struct uio *
afsio_partialcopy(struct uio *auio, size_t size)
{
struct uio *res;
int i;
user_addr_t iovaddr;
user_size_t iovsize;
if (proc_is64bit(current_proc())) {
res = uio_create(uio_iovcnt(auio), uio_offset(auio),
uio_isuserspace(auio) ? UIO_USERSPACE64 : UIO_SYSSPACE32,
uio_rw(auio));
} else {
res = uio_create(uio_iovcnt(auio), uio_offset(auio),
uio_isuserspace(auio) ? UIO_USERSPACE32 : UIO_SYSSPACE32,
uio_rw(auio));
}
for (i = 0;i < uio_iovcnt(auio) && size > 0;i++) {
if (uio_getiov(auio, i, &iovaddr, &iovsize))
break;
if (iovsize > size)
iovsize = size;
if (uio_addiov(res, iovaddr, iovsize))
break;
size -= iovsize;
}
return res;
}
int
physio( void (*f_strategy)(buf_t),
buf_t bp,
dev_t dev,
int flags,
u_int (*f_minphys)(buf_t),
struct uio *uio,
int blocksize)
{
struct proc *p = current_proc();
int error, i, buf_allocated, todo, iosize;
int orig_bflags = 0;
int64_t done;
error = 0;
flags &= B_READ | B_WRITE;
buf_allocated = 0;
/*
* [check user read/write access to the data buffer]
*
* Check each iov one by one. Note that we know if we're reading or
* writing, so we ignore the uio's rw parameter. Also note that if
* we're doing a read, that's a *write* to user-space.
*/
for (i = 0; i < uio->uio_iovcnt; i++) {
if (UIO_SEG_IS_USER_SPACE(uio->uio_segflg)) {
user_addr_t base;
user_size_t len;
if (uio_getiov(uio, i, &base, &len) ||
!useracc(base,
len,
(flags == B_READ) ? B_WRITE : B_READ))
return (EFAULT);
}
}
/*
* Make sure we have a buffer, creating one if necessary.
*/
if (bp == NULL) {
bp = buf_alloc((vnode_t)0);
buf_allocated = 1;
} else
orig_bflags = buf_flags(bp);
/*
* at this point we should have a buffer
* that is marked BL_BUSY... we either
* acquired it via buf_alloc, or it was
* passed into us... if it was passed
* in, it needs to already be owned by
* the caller (i.e. BL_BUSY is set)
*/
assert(bp->b_lflags & BL_BUSY);
/*
* [set up the fixed part of the buffer for a transfer]
*/
bp->b_dev = dev;
bp->b_proc = p;
/*
* [mark the buffer busy for physical I/O]
* (i.e. set B_PHYS (because it's an I/O to user
* memory, and B_RAW, because B_RAW is to be
* "Set by physio for raw transfers.", in addition
* to the read/write flag.)
*/
buf_setflags(bp, B_PHYS | B_RAW);
/*
* [while there is data to transfer and no I/O error]
* Note that I/O errors are handled with a 'goto' at the bottom
* of the 'while' loop.
*/
while (uio_resid(uio) > 0) {
if ( (iosize = uio_curriovlen(uio)) > MAXPHYSIO_WIRED)
iosize = MAXPHYSIO_WIRED;
/*
* make sure we're set to issue a fresh I/O
* in the right direction
*/
buf_reset(bp, flags);
/* [set up the buffer for a maximum-sized transfer] */
buf_setblkno(bp, uio_offset(uio) / blocksize);
buf_setcount(bp, iosize);
buf_setdataptr(bp, (uintptr_t)CAST_DOWN(caddr_t, uio_curriovbase(uio)));
/*
* [call f_minphys to bound the tranfer size]
* and remember the amount of data to transfer,
* for later comparison.
*/
(*f_minphys)(bp);
todo = buf_count(bp);
/*
* [lock the part of the user address space involved
* in the transfer]
*/
if(UIO_SEG_IS_USER_SPACE(uio->uio_segflg)) {
error = vslock(CAST_USER_ADDR_T(buf_dataptr(bp)),
(user_size_t)todo);
if (error)
goto done;
}
/* [call f_strategy to start the transfer] */
(*f_strategy)(bp);
/* [wait for the transfer to complete] */
error = (int)buf_biowait(bp);
/*
* [unlock the part of the address space previously
* locked]
*/
if(UIO_SEG_IS_USER_SPACE(uio->uio_segflg))
vsunlock(CAST_USER_ADDR_T(buf_dataptr(bp)),
(user_size_t)todo,
(flags & B_READ));
/*
* [deduct the transfer size from the total number
* of data to transfer]
*/
done = buf_count(bp) - buf_resid(bp);
uio_update(uio, done);
/*
* Now, check for an error.
* Also, handle weird end-of-disk semantics.
*/
if (error || done < todo)
goto done;
}
done:
if (buf_allocated)
buf_free(bp);
else
buf_setflags(bp, orig_bflags);
return (error);
}