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minix/servers/vfs/main.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

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/*
* a loop that gets messages requesting work, carries out the work, and sends
* replies.
*
* The entry points into this file are:
* main: main program of the Virtual File System
* reply: send a reply to a process after the requested work is done
*
* Changes for VFS:
* Jul 2006 (Balazs Gerofi)
*/
#include "fs.h"
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <signal.h>
#include <assert.h>
#include <stdlib.h>
#include <sys/ioc_memory.h>
#include <sys/svrctl.h>
#include <sys/select.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/keymap.h>
#include <minix/const.h>
#include <minix/endpoint.h>
#include <minix/safecopies.h>
#include <minix/debug.h>
#include "file.h"
#include "fproc.h"
#include "param.h"
#include <minix/vfsif.h>
#include "vmnt.h"
#include "vnode.h"
#if ENABLE_SYSCALL_STATS
EXTERN unsigned long calls_stats[NCALLS];
#endif
FORWARD _PROTOTYPE( void get_work, (void) );
FORWARD _PROTOTYPE( void init_root, (void) );
FORWARD _PROTOTYPE( void service_pm, (void) );
/* SEF functions and variables. */
FORWARD _PROTOTYPE( void sef_local_startup, (void) );
FORWARD _PROTOTYPE( int sef_cb_init_fresh, (int type, sef_init_info_t *info) );
/*===========================================================================*
* main *
*===========================================================================*/
PUBLIC int main(void)
{
/* This is the main program of the file system. The main loop consists of
* three major activities: getting new work, processing the work, and sending
* the reply. This loop never terminates as long as the file system runs.
*/
int error;
/* SEF local startup. */
sef_local_startup();
/* This is the main loop that gets work, processes it, and sends replies. */
while (TRUE) {
SANITYCHECK;
get_work(); /* sets who and call_nr */
if (call_nr == DEV_REVIVE)
{
endpoint_t endpt;
endpt = m_in.REP_ENDPT;
if(endpt == VFS_PROC_NR) {
endpt = suspended_ep(m_in.m_source, m_in.REP_IO_GRANT);
if(endpt == NONE) {
printf("FS: proc with "
"grant %d from %d not found (revive)\n",
m_in.REP_IO_GRANT, m_in.m_source);
continue;
}
}
revive(endpt, m_in.REP_STATUS);
continue;
}
if (call_nr == DEV_REOPEN_REPL)
{
reopen_reply();
continue;
}
if (call_nr == DEV_CLOSE_REPL)
{
close_reply();
continue;
}
if (call_nr == DEV_SEL_REPL1)
{
select_reply1(m_in.m_source, m_in.DEV_MINOR, m_in.DEV_SEL_OPS);
continue;
}
if (call_nr == DEV_SEL_REPL2)
{
select_reply2(m_in.m_source, m_in.DEV_MINOR, m_in.DEV_SEL_OPS);
continue;
}
/* Check for special control messages first. */
if (is_notify(call_nr)) {
if (who_e == CLOCK)
{
/* Alarm timer expired. Used only for select().
* Check it.
