minix/servers/fs/misc.c
Ben Gras 2384a85296 FS support for grant-based i/o.
For character device i/o, FS does a so-called 'magic' grant to let the
driver copy from or to user space. As this is done in FS address space,
the driver is told to do this in FS address space. The redirection to
the right user process then happens at copy-time in the kernel, using the
FS grant table. This also happens for DEV_READ and DEV_WRITE on block
devices.

For other block device i/o, which happens from/to FS buffers, FS does
a 'direct' grant to its own address space for the driver.

After the i/o returns, this access has to be K-I-L-L-E-D, revoked.
Sometimes this is after a SUSPEND and DEV_REVIVE, in which case the
revoking happens in pipe.c.

This conversion happens in safe_io_conversion() in device.c, called
by dev_io and dev_bio.

FS has to pre-allocate its own space for these grant tables. This happens
in main.c.
2006-06-20 10:12:09 +00:00

828 lines
22 KiB
C

/* This file contains a collection of miscellaneous procedures. Some of them
* perform simple system calls. Some others do a little part of system calls
* that are mostly performed by the Memory Manager.
*
* The entry points into this file are
* do_dup: perform the DUP system call
* do_fcntl: perform the FCNTL system call
* do_sync: perform the SYNC system call
* do_fsync: perform the FSYNC system call
* pm_reboot: sync disks and prepare for shutdown
* pm_fork: adjust the tables after MM has performed a FORK system call
* do_exec: handle files with FD_CLOEXEC on after MM has done an EXEC
* do_exit: a process has exited; note that in the tables
* pm_setgid: set group ids for some process
* pm_setuid: set user ids for some process
* do_svrctl: file system control
* do_getsysinfo: request copy of FS data structure
* pm_dumpcore: create a core dump
*/
#include "fs.h"
#include <fcntl.h>
#include <assert.h>
#include <unistd.h> /* cc runs out of memory with unistd.h :-( */
#include <minix/callnr.h>
#include <minix/safecopies.h>
#include <minix/endpoint.h>
#include <minix/com.h>
#include <sys/ptrace.h>
#include <sys/svrctl.h>
#include "buf.h"
#include "file.h"
#include "fproc.h"
#include "inode.h"
#include "param.h"
#include "super.h"
#define CORE_NAME "core"
#define CORE_MODE 0777 /* mode to use on core image files */
FORWARD _PROTOTYPE( void free_proc, (struct fproc *freed, int flags));
FORWARD _PROTOTYPE( int dumpcore, (int proc_e, struct mem_map *seg_ptr));
FORWARD _PROTOTYPE( int write_bytes, (struct inode *rip, off_t off,
char *buf, size_t bytes));
FORWARD _PROTOTYPE( int write_seg, (struct inode *rip, off_t off, int proc_e,
int seg, off_t seg_off, phys_bytes seg_bytes));
#define FP_EXITING 1
/*===========================================================================*
* do_getsysinfo *
*===========================================================================*/
PUBLIC int do_getsysinfo()
{
struct fproc *proc_addr;
vir_bytes src_addr, dst_addr;
size_t len;
int s;
if (!super_user)
{
printf("FS: unauthorized call of do_getsysinfo by proc %d\n", who_e);
return(EPERM); /* only su may call do_getsysinfo. This call may leak
* information (and is not stable enough to be part
* of the API/ABI).
*/
}
switch(m_in.info_what) {
case SI_PROC_ADDR:
proc_addr = &fproc[0];
src_addr = (vir_bytes) &proc_addr;
len = sizeof(struct fproc *);
break;
case SI_PROC_TAB:
src_addr = (vir_bytes) fproc;
len = sizeof(struct fproc) * NR_PROCS;
break;
case SI_DMAP_TAB:
src_addr = (vir_bytes) dmap;
len = sizeof(struct dmap) * NR_DEVICES;
break;
default:
return(EINVAL);
}
dst_addr = (vir_bytes) m_in.info_where;
if (OK != (s=sys_datacopy(SELF, src_addr, who_e, dst_addr, len)))
return(s);
return(OK);
}
/*===========================================================================*
* do_dup *
*===========================================================================*/
PUBLIC int do_dup()
{
/* Perform the dup(fd) or dup2(fd,fd2) system call. These system calls are
* obsolete. In fact, it is not even possible to invoke them using the
* current library because the library routines call fcntl(). They are
* provided to permit old binary programs to continue to run.
