minix/lib/libblockdriver/driver.c
David van Moolenbroek 4005bba437 libblockdriver: clear IPC only on stateful restart
This removes a race condition when the block driver performs a
complete restart after a crash (the new default). If any user of
the driver finds out its new endpoint and sends a request to the
new driver instance before this instance has had the chance to
initialize, then its initialization would clear all IPC state and
thereby erroneously cancel the incoming request. Clearing IPC
state is only desired upon a stateful restart (where the driver's
endpoint is retained). This information is now passed to and used
by libblockdriver accordingly.
2011-12-11 22:36:19 +01:00

432 lines
14 KiB
C

/* This file contains the device independent block driver interface.
*
* Block drivers support the following requests. Message format m10 is used.
* Field names are prefixed with BDEV_. Separate field names are used for the
* "access" and "request" fields.
*
* m_type MINOR COUNT GRANT FLAGS ID POS_LO POS_HI
* +--------------+--------+----------+-------+-------+------+------+------+
* | BDEV_OPEN | minor | access | | | id | | |
* |--------------+--------+----------+-------+-------+------+------+------|
* | BDEV_CLOSE | minor | | | | id | | |
* |--------------+--------+----------+-------+-------+------+------+------|
* | BDEV_READ | minor | bytes | grant | flags | id | position |
* |--------------+--------+----------+-------+-------+------+------+------|
* | BDEV_WRITE | minor | bytes | grant | flags | id | position |
* |--------------+--------+----------+-------+-------+------+------+------|
* | BDEV_GATHER | minor | elements | grant | flags | id | position |
* |--------------+--------+----------+-------+-------+------+------+------|
* | BDEV_SCATTER | minor | elements | grant | flags | id | position |
* |--------------+--------+----------+-------+-------+------+------+------|
* | BDEV_IOCTL | minor | request | grant | flags | id | | |
* -------------------------------------------------------------------------
*
* The following reply message is used for all requests.
*
* m_type STATUS ID
* +--------------+--------+----------+-------+-------+------+------+------+
* | BDEV_REPLY | status | | | | id | | |
* -------------------------------------------------------------------------
*
* Changes:
* Oct 16, 2011 split character and block protocol (D.C. van Moolenbroek)
* Aug 27, 2011 move common functions into driver.c (A. Welzel)
* Jul 25, 2005 added SYS_SIG type for signals (Jorrit N. Herder)
* Sep 15, 2004 added SYN_ALARM type for timeouts (Jorrit N. Herder)
* Jul 23, 2004 removed kernel dependencies (Jorrit N. Herder)
* Apr 02, 1992 constructed from AT wini and floppy driver (Kees J. Bot)
*/
#include <minix/drivers.h>
#include <minix/blockdriver.h>
#include <minix/ds.h>
#include <sys/ioc_block.h>
#include <sys/ioc_disk.h>
#include "driver.h"
#include "mq.h"
#include "trace.h"
/* Management data for opened devices. */
PRIVATE int open_devs[MAX_NR_OPEN_DEVICES];
PRIVATE int next_open_devs_slot = 0;
/*===========================================================================*
* clear_open_devs *
*===========================================================================*/
PRIVATE void clear_open_devs(void)
{
/* Reset the set of previously opened minor devices. */
next_open_devs_slot = 0;
}
/*===========================================================================*
* is_open_dev *
*===========================================================================*/
PRIVATE int is_open_dev(int device)
{
/* Check whether the given minor device has previously been opened. */
int i;
for (i = 0; i < next_open_devs_slot; i++)
if (open_devs[i] == device)
return TRUE;
return FALSE;
}
/*===========================================================================*
* set_open_dev *
*===========================================================================*/
PRIVATE void set_open_dev(int device)
{
/* Mark the given minor device as having been opened. */
if (next_open_devs_slot >= MAX_NR_OPEN_DEVICES)
panic("out of slots for open devices");
open_devs[next_open_devs_slot] = device;
next_open_devs_slot++;
}
/*===========================================================================*
* blockdriver_announce *
*===========================================================================*/
PUBLIC void blockdriver_announce(int type)
{
/* Announce we are up after a fresh start or a restart. */
int r;
char key[DS_MAX_KEYLEN];
char label[DS_MAX_KEYLEN];
char *driver_prefix = "drv.blk.";
/* Callers are allowed to use sendrec to communicate with drivers.
* For this reason, there may blocked callers when a driver restarts.
* Ask the kernel to unblock them (if any). Note that most block drivers
* will not restart statefully, and thus will skip this code.