*/
expire_timers(m_in.NOTIFY_TIMESTAMP);
}
else if(who_e == DS_PROC_NR)
{
/* DS notifies us of an event. */
ds_event();
}
else
{
/* Device notifies us of an event. */
dev_status(&m_in);
}
SANITYCHECK;
continue;
}
/* We only expect notify()s from tasks. */
if(who_p < 0) {
printf("FS: ignoring message from %d (%d)\n",
who_e, m_in.m_type);
continue;
}
/* Now it's safe to set and check fp. */
fp = &fproc[who_p]; /* pointer to proc table struct */
super_user = (fp->fp_effuid == SU_UID ? TRUE : FALSE); /* su? */
#if DO_SANITYCHECKS
if(fp_is_blocked(fp)) {
printf("VFS: requester %d call %d: suspended\n",
who_e, call_nr);
panic("requester suspended");
}
#endif
/* Calls from PM. */
if (who_e == PM_PROC_NR) {
service_pm();
continue;
}
SANITYCHECK;
/* Other calls. */
switch(call_nr)
{
case MAPDRIVER:
error= do_mapdriver();
if (error != SUSPEND) reply(who_e, error);
break;
case COMMON_GETSYSINFO:
error= do_getsysinfo();
if (error != SUSPEND) reply(who_e, error);
break;
default:
/* Call the internal function that does the work. */
if (call_nr < 0 || call_nr >= NCALLS) {
error = ENOSYS;
/* Not supposed to happen. */
} else if (fp->fp_pid == PID_FREE) {
error = ENOSYS;
printf(
"FS, bad process, who = %d, call_nr = %d, endpt1 = %d\n",
who_e, call_nr, m_in.endpt1);
} else {
#if ENABLE_SYSCALL_STATS
calls_stats[call_nr]++;
#endif
SANITYCHECK;
error = (*call_vec[call_nr])();
SANITYCHECK;
}
/* Copy the results back to the user and send reply. */
if (error != SUSPEND) { reply(who_e, error); }
}
SANITYCHECK;
}
return(OK); /* shouldn't come here */
}
/*===========================================================================*
* sef_local_startup *
*===========================================================================*/
PRIVATE void sef_local_startup()
{
/* Register init callbacks. */
sef_setcb_init_fresh(sef_cb_init_fresh);
sef_setcb_init_restart(sef_cb_init_fail);
/* No live update support for now. */
/* Let SEF perform startup. */
sef_startup();
}
/*===========================================================================*
* sef_cb_init_fresh *
*===========================================================================*/
PRIVATE int sef_cb_init_fresh(int type, sef_init_info_t *info)
{
/* Initialize the virtual file server. */
int s, i;
register struct fproc *rfp;
struct vmnt *vmp;
struct vnode *root_vp;
message mess;
struct rprocpub rprocpub[NR_BOOT_PROCS];
/* Clear endpoint field */
mount_m_in.m1_p3 = (char *) NONE;
/* Initialize the process table with help of the process manager messages.
* Expect one message for each system process with its slot number and pid.
* When no more processes follow, the magic process number NONE is sent.
* Then, stop and synchronize with the PM.
*/
do {
if (OK != (s=sef_receive(PM_PROC_NR, &mess)))
panic("FS couldn't receive from PM: %d", s);
if (mess.m_type != PM_INIT)
panic("unexpected message from PM: %d", mess.m_type);
if (NONE == mess.PM_PROC) break;
rfp = &fproc[mess.PM_SLOT];
rfp->fp_pid = mess.PM_PID;
rfp->fp_endpoint = mess.PM_PROC;
rfp->fp_realuid = (uid_t) SYS_UID;
rfp->fp_effuid = (uid_t) SYS_UID;
rfp->fp_realgid = (gid_t) SYS_GID;
rfp->fp_effgid = (gid_t) SYS_GID;
rfp->fp_umask = ~0;
rfp->fp_grant = GRANT_INVALID;
rfp->fp_blocked_on = FP_BLOCKED_ON_NONE;
rfp->fp_revived = NOT_REVIVING;
} while (TRUE); /* continue until process NONE */
mess.m_type = OK; /* tell PM that we succeeded */
s = send(PM_PROC_NR, &mess); /* send synchronization message */
/* All process table entries have been set. Continue with initialization. */
/* The following initializations are needed to let dev_opcl succeed .*/
fp = (struct fproc *) NULL;
who_e = who_p = VFS_PROC_NR;
/* Initialize device table. */
build_dmap();
/* Map all the services in the boot image. */
if((s = sys_safecopyfrom(RS_PROC_NR, info->rproctab_gid, 0,
(vir_bytes) rprocpub, sizeof(rprocpub), S)) != OK) {
panic("sys_safecopyfrom failed: %d", s);
}
for(i=0;i < NR_BOOT_PROCS;i++) {
if(rprocpub[i].in_use) {
if((s = map_service(&rprocpub[i])) != OK) {
panic("unable to map service: %d", s);
}
}
}
init_root(); /* init root device and load super block */
init_select(); /* init select() structures */
vmp = &vmnt[0]; /* Should be the root filesystem */
if (vmp->m_dev == NO_DEV)
panic("vfs: no root filesystem");
root_vp= vmp->m_root_node;
/* The root device can now be accessed; set process directories. */
for (rfp=&fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
FD_ZERO(&(rfp->fp_filp_inuse));
if (rfp->fp_pid != PID_FREE) {
dup_vnode(root_vp);
rfp->fp_rd = root_vp;
dup_vnode(root_vp);
rfp->fp_wd = root_vp;
} else rfp->fp_endpoint = NONE;
}
system_hz = sys_hz();
/* Subscribe to block and character driver events. */
s = ds_subscribe("drv\\.[bc]..\\..*", DSF_INITIAL | DSF_OVERWRITE);
if(s != OK) {
panic("vfs: can't subscribe to driver events");
}
SANITYCHECK;
#if DO_SANITYCHECKS
FIXME("VFS: DO_SANITYCHECKS is on");
#endif
return(OK);
}
/*===========================================================================*
* get_work *
*===========================================================================*/
PRIVATE void get_work()
{
/* Normally wait for new input. However, if 'reviving' is
* nonzero, a suspended process must be awakened.