*/
register int rfd;
register struct filp *f;
struct filp *dummy;
int r;
/* Is the file descriptor valid? */
rfd = m_in.fd & ~DUP_MASK; /* kill off dup2 bit, if on */
if ((f = get_filp(rfd)) == NIL_FILP) return(err_code);
/* Distinguish between dup and dup2. */
if (m_in.fd == rfd) { /* bit not on */
/* dup(fd) */
if ( (r = get_fd(0, 0, &m_in.fd2, &dummy)) != OK) return(r);
} else {
/* dup2(fd, fd2) */
if (m_in.fd2 < 0 || m_in.fd2 >= OPEN_MAX) return(EBADF);
if (rfd == m_in.fd2) return(m_in.fd2); /* ignore the call: dup2(x, x) */
m_in.fd = m_in.fd2; /* prepare to close fd2 */
(void) do_close(); /* cannot fail */
}
/* Success. Set up new file descriptors. */
f->filp_count++;
fp->fp_filp[m_in.fd2] = f;
FD_SET(m_in.fd2, &fp->fp_filp_inuse);
return(m_in.fd2);
}
/*===========================================================================*
* do_fcntl *
*===========================================================================*/
PUBLIC int do_fcntl()
{
/* Perform the fcntl(fd, request, ...) system call. */
register struct filp *f;
int new_fd, r, fl;
long cloexec_mask; /* bit map for the FD_CLOEXEC flag */
long clo_value; /* FD_CLOEXEC flag in proper position */
struct filp *dummy;
/* Is the file descriptor valid? */
if ((f = get_filp(m_in.fd)) == NIL_FILP) return(err_code);
switch (m_in.request) {
case F_DUPFD:
/* This replaces the old dup() system call. */
if (m_in.addr < 0 || m_in.addr >= OPEN_MAX) return(EINVAL);
if ((r = get_fd(m_in.addr, 0, &new_fd, &dummy)) != OK) return(r);
f->filp_count++;
fp->fp_filp[new_fd] = f;
return(new_fd);
case F_GETFD:
/* Get close-on-exec flag (FD_CLOEXEC in POSIX Table 6-2). */
return( ((fp->fp_cloexec >> m_in.fd) & 01) ? FD_CLOEXEC : 0);
case F_SETFD:
/* Set close-on-exec flag (FD_CLOEXEC in POSIX Table 6-2). */
cloexec_mask = 1L << m_in.fd; /* singleton set position ok */
clo_value = (m_in.addr & FD_CLOEXEC ? cloexec_mask : 0L);
fp->fp_cloexec = (fp->fp_cloexec & ~cloexec_mask) | clo_value;
return(OK);
case F_GETFL:
/* Get file status flags (O_NONBLOCK and O_APPEND). */
fl = f->filp_flags & (O_NONBLOCK | O_APPEND | O_ACCMODE);
return(fl);
case F_SETFL:
/* Set file status flags (O_NONBLOCK and O_APPEND). */
fl = O_NONBLOCK | O_APPEND;
f->filp_flags = (f->filp_flags & ~fl) | (m_in.addr & fl);
return(OK);
case F_GETLK:
case F_SETLK:
case F_SETLKW:
/* Set or clear a file lock. */
r = lock_op(f, m_in.request);
return(r);
case F_FREESP:
{
/* Free a section of a file. Preparation is done here,
* actual freeing in freesp_inode().
*/
off_t start, end;
struct flock flock_arg;
signed long offset;
/* Check if it's a regular file. */
if((f->filp_ino->i_mode & I_TYPE) != I_REGULAR) {
return EINVAL;
}
/* Copy flock data from userspace. */
if((r = sys_datacopy(who_e, (vir_bytes) m_in.name1,
SELF, (vir_bytes) &flock_arg,
(phys_bytes) sizeof(flock_arg))) != OK)
return r;
/* Convert starting offset to signed. */
offset = (signed long) flock_arg.l_start;
/* Figure out starting position base. */
switch(flock_arg.l_whence) {
case SEEK_SET: start = 0; if(offset < 0) return EINVAL; break;
case SEEK_CUR: start = f->filp_pos; break;
case SEEK_END: start = f->filp_ino->i_size; break;
default: return EINVAL;
}
/* Check for overflow or underflow. */
if(offset > 0 && start + offset < start) { return EINVAL; }
if(offset < 0 && start + offset > start) { return EINVAL; }
start += offset;
if(flock_arg.l_len > 0) {
end = start + flock_arg.l_len;
if(end <= start) {
return EINVAL;
}
r = freesp_inode(f->filp_ino, start, end);
} else {
r = truncate_inode(f->filp_ino, start);
}
return r;
}
default:
return(EINVAL);
}
}
/*===========================================================================*
* do_sync *
*===========================================================================*/
PUBLIC int do_sync()
{
/* Perform the sync() system call. Flush all the tables.
