minix3/lib/libbdev/bdev.c

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2020-02-21 00:59:27 +05:30
/* libbdev - block device interfacing library, by D.C. van Moolenbroek */
#include <minix/drivers.h>
#include <minix/bdev.h>
#include <minix/ioctl.h>
#include <assert.h>
#include "const.h"
#include "type.h"
#include "proto.h"
void bdev_driver(dev_t dev, char *label)
{
/* Associate a driver with the given (major) device, using its endpoint.
* File system usage note: typically called from mount and newdriver.
*/
static int first = TRUE;
if (first) {
/* Initialize the driver endpoint array. */
bdev_driver_init();
first = FALSE;
}
bdev_update(dev, label);
}
static int bdev_retry(int *driver_tries, int *transfer_tries, int *result)
{
/* Return TRUE iff the call result implies that we should retry the operation.
*/
switch (*result) {
case ERESTART:
/* We get this error internally if the driver has restarted and the
* current operation may now go through. Check the retry count for
* driver restarts first, as we don't want to keep trying forever.
*/
if (++*driver_tries < DRIVER_TRIES)
return TRUE;
*result = EDEADSRCDST;
break;
case EIO:
/* The 'transfer_tries' pointer is non-NULL if this was a transfer
* request. If we get back an I/O failure, keep retrying the request
* until we hit the transfer retry limit.
*/
if (transfer_tries != NULL && ++*transfer_tries < TRANSFER_TRIES)
return TRUE;
break;
}
return FALSE;
}
static int bdev_opcl(int req, dev_t dev, int access)
{
/* Open or close the given minor device.
*/
message m;
int r, driver_tries = 0;
do {
memset(&m, 0, sizeof(m));
m.m_type = req;
m.m_lbdev_lblockdriver_msg.minor = minor(dev);
m.m_lbdev_lblockdriver_msg.access = access;
r = bdev_sendrec(dev, &m);
} while (bdev_retry(&driver_tries, NULL, &r));
return r;
}
int bdev_open(dev_t dev, int access)
{
/* Open the given minor device.
* File system usage note: typically called from mount, after bdev_driver.
*/
int r;
r = bdev_opcl(BDEV_OPEN, dev, access);
if (r == OK)
bdev_minor_add(dev, access);
return r;
}
int bdev_close(dev_t dev)
{
/* Close the given minor device.
* File system usage note: typically called from unmount.
*/
int r;
bdev_flush_asyn(dev);
r = bdev_opcl(BDEV_CLOSE, dev, 0);
if (r == OK)
bdev_minor_del(dev);
return r;
}
static int bdev_rdwt_setup(int req, dev_t dev, u64_t pos, char *buf,
size_t count, int flags, message *m)
{
/* Set up a single-buffer read/write request.
*/
endpoint_t endpt;
cp_grant_id_t grant;
int access;
assert((ssize_t) count >= 0);
if ((endpt = bdev_driver_get(dev)) == NONE)
return EDEADSRCDST;
access = (req == BDEV_READ) ? CPF_WRITE : CPF_READ;
grant = cpf_grant_direct(endpt, (vir_bytes) buf, count, access);
if (!GRANT_VALID(grant)) {
printf("bdev: unable to allocate grant!\n");
return EINVAL;
}
memset(m, 0, sizeof(*m));
m->m_type = req;
m->m_lbdev_lblockdriver_msg.minor = minor(dev);
m->m_lbdev_lblockdriver_msg.pos = pos;
m->m_lbdev_lblockdriver_msg.count = count;
m->m_lbdev_lblockdriver_msg.grant = grant;
m->m_lbdev_lblockdriver_msg.flags = flags;
return OK;
}
static void bdev_rdwt_cleanup(const message *m)
{
/* Clean up a single-buffer read/write request.
*/
cpf_revoke(m->m_lbdev_lblockdriver_msg.grant);
}
static ssize_t bdev_rdwt(int req, dev_t dev, u64_t pos, char *buf,
size_t count, int flags)
{
/* Perform a synchronous read or write call using a single buffer.
*/
message m;
int r, driver_tries = 0, transfer_tries = 0;
do {
if ((r = bdev_rdwt_setup(req, dev, pos, buf, count, flags, &m)) != OK)
break;
r = bdev_sendrec(dev, &m);
bdev_rdwt_cleanup(&m);
} while (bdev_retry(&driver_tries, &transfer_tries, &r));
return r;
}
static int bdev_vrdwt_setup(int req, dev_t dev, u64_t pos, iovec_t *vec,
int count, int flags, message *m, iovec_s_t *gvec)
{
/* Set up a vectored read/write request.
