struct cch_buf *
_cch_getblk(
struct cch_f *cch_info, /* cch_f structure for the file */
struct fdinfo *llfio, /* ffio file descriptor for underlying layer */
off_t fileaddr, /* bit offset within the file of the buffer.
* This number must be a multiple of the buffer
* size. */
int64 *nblkp, /* on input, the number of contiguous buffer
* blocks sought. On output, assigned the
* actual number of contiguous buffer blocks
* assigned. */
int rd, /* 0 if all of the new blocks may be
* assigned without reading the file page.
* != 0 if the pages must be read. */
int valid, /* 0 if the CCH_VALIDBUFFER bit should */
/* not be set in the new blocks */
struct ffsw *stat /* pointer to status return word */
)
{
int i, nbu, ret;
int bs;
int lru_id; /* buffer number of least recently */
/* used buffer. */
int limit;
int64 nblk;
off_t endaddr, firstpaddr, faddr;
long *wptr;
long lru_tm;
struct cch_buf *cubuf;
struct cch_buf *cbufs;
struct cch_buf *fb;
CCH_DEBUG(("_cch_getblk EN: to bit offset %d\n",fileaddr));
nbu = cch_info->nbufs;
cbufs = cch_info->bufs;
bs = cch_info->bsize;
nblk = *nblkp;
if (nblk > 1) {
/*
* Find the first page in the consecutive list of pages which
* is buffer-resident.
*/
endaddr = fileaddr + nblk * bs;
firstpaddr = endaddr;
for (i=0; i<nbu; i++) {
off_t x;
cubuf = &cbufs[i];
x = cubuf->filead;
if (fileaddr <= x && x < firstpaddr)
firstpaddr = x;
}
if (firstpaddr < endaddr) /* a page is buffer resident */
nblk = *nblkp = (firstpaddr - fileaddr) / bs;
if (nblk <= 0)
return((struct cch_buf *)NULL); /* shouldn't happen ! */
}
/*
* Find the least-recently accessed sequence of *nblkp contiguous buffers.
* Free buffers are counted as if their last access time was 0.
* Search the buffers in groups of size nblk to speed this search and
* reduce fragmentation of the cache. When nblk>1, this algorithm
* approximates LRU and, most importantly, is deterministic.
*/
lru_tm = MAXLONG; /* min _rtc() value in upcoming loop */
lru_id = 0;
for (i=0; i<(nbu-nblk+1); i+=nblk) {
long last_access = 0; /* free pages have last_access == 0 */
if (cbufs[i].filead >= 0)
last_access = cbufs[i].atime;
if (last_access < lru_tm) {
lru_tm = last_access;
lru_id = i;
}
}
/*
* Use the least recently used page buffer or group of page buffers.
* Flush any of these page buffers which have the dirty bit set. When
* several adjacent buffers are dirty and correspond to adjacent pages
* in the file, they can be flushed with one request.
*/
fb = &cbufs[lru_id];
for (i=0; i<nblk; i++) {
int contig = 0; /* number of contiguous dirty buffers */
faddr = fb[i].filead;
if (faddr == -1)
continue; /* buffer is free */
while (i+contig < nblk && (fb[i+contig].flags & CCH_DIRTY) &&
fb[i+contig].filead == faddr) {
if (fb[i+contig].lastdata || fb[i+contig].firstdata) {
if (contig == 0)
contig = 1;
break;
}
contig++;
faddr += bs;
}
if (contig > 0) {
if (faddr > cch_info->fsize) {
/* eof is in the last buffer */
/* clear it if necessary */
if ((fb[i+contig-1].flags & CCH_ZEROED) == 0){
bitptr toptr;
off_t eofaddr;
int pgoff;
eofaddr = CCHFLOOR(cch_info->fsize, bs);
pgoff = cch_info->fsize - eofaddr;
SET_BPTR(toptr,
INC_BPTR(fb[i+contig-1].buf,
pgoff));
CCH_MEMCLEAR(toptr,(bs - pgoff));
fb[i+contig-1].flags |= CCH_ZEROED;
}
}
ret = _cch_wrabuf(cch_info, llfio, &fb[i],
BITS2BYTES(bs),
BITS2BYTES(fb[i].filead),
contig,
&cch_info->feof,
#if defined(__mips) || defined(_LITTLE_ENDIAN)
's', /* flush synchronously */
#else
'a', /* flush asynchronously */
#endif
stat);
if (ret == ERR)
return((struct cch_buf *)NULL);
i += contig - 1;
}
}
/*
* Wait for any active page buffer I/O, and then requisition the buffers
* for the appropriate file pages.
