701 lines
28 KiB
C
701 lines
28 KiB
C
/*-
|
||
* Copyright (c) 1997, 1998
|
||
* Cybernet Corporation and Nan Yang Computer Services Limited.
|
||
* All rights reserved.
|
||
*
|
||
* This software was developed as part of the NetMAX project.
|
||
*
|
||
* Written by Greg Lehey
|
||
*
|
||
* This software is distributed under the so-called ``Berkeley
|
||
* License'':
|
||
*
|
||
* Redistribution and use in source and binary forms, with or without
|
||
* modification, are permitted provided that the following conditions
|
||
* are met:
|
||
* 1. Redistributions of source code must retain the above copyright
|
||
* notice, this list of conditions and the following disclaimer.
|
||
* 2. Redistributions in binary form must reproduce the above copyright
|
||
* notice, this list of conditions and the following disclaimer in the
|
||
* documentation and/or other materials provided with the distribution.
|
||
* 3. All advertising materials mentioning features or use of this software
|
||
* must display the following acknowledgement:
|
||
* This product includes software developed by Cybernet Corporation
|
||
* and Nan Yang Computer Services Limited
|
||
* 4. Neither the name of the Companies nor the names of its contributors
|
||
* may be used to endorse or promote products derived from this software
|
||
* without specific prior written permission.
|
||
*
|
||
* This software is provided ``as is'', and any express or implied
|
||
* warranties, including, but not limited to, the implied warranties of
|
||
* merchantability and fitness for a particular purpose are disclaimed.
|
||
* In no event shall the company or contributors be liable for any
|
||
* direct, indirect, incidental, special, exemplary, or consequential
|
||
* damages (including, but not limited to, procurement of substitute
|
||
* goods or services; loss of use, data, or profits; or business
|
||
* interruption) however caused and on any theory of liability, whether
|
||
* in contract, strict liability, or tort (including negligence or
|
||
* otherwise) arising in any way out of the use of this software, even if
|
||
* advised of the possibility of such damage.
|
||
*
|
||
* $Id: vinumraid5.c,v 1.23 2003/02/08 03:32:45 grog Exp $
|
||
*/
|
||
|
||
#include <sys/cdefs.h>
|
||
__FBSDID("$FreeBSD$");
|
||
#include <dev/vinum/vinumhdr.h>
|
||
#include <dev/vinum/request.h>
|
||
#include <sys/resourcevar.h>
|
||
|
||
/*
|
||
* Parameters which describe the current transfer.
|
||
* These are only used for calculation, but they
|
||
* need to be passed to other functions, so it's
|
||
* tidier to put them in a struct
|
||
*/
|
||
struct metrics {
|
||
daddr_t stripebase; /* base address of stripe (1st subdisk) */
|
||
int stripeoffset; /* offset in stripe */
|
||
int stripesectors; /* total sectors to transfer in this stripe */
|
||
daddr_t sdbase; /* offset in subdisk of stripe base */
|
||
int sdcount; /* number of disks involved in this transfer */
|
||
daddr_t diskstart; /* remember where this transfer starts */
|
||
int psdno; /* number of parity subdisk */
|
||
int badsdno; /* number of down subdisk, if there is one */
|
||
int firstsdno; /* first data subdisk number */
|
||
/* These correspond to the fields in rqelement, sort of */
|
||
int useroffset;
|
||
/*
|
||
* Initial offset and length values for the first
|
||
* data block
|
||
*/
|
||
int initoffset; /* start address of block to transfer */
|
||
short initlen; /* length in sectors of data transfer */
|
||
/* Define a normal operation */
|
||
int dataoffset; /* start address of block to transfer */
|
||
int datalen; /* length in sectors of data transfer */
|
||
/* Define a group operation */
|
||
int groupoffset; /* subdisk offset of group operation */
|
||
int grouplen; /* length in sectors of group operation */
|
||
/* Define a normal write operation */
|
||
int writeoffset; /* subdisk offset of normal write */
|
||
int writelen; /* length in sectors of write operation */
|
||
enum xferinfo flags; /* to check what we're doing */
|
||
int rqcount; /* number of elements in request */
|
||
};
|
||
|
||
enum requeststatus bre5(struct request *rq,
|
||
int plexno,
|
||
daddr_t * diskstart,
|
||
daddr_t diskend);
|
||
void complete_raid5_write(struct rqelement *);
|
||
enum requeststatus build_rq_buffer(struct rqelement *rqe, struct plex *plex);
|
||
void setrqebounds(struct rqelement *rqe, struct metrics *mp);
|
||
|
||
/*
|
||
* define the low-level requests needed to perform
|
||
* a high-level I/O operation for a specific plex
|
||
* 'plexno'.
