sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity
minix/servers/vfs/device.c
Thomas Veerman 992799b91f VFS: make all IPC asynchronous 
By decoupling synchronous drivers from VFS, we are a big step closer to
supporting driver crashes under all circumstances. That is, VFS can't
become stuck on IPC with a synchronous driver (e.g., INET) and can
recover from crashing block drivers during open/close/ioctl or during
communication with an FS.

In order to maintain serialized communication with a synchronous driver,
the communication is wrapped by a mutex on a per driver basis (not major
numbers as there can be multiple majors with identical endpoints). Majors
that share a driver endpoint point to a single mutex object.

In order to support crashes from block drivers, the file reopen tactic
had to be changed; first reopen files associated with the crashed
driver, then send the new driver endpoint to FSes. This solves a
deadlock between the FS and the block driver;
  - VFS would send REQ_NEW_DRIVER to an FS, but he FS only receives it
    after retrying the current request to the newly started driver.
  - The block driver would refuse the retried request until all files
    had been reopened.
  - VFS would reopen files only after getting a reply from the initial
    REQ_NEW_DRIVER.

When a character special driver crashes, all associated files have to
be marked invalid and closed (or reopened if flagged as such). However,
they can only be closed if a thread holds exclusive access to it. To
obtain exclusive access, the worker thread (which handles the new driver
endpoint event from DS) schedules a new job to garbage collect invalid
files. This way, we can signal the worker thread that was talking to the
crashed driver and will release exclusive access to a file associated
with the crashed driver and prevent the garbage collecting worker thread
from dead locking on that file.

Also, when a character special driver crashes, RS will unmap the driver
and remap it upon restart. During unmapping, associated files are marked
invalid instead of waiting for an endpoint up event from DS, as that
event might come later than new read/write/select requests and thus
cause confusion in the freshly started driver.

When locking a filp, the usage counters are no longer checked. The usage
counter can legally go down to zero during filp invalidation while there
are locks pending.

DS events are handled by a separate worker thread instead of the main
thread as reopening files could lead to another crash and a stuck thread.
An additional worker thread is then necessary to unlock it.

Finally, with everything asynchronous a race condition in do_select
surfaced. A select entry was only marked in use after succesfully sending
initial select requests to drivers and having to wait. When multiple
select() calls were handled there was opportunity that these entries
were overwritten. This had as effect that some select results were
ignored (and select() remained blocking instead if returning) or do_select
tried to access filps that were not present (because thrown away by
secondary select()). This bug manifested itself with sendrecs, but was
very hard to reproduce. However, it became awfully easy to trigger with
asynsends only.
2012-09-17 11:01:45 +00:00

1249 lines
35 KiB
C
Raw Blame History

/* When a needed block is not in the cache, it must be fetched from the disk.
* Special character files also require I/O. The routines for these are here.
*
* The entry points in this file are:
* dev_open: open a character device
* dev_reopen: reopen a character device after a driver crash
* dev_close: close a character device
* bdev_open: open a block device
* bdev_close: close a block device
* dev_io: FS does a read or write on a device
* dev_status: FS processes callback request alert
* gen_opcl: generic call to a task to perform an open/close
* gen_io: generic call to a task to perform an I/O operation
* no_dev: open/close processing for devices that don't exist
* no_dev_io: i/o processing for devices that don't exist
* tty_opcl: perform tty-specific processing for open/close
* ctty_opcl: perform controlling-tty-specific processing for open/close
* ctty_io: perform controlling-tty-specific processing for I/O
* pm_setsid: perform VFS's side of setsid system call
* do_ioctl: perform the IOCTL system call
*/
#include "fs.h"
#include <string.h>
#include <fcntl.h>
#include <assert.h>
#include <sys/stat.h>
#include <minix/callnr.h>
#include <minix/com.h>
#include <minix/endpoint.h>
#include <minix/ioctl.h>
#include <minix/u64.h>
#include "file.h"
#include "fproc.h"
#include "scratchpad.h"
#include "dmap.h"
#include <minix/vfsif.h>
#include "vnode.h"
#include "vmnt.h"
#include "param.h"
static void restart_reopen(int major);
static int safe_io_conversion(endpoint_t, cp_grant_id_t *, int *,
endpoint_t *, void **, size_t, u32_t *);
static int dummyproc;
/*===========================================================================*
* dev_open *
*===========================================================================*/
int dev_open(
dev_t dev, /* device to open */
endpoint_t proc_e, /* process to open for */
int flags /* mode bits and flags */
)
{
/* Open a character device. */
int major, r;
/* Determine the major device number so as to call the device class specific
* open/close routine. (This is the only routine that must check the
* device number for being in range. All others can trust this check.)
*/
major = major(dev);
if (major < 0 || major >= NR_DEVICES) major = 0;
if (dmap[major].dmap_driver == NONE) return(ENXIO);
r = (*dmap[major].dmap_opcl)(DEV_OPEN, dev, proc_e, flags);
return(r);
}
/*===========================================================================*
* dev_reopen *
*===========================================================================*/
int dev_reopen(
dev_t dev, /* device to open */
int filp_no, /* filp to reopen for */
int flags /* mode bits and flags */
)
{
/* Reopen a character device after a failing device driver. */
int major, r;
struct dmap *dp;
/* Determine the major device number and call the device class specific
* open/close routine. (This is the only routine that must check the device
* number for being in range. All others can trust this check.)