*/
for (i=0; i<nblk; i++) {
if (fb[i].flags & (CCH_WRITING | CCH_READING)) {
CCHWAITIO(llfio,&fb[i],stat,ret);
if (ret == ERR)
return((struct cch_buf *)NULL);
}
fb[i].filead = fileaddr + i * bs;
fb[i].flags = CCH_VALID;
fb[i].firstdata = fb[i].lastdata = 0;
if (valid)
fb[i].flags |= CCH_VALIDBUFFER;
}
/*
* Now start the synchronous reading of the file page into the buffer. If
* all of the pages lie beyond the EOF, then suppress the read.
*/
if (rd) {
if (fileaddr < cch_info->feof) {
int by_tran;
fb->sw.sw_flag = 0; /* indicate I/O in progress */
ret = _cch_rdabuf(cch_info, llfio, fb, BITS2BYTES(bs),
BITS2BYTES(fb->filead), nblk, 's',stat);
if (ret == ERR)
return((struct cch_buf *)NULL);
/*
* Zero portions of the buffers past the end of file.
*/
by_tran = fb->sw.sw_count;
#ifdef CCH_SDS_SUPPORTED
if (cch_info->optflags & CCHOPT_SDS) {
int ret;
ret = _sdsset(
(BPTR2CP(fb->buf) - (char*)NULL) +
by_tran,
0,
nblk * BITS2BYTES(bs) - by_tran);
if (ret == ERR) {
_SETERROR(stat, errno, 0);
return((struct cch_buf *)NULL);
}
}
else
#endif
{
if ((nblk*BITS2BYTES(bs)-by_tran) != 0)
(void)memset(BPTR2CP(
fb->buf) + by_tran,
0,
nblk * BITS2BYTES(bs) - by_tran);
}
for (i=0; i<nblk; i++) {
fb[i].flags |= CCH_ZEROED;
}
}
else { /* page lies beyond EOF */
/*
* Zero the entire buffer.
*/
#ifdef CCH_SDS_SUPPORTED
if (cch_info->optflags & CCHOPT_SDS) {
int ret;
ret = _sdsset(
(BPTR2CP(fb->buf) - (char*)NULL),
0,
nblk * BITS2BYTES(bs));
if (ret == ERR) {
_SETERROR(stat, errno, 0);
return((struct cch_buf *)NULL);
}
for (i=0; i<nblk; i++) {
fb[i].flags |= CCH_ZEROED;
}
}
else
#endif
if (fileaddr < cch_info->fsize){
/* this block is between cch_info->feof and */
/* cch_info->fsize, so we must zero it */
/* Logic in other parts of this layer will */
/* only zero what is beyond cch_info->fsize */
#ifdef _CRAY1
wptr = BPTR2WP(fb->buf);
limit = (nblk * bs) >> 6; /* convert to words */
/* this loop vectorizes! */
for (i=0; i<limit; i++)
wptr[i] = 0;
#else
memset(BPTR2CP(fb->buf), 0,
(nblk * BITS2BYTES(bs)));
#endif
for (i=0; i<nblk; i++) {
fb[i].flags |= CCH_ZEROED;
}
}
}
}
/*
* _cch_write
*
* Process write requests for the cache layer.
*
* Return value:
*
* The number of bytes transferred is returned upon successful completion.
* If an error occurs, -1 is returned.
*
* The stat->sw_stat field is set to FFCNT upon normal return.
*/
ssize_t
_cch_write(
struct fdinfo *fio, /* ffio file descriptor. */
bitptr datptr, /* bit pointer to the user's data. */
size_t nbytes, /* Nuber of bytes to be written. */
struct ffsw *stat, /* pointer to status return word */
int fulp, /* full or partial write mode flag */
int *ubcp /* pointer to unused bit count. On return, */
/* *ubcp is updated to contain the unused bit */
/* count in the data returned. */
)
{
off_t cpos; /* bit position in file */
int64 moved; /* number of bits transfered */
int64 bytes_moved; /* number of bytes transfered */
int64 morebits; /* bits moved in current iteration */
int64 numblocks; /* num of pages to process this iter */
int pgoff;
off_t fileaddr;
off_t eofaddr;
int gb_rd; /* nonzero if pages must be read */
int valid; /* nonzero if CCH_VALIDBUFFER should */
/* be set */
int64 nbits;
int64 i;
int bs, nbu;
off_t olpos, endpos, endoff;
bitptr toptr;
struct ffsw locstat;
struct fdinfo *llfio;
struct cch_f *cch_info;
struct cch_buf *cubuf;
int err;
short firsteof = 0;
short setfirst;
CCH_DEBUG(("_cch_write EN: nbytes=%d fulp=%d ubc=%d\n",nbytes,fulp,
*ubcp));
CLRSTAT(locstat);