*/
int r, found_one, fd_nr;
struct filp *f;
register struct fproc *rp;
while (reviving != 0) {
found_one= FALSE;
/* Revive a suspended process. */
for (rp = &fproc[0]; rp < &fproc[NR_PROCS]; rp++)
if (rp->fp_pid != PID_FREE && rp->fp_revived == REVIVING) {
int blocked_on = rp->fp_blocked_on;
found_one= TRUE;
who_p = (int)(rp - fproc);
who_e = rp->fp_endpoint;
call_nr = rp->fp_block_callnr;
m_in.fd = rp->fp_block_fd;
m_in.buffer = rp->fp_buffer;
m_in.nbytes = rp->fp_nbytes;
/*no longer hanging*/
rp->fp_blocked_on = FP_BLOCKED_ON_NONE;
rp->fp_revived = NOT_REVIVING;
reviving--;
/* This should be a pipe I/O, not a device I/O.
* If it is, it'll 'leak' grants.
*/
assert(!GRANT_VALID(rp->fp_grant));
if (blocked_on == FP_BLOCKED_ON_PIPE)
{
fp= rp;
fd_nr= rp->fp_block_fd;
f= get_filp(fd_nr);
assert(f != NULL);
r= rw_pipe((call_nr == READ) ? READING :
WRITING, who_e, fd_nr, f,
rp->fp_buffer, rp->fp_nbytes);
if (r != SUSPEND)
reply(who_e, r);
continue;
}
return;
}
if (!found_one)
panic("get_work couldn't revive anyone");
}
for(;;) {
int r;
/* Normal case. No one to revive. */
if ((r=sef_receive(ANY, &m_in)) != OK)
panic("fs sef_receive error: %d", r);
who_e = m_in.m_source;
who_p = _ENDPOINT_P(who_e);
/*
* negative who_p is never used to access the fproc array. Negative numbers
* (kernel tasks) are treated in a special way
*/
if(who_p >= (int)(sizeof(fproc) / sizeof(struct fproc)))
panic("receive process out of range: %d", who_p);
if(who_p >= 0 && fproc[who_p].fp_endpoint == NONE) {
printf("FS: ignoring request from %d, endpointless slot %d (%d)\n",
m_in.m_source, who_p, m_in.m_type);
continue;
}
if(who_p >= 0 && fproc[who_p].fp_endpoint != who_e) {
if(fproc[who_p].fp_endpoint == NONE) {
printf("slot unknown even\n");
}
printf("FS: receive endpoint inconsistent (source %d, who_p %d, stored ep %d, who_e %d).\n",
m_in.m_source, who_p, fproc[who_p].fp_endpoint, who_e);
#if 0
panic("FS: inconsistent endpoint ");
#endif
continue;
}
call_nr = m_in.m_type;
return;
}
}
/*===========================================================================*
* reply *
*===========================================================================*/
PUBLIC void reply(whom, result)
int whom; /* process to reply to */
int result; /* result of the call (usually OK or error #) */
{
/* Send a reply to a user process. If the send fails, just ignore it. */
int s;
#if 0
if (call_nr == SYMLINK)
printf("vfs:reply: replying %d for call %d\n", result, call_nr);
#endif
m_out.reply_type = result;
s = sendnb(whom, &m_out);
if (s != OK) printf("VFS: couldn't send reply %d to %d: %d\n",
result, whom, s);
}
/*===========================================================================*
* init_root *
*===========================================================================*/
PRIVATE void init_root()
{
int r = OK;
struct vmnt *vmp;
struct vnode *root_node;
struct dmap *dp;
char *label;
struct node_details res;
/* Open the root device. */
root_dev = DEV_IMGRD;
ROOT_FS_E = MFS_PROC_NR;
/* Initialize vmnt table */
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
vmp->m_dev = NO_DEV;
vmp = &vmnt[0];
/* We'll need a vnode for the root inode, check whether there is one */
if ((root_node = get_free_vnode()) == NULL)