* The order in which the various tables are flushed is critical. The
* blocks must be flushed last, since rw_inode() leaves its results in
* the block cache.
*/
register struct inode *rip;
register struct buf *bp;
/* Write all the dirty inodes to the disk. */
for (rip = &inode[0]; rip < &inode[NR_INODES]; rip++)
if (rip->i_count > 0 && rip->i_dirt == DIRTY) rw_inode(rip, WRITING);
/* Write all the dirty blocks to the disk, one drive at a time. */
for (bp = &buf[0]; bp < &buf[NR_BUFS]; bp++)
if (bp->b_dev != NO_DEV && bp->b_dirt == DIRTY) flushall(bp->b_dev);
return(OK); /* sync() can't fail */
}
/*===========================================================================*
* do_fsync *
*===========================================================================*/
PUBLIC int do_fsync()
{
/* Perform the fsync() system call. For now, don't be unnecessarily smart. */
do_sync();
return(OK);
}
/*===========================================================================*
* pm_reboot *
*===========================================================================*/
PUBLIC void pm_reboot()
{
/* Perform the FS side of the reboot call. */
int i;
struct super_block *sp;
struct inode dummy;
/* Do exit processing for all leftover processes and servers,
* but don't actually exit them (if they were really gone, PM
* will tell us about it).
*/
for (i = 0; i < NR_PROCS; i++)
if((m_in.endpt1 = fproc[i].fp_endpoint) != NONE)
free_proc(&fproc[i], 0);
/* The root file system is mounted onto itself, which keeps it from being
* unmounted. Pull an inode out of thin air and put the root on it.
*/
put_inode(super_block[0].s_imount);
super_block[0].s_imount= &dummy;
dummy.i_count = 2; /* expect one "put" */
/* Unmount all filesystems. File systems are mounted on other file systems,
* so you have to pull off the loose bits repeatedly to get it all undone.
*/
for (i= 0; i < NR_SUPERS; i++) {
/* Unmount at least one. */
for (sp= &super_block[0]; sp < &super_block[NR_SUPERS]; sp++) {
if (sp->s_dev != NO_DEV) (void) unmount(sp->s_dev);
}
}
/* Sync any unwritten buffers. */
do_sync();
}
/*===========================================================================*
* pm_fork *
*===========================================================================*/
PUBLIC void pm_fork(pproc, cproc, cpid)
int pproc; /* Parent process */
int cproc; /* Child process */
int cpid; /* Child process id */
{
/* Perform those aspects of the fork() system call that relate to files.
* In particular, let the child inherit its parent's file descriptors.
* The parent and child parameters tell who forked off whom. The file
* system uses the same slot numbers as the kernel.
*/
register struct fproc *cp;
int i, parentno, childno;
/* Check up-to-dateness of fproc. */
okendpt(pproc, &parentno);
/* PM gives child endpoint, which implies process slot information.
* Don't call isokendpt, because that will verify if the endpoint
* number is correct in fproc, which it won't be.
*/
childno = _ENDPOINT_P(cproc);
if(childno < 0 || childno >= NR_PROCS)
panic(__FILE__, "FS: bogus child for forking", m_in.child_endpt);
if(fproc[childno].fp_pid != PID_FREE)
panic(__FILE__, "FS: forking on top of in-use child", childno);
/* Copy the parent's fproc struct to the child. */
fproc[childno] = fproc[parentno];
/* Increase the counters in the 'filp' table. */
cp = &fproc[childno];
for (i = 0; i < OPEN_MAX; i++)
if (cp->fp_filp[i] != NIL_FILP) cp->fp_filp[i]->filp_count++;
/* Fill in new process and endpoint id. */
cp->fp_pid = cpid;
cp->fp_endpoint = cproc;
/* A forking process never has an outstanding grant,
* as it isn't blocking on i/o.