*/
if (type == SEF_INIT_RESTART) {
#if USE_STATECTL
if ((r = sys_statectl(SYS_STATE_CLEAR_IPC_REFS)) != OK)
panic("blockdriver_init: sys_statectl failed: %d", r);
#endif
}
/* Publish a driver up event. */
if ((r = ds_retrieve_label_name(label, getprocnr())) != OK)
panic("blockdriver_init: unable to get own label: %d", r);
snprintf(key, DS_MAX_KEYLEN, "%s%s", driver_prefix, label);
if ((r = ds_publish_u32(key, DS_DRIVER_UP, DSF_OVERWRITE)) != OK)
panic("blockdriver_init: unable to publish driver up event: %d", r);
/* Expect an open for any device before serving regular driver requests. */
clear_open_devs();
/* Initialize or reset the message queue. */
mq_init();
}
/*===========================================================================*
* blockdriver_reply *
*===========================================================================*/
PUBLIC void blockdriver_reply(message *m_ptr, int ipc_status, int reply)
{
/* Reply to a block request sent to the driver. */
endpoint_t caller_e;
long id;
int r;
if (reply == EDONTREPLY)
return;
caller_e = m_ptr->m_source;
id = m_ptr->BDEV_ID;
memset(m_ptr, 0, sizeof(*m_ptr));
m_ptr->m_type = BDEV_REPLY;
m_ptr->BDEV_STATUS = reply;
m_ptr->BDEV_ID = id;
/* If we would block sending the message, send it asynchronously. The NOREPLY
* flag is set because the caller may also issue a SENDREC (mixing sync and
* async comm), and the asynchronous reply could otherwise end up satisfying
* the SENDREC's receive part, after which our next SENDNB call would fail.
*/
if (IPC_STATUS_CALL(ipc_status) == SENDREC)
r = sendnb(caller_e, m_ptr);
else
r = asynsend3(caller_e, m_ptr, AMF_NOREPLY);
if (r != OK)
printf("blockdriver_reply: unable to send reply to %d: %d\n",
caller_e, r);
}
/*===========================================================================*
* do_open *
*===========================================================================*/
PRIVATE int do_open(struct blockdriver *bdp, message *mp)
{
/* Open a minor device. */
return (*bdp->bdr_open)(mp->BDEV_MINOR, mp->BDEV_ACCESS);
}
/*===========================================================================*
* do_close *
*===========================================================================*/
PRIVATE int do_close(struct blockdriver *bdp, message *mp)
{
/* Close a minor device. */
return (*bdp->bdr_close)(mp->BDEV_MINOR);
}
/*===========================================================================*
* do_rdwt *
*===========================================================================*/
PRIVATE int do_rdwt(struct blockdriver *bdp, message *mp)
{
/* Carry out a single read or write request. */
iovec_t iovec1;
u64_t position;
int do_write;
ssize_t r;
/* Disk address? Address and length of the user buffer? */
if (mp->BDEV_COUNT < 0) return EINVAL;
/* Create a one element scatter/gather vector for the buffer. */
iovec1.iov_addr = mp->BDEV_GRANT;
iovec1.iov_size = mp->BDEV_COUNT;
/* Transfer bytes from/to the device. */
do_write = (mp->m_type == BDEV_WRITE);
position = make64(mp->BDEV_POS_LO, mp->BDEV_POS_HI);
r = (*bdp->bdr_transfer)(mp->BDEV_MINOR, do_write, position, mp->m_source,
&iovec1, 1, mp->BDEV_FLAGS);
/* Return the number of bytes transferred or an error code. */
return r;
}
/*===========================================================================*
* do_vrdwt *
*===========================================================================*/
PRIVATE int do_vrdwt(struct blockdriver *bdp, message *mp, thread_id_t id)
{
/* Carry out an device read or write to/from a vector of buffers. */
iovec_t iovec[NR_IOREQS];
unsigned nr_req;
u64_t position;
int i, do_write;
ssize_t r, size;
/* Copy the vector from the caller to kernel space. */
nr_req = mp->BDEV_COUNT; /* Length of I/O vector */
if (nr_req > NR_IOREQS) nr_req = NR_IOREQS;
if (OK != sys_safecopyfrom(mp->m_source, (vir_bytes) mp->BDEV_GRANT,
0, (vir_bytes) iovec, nr_req * sizeof(iovec[0]), D)) {
printf("blockdriver: bad I/O vector by: %d\n", mp->m_source);
return EINVAL;
}
/* Check for overflow condition, and update the size for block tracing. */
for (i = size = 0; i < nr_req; i++) {
if ((ssize_t) (size + iovec[i].iov_size) < size) return EINVAL;
size += iovec[i].iov_size;
}
trace_setsize(id, size);
/* Transfer bytes from/to the device. */
do_write = (mp->m_type == BDEV_SCATTER);
position = make64(mp->BDEV_POS_LO, mp->BDEV_POS_HI);
r = (*bdp->bdr_transfer)(mp->BDEV_MINOR, do_write, position, mp->m_source,
iovec, nr_req, mp->BDEV_FLAGS);
/* Return the number of bytes transferred or an error code. */
return r;
}
/*===========================================================================*
* do_dioctl *
*===========================================================================*/
PRIVATE int do_dioctl(struct blockdriver *bdp, dev_t minor,
unsigned int request, endpoint_t endpt, cp_grant_id_t grant)
{
/* Carry out a disk-specific I/O control request. */
struct device *dv;
struct partition entry;
int r = EINVAL;
switch (request) {
case DIOCSETP:
/* Copy just this one partition table entry. */
r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes) &entry,
sizeof(entry), D);
if (r != OK)
return r;
if ((dv = (*bdp->bdr_part)(minor)) == NULL)
return ENXIO;
dv->dv_base = entry.base;
dv->dv_size = entry.size;
break;
case DIOCGETP:
/* Return a partition table entry and the geometry of the drive. */
if ((dv = (*bdp->bdr_part)(minor)) == NULL)
return ENXIO;
entry.base = dv->dv_base;
entry.size = dv->dv_size;
if (bdp->bdr_geometry) {
(*bdp->bdr_geometry)(minor, &entry);
} else {
/* The driver doesn't care -- make up fake geometry. */
entry.cylinders = div64u(entry.size, SECTOR_SIZE);
entry.heads = 64;
entry.sectors = 32;
}
r = sys_safecopyto(endpt, grant, 0, (vir_bytes) &entry, sizeof(entry),
D);
break;
}
return r;
}
/*===========================================================================*
* do_ioctl *
*===========================================================================*/
PRIVATE int do_ioctl(struct blockdriver *bdp, message *mp)
{
/* Carry out an I/O control request. We forward block trace control requests
* to the tracing module, and handle setting/getting partitions when the driver
* has specified that it is a disk driver.
