/*===========================================================================*
* put_vnode *
*===========================================================================*/
PUBLIC void put_vnode(struct vnode *vp)
{
/* Decrease vnode's usage counter and decrease inode's usage counter in the
* corresponding FS process. Decreasing the fs_count each time we decrease the
* ref count would lead to poor performance. Instead, only decrease fs_count
* when the ref count hits zero. However, this could lead to fs_count to wrap.
* To prevent this, we drop the counter to 1 when the counter hits 256.
* We maintain fs_count as a sanity check to make sure VFS and the FS are in
* sync.
*/
int r, lock_vp;
ASSERTVP(vp);
/* Lock vnode. It's quite possible this thread already has a lock on this
* vnode. That's no problem, because the reference counter will not decrease
* to zero in that case. However, if the counter does decrease to zero *and*
* is already locked, we have a consistency problem somewhere. */
lock_vp = lock_vnode(vp, VNODE_OPCL);
if (vp->v_ref_count > 1) {
/* Decrease counter */
vp->v_ref_count--;
if (vp->v_fs_count > 256)
vnode_clean_refs(vp);
if (lock_vp != EBUSY) unlock_vnode(vp);
return;
}
/* If we already had a lock, there is a consistency problem */
assert(lock_vp != EBUSY);
tll_upgrade(&vp->v_lock); /* Make sure nobody else accesses this vnode */
/* A vnode that's not in use can't be put back. */
if (vp->v_ref_count <= 0)
panic("put_vnode failed: bad v_ref_count %d\n", vp->v_ref_count);
/* fs_count should indicate that the file is in use. */
if (vp->v_fs_count <= 0)
panic("put_vnode failed: bad v_fs_count %d\n", vp->v_fs_count);
/* Tell FS we don't need this inode to be open anymore. */
r = req_putnode(vp->v_fs_e, vp->v_inode_nr, vp->v_fs_count);
if (r != OK) {
printf("VFS: putnode failed: %d\n", r);
util_stacktrace();
}
/* This inode could've been mapped. If so, tell mapped FS to close it as
* well. If mapped onto same FS, this putnode is not needed. */
if (vp->v_mapfs_e != NONE && vp->v_mapfs_e != vp->v_fs_e)
req_putnode(vp->v_mapfs_e, vp->v_mapinode_nr, vp->v_mapfs_count);
vp->v_fs_count = 0;
vp->v_ref_count = 0;
vp->v_mapfs_count = 0;
unlock_vnode(vp);
}
/*===========================================================================*
* lock_vmnt *
*===========================================================================*/
PUBLIC int lock_vmnt(struct vmnt *vmp, tll_access_t locktype)
{
int r;
tll_access_t initial_locktype;
ASSERTVMP(vmp);
initial_locktype = (locktype == VMNT_EXCL) ? VMNT_WRITE : locktype;
if (vmp->m_fs_e == who_e) return(EDEADLK);
r = tll_lock(&vmp->m_lock, initial_locktype);
if (r == EBUSY) return(r);
if (initial_locktype != locktype) {
tll_upgrade(&vmp->m_lock);
}
#if LOCK_DEBUG
if (locktype == VMNT_READ)
fp->fp_vmnt_rdlocks++;
#endif
return(OK);
}
/*===========================================================================*
* common_open *
*===========================================================================*/
int common_open(char path[PATH_MAX], int oflags, mode_t omode)
{
/* Common code from do_creat and do_open. */
int b, r, exist = TRUE, major_dev;
dev_t dev;
mode_t bits;
struct filp *filp, *filp2;
struct vnode *vp;
struct vmnt *vmp;
struct dmap *dp;
struct lookup resolve;
/* Remap the bottom two bits of oflags. */
bits = (mode_t) mode_map[oflags & O_ACCMODE];
if (!bits) return(EINVAL);
/* See if file descriptor and filp slots are available. */
if ((r = get_fd(0, bits, &(scratch(fp).file.fd_nr), &filp)) != OK) return(r);
lookup_init(&resolve, path, PATH_NOFLAGS, &vmp, &vp);
/* If O_CREATE is set, try to make the file. */
if (oflags & O_CREAT) {
omode = I_REGULAR | (omode & ALLPERMS & fp->fp_umask);
vp = new_node(&resolve, oflags, omode);
r = err_code;
if (r == OK) exist = FALSE; /* We just created the file */
else if (r != EEXIST) { /* other error */
if (vp) unlock_vnode(vp);
unlock_filp(filp);
return(r);
}
else exist = !(oflags & O_EXCL);/* file exists, if the O_EXCL
flag is set this is an error */
} else {
/* Scan path name */
resolve.l_vmnt_lock = VMNT_READ;