*/
assert(!GRANT_VALID(fp->fp_grant));
assert(!GRANT_VALID(cp->fp_grant));
/* A child is not a process leader. */
cp->fp_sesldr = 0;
/* This child has not exec()ced yet. */
cp->fp_execced = 0;
/* Record the fact that both root and working dir have another user. */
dup_inode(cp->fp_rootdir);
dup_inode(cp->fp_workdir);
}
/*===========================================================================*
* free_proc *
*===========================================================================*/
PRIVATE void free_proc(struct fproc *exiter, int flags)
{
int i, task;
register struct fproc *rfp;
register struct filp *rfilp;
register struct inode *rip;
dev_t dev;
fp = exiter; /* get_filp() needs 'fp' */
if (fp->fp_suspended == SUSPENDED) {
task = -fp->fp_task;
if (task == XPIPE || task == XPOPEN) susp_count--;
unpause(fp->fp_endpoint);
fp->fp_suspended = NOT_SUSPENDED;
}
/* Loop on file descriptors, closing any that are open. */
for (i = 0; i < OPEN_MAX; i++) {
(void) close_fd(fp, i);
}
/* Release root and working directories. */
put_inode(fp->fp_rootdir);
put_inode(fp->fp_workdir);
fp->fp_rootdir = NIL_INODE;
fp->fp_workdir = NIL_INODE;
/* Check if any process is SUSPENDed on this driver.
* If a driver exits, unmap its entries in the dmap table.
* (unmapping has to be done after the first step, because the
* dmap table is used in the first step.)
*/
unsuspend_by_endpt(fp->fp_endpoint);
/* The rest of these actions is only done when processes actually
* exit.
*/
if(!(flags & FP_EXITING))
return;
/* Invalidate endpoint number for error and sanity checks. */
fp->fp_endpoint = NONE;
/* If a session leader exits and it has a controlling tty, then revoke
* access to its controlling tty from all other processes using it.
*/
if (fp->fp_sesldr && fp->fp_tty != 0) {
dev = fp->fp_tty;
for (rfp = &fproc[0]; rfp < &fproc[NR_PROCS]; rfp++) {
if(rfp->fp_pid == PID_FREE) continue;
if (rfp->fp_tty == dev) rfp->fp_tty = 0;
for (i = 0; i < OPEN_MAX; i++) {
if ((rfilp = rfp->fp_filp[i]) == NIL_FILP) continue;
if (rfilp->filp_mode == FILP_CLOSED) continue;
rip = rfilp->filp_ino;
if ((rip->i_mode & I_TYPE) != I_CHAR_SPECIAL) continue;
if ((dev_t) rip->i_zone[0] != dev) continue;
dev_close(dev);
rfilp->filp_mode = FILP_CLOSED;
}
}
}
/* Exit done. Mark slot as free. */
fp->fp_pid = PID_FREE;
}
/*===========================================================================*
* pm_exit *
*===========================================================================*/
PUBLIC void pm_exit(proc)
int proc;
{
int exitee_p;
/* Perform the file system portion of the exit(status) system call. */
/* Nevertheless, pretend that the call came from the user. */
okendpt(proc, &exitee_p);
free_proc(&fproc[exitee_p], FP_EXITING);
}
/*===========================================================================*
* pm_setgid *
*===========================================================================*/
PUBLIC void pm_setgid(proc_e, egid, rgid)
int proc_e;
int egid;
int rgid;
{
register struct fproc *tfp;
int slot;
okendpt(proc_e, &slot);
tfp = &fproc[slot];
tfp->fp_effgid = egid;
tfp->fp_realgid = rgid;
}
/*===========================================================================*
* pm_setuid *
*===========================================================================*/
PUBLIC void pm_setuid(proc_e, euid, ruid)
int proc_e;
int euid;
int ruid;
{
register struct fproc *tfp;
int slot;
okendpt(proc_e, &slot);
tfp = &fproc[slot];
tfp->fp_effuid = euid;
tfp->fp_realuid = ruid;
}
/*===========================================================================*
* do_svrctl *
*===========================================================================*/
PUBLIC int do_svrctl()
{
switch (m_in.svrctl_req) {
case FSSIGNON: {
/* A server in user space calls in to manage a device. */
struct fssignon device;
int r, major, proc_nr_n;
if (fp->fp_effuid != SU_UID && fp->fp_effuid != SERVERS_UID)
return(EPERM);
/* Try to copy request structure to FS. */
if ((r = sys_datacopy(who_e, (vir_bytes) m_in.svrctl_argp,
FS_PROC_NR, (vir_bytes) &device,
(phys_bytes) sizeof(device))) != OK)
return(r);
if (isokendpt(who_e, &proc_nr_n) != OK)
return(EINVAL);
/* Try to update device mapping. */
major = (device.dev >> MAJOR) & BYTE;
r=map_driver(major, who_e, device.style, 0 /* !force */);
if (r == OK)
{
/* If a driver has completed its exec(), it can be announced
* to be up.