*/
ssize_t size;
endpoint_t endpt;
cp_grant_id_t grant;
int i, access;
assert(count <= NR_IOREQS);
if ((endpt = bdev_driver_get(dev)) == NONE)
return EDEADSRCDST;
access = (req == BDEV_GATHER) ? CPF_WRITE : CPF_READ;
size = 0;
for (i = 0; i < count; i++) {
grant = cpf_grant_direct(endpt, vec[i].iov_addr, vec[i].iov_size,
access);
if (!GRANT_VALID(grant)) {
printf("bdev: unable to allocate grant!\n");
for (i--; i >= 0; i--)
cpf_revoke(gvec[i].iov_grant);
return EINVAL;
}
gvec[i].iov_grant = grant;
gvec[i].iov_size = vec[i].iov_size;
assert(vec[i].iov_size > 0);
assert((ssize_t) (size + vec[i].iov_size) > size);
size += vec[i].iov_size;
}
grant = cpf_grant_direct(endpt, (vir_bytes) gvec, sizeof(gvec[0]) * count,
CPF_READ);
if (!GRANT_VALID(grant)) {
printf("bdev: unable to allocate grant!\n");
for (i = count - 1; i >= 0; i--)
cpf_revoke(gvec[i].iov_grant);
return EINVAL;
}
memset(m, 0, sizeof(*m));
m->m_type = req;
m->m_lbdev_lblockdriver_msg.minor = minor(dev);
m->m_lbdev_lblockdriver_msg.pos = pos;
m->m_lbdev_lblockdriver_msg.count = count;
m->m_lbdev_lblockdriver_msg.grant = grant;
m->m_lbdev_lblockdriver_msg.flags = flags;
return OK;
}
static void bdev_vrdwt_cleanup(const message *m, iovec_s_t *gvec)
{
/* Clean up a vectored read/write request.
*/
cp_grant_id_t grant;
int i;
grant = m->m_lbdev_lblockdriver_msg.grant;
cpf_revoke(grant);
for (i = m->m_lbdev_lblockdriver_msg.count - 1; i >= 0; i--)
cpf_revoke(gvec[i].iov_grant);
}
static ssize_t bdev_vrdwt(int req, dev_t dev, u64_t pos, iovec_t *vec,
int count, int flags)
{
/* Perform a synchronous read or write call using a vector of buffers.
*/
iovec_s_t gvec[NR_IOREQS];
message m;
int r, driver_tries = 0, transfer_tries = 0;
do {
if ((r = bdev_vrdwt_setup(req, dev, pos, vec, count, flags, &m,
gvec)) != OK)
break;
r = bdev_sendrec(dev, &m);
bdev_vrdwt_cleanup(&m, gvec);
} while (bdev_retry(&driver_tries, &transfer_tries, &r));
return r;
}
ssize_t bdev_read(dev_t dev, u64_t pos, char *buf, size_t count, int flags)
{
/* Perform a synchronous read call into a single buffer.
*/
return bdev_rdwt(BDEV_READ, dev, pos, buf, count, flags);
}
ssize_t bdev_write(dev_t dev, u64_t pos, char *buf, size_t count, int flags)
{
/* Perform a synchronous write call from a single buffer.
*/
return bdev_rdwt(BDEV_WRITE, dev, pos, buf, count, flags);
}
ssize_t bdev_gather(dev_t dev, u64_t pos, iovec_t *vec, int count, int flags)
{
/* Perform a synchronous read call into a vector of buffers.
*/
return bdev_vrdwt(BDEV_GATHER, dev, pos, vec, count, flags);
}
ssize_t bdev_scatter(dev_t dev, u64_t pos, iovec_t *vec, int count, int flags)
{
/* Perform a synchronous write call from a vector of buffers.
*/
return bdev_vrdwt(BDEV_SCATTER, dev, pos, vec, count, flags);
}
static int bdev_ioctl_setup(dev_t dev, int request, void *buf,
endpoint_t user_endpt, message *m)
{
/* Set up an I/O control request.