*/
dev_t minor;
unsigned int request;
cp_grant_id_t grant;
int r;
minor = mp->BDEV_MINOR;
request = mp->BDEV_REQUEST;
grant = mp->BDEV_GRANT;
switch (request) {
case BIOCTRACEBUF:
case BIOCTRACECTL:
case BIOCTRACEGET:
/* Block trace control. */
r = trace_ctl(minor, request, mp->m_source, grant);
break;
case DIOCSETP:
case DIOCGETP:
/* Handle disk-specific IOCTLs only for disk-type drivers. */
if (bdp->bdr_type == BLOCKDRIVER_TYPE_DISK) {
/* Disk partition control. */
r = do_dioctl(bdp, minor, request, mp->m_source, grant);
break;
}
/* fall-through */
default:
if (bdp->bdr_ioctl)
r = (*bdp->bdr_ioctl)(minor, request, mp->m_source, grant);
else
r = EINVAL;
}
return r;
}
/*===========================================================================*
* blockdriver_handle_notify *
*===========================================================================*/
PUBLIC void blockdriver_handle_notify(struct blockdriver *bdp, message *m_ptr)
{
/* Take care of the notifications (interrupt and clock messages) by calling
* the appropiate callback functions. Never send a reply.
*/
/* Call the appropriate function for this notification. */
switch (_ENDPOINT_P(m_ptr->m_source)) {
case HARDWARE:
if (bdp->bdr_intr)
(*bdp->bdr_intr)(m_ptr->NOTIFY_ARG);
break;
case CLOCK:
if (bdp->bdr_alarm)
(*bdp->bdr_alarm)(m_ptr->NOTIFY_TIMESTAMP);
break;
default:
if (bdp->bdr_other)
(void) (*bdp->bdr_other)(m_ptr);
}
}
/*===========================================================================*
* blockdriver_handle_request *
*===========================================================================*/
PUBLIC int blockdriver_handle_request(struct blockdriver *bdp, message *m_ptr,
thread_id_t id)
{
/* Call the appropiate driver function, based on the type of request. Return
* the result code that is to be sent back to the caller, or EDONTREPLY if no
* reply is to be sent.
*/
int r;
/* We might get spurious requests if the driver has been restarted. Deny any
* requests on devices that have not previously been opened, signaling the
* caller that something went wrong.
*/
if (IS_BDEV_RQ(m_ptr->m_type) && !is_open_dev(m_ptr->BDEV_MINOR)) {
/* Reply ERESTART to spurious requests for unopened devices. */
if (m_ptr->m_type != BDEV_OPEN)
return ERESTART;
/* Mark the device as opened otherwise. */
set_open_dev(m_ptr->BDEV_MINOR);
}
trace_start(id, m_ptr);
/* Call the appropriate function(s) for this request. */
switch (m_ptr->m_type) {
case BDEV_OPEN: r = do_open(bdp, m_ptr); break;
case BDEV_CLOSE: r = do_close(bdp, m_ptr); break;
case BDEV_READ:
case BDEV_WRITE: r = do_rdwt(bdp, m_ptr); break;
case BDEV_GATHER:
case BDEV_SCATTER: r = do_vrdwt(bdp, m_ptr, id); break;
case BDEV_IOCTL: r = do_ioctl(bdp, m_ptr); break;
default:
if (bdp->bdr_other)
r = bdp->bdr_other(m_ptr);
else
r = EINVAL;
}
/* Let the driver perform any cleanup. */
if (bdp->bdr_cleanup != NULL)
(*bdp->bdr_cleanup)();
trace_finish(id, r);
return r;
}