panic("Cannot get free vnode: %d", r);
/* Get driver process' endpoint */
dp = &dmap[(root_dev >> MAJOR) & BYTE];
if (dp->dmap_driver == NONE) {
panic("No driver for root device: %d", r);
}
label= dp->dmap_label;
if (strlen(label) == 0)
{
panic("vfs:init_root: no label for major: %d", root_dev >> MAJOR);
}
/* Issue request */
r = req_readsuper(ROOT_FS_E, label, root_dev, 0 /*!readonly*/,
1 /*isroot*/, &res);
if (r != OK) {
panic("Cannot read superblock from root: %d", r);
}
/* Fill in root node's fields */
root_node->v_fs_e = res.fs_e;
root_node->v_inode_nr = res.inode_nr;
root_node->v_mode = res.fmode;
root_node->v_size = res.fsize;
root_node->v_sdev = NO_DEV;
root_node->v_fs_count = 1;
root_node->v_ref_count = 1;
/* Fill in max file size and blocksize for the vmnt */
vmp->m_fs_e = res.fs_e;
vmp->m_dev = root_dev;
vmp->m_flags = 0;
/* Root node is indeed on the partition */
root_node->v_vmnt = vmp;
root_node->v_dev = vmp->m_dev;
/* Root directory is not mounted on a vnode. */
vmp->m_mounted_on = NULL;
vmp->m_root_node = root_node;
strcpy(vmp->m_label, "fs_imgrd"); /* FIXME: obtain this from RS */
}
/*===========================================================================*
* service_pm *
*===========================================================================*/
PRIVATE void service_pm()
{
int r;
vir_bytes pc;
switch (call_nr) {
case PM_SETUID:
pm_setuid(m_in.PM_PROC, m_in.PM_EID, m_in.PM_RID);
m_out.m_type = PM_SETUID_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_SETGID:
pm_setgid(m_in.PM_PROC, m_in.PM_EID, m_in.PM_RID);
m_out.m_type = PM_SETGID_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_SETSID:
pm_setsid(m_in.PM_PROC);
m_out.m_type = PM_SETSID_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_EXEC:
r = pm_exec(m_in.PM_PROC, m_in.PM_PATH, m_in.PM_PATH_LEN,
m_in.PM_FRAME, m_in.PM_FRAME_LEN, &pc);
/* Reply status to PM */
m_out.m_type = PM_EXEC_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
m_out.PM_PC = (void*)pc;
m_out.PM_STATUS = r;
break;
case PM_EXIT:
pm_exit(m_in.PM_PROC);
/* Reply dummy status to PM for synchronization */
m_out.m_type = PM_EXIT_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_DUMPCORE:
r = pm_dumpcore(m_in.PM_PROC, m_in.PM_TERM_SIG, m_in.PM_PATH);
/* Reply status to PM */
m_out.m_type = PM_CORE_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
m_out.PM_TRACED_PROC = m_in.PM_TRACED_PROC;
m_out.PM_STATUS = r;
break;
case PM_FORK:
case PM_SRV_FORK:
pm_fork(m_in.PM_PPROC, m_in.PM_PROC, m_in.PM_CPID);
m_out.m_type = (call_nr == PM_FORK) ? PM_FORK_REPLY : PM_SRV_FORK_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_SETGROUPS:
pm_setgroups(m_in.PM_PROC, m_in.PM_GROUP_NO, (gid_t *) m_in.PM_GROUP_ADDR);
m_out.m_type = PM_SETGROUPS_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_UNPAUSE:
unpause(m_in.PM_PROC);
m_out.m_type = PM_UNPAUSE_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
break;
case PM_REBOOT:
pm_reboot();
/* Reply dummy status to PM for synchronization */
m_out.m_type = PM_REBOOT_REPLY;
break;
default:
printf("VFS: don't know how to handle PM request %x\n", call_nr);
return;
}
r = send(PM_PROC_NR, &m_out);
if (r != OK)
panic("service_pm: send failed: %d", r);
}
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