*/
endpoint_t endpt;
size_t size;
cp_grant_id_t grant;
int access;
if ((endpt = bdev_driver_get(dev)) == NONE)
return EDEADSRCDST;
if (_MINIX_IOCTL_BIG(request))
size = _MINIX_IOCTL_SIZE_BIG(request);
else
size = _MINIX_IOCTL_SIZE(request);
access = 0;
if (_MINIX_IOCTL_IOR(request)) access |= CPF_WRITE;
if (_MINIX_IOCTL_IOW(request)) access |= CPF_READ;
/* The size may be 0, in which case 'buf' need not be a valid pointer. */
grant = cpf_grant_direct(endpt, (vir_bytes) buf, size, access);
if (!GRANT_VALID(grant)) {
printf("bdev: unable to allocate grant!\n");
return EINVAL;
}
memset(m, 0, sizeof(*m));
m->m_type = BDEV_IOCTL;
m->m_lbdev_lblockdriver_msg.minor = minor(dev);
m->m_lbdev_lblockdriver_msg.request = request;
m->m_lbdev_lblockdriver_msg.grant = grant;
m->m_lbdev_lblockdriver_msg.user = user_endpt;
return OK;
}
static void bdev_ioctl_cleanup(const message *m)
{
/* Clean up an I/O control request.
*/
cpf_revoke(m->m_lbdev_lblockdriver_msg.grant);
}
int bdev_ioctl(dev_t dev, int request, void *buf, endpoint_t user_endpt)
{
/* Perform a synchronous I/O control request.
*/
message m;
int r, driver_tries = 0;
do {
if ((r = bdev_ioctl_setup(dev, request, buf, user_endpt, &m)) != OK)
break;
r = bdev_sendrec(dev, &m);
bdev_ioctl_cleanup(&m);
} while (bdev_retry(&driver_tries, NULL, &r));
return r;
}
void bdev_flush_asyn(dev_t dev)
{
/* Flush all ongoing asynchronous requests to the given minor device. This
* involves blocking until all I/O for it has completed.
* File system usage note: typically called from flush.
*/
bdev_call_t *call;
while ((call = bdev_call_find(dev)) != NULL)
(void) bdev_wait_asyn(call->id);
}
static bdev_id_t bdev_rdwt_asyn(int req, dev_t dev, u64_t pos, char *buf,
size_t count, int flags, bdev_callback_t callback, bdev_param_t param)
{
/* Perform an asynchronous read or write call using a single buffer.
*/
bdev_call_t *call;
int r;
if ((call = bdev_call_alloc(1)) == NULL)
return ENOMEM;
if ((r = bdev_rdwt_setup(req, dev, pos, buf, count, flags, &call->msg)) !=
OK) {
bdev_call_free(call);
return r;
}
if ((r = bdev_senda(dev, &call->msg, call->id)) != OK) {
bdev_rdwt_cleanup(&call->msg);
bdev_call_free(call);
return r;
}
call->dev = dev;
call->callback = callback;
call->param = param;
call->driver_tries = 0;
call->transfer_tries = 0;
call->vec[0].iov_addr = (vir_bytes) buf;
call->vec[0].iov_size = count;
return call->id;
}
static bdev_id_t bdev_vrdwt_asyn(int req, dev_t dev, u64_t pos, iovec_t *vec,
int count, int flags, bdev_callback_t callback, bdev_param_t param)
{
/* Perform an asynchronous read or write call using a vector of buffers.
*/
bdev_call_t *call;
int r;
if ((call = bdev_call_alloc(count)) == NULL)
return ENOMEM;
if ((r = bdev_vrdwt_setup(req, dev, pos, vec, count, flags, &call->msg,
call->gvec)) != OK) {
bdev_call_free(call);
return r;
}
if ((r = bdev_senda(dev, &call->msg, call->id)) != OK) {
bdev_vrdwt_cleanup(&call->msg, call->gvec);
bdev_call_free(call);
return r;
}
call->dev = dev;
call->callback = callback;
call->param = param;
call->driver_tries = 0;
call->transfer_tries = 0;
memcpy(call->vec, vec, sizeof(vec[0]) * count);
return call->id;
}
bdev_id_t bdev_read_asyn(dev_t dev, u64_t pos, char *buf, size_t count,
int flags, bdev_callback_t callback, bdev_param_t param)
{
/* Perform an asynchronous read call into a single buffer.
*/
return bdev_rdwt_asyn(BDEV_READ, dev, pos, buf, count, flags, callback,
param);
}
bdev_id_t bdev_write_asyn(dev_t dev, u64_t pos, char *buf, size_t count,
int flags, bdev_callback_t callback, bdev_param_t param)
{
/* Perform an asynchronous write call from a single buffer.
*/
return bdev_rdwt_asyn(BDEV_WRITE, dev, pos, buf, count, flags, callback,
param);
}
bdev_id_t bdev_gather_asyn(dev_t dev, u64_t pos, iovec_t *vec, int count,
int flags, bdev_callback_t callback, bdev_param_t param)
{
/* Perform an asynchronous read call into a vector of buffers.
