minix/servers/vfs/filedes.c
Ben Gras cef94e096e vfs: make m_out non-global
m_out is shared between threads as the reply message, and it can happen
results get overwritten by another thread before the reply is sent. This
change

	. makes m_out local to the message handling function,
	  declared on the stack of the caller
	. forces callers of reply() to give it a message, or
	  declare the reply message has no significant fields except
	  for the return code by calling replycode()

Change-Id: Id06300083a63c72c00f34f86a5c7d96e4bbdf9f6
2013-04-12 23:40:38 +00:00

683 lines
19 KiB
C

/* This file contains the procedures that manipulate file descriptors.
*
* The entry points into this file are
* get_fd: look for free file descriptor and free filp slots
* get_filp: look up the filp entry for a given file descriptor
* find_filp: find a filp slot that points to a given vnode
* inval_filp: invalidate a filp and associated fd's, only let close()
* happen on it
* do_verify_fd: verify whether the given file descriptor is valid for
* the given endpoint.
* do_set_filp: marks a filp as in-flight.
* do_copy_filp: copies a filp to another endpoint.
* do_put_filp: marks a filp as not in-flight anymore.
* do_cancel_fd: cancel the transaction when something goes wrong for
* the receiver.
*/
#include <sys/select.h>
#include <minix/callnr.h>
#include <minix/u64.h>
#include <assert.h>
#include <sys/stat.h>
#include "fs.h"
#include "file.h"
#include "fproc.h"
#include "vnode.h"
static filp_id_t verify_fd(endpoint_t ep, int fd);
#if LOCK_DEBUG
/*===========================================================================*
* check_filp_locks *
*===========================================================================*/
void check_filp_locks_by_me(void)
{
/* Check whether this thread still has filp locks held */
struct filp *f;
int r;
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
r = mutex_trylock(&f->filp_lock);
if (r == -EDEADLK)
panic("Thread %d still holds filp lock on filp %p call_nr=%d\n",
mthread_self(), f, job_call_nr);
else if (r == 0) {
/* We just obtained the lock, release it */
mutex_unlock(&f->filp_lock);
}
}
}
#endif
/*===========================================================================*
* check_filp_locks *
*===========================================================================*/
void check_filp_locks(void)
{
struct filp *f;
int r, count = 0;
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
r = mutex_trylock(&f->filp_lock);
if (r == -EBUSY) {
/* Mutex is still locked */
count++;
} else if (r == 0) {
/* We just obtained a lock, don't want it */
mutex_unlock(&f->filp_lock);
} else
panic("filp_lock weird state");
}
if (count) panic("locked filps");
#if 0
else printf("check_filp_locks OK\n");
#endif
}
/*===========================================================================*
* do_filp_gc *
*===========================================================================*/
void *do_filp_gc(void *UNUSED(arg))
{
struct filp *f;
struct vnode *vp;
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
if (!(f->filp_state & FS_INVALIDATED)) continue;
if (f->filp_mode == FILP_CLOSED || f->filp_vno == NULL) {
/* File was already closed before gc could kick in */
assert(f->filp_count <= 0);
f->filp_state &= ~FS_INVALIDATED;
f->filp_count = 0;
continue;
}
assert(f->filp_vno != NULL);
vp = f->filp_vno;
/* Synchronize with worker thread that might hold a lock on the vp */
lock_vnode(vp, VNODE_OPCL);
unlock_vnode(vp);
/* If garbage collection was invoked due to a failed device open
* request, then common_open has already cleaned up and we have
* nothing to do.
*/
if (!(f->filp_state & FS_INVALIDATED)) {
continue;
}
/* If garbage collection was invoked due to a failed device close
* request, the close_filp has already cleaned up and we have nothing
* to do.