*/
major = major(dev);
if (major < 0 || major >= NR_DEVICES) major = 0;
dp = &dmap[major];
if (dp->dmap_driver == NONE) return(ENXIO);
r = (*dp->dmap_opcl)(DEV_REOPEN, dev, filp_no, flags);
if (r == SUSPEND) r = OK;
return(r);
}
/*===========================================================================*
* dev_close *
*===========================================================================*/
int dev_close(
dev_t dev, /* device to close */
int filp_no
)
{
/* Close a character device. */
int r, major;
/* See if driver is roughly valid. */
major = major(dev);
if (major < 0 || major >= NR_DEVICES) return(ENXIO);
if (dmap[major].dmap_driver == NONE) return(ENXIO);
r = (*dmap[major].dmap_opcl)(DEV_CLOSE, dev, filp_no, 0);
return(r);
}
/*===========================================================================*
* dev_open *
*===========================================================================*/
int bdev_open(dev_t dev, int access)
{
/* Open a block device. */
int major;
major = major(dev);
if (major < 0 || major >= NR_DEVICES) return(ENXIO);
if (dmap[major].dmap_driver == NONE) return(ENXIO);
return (*dmap[major].dmap_opcl)(BDEV_OPEN, dev, 0, access);
}
/*===========================================================================*
* bdev_close *
*===========================================================================*/
int bdev_close(dev_t dev)
{
/* Close a block device. */
int major;
major = major(dev);
if (major < 0 || major >= NR_DEVICES) return(ENXIO);
if (dmap[major].dmap_driver == NONE) return(ENXIO);
return (*dmap[major].dmap_opcl)(BDEV_CLOSE, dev, 0, 0);
}
/*===========================================================================*
* bdev_ioctl *
*===========================================================================*/
static int bdev_ioctl(dev_t dev, endpoint_t proc_e, int req, void *buf)
{
/* Perform an I/O control operation on a block device. */
struct dmap *dp;
u32_t dummy;
cp_grant_id_t gid;
message dev_mess;
int op, major_dev, minor_dev;
major_dev = major(dev);
minor_dev = minor(dev);
/* Determine task dmap. */
dp = &dmap[major_dev];
if (dp->dmap_driver == NONE) {
printf("VFS: dev_io: no driver for major %d\n", major_dev);
return(ENXIO);
}
/* Set up a grant if necessary. */
op = VFS_DEV_IOCTL;
(void) safe_io_conversion(dp->dmap_driver, &gid, &op, &proc_e, &buf, req,
&dummy);
/* Set up the message passed to the task. */
memset(&dev_mess, 0, sizeof(dev_mess));
dev_mess.m_type = BDEV_IOCTL;
dev_mess.BDEV_MINOR = minor_dev;
dev_mess.BDEV_REQUEST = req;
dev_mess.BDEV_GRANT = gid;
dev_mess.BDEV_ID = 0;
/* Call the task. */
(*dp->dmap_io)(dp->dmap_driver, &dev_mess);
/* Clean up. */
if (GRANT_VALID(gid)) cpf_revoke(gid);
if (dp->dmap_driver == NONE) {
printf("VFS: block driver gone!?\n");
return(EIO);
}
/* Return the result. */
return(dev_mess.BDEV_STATUS);
}
/*===========================================================================*
* find_suspended_ep *
*===========================================================================*/
endpoint_t find_suspended_ep(endpoint_t driver, cp_grant_id_t g)
{
/* A process is suspended on a driver for which VFS issued a grant. Find out
* which process it was.
*/
struct fproc *rfp;
for (rfp = &fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
if(rfp->fp_pid == PID_FREE)
continue;
if(rfp->fp_blocked_on == FP_BLOCKED_ON_OTHER &&
rfp->fp_task == driver && rfp->fp_grant == g)
return(rfp->fp_endpoint);
}
return(NONE);
}
/*===========================================================================*
* dev_status *
*===========================================================================*/
void dev_status(endpoint_t drv_e)
{
/* A device sent us a notification it has something for us. Retrieve it. */
message st;
int major, get_more = 1;
endpoint_t endpt;
for (major = 0; major < NR_DEVICES; major++)
if (dmap_driver_match(drv_e, major))
break; /* 'major' is the device that sent the message */
if (major >= NR_DEVICES) /* Device endpoint not found; nothing to do */
return;
if (dev_style_asyn(dmap[major].dmap_style)) {
printf("VFS: not doing dev_status for async driver %d\n", drv_e);
return;
}
/* Continuously send DEV_STATUS messages until the device has nothing to
* say to us anymore. */
do {
int r;
st.m_type = DEV_STATUS;
r = drv_sendrec(drv_e, &st);
if (r == OK && st.REP_STATUS == ERESTART) r = EDEADEPT;
if (r != OK) {
printf("VFS: DEV_STATUS failed to %d: %d\n", drv_e, r);
if (r == EDEADSRCDST || r == EDEADEPT) return;
panic("VFS: couldn't sendrec for DEV_STATUS: %d", r);
}
switch(st.m_type) {
case DEV_REVIVE:
/* We've got results for a read/write/ioctl call to a
* synchronous character driver */
endpt = st.REP_ENDPT;
if (endpt == VFS_PROC_NR) {
endpt = find_suspended_ep(drv_e, st.REP_IO_GRANT);
if (endpt == NONE) {
printf("VFS: proc with grant %d from %d not found\n",
st.REP_IO_GRANT, st.m_source);
continue;
}
}
revive(endpt, st.REP_STATUS);
break;
case DEV_IO_READY:
/* Reply to a select request: driver is ready for I/O */
select_reply2(st.m_source, st.DEV_MINOR, st.DEV_SEL_OPS);
break;
default:
printf("VFS: unrecognized reply %d to DEV_STATUS\n",st.m_type);
/* Fall through. */
case DEV_NO_STATUS:
get_more = 0;
break;
}
} while(get_more);
}
/*===========================================================================*
* safe_io_conversion *
*===========================================================================*/
static int safe_io_conversion(driver, gid, op, io_ept, buf, bytes, pos_lo)
endpoint_t driver;
cp_grant_id_t *gid;
int *op;
endpoint_t *io_ept;
void **buf;
size_t bytes;
u32_t *pos_lo;
{
/* Convert operation to the 'safe' variant (i.e., grant based) if applicable.