*/
if(fproc[proc_nr_n].fp_execced) {
dev_up(major);
} else {
dmap[major].dmap_flags |= DMAP_BABY;
}
}
return(r);
}
case FSDEVUNMAP: {
struct fsdevunmap fdu;
int r, major;
/* Try to copy request structure to FS. */
if ((r = sys_datacopy(who_e, (vir_bytes) m_in.svrctl_argp,
FS_PROC_NR, (vir_bytes) &fdu,
(phys_bytes) sizeof(fdu))) != OK)
return(r);
major = (fdu.dev >> MAJOR) & BYTE;
r=map_driver(major, NONE, 0, 0);
return(r);
}
default:
return(EINVAL);
}
}
/*===========================================================================*
* pm_dumpcore *
*===========================================================================*/
PUBLIC int pm_dumpcore(proc_e, seg_ptr)
int proc_e;
struct mem_map *seg_ptr;
{
int r, proc_s;
r= dumpcore(proc_e, seg_ptr);
/* Terminate the process */
okendpt(proc_e, &proc_s);
free_proc(&fproc[proc_s], FP_EXITING);
return r;
}
/*===========================================================================*
* dumpcore *
*===========================================================================*/
PRIVATE int dumpcore(proc_e, seg_ptr)
int proc_e;
struct mem_map *seg_ptr;
{
int r, seg, proc_s, exists;
mode_t omode;
vir_bytes len;
off_t off, seg_off;
long trace_off, trace_data;
struct fproc *rfp;
struct inode *rip, *ldirp;
struct mem_map segs[NR_LOCAL_SEGS];
okendpt(proc_e, &proc_s);
rfp= fp= &fproc[proc_s];
who_e= proc_e;
who_p= proc_s;
super_user = (fp->fp_effuid == SU_UID ? TRUE : FALSE); /* su? */
/* We need the equivalent of
* open(CORE_NAME, O_WRONLY|O_CREAT|O_TRUNC|O_NONBLOCK, CORE_MODE)
*/
/* Create a new inode by calling new_node(). */
omode = I_REGULAR | (CORE_MODE & ALL_MODES & rfp->fp_umask);
rip = new_node(&ldirp, CORE_NAME, omode, NO_ZONE, 0, NULL);
r = err_code;
put_inode(ldirp);
exists= (r == EEXIST);
if (r != OK && r != EEXIST) return(r); /* error */
/* Only do the normal open code if we didn't just create the file. */
if (exists) {
/* Check protections. */
r = forbidden(rip, W_BIT);
if (r != OK)
{
put_inode(rip);
return r;
}
/* Make sure it is a regular file */
switch (rip->i_mode & I_TYPE) {
case I_REGULAR:
break;
case I_DIRECTORY:
/* Directories may be read but not written. */
r = EISDIR;
break;
case I_CHAR_SPECIAL:
case I_BLOCK_SPECIAL:
case I_NAMED_PIPE:
r = EPERM;
break;
}
if (r != OK)
{
put_inode(rip);
return r;
}
/* Truncate the file */
truncate_inode(rip, 0);
wipe_inode(rip);
/* Send the inode from the inode cache to the
* block cache, so it gets written on the next
* cache flush.