cch_info = (struct cch_f *)fio->lyr_info;
nbits = BYTES2BITS(nbytes) - *ubcp;
fio->rwflag = WRITIN;
#if defined(__mips) || defined(_LITTLE_ENDIAN)
/* Although this layer is capable of handling non-zero ubc */
/* and bitptrs that aren't on a byte boundary, we are not */
/* supporting this right now on mips systems. */
if (*ubcp != 0) {
err = FDC_ERR_UBC;
goto err1_ret;
}
if ((BPBITOFF(datptr) & 07) != 0) {
err = FDC_ERR_REQ;
goto err1_ret;
}
#endif
if (nbits == 0) { /* quick return for nbits == 0*/
SETSTAT(stat, FFCNT, 0);
return(0);
}
/*
* Move data from user to buffer
*/
llfio = fio->fioptr;
bs = cch_info->bsize; /* bit size of each buffer */
cpos = cch_info->cpos; /* current file position */
olpos = cpos; /* save original position */
fileaddr = CCHFLOOR(cpos,bs); /* bit offset within the file of the
* start of the current page */
if (cpos > cch_info->fsize) {
firsteof = 1;
/* Is the page with eof in memory? */
/* If so, zero out the portion beyond eof. */
eofaddr = CCHFLOOR(cch_info->fsize, bs);
CCH_FINDBLK(cch_info, eofaddr, cubuf);
if (cubuf != NULL && (cubuf->flags & CCH_ZEROED) == 0) {
#ifdef CCH_SDS_SUPPORTED
if (cch_info->optflags & CCHOPT_SDS) {
/* should never happen */
ERETURN(stat, FDC_ERR_INTERR, 0);
}
#endif
pgoff = cch_info->fsize - eofaddr; /* offset of eof */
/* within the page */
SET_BPTR(toptr, INC_BPTR(cubuf->buf, pgoff));
morebits = bs - pgoff;
if (morebits != 0) {
CCH_MEMCLEAR(toptr, morebits);
}
cubuf->flags |= CCH_ZEROED;
}
}
while (nbits > 0) {
/*
* Find the cache buffer assigned to the current page. If
* no buffer is currently assigned, then _cch_getblk assigns
* one.
*/
pgoff = cpos - fileaddr; /* offset within the page */
numblocks = 1; /* number of of pages to prcess
* in this iteration */
CCH_FINDBLK(cch_info, fileaddr, cubuf);
if (cubuf == NULL) { /* if data not buffer-resident*/
if (nbits > cch_info->bypasssize
#ifdef CCH_SDS_SUPPORTED
&& !(cch_info->optflags & CCHOPT_SDS)
#endif
) {
/* Maybe we can bypass buffering */
if ((morebits= _cch_bypass(cch_info, nbits, cpos,
datptr, fileaddr, 'w', llfio, &locstat))>0)
goto adjust;
else if (morebits < 0) {
/* Is it right to return the count */
/* in locstat? Because we might */
/* have read some data... */
goto er1;
}
/* we weren't able to bypass buffering */
}
morebits = nbits;
endpos = cpos + morebits; /*1 bit past the end*/
endoff = endpos - CCHFLOOR(endpos,bs);
if (endpos > fileaddr + bs) {
numblocks = (endpos-fileaddr-1)/bs + 1;
nbu = cch_info->nbufs;
/*
* Handle at most a cache full at a time
*/
if (numblocks > nbu) {
numblocks = nbu;
endpos = fileaddr + nbu * bs;
endoff = 0;
morebits = endpos - cpos;
}
}
/*
* It is possible that the first or last
* page must be read because the transfer
* fills only part of these pages. In each
* iteration, _cch_getblk requires that
* consecutive buffer pages must all be read,
* or else all be assigned without pre-reading.
* The following code breaks off the current
* portion of the transfer when necessary to
* accomplish this.
*/
if (numblocks > 1) {
if (numblocks == 2) {
if ((pgoff == 0) != (endoff == 0)) {
/* process only first page */
numblocks = 1;
endoff = 0;
morebits = bs - pgoff;
}
}
else {
if (pgoff) {
/* process only first page */
numblocks = 1;
endoff = 0;
morebits = bs - pgoff;
}
else if (endoff) {
/* process all but last page */
numblocks -= 1;
endoff = 0;
morebits -= endoff;
}
}
}
/*
* Request that _cch_getblk read in the file
* pages if partial pages of data will be
* written.