* If no copying of data is involved, there is also no need to convert. */
int access = 0;
size_t size;
*gid = GRANT_INVALID; /* Grant to buffer */
switch(*op) {
case VFS_DEV_READ:
case VFS_DEV_WRITE:
/* Change to safe op. */
*op = (*op == VFS_DEV_READ) ? DEV_READ_S : DEV_WRITE_S;
*gid = cpf_grant_magic(driver, *io_ept, (vir_bytes) *buf, bytes,
*op == DEV_READ_S ? CPF_WRITE : CPF_READ);
if (*gid < 0)
panic("VFS: cpf_grant_magic of READ/WRITE buffer failed");
break;
case VFS_DEV_IOCTL:
*pos_lo = *io_ept; /* Old endpoint in POSITION field. */
*op = DEV_IOCTL_S;
/* For IOCTLs, the bytes parameter encodes requested access method
* and buffer size */
if(_MINIX_IOCTL_IOR(bytes)) access |= CPF_WRITE;
if(_MINIX_IOCTL_IOW(bytes)) access |= CPF_READ;
if(_MINIX_IOCTL_BIG(bytes))
size = _MINIX_IOCTL_SIZE_BIG(bytes);
else
size = _MINIX_IOCTL_SIZE(bytes);
/* Grant access to the buffer even if no I/O happens with the ioctl, in
* order to disambiguate requests with DEV_IOCTL_S.
*/
*gid = cpf_grant_magic(driver, *io_ept, (vir_bytes) *buf, size, access);
if (*gid < 0)
panic("VFS: cpf_grant_magic IOCTL buffer failed");
break;
case VFS_DEV_SELECT:
*op = DEV_SELECT;
break;
default:
panic("VFS: unknown operation %d for safe I/O conversion", *op);
}
/* If we have converted to a safe operation, I/O endpoint becomes VFS if it
* wasn't already.
*/
if(GRANT_VALID(*gid)) {
*io_ept = VFS_PROC_NR;
return(1);
}
/* Not converted to a safe operation (because there is no copying involved in
* this operation).
*/
return(0);
}
static int cancel_nblock(struct dmap * dp,
int minor,
int call,
endpoint_t ioproc,
cp_grant_id_t gid)
{
message dev_mess;
dev_mess.m_type = CANCEL;
dev_mess.USER_ENDPT = ioproc;
dev_mess.IO_GRANT = (char *) gid;
/* This R_BIT/W_BIT check taken from suspend()/unpause()
* logic. Mode is expected in the COUNT field.
*/
dev_mess.COUNT = 0;
if (call == READ)
dev_mess.COUNT = R_BIT;
else if (call == WRITE)
dev_mess.COUNT = W_BIT;
dev_mess.DEVICE = minor;
(*dp->dmap_io)(dp->dmap_driver, &dev_mess);
return dev_mess.REP_STATUS;
}
/*===========================================================================*
* dev_io *
*===========================================================================*/
int dev_io(
int op, /* DEV_READ, DEV_WRITE, DEV_IOCTL, etc. */
dev_t dev, /* major-minor device number */
int proc_e, /* in whose address space is buf? */
void *buf, /* virtual address of the buffer */
u64_t pos, /* byte position */
size_t bytes, /* how many bytes to transfer */
int flags, /* special flags, like O_NONBLOCK */
int suspend_reopen /* Just suspend the process */
)
{
/* Read from or write to a device. The parameter 'dev' tells which one. */
struct dmap *dp;
u32_t pos_lo, pos_high;
message dev_mess;
cp_grant_id_t gid = GRANT_INVALID;
int safe, minor_dev, major_dev;
void *buf_used;
endpoint_t ioproc;
int ret, is_asyn;
pos_lo = ex64lo(pos);
pos_high = ex64hi(pos);
major_dev = major(dev);
minor_dev = minor(dev);
/* Determine task dmap. */
dp = &dmap[major_dev];
/* See if driver is roughly valid. */
if (dp->dmap_driver == NONE) return(ENXIO);
if (suspend_reopen) {
/* Suspend user. */
fp->fp_grant = GRANT_INVALID;
fp->fp_ioproc = NONE;
wait_for(dp->dmap_driver);
fp->fp_flags |= FP_SUSP_REOPEN;
return(SUSPEND);
}
if(isokendpt(dp->dmap_driver, &dummyproc) != OK) {
printf("VFS: dev_io: old driver for major %x (%d)\n", major_dev,
dp->dmap_driver);
return(ENXIO);
}
/* By default, these are right. */
dev_mess.USER_ENDPT = proc_e;
dev_mess.ADDRESS = buf;
/* Convert DEV_* to DEV_*_S variants. */
buf_used = buf;
safe = safe_io_conversion(dp->dmap_driver, &gid, &op,
(endpoint_t *) &dev_mess.USER_ENDPT, &buf_used,
bytes, &pos_lo);
is_asyn = dev_style_asyn(dp->dmap_style);
/* If the safe conversion was done, set the IO_GRANT to
* the grant id.
