style, int atapi, u8_t *tmp_buf) );
FORWARD _PROTOTYPE( void extpartition, (struct blockdriver *bdp, int extdev,
unsigned long extbase, u8_t *tmp_buf) );
FORWARD _PROTOTYPE( int get_part_table, (struct blockdriver *bdp, int device,
unsigned long offset, struct part_entry *table, u8_t *tmp_buf) );
FORWARD _PROTOTYPE( void sort, (struct part_entry *table) );
/*============================================================================*
* partition *
*============================================================================*/
PUBLIC void partition(bdp, device, style, atapi)
struct blockdriver *bdp; /* device dependent entry points */
int device; /* device to partition */
int style; /* partitioning style: floppy, primary, sub. */
int atapi; /* atapi device */
{
/* This routine is called on first open to initialize the partition tables
* of a device.
*/
u8_t *tmp_buf;
if ((*bdp->bdr_part)(device) == NULL)
return;
/* For multithreaded drivers, multiple partition() calls may be made on
* different devices in parallel. Hence we need a separate temporary buffer
* for each request.
*/
if (!(tmp_buf = alloc_contig(CD_SECTOR_SIZE, AC_ALIGN4K, NULL)))
panic("partition: unable to allocate temporary buffer");
parse_part_table(bdp, device, style, atapi, tmp_buf);
free_contig(tmp_buf, CD_SECTOR_SIZE);
}
/*============================================================================*
* parse_part_table *
*============================================================================*/
PRIVATE void parse_part_table(bdp, device, style, atapi, tmp_buf)
struct blockdriver *bdp; /* device dependent entry points */
int device; /* device to partition */
int style; /* partitioning style: floppy, primary, sub. */
int atapi; /* atapi device */
u8_t *tmp_buf; /* temporary buffer */
{
/* This routine reads and parses a partition table. It may be called
* recursively. It makes sure that each partition falls safely within the
* device's limits. Depending on the partition style we are either making
* floppy partitions, primary partitions or subpartitions. Only primary
* partitions are sorted, because they are shared with other operating
* systems that expect this.
*/
struct part_entry table[NR_PARTITIONS], *pe;
int disk, par;
struct device *dv;
unsigned long base, limit, part_limit;
/* Get the geometry of the device to partition */
if ((dv = (*bdp->bdr_part)(device)) == NULL
|| cmp64u(dv->dv_size, 0) == 0) return;
base = div64u(dv->dv_base, SECTOR_SIZE);
limit = base + div64u(dv->dv_size, SECTOR_SIZE);
/* Read the partition table for the device. */
if(!get_part_table(bdp, device, 0L, table, tmp_buf)) {
return;
}
/* Compute the device number of the first partition. */
switch (style) {
case P_FLOPPY:
device += MINOR_fd0p0;
break;
case P_PRIMARY:
sort(table); /* sort a primary partition table */
device += 1;
break;
case P_SUB:
disk = device / DEV_PER_DRIVE;
par = device % DEV_PER_DRIVE - 1;
device = MINOR_d0p0s0 + (disk * NR_PARTITIONS + par) * NR_PARTITIONS;
}
/* Find an array of devices. */
if ((dv = (*bdp->bdr_part)(device)) == NULL) return;
/* Set the geometry of the partitions from the partition table. */
for (par = 0; par < NR_PARTITIONS; par++, dv++) {
/* Shrink the partition to fit within the device. */
pe = &table[par];
part_limit = pe->lowsec + pe->size;
if (part_limit < pe->lowsec) part_limit = limit;
if (part_limit > limit) part_limit = limit;
if (pe->lowsec < base) pe->lowsec = base;
if (part_limit < pe->lowsec) part_limit = pe->lowsec;
dv->dv_base = mul64u(pe->lowsec, SECTOR_SIZE);
dv->dv_size = mul64u(part_limit - pe->lowsec, SECTOR_SIZE);
if (style == P_PRIMARY) {
/* Each Minix primary partition can be subpartitioned. */
if (pe->sysind == MINIX_PART)
parse_part_table(bdp, device + par, P_SUB, atapi,
tmp_buf);
/* An extended partition has logical partitions. */
if (ext_part(pe->sysind))
extpartition(bdp, device + par, pe->lowsec, tmp_buf);
}
}
}
/*============================================================================*
* extpartition *
*============================================================================*/
PRIVATE void extpartition(bdp, extdev, extbase, tmp_buf)
struct blockdriver *bdp; /* device dependent entry points */
int extdev; /* extended partition to scan */
unsigned long extbase; /* sector offset of the base ext. partition */
u8_t *tmp_buf; /* temporary buffer */
{
/* Extended partitions cannot be ignored alas, because people like to move
* files to and from DOS partitions. Avoid reading this code, it's no fun.