*/
gb_rd = (pgoff || endoff);
/* The pages will be valid if we do not */
/* have to read them. That's because */
/* we will be writing to the entire page */
/* The page will also be valid if we do read it */
valid = 1;
setfirst = 0;
if (gb_rd &&
#ifdef CCH_SDS_SUPPORTED
!(cch_info->optflags & CCHOPT_SDS) &&
#endif
(numblocks == 1) &&
((fileaddr+bs) < cch_info->feof) &&
(_CCH_ALIGN(pgoff) && _CCH_ALIGN(endoff))) {
/* do we really need to read the page in? */
/* if pgoff and endoff are properly aligned, */
/* we do not */
/* Note that if any part of the page is */
/* beyond feof, we want to read it in. */
/* That's because code in _cch_rdabuf */
/* that handles having a partially dirty */
/* page expects to be able to read the */
/* data preceding the dirty data */
gb_rd = 0;
valid = 0; /* the page will not be valid */
setfirst = 1;
}
cubuf = _cch_getblk(cch_info, llfio, fileaddr,
&numblocks, gb_rd, valid, &locstat);
if (cubuf == NULL) {
goto er1;
}
if (setfirst) {
cubuf->firstdata = pgoff;
if (endoff == 0)
cubuf->lastdata = bs;
else
cubuf->lastdata = endoff;
}
if (firsteof && pgoff != 0) {
/* There is a gap between the eof and */
/* this data. Zero it if necessary. */
if ((cubuf->flags & CCH_ZEROED) == 0) {
int zbits;
#ifdef CCH_SDS_SUPPORTED
if (cch_info->optflags & CCHOPT_SDS) {
/* should never happen */
ERETURN(stat, FDC_ERR_INTERR, 0);
}
#endif
if ((eofaddr == fileaddr)) {
/* the eof is on this page */
zbits = bs - (cch_info->fsize - eofaddr);
SET_BPTR(toptr, INC_BPTR(cubuf->buf,
(cch_info->fsize - eofaddr)));
}
else {
/* the eof is not on this page */
/* zero the entire page */
zbits = bs;
toptr = cubuf->buf;
}
CCH_MEMCLEAR(toptr, zbits);
cubuf->flags |= CCH_ZEROED;
}
}
morebits = MIN(nbits, bs * numblocks - pgoff);
/* remember the last buffer page for next time */
cch_info->cubuf = cubuf + numblocks - 1;
}
else {
morebits = MIN(nbits, bs - pgoff);
if (!(cubuf->flags & CCH_VALIDBUFFER)) {
/* The buffer is there, but it */
/* is not entirely valid, because */
/* we never read into it. */
/* We can continue to just dirty it, */
/* provided that the dirty part is */
/* contiguous, and is properly aligned */
endoff = pgoff + morebits;
if ((pgoff == cubuf->lastdata &&
_CCH_ALIGN(endoff))|| (endoff ==
cubuf->firstdata && _CCH_ALIGN(pgoff))
|| (pgoff >= cubuf->firstdata &&
endoff <= cubuf->lastdata)) {
cubuf->firstdata = MIN(pgoff,
cubuf->firstdata);
cubuf->lastdata = MAX(endoff,
cubuf->lastdata);
if (cubuf->firstdata == 0 &&
cubuf->lastdata == bs) {
cubuf->lastdata = 0;
cubuf->flags |=CCH_VALIDBUFFER;
}
} else {
/* We can't just keep on putting */
/* stuff in the buffer without */
/* prereading it. So, we will call */
/* _cch_rdabuf, which has the */
/* smarts to read only the non-dirty */
/* parts */
if (_cch_rdabuf(cch_info, llfio, cubuf,
BITS2BYTES(cch_info->bsize),
BITS2BYTES(cubuf->filead), 1, 's',
&locstat)) {
goto er1;
}
}
}
}
for (i=0; i<numblocks; i++) {
/* adjust last access time */
CCH_CHRONOMETER(cubuf[i],cch_info);
cubuf[i].flags |= CCH_DIRTY;
}
SET_BPTR(toptr, INC_BPTR(cubuf->buf, pgoff));
#ifdef CCH_SDS_SUPPORTED
if (cch_info->optflags & CCHOPT_SDS) {
if (_sds_fr_mem(toptr, datptr, morebits) == ERR)
ERETURN(stat, errno, 0);
}
else
_CCH_MOV_BITS(toptr, datptr, morebits); /* contiguous bufs */
#else
_CCH_MOV_BITS(toptr, datptr, morebits); /* contiguous bufs */
#endif
adjust:
SET_BPTR(datptr, INC_BPTR(datptr, morebits));
cpos += morebits;
nbits -= morebits;
fileaddr = CCHFLOOR(cpos,bs);
/* bit offset within the file of the page */
firsteof = 0;
if (cpos > cch_info->fsize) {
cch_info->fsize = cpos;
}
}
cch_info->cpos = cpos;
moved = cpos - olpos;
fio->recbits += moved;
bytes_moved = BITS2BYTES(moved);
SETSTAT(stat, FFCNT, bytes_moved);
return(bytes_moved);
err1_ret:
ERETURN(stat, err, 0);
er1:
*stat = locstat;
return(ERR);
}