*/
if(safe) dev_mess.IO_GRANT = (char *) gid;
/* Set up the rest of the message passed to task. */
dev_mess.m_type = op;
dev_mess.DEVICE = minor_dev;
dev_mess.POSITION = pos_lo;
dev_mess.COUNT = bytes;
dev_mess.HIGHPOS = pos_high;
dev_mess.FLAGS = 0;
if (flags & O_NONBLOCK)
dev_mess.FLAGS |= FLG_OP_NONBLOCK;
/* This will be used if the i/o is suspended. */
ioproc = dev_mess.USER_ENDPT;
/* Call the task. */
(*dp->dmap_io)(dp->dmap_driver, &dev_mess);
if(dp->dmap_driver == NONE) {
/* Driver has vanished. */
printf("VFS: driver gone?!\n");
if(safe) cpf_revoke(gid);
return(EIO);
}
ret = dev_mess.REP_STATUS;
/* Task has completed. See if call completed. */
if (ret == SUSPEND) {
if ((flags & O_NONBLOCK) && !is_asyn) {
/* Not supposed to block. */
ret = cancel_nblock(dp, minor_dev, job_call_nr, ioproc, gid);
if (ret == EINTR)
ret = EAGAIN;
} else {
/* select() will do suspending itself. */
if(op != DEV_SELECT) {
/* Suspend user. */
wait_for(dp->dmap_driver);
}
assert(!GRANT_VALID(fp->fp_grant));
fp->fp_grant = gid; /* revoke this when unsuspended. */
fp->fp_ioproc = ioproc;
if ((flags & O_NONBLOCK) && !is_asyn) {
/* Not supposed to block, send cancel message */
cancel_nblock(dp, minor_dev, job_call_nr, ioproc, gid);
/*
* FIXME Should do something about EINTR -> EAGAIN
* mapping
*/
}
return(SUSPEND);
}
}
/* No suspend, or cancelled suspend, so I/O is over and can be cleaned up. */
if(safe) cpf_revoke(gid);
return ret;
}
/*===========================================================================*
* gen_opcl *
*===========================================================================*/
int gen_opcl(
int op, /* operation, (B)DEV_OPEN or (B)DEV_CLOSE */
dev_t dev, /* device to open or close */
endpoint_t proc_e, /* process to open/close for */
int flags /* mode bits and flags */
)
{
/* Called from the dmap struct on opens & closes of special files.*/
int r, minor_dev, major_dev, is_bdev;
struct dmap *dp;
message dev_mess;
/* Determine task dmap. */
major_dev = major(dev);
minor_dev = minor(dev);
assert(major_dev >= 0 && major_dev < NR_DEVICES);
dp = &dmap[major_dev];
assert(dp->dmap_driver != NONE);
is_bdev = IS_BDEV_RQ(op);
if (is_bdev) {
memset(&dev_mess, 0, sizeof(dev_mess));
dev_mess.m_type = op;
dev_mess.BDEV_MINOR = minor_dev;
dev_mess.BDEV_ACCESS = flags;
dev_mess.BDEV_ID = 0;
} else {
dev_mess.m_type = op;
dev_mess.DEVICE = minor_dev;
dev_mess.USER_ENDPT = proc_e;
dev_mess.COUNT = flags;
}
/* Call the task. */
r = (*dp->dmap_io)(dp->dmap_driver, &dev_mess);
if (r != OK) return(r);
if (op == DEV_OPEN && dp->dmap_style == STYLE_DEVA) {
fp->fp_task = dp->dmap_driver;
worker_wait();
}
if (is_bdev)
return(dev_mess.BDEV_STATUS);
else
return(dev_mess.REP_STATUS);
}
/*===========================================================================*
* tty_opcl *
*===========================================================================*/
int tty_opcl(
int op, /* operation, DEV_OPEN or DEV_CLOSE */
dev_t dev, /* device to open or close */
endpoint_t proc_e, /* process to open/close for */
int flags /* mode bits and flags */
)
{
/* This procedure is called from the dmap struct on tty open/close. */
int r;
register struct fproc *rfp;
assert(!IS_BDEV_RQ(op));
/* Add O_NOCTTY to the flags if this process is not a session leader, or
* if it already has a controlling tty, or if it is someone elses
* controlling tty.