*/
if (f->filp_mode != FILP_CLOSED) {
assert(f->filp_count == 0);
f->filp_count = 1; /* So lock_filp and close_filp will do
* their job */
lock_filp(f, VNODE_READ);
close_filp(f);
}
f->filp_state &= ~FS_INVALIDATED;
}
thread_cleanup(NULL);
return(NULL);
}
/*===========================================================================*
* init_filps *
*===========================================================================*/
void init_filps(void)
{
/* Initialize filps */
struct filp *f;
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
if (mutex_init(&f->filp_lock, NULL) != 0)
panic("Failed to initialize filp mutex");
}
}
/*===========================================================================*
* get_fd *
*===========================================================================*/
int get_fd(int start, mode_t bits, int *k, struct filp **fpt)
{
/* Look for a free file descriptor and a free filp slot. Fill in the mode word
* in the latter, but don't claim either one yet, since the open() or creat()
* may yet fail.
*/
register struct filp *f;
register int i;
/* Search the fproc fp_filp table for a free file descriptor. */
for (i = start; i < OPEN_MAX; i++) {
if (fp->fp_filp[i] == NULL && !FD_ISSET(i, &fp->fp_filp_inuse)) {
/* A file descriptor has been located. */
*k = i;
break;
}
}
/* Check to see if a file descriptor has been found. */
if (i >= OPEN_MAX) return(EMFILE);
/* If we don't care about a filp, return now */
if (fpt == NULL) return(OK);
/* Now that a file descriptor has been found, look for a free filp slot. */
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
assert(f->filp_count >= 0);
if (f->filp_count == 0 && mutex_trylock(&f->filp_lock) == 0) {
f->filp_mode = bits;
f->filp_pos = cvu64(0);
f->filp_selectors = 0;
f->filp_select_ops = 0;
f->filp_pipe_select_ops = 0;
f->filp_flags = 0;
f->filp_state = FS_NORMAL;
f->filp_select_flags = 0;
f->filp_softlock = NULL;
*fpt = f;
return(OK);
}
}
/* If control passes here, the filp table must be full. Report that back. */
return(ENFILE);
}
/*===========================================================================*
* get_filp *
*===========================================================================*/
struct filp *get_filp(fild, locktype)
int fild; /* file descriptor */
tll_access_t locktype;
{
/* See if 'fild' refers to a valid file descr. If so, return its filp ptr. */
return get_filp2(fp, fild, locktype);
}
/*===========================================================================*
* get_filp2 *
*===========================================================================*/
struct filp *get_filp2(rfp, fild, locktype)
register struct fproc *rfp;
int fild; /* file descriptor */
tll_access_t locktype;
{
/* See if 'fild' refers to a valid file descr. If so, return its filp ptr. */
struct filp *filp;
filp = NULL;
if (fild < 0 || fild >= OPEN_MAX)
err_code = EBADF;
else if (rfp->fp_filp[fild] == NULL && FD_ISSET(fild, &rfp->fp_filp_inuse))
err_code = EIO; /* The filedes is not there, but is not closed either.
*/
else if ((filp = rfp->fp_filp[fild]) == NULL)
err_code = EBADF;
else
lock_filp(filp, locktype); /* All is fine */
return(filp); /* may also be NULL */
}
/*===========================================================================*
* find_filp *
*===========================================================================*/
struct filp *find_filp(struct vnode *vp, mode_t bits)
{
/* Find a filp slot that refers to the vnode 'vp' in a way as described
* by the mode bit 'bits'. Used for determining whether somebody is still
* interested in either end of a pipe. Also used when opening a FIFO to
* find partners to share a filp field with (to shared the file position).
* Like 'get_fd' it performs its job by linear search through the filp table.
