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minix/servers/vfs/main.c
Cristiano Giuffrida cb176df60f New RS and new signal handling for system processes. 
UPDATING INFO:
20100317:
        /usr/src/etc/system.conf updated to ignore default kernel calls: copy
        it (or merge it) to /etc/system.conf.
        The hello driver (/dev/hello) added to the distribution:
        # cd /usr/src/commands/scripts && make clean install
        # cd /dev && MAKEDEV hello

KERNEL CHANGES:
- Generic signal handling support. The kernel no longer assumes PM as a signal
manager for every process. The signal manager of a given process can now be
specified in its privilege slot. When a signal has to be delivered, the kernel
performs the lookup and forwards the signal to the appropriate signal manager.
PM is the default signal manager for user processes, RS is the default signal
manager for system processes. To enable ptrace()ing for system processes, it
is sufficient to change the default signal manager to PM. This will temporarily
disable crash recovery, though.
- sys_exit() is now split into sys_exit() (i.e. exit() for system processes,
which generates a self-termination signal), and sys_clear() (i.e. used by PM
to ask the kernel to clear a process slot when a process exits).
- Added a new kernel call (i.e. sys_update()) to swap two process slots and
implement live update.

PM CHANGES:
- Posix signal handling is no longer allowed for system processes. System
signals are split into two fixed categories: termination and non-termination
signals. When a non-termination signaled is processed, PM transforms the signal
into an IPC message and delivers the message to the system process. When a
termination signal is processed, PM terminates the process.
- PM no longer assumes itself as the signal manager for system processes. It now
makes sure that every system signal goes through the kernel before being
actually processes. The kernel will then dispatch the signal to the appropriate
signal manager which may or may not be PM.

SYSLIB CHANGES:
- Simplified SEF init and LU callbacks.
- Added additional predefined SEF callbacks to debug crash recovery and
live update.
- Fixed a temporary ack in the SEF init protocol. SEF init reply is now
completely synchronous.
- Added SEF signal event type to provide a uniform interface for system
processes to deal with signals. A sef_cb_signal_handler() callback is
available for system processes to handle every received signal. A
sef_cb_signal_manager() callback is used by signal managers to process
system signals on behalf of the kernel.
- Fixed a few bugs with memory mapping and DS.

VM CHANGES:
- Page faults and memory requests coming from the kernel are now implemented
using signals.
- Added a new VM call to swap two process slots and implement live update.
- The call is used by RS at update time and in turn invokes the kernel call
sys_update().

RS CHANGES:
- RS has been reworked with a better functional decomposition.
- Better kernel call masks. com.h now defines the set of very basic kernel calls
every system service is allowed to use. This makes system.conf simpler and
easier to maintain. In addition, this guarantees a higher level of isolation
for system libraries that use one or more kernel calls internally (e.g. printf).
- RS is the default signal manager for system processes. By default, RS
intercepts every signal delivered to every system process. This makes crash
recovery possible before bringing PM and friends in the loop.
- RS now supports fast rollback when something goes wrong while initializing
the new version during a live update.
- Live update is now implemented by keeping the two versions side-by-side and
swapping the process slots when the old version is ready to update.
- Crash recovery is now implemented by keeping the two versions side-by-side
and cleaning up the old version only when the recovery process is complete.

DS CHANGES:
- Fixed a bug when the process doing ds_publish() or ds_delete() is not known
by DS.
- Fixed the completely broken support for strings. String publishing is now
implemented in the system library and simply wraps publishing of memory ranges.
Ideally, we should adopt a similar approach for other data types as well.
- Test suite fixed.

DRIVER CHANGES:
- The hello driver has been added to the Minix distribution to demonstrate basic
live update and crash recovery functionalities.
- Other drivers have been adapted to conform the new SEF interface.
2010-03-17 01:15:29 +00:00

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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 == FS_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();
continue;
}
if (call_nr == DEV_SEL_REPL2)
{
select_reply2();
continue;
}
/* Check for special control messages first. */
if (is_notify(call_nr)) {
if (who_p == CLOCK)
{
/* Alarm timer expired. Used only for select().
* Check it.
*/
fs_expire_timers(m_in.NOTIFY_TIMESTAMP);
}
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;
default:
/* Call the internal function that does the work. */
if (call_nr < 0 || call_nr >= NCALLS) {
error = SUSPEND;
/* Not supposed to happen. */
printf("VFS: illegal %d system call by %d\n",
call_nr, who_e);
} 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;
register struct fproc *rfp;
struct vmnt *vmp;
struct vnode *root_vp;
message mess;
/* Clear endpoint field */
last_login_fs_e = NONE;
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 FS initialization.
* Certain relations must hold for the file system to work at all. Some
* extra block_size requirements are checked at super-block-read-in time.
*/
if (OPEN_MAX > 127) panic("OPEN_MAX > 127");
/* The following initializations are needed to let dev_opcl succeed .*/
fp = (struct fproc *) NULL;
who_e = who_p = FS_PROC_NR;
build_dmap(); /* build device table and map boot driver */
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();
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_fd & BYTE;
m_in.fd = (rp->fp_fd >>8) & BYTE;
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_fd >> 8);
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;
message m;
struct node_details res;
/* Open the root device. */
root_dev = DEV_IMGRD;
ROOT_FS_E = MFS_PROC_NR;
/* Wait FS login message */
if (last_login_fs_e != ROOT_FS_E) {
/* Wait FS login message */
if (sef_receive(ROOT_FS_E, &m) != OK) {
printf("VFS: Error receiving login request from FS_e %d\n",
ROOT_FS_E);
panic("Error receiving login request from root filesystem: %d", ROOT_FS_E);
}
if (m.m_type != FS_READY) {
printf("VFS: Invalid login request from FS_e %d\n",
ROOT_FS_E);
panic("Error receiving login request from root filesystem: %d", ROOT_FS_E);
}
}
last_login_fs_e = NONE;
/* 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()) == NIL_VNODE)
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;
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);
/* Reply status to PM */
m_out.m_type = PM_EXEC_REPLY;
m_out.PM_PROC = m_in.PM_PROC;
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,
NULL /* (struct mem_map *) m_in.PM_SEGPTR */);
/* Reply status to PM */
m_out.m_type = PM_CORE_REPLY;
m_out.PM_PROC = m_in.PM_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, 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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