minix/servers/avfs/filedes.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

562 lines
16 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 "fs.h"
#include "file.h"
#include "fproc.h"
#include "vnode.h"
FORWARD _PROTOTYPE( filp_id_t verify_fd, (endpoint_t ep, int fd) );
#if LOCK_DEBUG
/*===========================================================================*
* check_filp_locks *
*===========================================================================*/
PUBLIC 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, call_nr);
else if (r == 0) {
/* We just obtained the lock, release it */
mutex_unlock(&f->filp_lock);
}
}
}
#endif
/*===========================================================================*
* check_filp_locks *
*===========================================================================*/
PUBLIC 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
}
/*===========================================================================*
* init_filps *
*===========================================================================*/
PUBLIC void init_filps(void)
{
/* Initialize filps */
struct filp *f;
for (f = &filp[0]; f < &filp[NR_FILPS]; f++) {
mutex_init(&f->filp_lock, NULL);
}
}
/*===========================================================================*
* get_fd *
*===========================================================================*/
PUBLIC 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) {
if (verbose) printf("get_fd: locking filp=%p\n", f);
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 *
*===========================================================================*/
PUBLIC 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 *
*===========================================================================*/
PUBLIC 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;
err_code = EBADF;
if (fild < 0 || fild >= OPEN_MAX ) return(NULL);
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.
*/
if ((filp = rfp->fp_filp[fild]) != NULL) lock_filp(filp, locktype);
return(filp); /* may also be NULL */
}
/*===========================================================================*
* find_filp *
*===========================================================================*/
PUBLIC 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 *
*===========================================================================*/
PUBLIC int invalidate(struct filp *fp)
{
/* 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] == fp) {
fproc[f].fp_filp[fd] = NULL;
n++;
}
}
}
return(n); /* Report back how often this filp has been invalidated. */
}
/*===========================================================================*
* lock_filp *
*===========================================================================*/
PUBLIC void lock_filp(filp, locktype)
struct filp *filp;
tll_access_t locktype;
{
message org_m_in;
struct fproc *org_fp;
struct worker_thread *org_self;
struct vnode *vp;
assert(filp->filp_count > 0);
vp = filp->filp_vno;
assert(vp != NULL);
if (verbose)
printf("lock_filp: filp=%p locking vnode %p with locktype %d\n", filp,
vp, locktype);
/* 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 {
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? */
assert(filp->filp_count > 0); /* filp still in use? */
/* 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_m_in = m_in;
org_fp = fp;
org_self = self;
assert(mutex_lock(&filp->filp_lock) == 0);
m_in = org_m_in;
fp = org_fp;
self = org_self;
}
assert(filp->filp_count > 0); /* Yet again; filp still in use? */
}
/*===========================================================================*
* unlock_filp *
*===========================================================================*/
PUBLIC 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) {
/* 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;
assert(mutex_unlock(&filp->filp_lock) == 0);
}
/*===========================================================================*
* unlock_filps *
*===========================================================================*/
PUBLIC 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;
assert(mutex_unlock(&filp2->filp_lock) == 0);
assert(mutex_unlock(&filp1->filp_lock) == 0);
}
/*===========================================================================*
* verify_fd *
*===========================================================================*/
PRIVATE 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 *
*===========================================================================*/
PUBLIC int do_verify_fd(void)
{
struct filp *rfilp;
rfilp = (struct filp *) verify_fd(m_in.USER_ENDPT, m_in.COUNT);
m_out.ADDRESS = (void *) rfilp;
if (rfilp != NULL) unlock_filp(rfilp);
return (rfilp != NULL) ? OK : EINVAL;
}
/*===========================================================================*
* set_filp *
*===========================================================================*/
PUBLIC 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 *
*===========================================================================*/
PUBLIC int do_set_filp(void)
{
return set_filp((filp_id_t) m_in.ADDRESS);
}
/*===========================================================================*
* copy_filp *
*===========================================================================*/
PUBLIC 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 *
*===========================================================================*/
PUBLIC int do_copy_filp(void)
{
return copy_filp(m_in.USER_ENDPT, (filp_id_t) m_in.ADDRESS);
}
/*===========================================================================*
* put_filp *
*===========================================================================*/
PUBLIC 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 *
*===========================================================================*/
PUBLIC int do_put_filp(void)
{
return put_filp((filp_id_t) m_in.ADDRESS);
}
/*===========================================================================*
* cancel_fd *
*===========================================================================*/
PUBLIC 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 *
*===========================================================================*/
PUBLIC int do_cancel_fd(void)
{
return cancel_fd(m_in.USER_ENDPT, m_in.COUNT);
}
/*===========================================================================*
* close_filp *
*===========================================================================*/
PUBLIC void close_filp(f)
struct filp *f;
{
/* Close a file. Will also unlock filp when done */
int mode_word, 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. */
mode_word = vp->v_mode & I_TYPE;
if (mode_word == I_CHAR_SPECIAL || mode_word == I_BLOCK_SPECIAL) {
dev = (dev_t) vp->v_sdev;
if (mode_word == I_BLOCK_SPECIAL) {
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();
}
/* Do any special processing on device close.
* Ignore any errors, even SUSPEND.
*/
if (mode_word == I_BLOCK_SPECIAL)
(void) bdev_close(dev);
else
(void) dev_close(dev, f-filp);
f->filp_mode = FILP_CLOSED;
}
}
/* If the inode being closed is a pipe, release everyone hanging on it. */
if (vp->v_pipe == I_PIPE) {
rw = (f->filp_mode & R_BIT ? WRITE : READ);
release(vp, rw, NR_PROCS);
}
/* If a write has been done, the inode is already marked as DIRTY. */
if (--f->filp_count == 0) {
if (vp->v_pipe == I_PIPE) {
/* 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);
} 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);
}