*/
if (!(fp->fp_flags & FP_SESLDR) || fp->fp_tty != 0) {
flags |= O_NOCTTY;
} else {
for (rfp = &fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
if(rfp->fp_pid == PID_FREE) continue;
if (rfp->fp_tty == dev) flags |= O_NOCTTY;
}
}
r = gen_opcl(op, dev, proc_e, flags);
/* Did this call make the tty the controlling tty? */
if (r == 1) {
fp->fp_tty = dev;
r = OK;
}
return(r);
}
/*===========================================================================*
* ctty_opcl *
*===========================================================================*/
int ctty_opcl(
int op, /* operation, DEV_OPEN or DEV_CLOSE */
dev_t UNUSED(dev), /* device to open or close */
endpoint_t UNUSED(proc_e), /* process to open/close for */
int UNUSED(flags) /* mode bits and flags */
)
{
/* This procedure is called from the dmap struct on opening or closing
* /dev/tty, the magic device that translates to the controlling tty.
*/
assert(!IS_BDEV_RQ(op));
return(fp->fp_tty == 0 ? ENXIO : OK);
}
/*===========================================================================*
* pm_setsid *
*===========================================================================*/
void pm_setsid(endpoint_t proc_e)
{
/* Perform the VFS side of the SETSID call, i.e. get rid of the controlling
* terminal of a process, and make the process a session leader.
*/
register struct fproc *rfp;
int slot;
/* Make the process a session leader with no controlling tty. */
okendpt(proc_e, &slot);
rfp = &fproc[slot];
rfp->fp_flags |= FP_SESLDR;
rfp->fp_tty = 0;
}
/*===========================================================================*
* do_ioctl *
*===========================================================================*/
int do_ioctl()
{
/* Perform the ioctl(ls_fd, request, argx) system call */
int r = OK, suspend_reopen, ioctlrequest;
struct filp *f;
register struct vnode *vp;
dev_t dev;
void *argx;
scratch(fp).file.fd_nr = job_m_in.ls_fd;
ioctlrequest = job_m_in.REQUEST;
argx = job_m_in.ADDRESS;
if ((f = get_filp(scratch(fp).file.fd_nr, VNODE_READ)) == NULL)
return(err_code);
vp = f->filp_vno; /* get vnode pointer */
if (!S_ISCHR(vp->v_mode) && !S_ISBLK(vp->v_mode)) {
r = ENOTTY;
}
if (r == OK) {
suspend_reopen = (f->filp_state & FS_NEEDS_REOPEN);
dev = (dev_t) vp->v_sdev;
if (S_ISBLK(vp->v_mode))
r = bdev_ioctl(dev, who_e, ioctlrequest, argx);
else
r = dev_io(VFS_DEV_IOCTL, dev, who_e, argx, cvu64(0),
ioctlrequest, f->filp_flags, suspend_reopen);
}
unlock_filp(f);
return(r);
}
/*===========================================================================*
* gen_io *
*===========================================================================*/
int gen_io(driver_e, mess_ptr)
endpoint_t driver_e; /* which endpoint to call */
message *mess_ptr; /* pointer to message for task */
{
/* All file system I/O ultimately comes down to I/O on major/minor device
* pairs. These lead to calls on the following routines via the dmap table.
*/
int r, status, proc_e = NONE, is_bdev, retry_count;
message mess_retry;
is_bdev = IS_BDEV_RQ(mess_ptr->m_type);
mess_retry = *mess_ptr;
retry_count = 0;
if (!is_bdev) proc_e = mess_ptr->USER_ENDPT;
do {
r = drv_sendrec(driver_e, mess_ptr);
if (r == OK) {
if (is_bdev)
status = mess_ptr->BDEV_STATUS;
else
status = mess_ptr->REP_STATUS;
if (status == ERESTART) {
r = EDEADEPT;
*mess_ptr = mess_retry;
retry_count++;
}
}
} while (r == EDEADEPT && retry_count < 5);
if (r != OK) {
if (r == EDEADSRCDST || r == EDEADEPT) {
printf("VFS: dead driver %d\n", driver_e);
dmap_unmap_by_endpt(driver_e);
return(r);
} else if (r == ELOCKED) {
printf("VFS: ELOCKED talking to %d\n", driver_e);
return(r);
}
panic("call_task: can't send/receive: %d", r);
}
/* Did the process we did the sendrec() for get a result? */
if (!is_bdev && mess_ptr->REP_ENDPT != proc_e && mess_ptr->m_type != EIO) {
printf("VFS: strange device reply from %d, type = %d, "
"proc = %d (not %d) (2) ignored\n", mess_ptr->m_source,
mess_ptr->m_type, proc_e, mess_ptr->REP_ENDPT);
return(EIO);
} else if (!IS_DRV_REPLY(mess_ptr->m_type))
return(EIO);
return(OK);
}
/*===========================================================================*
* asyn_io *
*===========================================================================*/
int asyn_io(endpoint_t drv_e, message *mess_ptr)
{
/* All file system I/O ultimately comes down to I/O on major/minor device
* pairs. These lead to calls on the following routines via the dmap table.