*/
struct filp *f;
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
if (f->filp_count != 0 && f->filp_vno == vp && (f->filp_mode & bits)) {
return(f);
}
}
/* If control passes here, the filp wasn't there. Report that back. */
return(NULL);
}
/*===========================================================================*
* invalidate_filp *
*===========================================================================*/
int invalidate_filp(struct filp *rfilp)
{
/* Invalidate filp. fp_filp_inuse is not cleared, so filp can't be reused
until it is closed first. */
int f, fd, n = 0;
for (f = 0; f < NR_PROCS; f++) {
if (fproc[f].fp_pid == PID_FREE) continue;
for (fd = 0; fd < OPEN_MAX; fd++) {
if(fproc[f].fp_filp[fd] && fproc[f].fp_filp[fd] == rfilp) {
fproc[f].fp_filp[fd] = NULL;
n++;
}
}
}
rfilp->filp_state |= FS_INVALIDATED;
return(n); /* Report back how often this filp has been invalidated. */
}
/*===========================================================================*
* invalidate_filp_by_char_major *
*===========================================================================*/
void invalidate_filp_by_char_major(int major)
{
struct filp *f;
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
if (f->filp_count != 0 && f->filp_vno != NULL) {
if (major(f->filp_vno->v_sdev) == major &&
S_ISCHR(f->filp_vno->v_mode)) {
(void) invalidate_filp(f);
}
}
}
}
/*===========================================================================*
* invalidate_filp_by_endpt *
*===========================================================================*/
void invalidate_filp_by_endpt(endpoint_t proc_e)
{
struct filp *f;
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
if (f->filp_count != 0 && f->filp_vno != NULL) {
if (f->filp_vno->v_fs_e == proc_e)
(void) invalidate_filp(f);
}
}
}
/*===========================================================================*
* lock_filp *
*===========================================================================*/
void lock_filp(filp, locktype)
struct filp *filp;
tll_access_t locktype;
{
struct fproc *org_fp;
struct worker_thread *org_self;
struct vnode *vp;
assert(filp->filp_count > 0);
vp = filp->filp_vno;
assert(vp != NULL);
/* Lock vnode only if we haven't already locked it. If already locked by us,
* we're allowed to have one additional 'soft' lock. */
if (tll_locked_by_me(&vp->v_lock)) {
assert(filp->filp_softlock == NULL);
filp->filp_softlock = fp;
} else {
/* We have to make an exception for vnodes belonging to pipes. Even
* read(2) operations on pipes change the vnode and therefore require
* exclusive access.
*/
if (S_ISFIFO(vp->v_mode) && locktype == VNODE_READ)
locktype = VNODE_WRITE;
lock_vnode(vp, locktype);
}
assert(vp->v_ref_count > 0); /* vnode still in use? */
assert(filp->filp_vno == vp); /* vnode still what we think it is? */
/* First try to get filp lock right off the bat */
if (mutex_trylock(&filp->filp_lock) != 0) {
/* Already in use, let's wait for our turn */
org_fp = fp;
org_self = self;
if (mutex_lock(&filp->filp_lock) != 0)
panic("unable to obtain lock on filp");
fp = org_fp;
self = org_self;
}
}
/*===========================================================================*
* unlock_filp *
*===========================================================================*/
void unlock_filp(filp)
struct filp *filp;
{
/* If this filp holds a soft lock on the vnode, we must be the owner */
if (filp->filp_softlock != NULL)
assert(filp->filp_softlock == fp);
if (filp->filp_count > 0 || filp->filp_state & FS_INVALIDATED) {
/* Only unlock vnode if filp is still in use */
/* and if we don't hold a soft lock */
if (filp->filp_softlock == NULL) {
assert(tll_islocked(&(filp->filp_vno->v_lock)));
unlock_vnode(filp->filp_vno);
}
}
filp->filp_softlock = NULL;
if (mutex_unlock(&filp->filp_lock) != 0)
panic("unable to release lock on filp");
}
/*===========================================================================*
* unlock_filps *
*===========================================================================*/
void unlock_filps(filp1, filp2)
struct filp *filp1;
struct filp *filp2;
{
/* Unlock two filps that are tied to the same vnode. As a thread can lock a
* vnode only once, unlocking the vnode twice would result in an error. */
/* No NULL pointers and not equal */
assert(filp1);
assert(filp2);
assert(filp1 != filp2);
/* Must be tied to the same vnode and not NULL */
assert(filp1->filp_vno == filp2->filp_vno);
assert(filp1->filp_vno != NULL);
if (filp1->filp_count > 0 && filp2->filp_count > 0) {
/* Only unlock vnode if filps are still in use */
unlock_vnode(filp1->filp_vno);
}
filp1->filp_softlock = NULL;
filp2->filp_softlock = NULL;
if (mutex_unlock(&filp2->filp_lock) != 0)
panic("unable to release filp lock on filp2");
if (mutex_unlock(&filp1->filp_lock) != 0)
panic("unable to release filp lock on filp1");
}
/*===========================================================================*
* verify_fd *
*===========================================================================*/
static filp_id_t verify_fd(ep, fd)
endpoint_t ep;
int fd;
{
/* Verify whether the file descriptor 'fd' is valid for the endpoint 'ep'. When
* the file descriptor is valid, verify_fd returns a pointer to that filp, else
* it returns NULL.