*/
struct part_entry table[NR_PARTITIONS], *pe;
int subdev, disk, par;
struct device *dv;
unsigned long offset, nextoffset;
disk = extdev / DEV_PER_DRIVE;
par = extdev % DEV_PER_DRIVE - 1;
subdev = MINOR_d0p0s0 + (disk * NR_PARTITIONS + par) * NR_PARTITIONS;
offset = 0;
do {
if (!get_part_table(bdp, extdev, offset, table, tmp_buf)) return;
sort(table);
/* The table should contain one logical partition and optionally
* another extended partition. (It's a linked list.)
*/
nextoffset = 0;
for (par = 0; par < NR_PARTITIONS; par++) {
pe = &table[par];
if (ext_part(pe->sysind)) {
nextoffset = pe->lowsec;
} else
if (pe->sysind != NO_PART) {
if ((dv = (*bdp->bdr_part)(subdev)) == NULL) return;
dv->dv_base = mul64u(extbase + offset + pe->lowsec,
SECTOR_SIZE);
dv->dv_size = mul64u(pe->size, SECTOR_SIZE);
/* Out of devices? */
if (++subdev % NR_PARTITIONS == 0) return;
}
}
} while ((offset = nextoffset) != 0);
}
/*============================================================================*
* get_part_table *
*============================================================================*/
PRIVATE int get_part_table(bdp, device, offset, table, tmp_buf)
struct blockdriver *bdp;
int device;
unsigned long offset; /* sector offset to the table */
struct part_entry *table; /* four entries */
u8_t *tmp_buf; /* temporary buffer */
{
/* Read the partition table for the device, return true iff there were no
* errors.
*/
iovec_t iovec1;
u64_t position;
int r;
position = mul64u(offset, SECTOR_SIZE);
iovec1.iov_addr = (vir_bytes) tmp_buf;
iovec1.iov_size = CD_SECTOR_SIZE;
r = (*bdp->bdr_transfer)(device, FALSE /*do_write*/, position, SELF,
&iovec1, 1, BDEV_NOFLAGS);
if (r != CD_SECTOR_SIZE) {
return 0;
}
if (tmp_buf[510] != 0x55 || tmp_buf[511] != 0xAA) {
/* Invalid partition table. */
return 0;
}
memcpy(table, (tmp_buf + PART_TABLE_OFF), NR_PARTITIONS * sizeof(table[0]));
return 1;
}
/*===========================================================================*
* sort *
*===========================================================================*/
PRIVATE void sort(table)
struct part_entry *table;
{
/* Sort a partition table. */
struct part_entry *pe, tmp;
int n = NR_PARTITIONS;
do {
for (pe = table; pe < table + NR_PARTITIONS-1; pe++) {
if (pe[0].sysind == NO_PART
|| (pe[0].lowsec > pe[1].lowsec
&& pe[1].sysind != NO_PART)) {
tmp = pe[0]; pe[0] = pe[1]; pe[1] = tmp;
}
}
} while (--n > 0);
}