*/
int r;
assert(!IS_BDEV_RQ(mess_ptr->m_type));
self->w_drv_sendrec = mess_ptr; /* Remember where result should be stored */
self->w_task = drv_e;
r = asynsend3(drv_e, mess_ptr, AMF_NOREPLY);
if (r != OK) panic("VFS: asynsend in asyn_io failed: %d", r);
/* Fake a SUSPEND */
mess_ptr->REP_STATUS = SUSPEND;
return(OK);
}
/*===========================================================================*
* ctty_io *
*===========================================================================*/
int ctty_io(
endpoint_t UNUSED(task_nr), /* not used - for compatibility with dmap_t */
message *mess_ptr /* pointer to message for task */
)
{
/* This routine is only called for one device, namely /dev/tty. Its job
* is to change the message to use the controlling terminal, instead of the
* major/minor pair for /dev/tty itself.
*/
struct dmap *dp;
if (fp->fp_tty == 0) {
/* No controlling tty present anymore, return an I/O error. */
mess_ptr->REP_STATUS = EIO;
} else {
/* Substitute the controlling terminal device. */
dp = &dmap[major(fp->fp_tty)];
mess_ptr->DEVICE = minor(fp->fp_tty);
if (dp->dmap_driver == NONE) {
printf("FS: ctty_io: no driver for dev\n");
return(EIO);
}
if (isokendpt(dp->dmap_driver, &dummyproc) != OK) {
printf("VFS: ctty_io: old driver %d\n", dp->dmap_driver);
return(EIO);
}
(*dp->dmap_io)(dp->dmap_driver, mess_ptr);
}
return(OK);
}
/*===========================================================================*
* no_dev *
*===========================================================================*/
int no_dev(
int UNUSED(op), /* operation, DEV_OPEN or DEV_CLOSE */
dev_t UNUSED(dev), /* device to open or close */
int UNUSED(proc), /* process to open/close for */
int UNUSED(flags) /* mode bits and flags */
)
{
/* Called when opening a nonexistent device. */
return(ENODEV);
}
/*===========================================================================*
* no_dev_io *
*===========================================================================*/
int no_dev_io(endpoint_t UNUSED(proc), message *UNUSED(m))
{
/* Called when doing i/o on a nonexistent device. */
printf("VFS: I/O on unmapped device number\n");
return(EIO);
}
/*===========================================================================*
* clone_opcl *
*===========================================================================*/
int clone_opcl(
int op, /* operation, DEV_OPEN or DEV_CLOSE */
dev_t dev, /* device to open or close */
int proc_e, /* process to open/close for */
int flags /* mode bits and flags */
)
{
/* Some devices need special processing upon open. Such a device is "cloned",
* i.e. on a succesful open it is replaced by a new device with a new unique
* minor device number. This new device number identifies a new object (such
* as a new network connection) that has been allocated within a task.
*/
struct dmap *dp;
int r, minor_dev, major_dev;
message dev_mess;
assert(!IS_BDEV_RQ(op));
/* Determine task dmap. */
minor_dev = minor(dev);
major_dev = major(dev);
assert(major_dev >= 0 && major_dev < NR_DEVICES);
dp = &dmap[major_dev];
assert(dp->dmap_driver != NONE);
dev_mess.m_type = op;
dev_mess.DEVICE = minor_dev;
dev_mess.USER_ENDPT = proc_e;
dev_mess.COUNT = flags;
if(isokendpt(dp->dmap_driver, &dummyproc) != OK) {
printf("VFS clone_opcl: bad driver endpoint for major %d (%d)\n",
major_dev, dp->dmap_driver);
return(ENXIO);
}
/* Call the task. */
r = (*dp->dmap_io)(dp->dmap_driver, &dev_mess);
if (r != OK) return(r);
if (op == DEV_OPEN && dev_style_asyn(dp->dmap_style)) {
/* Wait for reply when driver is asynchronous */
fp->fp_task = dp->dmap_driver;
worker_wait();
}
if (op == DEV_OPEN && dev_mess.REP_STATUS >= 0) {
if (dev_mess.REP_STATUS != minor_dev) {
struct vnode *vp;
struct node_details res;
/* A new minor device number has been returned.
* Request PFS to create a temporary device file to hold it.
*/
/* Device number of the new device. */
dev = (dev & ~(BYTE << MINOR)) | (dev_mess.REP_STATUS << MINOR);
/* Issue request */
r = req_newnode(PFS_PROC_NR, fp->fp_effuid, fp->fp_effgid,
ALL_MODES | I_CHAR_SPECIAL, dev, &res);
if (r != OK) {
(void) clone_opcl(DEV_CLOSE, dev, proc_e, 0);
return r;
}
/* Drop old node and use the new values */
if ((vp = get_free_vnode()) == NULL)
return(err_code);
lock_vnode(vp, VNODE_OPCL);
assert(FD_ISSET(scratch(fp).file.fd_nr, &fp->fp_filp_inuse));
unlock_vnode(fp->fp_filp[scratch(fp).file.fd_nr]->filp_vno);
put_vnode(fp->fp_filp[scratch(fp).file.fd_nr]->filp_vno);
vp->v_fs_e = res.fs_e;
vp->v_vmnt = NULL;
vp->v_dev = NO_DEV;
vp->v_fs_e = res.fs_e;
vp->v_inode_nr = res.inode_nr;
vp->v_mode = res.fmode;
vp->v_sdev = dev;
vp->v_fs_count = 1;
vp->v_ref_count = 1;
fp->fp_filp[scratch(fp).file.fd_nr]->filp_vno = vp;
}
dev_mess.REP_STATUS = OK;
}
return(dev_mess.REP_STATUS);
}
/*===========================================================================*
* bdev_up *
*===========================================================================*/
void bdev_up(int maj)
{
/* A new block device driver has been mapped in. This may affect both mounted
* file systems and open block-special files.