*/
int slot;
struct filp *rfilp;
if (isokendpt(ep, &slot) != OK)
return(NULL);
rfilp = get_filp2(&fproc[slot], fd, VNODE_READ);
return(rfilp);
}
/*===========================================================================*
* do_verify_fd *
*===========================================================================*/
int do_verify_fd(message *m_out)
{
struct filp *rfilp;
endpoint_t proc_e;
int fd;
proc_e = job_m_in.USER_ENDPT;
fd = job_m_in.COUNT;
rfilp = (struct filp *) verify_fd(proc_e, fd);
m_out->ADDRESS = (void *) rfilp;
if (rfilp != NULL) unlock_filp(rfilp);
return (rfilp != NULL) ? OK : EINVAL;
}
/*===========================================================================*
* set_filp *
*===========================================================================*/
int set_filp(sfilp)
filp_id_t sfilp;
{
if (sfilp == NULL) return(EINVAL);
lock_filp(sfilp, VNODE_READ);
sfilp->filp_count++;
unlock_filp(sfilp);
return(OK);
}
/*===========================================================================*
* do_set_filp *
*===========================================================================*/
int do_set_filp(message *UNUSED(m_out))
{
filp_id_t f;
f = (filp_id_t) job_m_in.ADDRESS;
return set_filp(f);
}
/*===========================================================================*
* copy_filp *
*===========================================================================*/
int copy_filp(to_ep, cfilp)
endpoint_t to_ep;
filp_id_t cfilp;
{
int fd;
int slot;
struct fproc *rfp;
if (isokendpt(to_ep, &slot) != OK) return(EINVAL);
rfp = &fproc[slot];
/* Find an open slot in fp_filp */
for (fd = 0; fd < OPEN_MAX; fd++) {
if (rfp->fp_filp[fd] == NULL &&
!FD_ISSET(fd, &rfp->fp_filp_inuse)) {
/* Found a free slot, add descriptor */
FD_SET(fd, &rfp->fp_filp_inuse);
rfp->fp_filp[fd] = cfilp;
rfp->fp_filp[fd]->filp_count++;
return(fd);
}
}
/* File descriptor table is full */
return(EMFILE);
}
/*===========================================================================*
* do_copy_filp *
*===========================================================================*/
int do_copy_filp(message *UNUSED(m_out))
{
endpoint_t proc_e;
filp_id_t f;
proc_e = job_m_in.USER_ENDPT;
f = (filp_id_t) job_m_in.ADDRESS;
return copy_filp(proc_e, f);
}
/*===========================================================================*
* put_filp *
*===========================================================================*/
int put_filp(pfilp)
filp_id_t pfilp;
{
if (pfilp == NULL) {
return EINVAL;
} else {
lock_filp(pfilp, VNODE_OPCL);
close_filp(pfilp);
return(OK);
}
}
/*===========================================================================*
* do_put_filp *
*===========================================================================*/
int do_put_filp(message *UNUSED(m_out))
{
filp_id_t f;
f = (filp_id_t) job_m_in.ADDRESS;
return put_filp(f);
}
/*===========================================================================*
* cancel_fd *