*/
rw_inode(rip, WRITING);
}
/* Copy segments from PM */
r= sys_datacopy(PM_PROC_NR, (vir_bytes)seg_ptr,
SELF, (vir_bytes)segs, sizeof(segs));
if (r != OK) panic(__FILE__, "dumpcore: cannot copy segment info", r);
off= 0;
r= write_bytes(rip, off, (char *)segs, sizeof(segs));
if (r != OK)
{
put_inode(rip);
return r;
}
off += sizeof(segs);
/* Write out the whole kernel process table entry to get the regs. */
for (trace_off= 0;; trace_off += sizeof(long))
{
r= sys_trace(T_GETUSER, proc_e, trace_off, &trace_data);
if (r != OK)
{
printf("dumpcore pid %d: sys_trace failed "
"at offset %d: %d\n",
rfp->fp_pid, trace_off, r);
break;
}
r= write_bytes(rip, off, (char *)&trace_data,
sizeof(trace_data));
if (r != OK)
{
put_inode(rip);
return r;
}
off += sizeof(trace_data);
}
/* Loop through segments and write the segments themselves out. */
for (seg = 0; seg < NR_LOCAL_SEGS; seg++) {
len= segs[seg].mem_len << CLICK_SHIFT;
seg_off= segs[seg].mem_vir << CLICK_SHIFT;
r= write_seg(rip, off, proc_e, seg, seg_off, len);
if (r != OK)
{
put_inode(rip);
return r;
}
off += len;
}
rip->i_size= off;
rip->i_dirt = DIRTY;
put_inode(rip);
return OK;
}
/*===========================================================================*
* write_bytes *
*===========================================================================*/
PRIVATE int write_bytes(rip, off, buf, bytes)
struct inode *rip; /* inode descriptor to read from */
off_t off; /* offset in file */
char *buf;
size_t bytes; /* how much is to be transferred? */
{
int r, block_size;
off_t n, o, b_off;
block_t b;
struct buf *bp;
block_size= rip->i_sp->s_block_size;
for (o= off - (off % block_size); o < off+bytes; o += block_size)
{
if (o < off)
b_off= off-o;
else
b_off= 0;
n= block_size-b_off;
if (o+b_off+n > off+bytes)
n= off+bytes-(o+b_off);
b = read_map(rip, o);
if (b == NO_BLOCK) {
/* Writing to a nonexistent block. Create and enter
* in inode.
*/
if ((bp= new_block(rip, o)) == NIL_BUF)
return(err_code);
}
else
{
/* Just read the block, no need to optimize for
* writing entire blocks.
*/
bp = get_block(rip->i_dev, b, NORMAL);
}
if (n != block_size && o >= rip->i_size && b_off == 0) {
zero_block(bp);
}
/* Copy a chunk from user space to the block buffer. */
memcpy((bp->b_data+b_off), buf, n);
bp->b_dirt = DIRTY;
if (b_off + n == block_size)
put_block(bp, FULL_DATA_BLOCK);
else
put_block(bp, PARTIAL_DATA_BLOCK);
buf += n;
}
return OK;
}
/*===========================================================================*
* write_seg *
*===========================================================================*/
PRIVATE int write_seg(rip, off, proc_e, seg, seg_off, seg_bytes)
struct inode *rip; /* inode descriptor to read from */
off_t off; /* offset in file */
int proc_e; /* process number (endpoint) */
int seg; /* T, D, or S */
off_t seg_off; /* Offset in segment */
phys_bytes seg_bytes; /* how much is to be transferred? */
{
int r, block_size, fl;
off_t n, o, b_off;
block_t b;
struct buf *bp;
block_size= rip->i_sp->s_block_size;
for (o= off - (off % block_size); o < off+seg_bytes; o += block_size)
{
if (o < off)
b_off= off-o;
else
b_off= 0;
n= block_size-b_off;
if (o+b_off+n > off+seg_bytes)
n= off+seg_bytes-(o+b_off);
b = read_map(rip, o);
if (b == NO_BLOCK) {
/* Writing to a nonexistent block. Create and enter in inode.*/
if ((bp= new_block(rip, o)) == NIL_BUF)
return(err_code);
} else {
/* Normally an existing block to be partially overwritten is
* first read in. However, a full block need not be read in.
* If it is already in the cache, acquire it, otherwise just
* acquire a free buffer.
*/
fl = (n == block_size ? NO_READ : NORMAL);
bp = get_block(rip->i_dev, b, fl);
}
if (n != block_size && o >= rip->i_size && b_off == 0) {
zero_block(bp);
}
/* Copy a chunk from user space to the block buffer. */
r = sys_vircopy(proc_e, seg, (phys_bytes) seg_off,
FS_PROC_NR, D, (phys_bytes) (bp->b_data+b_off),
(phys_bytes) n);
bp->b_dirt = DIRTY;
fl = (b_off + n == block_size ? FULL_DATA_BLOCK : PARTIAL_DATA_BLOCK);
put_block(bp, fl);
seg_off += n;
}
return OK;
}