*/
int r, found, bits;
struct filp *rfilp;
struct vmnt *vmp;
struct vnode *vp;
char *label;
if (maj < 0 || maj >= NR_DEVICES) panic("VFS: out-of-bound major");
label = dmap[maj].dmap_label;
found = 0;
/* For each block-special file that was previously opened on the affected
* device, we need to reopen it on the new driver.
*/
for (rfilp = filp; rfilp < &filp[NR_FILPS]; rfilp++) {
if (rfilp->filp_count < 1 || !(vp = rfilp->filp_vno)) continue;
if (major(vp->v_sdev) != maj) continue;
if (!S_ISBLK(vp->v_mode)) continue;
/* Reopen the device on the driver, once per filp. */
bits = mode_map[rfilp->filp_mode & O_ACCMODE];
if ((r = bdev_open(vp->v_sdev, bits)) != OK) {
printf("VFS: mounted dev %d/%d re-open failed: %d.\n",
maj, minor(vp->v_sdev), r);
dmap[maj].dmap_recovering = 0;
return; /* Give up entirely */
}
found = 1;
}
/* Tell each affected mounted file system about the new endpoint.
*/
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp) {
if (major(vmp->m_dev) != maj) continue;
/* Send the driver label to the mounted file system. */
if (OK != req_newdriver(vmp->m_fs_e, vmp->m_dev, label))
printf("VFS dev_up: error sending new driver label to %d\n",
vmp->m_fs_e);
}
/* If any block-special file was open for this major at all, also inform the
* root file system about the new driver. We do this even if the
* block-special file is linked to another mounted file system, merely
* because it is more work to check for that case.
*/
if (found) {
if (OK != req_newdriver(ROOT_FS_E, makedev(maj, 0), label))
printf("VFSdev_up: error sending new driver label to %d\n",
ROOT_FS_E);
}
}
/*===========================================================================*
* cdev_up *
*===========================================================================*/
void cdev_up(int maj)
{
/* A new character device driver has been mapped in.
*/
int needs_reopen, fd_nr;
struct filp *rfilp;
struct fproc *rfp;
struct vnode *vp;
/* Look for processes that are suspended in an OPEN call. Set FP_SUSP_REOPEN
* to indicate that this process was suspended before the call to dev_up.
*/
for (rfp = &fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
if(rfp->fp_pid == PID_FREE) continue;
if(rfp->fp_blocked_on != FP_BLOCKED_ON_DOPEN) continue;
fd_nr = scratch(rfp).file.fd_nr;
printf("VFS: dev_up: found process in FP_BLOCKED_ON_DOPEN, fd %d\n",
fd_nr);
rfilp = rfp->fp_filp[fd_nr];
vp = rfilp->filp_vno;
if (!vp) panic("VFS: cdev_up: no vp");
if (!S_ISCHR(vp->v_mode)) continue;
if (major(vp->v_sdev) != maj) continue;
rfp->fp_flags |= FP_SUSP_REOPEN;
}
needs_reopen= FALSE;
for (rfilp = filp; rfilp < &filp[NR_FILPS]; rfilp++) {
if (rfilp->filp_count < 1 || !(vp = rfilp->filp_vno)) continue;
if (major(vp->v_sdev) != maj) continue;
if (!S_ISCHR(vp->v_mode)) continue;
rfilp->filp_state |= FS_NEEDS_REOPEN;
needs_reopen = TRUE;
}
if (needs_reopen)
restart_reopen(maj);
}
/*===========================================================================*
* open_reply *
*===========================================================================*/
void open_reply(void)
{
struct fproc *rfp;
struct worker_thread *wp;
endpoint_t proc_e;
int slot;
proc_e = job_m_in.REP_ENDPT;
if (isokendpt(proc_e, &slot) != OK) return;
rfp = &fproc[slot];
wp = worker_get(rfp->fp_wtid);
if (wp == NULL || wp->w_task != who_e) {
printf("VFS: no worker thread waiting for a reply from %d\n", who_e);
return;
}
*wp->w_drv_sendrec = job_m_in;
wp->w_drv_sendrec = NULL;
wp->w_task = NONE;
worker_signal(wp); /* Continue open */
}
/*===========================================================================*
* dev_reply *
*===========================================================================*/
void dev_reply(struct dmap *dp)
{
struct worker_thread *wp;
assert(dp != NULL);
assert(dp->dmap_servicing != NONE);
wp = worker_get(dp->dmap_servicing);
if (wp == NULL || wp->w_task != who_e) {
printf("VFS: no worker thread waiting for a reply from %d\n",
who_e);
return;
}
assert(wp->w_drv_sendrec != NULL);
*wp->w_drv_sendrec = m_in;
wp->w_drv_sendrec = NULL;
worker_signal(wp);
}
/*===========================================================================*
* restart_reopen *
*===========================================================================*/
static void restart_reopen(maj)
int maj;
{
int n, r, minor_dev, major_dev, fd_nr;
endpoint_t driver_e;
struct vnode *vp;
struct filp *rfilp;
struct fproc *rfp;
if (maj < 0 || maj >= NR_DEVICES) panic("VFS: out-of-bound major");
for (rfilp = filp; rfilp < &filp[NR_FILPS]; rfilp++) {
if (rfilp->filp_count < 1 || !(vp = rfilp->filp_vno)) continue;
if (!(rfilp->filp_state & FS_NEEDS_REOPEN)) continue;
if (!S_ISCHR(vp->v_mode)) continue;
major_dev = major(vp->v_sdev);
minor_dev = minor(vp->v_sdev);
if (major_dev != maj) continue;
if (rfilp->filp_flags & O_REOPEN) {
/* Try to reopen a file upon driver restart */
r = dev_reopen(vp->v_sdev, rfilp-filp,
vp->v_mode & (R_BIT|W_BIT));
if (r == OK)
return;
printf("VFS: file on dev %d/%d re-open failed: %d; "
"invalidated %d fd's.\n", major_dev, minor_dev, r, n);
}
/* File descriptor is to be closed when driver restarts. */
n = invalidate_filp(rfilp);
if (n != rfilp->filp_count) {
printf("VFS: warning: invalidate/count "
"discrepancy (%d, %d)\n", n, rfilp->filp_count);
}
rfilp->filp_count = 0;
/* We have to clean up this filp and vnode, but can't do that yet as
* it's locked by a worker thread. Start a new job to garbage collect
* invalidated filps associated with this device driver.