*===========================================================================*/
int cancel_fd(ep, fd)
endpoint_t ep;
int fd;
{
int slot;
struct fproc *rfp;
struct filp *rfilp;
if (isokendpt(ep, &slot) != OK) return(EINVAL);
rfp = &fproc[slot];
/* Check that the input 'fd' is valid */
rfilp = (struct filp *) verify_fd(ep, fd);
if (rfilp != NULL) {
/* Found a valid descriptor, remove it */
FD_CLR(fd, &rfp->fp_filp_inuse);
if (rfp->fp_filp[fd]->filp_count == 0) {
unlock_filp(rfilp);
printf("VFS: filp_count for slot %d fd %d already zero", slot,
fd);
return(EINVAL);
}
rfp->fp_filp[fd]->filp_count--;
rfp->fp_filp[fd] = NULL;
unlock_filp(rfilp);
return(fd);
}
/* File descriptor is not valid for the endpoint. */
return(EINVAL);
}
/*===========================================================================*
* do_cancel_fd *
*===========================================================================*/
int do_cancel_fd(message *UNUSED(m_out))
{
endpoint_t proc_e;
int fd;
proc_e = job_m_in.USER_ENDPT;
fd = job_m_in.COUNT;
return cancel_fd(proc_e, fd);
}
/*===========================================================================*
* close_filp *
*===========================================================================*/
void close_filp(f)
struct filp *f;
{
/* Close a file. Will also unlock filp when done */
int rw;
dev_t dev;
struct vnode *vp;
/* Must be locked */
assert(mutex_trylock(&f->filp_lock) == -EDEADLK);
assert(tll_islocked(&f->filp_vno->v_lock));
vp = f->filp_vno;
if (f->filp_count - 1 == 0 && f->filp_mode != FILP_CLOSED) {
/* Check to see if the file is special. */
if (S_ISCHR(vp->v_mode) || S_ISBLK(vp->v_mode)) {
dev = (dev_t) vp->v_sdev;
if (S_ISBLK(vp->v_mode)) {
lock_bsf();
if (vp->v_bfs_e == ROOT_FS_E) {
/* Invalidate the cache unless the special is
* mounted. Assume that the root filesystem's
* is open only for fsck.
*/
req_flush(vp->v_bfs_e, dev);
}
unlock_bsf();
/* Attempt to close only when feasible */
if (!(f->filp_state & FS_INVALIDATED)) {
(void) bdev_close(dev); /* Ignore errors */
}
} else {
/* Attempt to close only when feasible */
if (!(f->filp_state & FS_INVALIDATED)) {
(void) dev_close(dev, f-filp);/*Ignore errors*/
}
}
f->filp_mode = FILP_CLOSED;
}
}
/* If the inode being closed is a pipe, release everyone hanging on it. */
if (S_ISFIFO(vp->v_mode)) {
rw = (f->filp_mode & R_BIT ? WRITE : READ);
release(vp, rw, susp_count);
}
f->filp_count--; /* If filp got invalidated at device closure, the
* count might've become negative now */
if (f->filp_count == 0 ||
(f->filp_count < 0 && f->filp_state & FS_INVALIDATED)) {
if (S_ISFIFO(vp->v_mode)) {
/* Last reader or writer is going. Tell PFS about latest
* pipe size.
*/
truncate_vnode(vp, vp->v_size);
}
unlock_vnode(f->filp_vno);
put_vnode(f->filp_vno);
f->filp_vno = NULL;
f->filp_mode = FILP_CLOSED;
f->filp_count = 0;
} else if (f->filp_count < 0) {
panic("VFS: invalid filp count: %d ino %d/%d", f->filp_count,
vp->v_dev, vp->v_inode_nr);
} else {
unlock_vnode(f->filp_vno);
}
mutex_unlock(&f->filp_lock);
}