*/
return bdev_vrdwt_asyn(BDEV_GATHER, dev, pos, vec, count, flags, callback,
param);
}
bdev_id_t bdev_scatter_asyn(dev_t dev, u64_t pos, iovec_t *vec, int count,
int flags, bdev_callback_t callback, bdev_param_t param)
{
/* Perform an asynchronous write call into a vector of buffers.
*/
return bdev_vrdwt_asyn(BDEV_SCATTER, dev, pos, vec, count, flags, callback,
param);
}
bdev_id_t bdev_ioctl_asyn(dev_t dev, int request, void *buf,
endpoint_t user_endpt, bdev_callback_t callback, bdev_param_t param)
{
/* Perform an asynchronous I/O control request.
*/
bdev_call_t *call;
int r;
if ((call = bdev_call_alloc(1)) == NULL)
return ENOMEM;
if ((r = bdev_ioctl_setup(dev, request, buf, user_endpt,
&call->msg)) != OK) {
bdev_call_free(call);
return r;
}
if ((r = bdev_senda(dev, &call->msg, call->id)) != OK) {
bdev_ioctl_cleanup(&call->msg);
bdev_call_free(call);
return r;
}
call->dev = dev;
call->callback = callback;
call->param = param;
call->driver_tries = 0;
call->vec[0].iov_addr = (vir_bytes) buf;
return call->id;
}
void bdev_callback_asyn(bdev_call_t *call, int result)
{
/* Perform the callback for an asynchronous request, with the given result.
* Clean up the call structure afterwards.
*/
/* If this was a transfer request and the result is EIO, we may want to retry
* the request first.
*/
switch (call->msg.m_type) {
case BDEV_READ:
case BDEV_WRITE:
case BDEV_GATHER:
case BDEV_SCATTER:
if (result == EIO && ++call->transfer_tries < TRANSFER_TRIES) {
result = bdev_senda(call->dev, &call->msg, call->id);
if (result == OK)
return;
}
}
/* Clean up. */
switch (call->msg.m_type) {
case BDEV_READ:
case BDEV_WRITE:
bdev_rdwt_cleanup(&call->msg);
break;
case BDEV_GATHER:
case BDEV_SCATTER:
bdev_vrdwt_cleanup(&call->msg, call->gvec);
break;
case BDEV_IOCTL:
bdev_ioctl_cleanup(&call->msg);
break;
default:
assert(0);
}
/* Call the callback function. */
/* FIXME: we assume all reasonable ssize_t values can be stored in an int. */
call->callback(call->dev, call->id, call->param, result);
/* Free up the call structure. */
bdev_call_free(call);
}
int bdev_restart_asyn(bdev_call_t *call)
{
/* The driver for the given call has restarted, and may now have a new
* endpoint. Recreate and resend the request for the given call.
*/
int type, r = OK;
/* Update and check the retry limit for driver restarts first. */
if (++call->driver_tries >= DRIVER_TRIES)
return EDEADSRCDST;
/* Recreate all grants for the new endpoint. */
type = call->msg.m_type;
switch (type) {
case BDEV_READ:
case BDEV_WRITE:
bdev_rdwt_cleanup(&call->msg);
r = bdev_rdwt_setup(type, call->dev,
call->msg.m_lbdev_lblockdriver_msg.pos,
(char *) call->vec[0].iov_addr, call->msg.m_lbdev_lblockdriver_msg.count,
call->msg.m_lbdev_lblockdriver_msg.flags, &call->msg);
break;
case BDEV_GATHER:
case BDEV_SCATTER:
bdev_vrdwt_cleanup(&call->msg, call->gvec);
r = bdev_vrdwt_setup(type, call->dev,
call->msg.m_lbdev_lblockdriver_msg.pos,
call->vec, call->msg.m_lbdev_lblockdriver_msg.count, call->msg.m_lbdev_lblockdriver_msg.flags,
&call->msg, call->gvec);
break;
case BDEV_IOCTL:
bdev_ioctl_cleanup(&call->msg);
r = bdev_ioctl_setup(call->dev, call->msg.m_lbdev_lblockdriver_msg.request,
(char *) call->vec[0].iov_addr, call->msg.m_lbdev_lblockdriver_msg.user,
&call->msg);
break;
default:
assert(0);
}
if (r != OK)
return r;
/* Try to resend the request. */
return bdev_senda(call->dev, &call->msg, call->id);
}