*/
sys_worker_start(do_filp_gc);
}
/* Nothing more to re-open. Restart suspended processes */
driver_e = dmap[maj].dmap_driver;
for (rfp = &fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
if(rfp->fp_pid == PID_FREE) continue;
if(rfp->fp_blocked_on == FP_BLOCKED_ON_OTHER &&
rfp->fp_task == driver_e && (rfp->fp_flags & FP_SUSP_REOPEN)) {
rfp->fp_flags &= ~FP_SUSP_REOPEN;
rfp->fp_blocked_on = FP_BLOCKED_ON_NONE;
reply(rfp->fp_endpoint, ERESTART);
}
}
/* Look for processes that are suspened in an OPEN call */
for (rfp = &fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
if (rfp->fp_pid == PID_FREE) continue;
if (rfp->fp_blocked_on == FP_BLOCKED_ON_DOPEN ||
!(rfp->fp_flags & FP_SUSP_REOPEN)) continue;
fd_nr = scratch(rfp).file.fd_nr;
printf("VFS: restart_reopen: process in FP_BLOCKED_ON_DOPEN fd=%d\n",
fd_nr);
rfilp = rfp->fp_filp[fd_nr];
if (!rfilp) {
/* Open failed, and automatic reopen was not requested */
rfp->fp_blocked_on = FP_BLOCKED_ON_NONE;
FD_CLR(fd_nr, &rfp->fp_filp_inuse);
reply(rfp->fp_endpoint, EIO);
continue;
}
vp = rfilp->filp_vno;
if (!vp) panic("VFS: restart_reopen: no vp");
if (!S_ISCHR(vp->v_mode)) continue;
if (major(vp->v_sdev) != maj) continue;
rfp->fp_blocked_on = FP_BLOCKED_ON_NONE;
reply(rfp->fp_endpoint, fd_nr);
}
}
/*===========================================================================*
* reopen_reply *
*===========================================================================*/
void reopen_reply()
{
endpoint_t driver_e;
int filp_no, status, maj;
struct filp *rfilp;
struct vnode *vp;
struct dmap *dp;
driver_e = job_m_in.m_source;
filp_no = job_m_in.REP_ENDPT;
status = job_m_in.REP_STATUS;
if (filp_no < 0 || filp_no >= NR_FILPS) {
printf("VFS: reopen_reply: bad filp number %d from driver %d\n",
filp_no, driver_e);
return;
}
rfilp = &filp[filp_no];
if (rfilp->filp_count < 1) {
printf("VFS: reopen_reply: filp number %d not inuse (from driver %d)\n",
filp_no, driver_e);
return;
}
vp = rfilp->filp_vno;
if (!vp) {
printf("VFS: reopen_reply: no vnode for filp number %d (from driver "
"%d)\n", filp_no, driver_e);
return;
}
if (!(rfilp->filp_state & FS_NEEDS_REOPEN)) {
printf("VFS: reopen_reply: bad state %d for filp number %d"
" (from driver %d)\n", rfilp->filp_state, filp_no, driver_e);
return;
}
if (!S_ISCHR(vp->v_mode)) {
printf("VFS: reopen_reply: bad mode 0%o for filp number %d"
" (from driver %d)\n", vp->v_mode, filp_no, driver_e);
return;
}
maj = major(vp->v_sdev);
dp = &dmap[maj];
if (dp->dmap_driver != driver_e) {
printf("VFS: reopen_reply: bad major %d for filp number %d "
"(from driver %d, current driver is %d)\n", maj, filp_no,
driver_e, dp->dmap_driver);
return;
}
if (status == OK) {
rfilp->filp_state &= ~FS_NEEDS_REOPEN;
} else {
printf("VFS: reopen_reply: should handle error status\n");
return;
}
restart_reopen(maj);
}
Reference in a new issue View git blame Copy permalink