resolve.l_vnode_lock = VNODE_OPCL;
if ((vp = eat_path(&resolve, fp)) == NULL) {
unlock_filp(filp);
return(err_code);
}
if (vmp != NULL) unlock_vmnt(vmp);
}
/* Claim the file descriptor and filp slot and fill them in. */
fp->fp_filp[scratch(fp).file.fd_nr] = filp;
FD_SET(scratch(fp).file.fd_nr, &fp->fp_filp_inuse);
filp->filp_count = 1;
filp->filp_vno = vp;
filp->filp_flags = oflags;
/* Only do the normal open code if we didn't just create the file. */
if (exist) {
/* Check protections. */
if ((r = forbidden(fp, vp, bits)) == OK) {
/* Opening reg. files, directories, and special files differ */
switch (vp->v_mode & S_IFMT) {
case S_IFREG:
/* Truncate regular file if O_TRUNC. */
if (oflags & O_TRUNC) {
if ((r = forbidden(fp, vp, W_BIT)) != OK)
break;
truncate_vnode(vp, 0);
}
break;
case S_IFDIR:
/* Directories may be read but not written. */
r = (bits & W_BIT ? EISDIR : OK);
break;
case S_IFCHR:
/* Invoke the driver for special processing. */
dev = (dev_t) vp->v_sdev;
/* TTY needs to know about the O_NOCTTY flag. */
r = dev_open(dev, who_e, bits | (oflags & O_NOCTTY));
if (r == SUSPEND) suspend(FP_BLOCKED_ON_DOPEN);
else vp = filp->filp_vno; /* Might be updated by
* dev_open/clone_opcl */
break;
case S_IFBLK:
lock_bsf();
/* Invoke the driver for special processing. */
dev = (dev_t) vp->v_sdev;
r = bdev_open(dev, bits);
if (r != OK) {
unlock_bsf();
break;
}
major_dev = major(vp->v_sdev);
dp = &dmap[major_dev];
if (dp->dmap_driver == NONE) {
printf("VFS: block driver disappeared!\n");
unlock_bsf();
r = ENXIO;
break;
}
/* Check whether the device is mounted or not. If so,
* then that FS is responsible for this device.
* Otherwise we default to ROOT_FS.
*/
vp->v_bfs_e = ROOT_FS_E; /* By default */
for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; ++vmp)
if (vmp->m_dev == vp->v_sdev &&
!(vmp->m_flags & VMNT_FORCEROOTBSF)) {
vp->v_bfs_e = vmp->m_fs_e;
}
/* Send the driver label to the file system that will
* handle the block I/O requests (even when its label
* and endpoint are known already), but only when it is
* the root file system. Other file systems will
* already have it anyway.
*/
if (vp->v_bfs_e != ROOT_FS_E) {
unlock_bsf();
break;
}
if (req_newdriver(vp->v_bfs_e, vp->v_sdev,
dp->dmap_label) != OK) {
printf("VFS: error sending driver label\n");
bdev_close(dev);
r = ENXIO;
}
unlock_bsf();
break;
case S_IFIFO:
/* Create a mapped inode on PFS which handles reads
and writes to this named pipe. */
tll_upgrade(&vp->v_lock);
r = map_vnode(vp, PFS_PROC_NR);
if (r == OK) {
if (vp->v_ref_count == 1) {
vp->v_pipe_rd_pos = 0;
vp->v_pipe_wr_pos = 0;
if (vp->v_size != 0)
r = truncate_vnode(vp, 0);
}
oflags |= O_APPEND; /* force append mode */
filp->filp_flags = oflags;
}
if (r == OK) {
r = pipe_open(vp, bits, oflags);
}
if (r != ENXIO) {
/* See if someone else is doing a rd or wt on
* the FIFO. If so, use its filp entry so the
* file position will be automatically shared.
*/
b = (bits & R_BIT ? R_BIT : W_BIT);
filp->filp_count = 0; /* don't find self */
if ((filp2 = find_filp(vp, b)) != NULL) {
/* Co-reader or writer found. Use it.*/
fp->fp_filp[scratch(fp).file.fd_nr] = filp2;
filp2->filp_count++;
filp2->filp_vno = vp;
filp2->filp_flags = oflags;
/* v_count was incremented after the vnode
* has been found. i_count was incremented
* incorrectly in FS, not knowing that we
* were going to use an existing filp
* entry. Correct this error.
*/
unlock_vnode(vp);
put_vnode(vp);
} else {
/* Nobody else found. Restore filp. */
filp->filp_count = 1;
}
}
break;
}
}
}
unlock_filp(filp);
/* If error, release inode. */
if (r != OK) {
if (r != SUSPEND) {
fp->fp_filp[scratch(fp).file.fd_nr] = NULL;
FD_CLR(scratch(fp).file.fd_nr, &fp->fp_filp_inuse);
filp->filp_count = 0;
filp->filp_vno = NULL;
put_vnode(vp);
}
} else {
r = scratch(fp).file.fd_nr;
}
return(r);
}
/*===========================================================================*
* vnode *
*===========================================================================*/
void upgrade_vnode_lock(struct vnode *vp)
{
ASSERTVP(vp);
tll_upgrade(&vp->v_lock);
}