|
||
*
|
||
* Return 0 if all subdisks involved in the
|
||
* request are up, 1 if some subdisks are not up,
|
||
* and -1 if the request is at least partially
|
||
* outside the bounds of the subdisks.
|
||
*
|
||
* Modify the pointer *diskstart to point to the
|
||
* end address. On read, return on the first bad
|
||
* subdisk, so that the caller
|
||
* (build_read_request) can try alternatives.
|
||
*
|
||
* On entry to this routine, the prq structures
|
||
* are not assigned. The assignment is performed
|
||
* by expandrq(). Strictly speaking, the elements
|
||
* rqe->sdno of all entries should be set to -1,
|
||
* since 0 (from bzero) is a valid subdisk number.
|
||
* We avoid this problem by initializing the ones
|
||
* we use, and not looking at the others (index >=
|
||
* prq->requests).
|
||
*/
|
||
enum requeststatus
|
||
bre5(struct request *rq,
|
||
int plexno,
|
||
daddr_t * diskaddr,
|
||
daddr_t diskend)
|
||
{
|
||
struct metrics m; /* most of the information */
|
||
struct sd *sd;
|
||
struct plex *plex;
|
||
struct buf *bp; /* user's bp */
|
||
struct rqgroup *rqg; /* the request group that we will create */
|
||
struct rqelement *rqe; /* point to this request information */
|
||
int rsectors; /* sectors remaining in this stripe */
|
||
int mysdno; /* another sd index in loops */
|
||
int rqno; /* request number */
|
||
|
||
rqg = NULL; /* shut up, damn compiler */
|
||
m.diskstart = *diskaddr; /* start of transfer */
|
||
bp = rq->bp; /* buffer pointer */
|
||
plex = &PLEX[plexno]; /* point to the plex */
|
||
|
||
|
||
while (*diskaddr < diskend) { /* until we get it all sorted out */
|
||
if (*diskaddr >= plex->length) /* beyond the end of the plex */
|
||
return REQUEST_EOF; /* can't continue */
|
||
|
||
m.badsdno = -1; /* no bad subdisk yet */
|
||
|
||
/* Part A: Define the request */
|
||
/*
|
||
* First, calculate some sizes:
|
||
* The offset of the start address from
|
||
* the start of the stripe.
|
||
*/
|
||
m.stripeoffset = *diskaddr % (plex->stripesize * (plex->subdisks - 1));
|
||
|
||
/*
|
||
* The plex-relative address of the
|
||
* start of the stripe.
|
||
*/
|
||
m.stripebase = *diskaddr - m.stripeoffset;
|
||
|
||
/* subdisk containing the parity stripe */
|
||
if (plex->organization == plex_raid5)
|
||
m.psdno = plex->subdisks - 1
|
||
- (*diskaddr / (plex->stripesize * (plex->subdisks - 1)))
|
||
% plex->subdisks;
|
||
else /* RAID-4 */
|
||
m.psdno = plex->subdisks - 1;
|
||
|
||
/*
|
||
* The number of the subdisk in which
|
||
* the start is located.
|
||
*/
|
||
m.firstsdno = m.stripeoffset / plex->stripesize;
|
||
if (m.firstsdno >= m.psdno) /* at or past parity sd */
|
||
m.firstsdno++; /* increment it */
|
||
|
||
/*
|
||
* The offset from the beginning of
|
||
* the stripe on this subdisk.
|
||
*/
|
||
m.initoffset = m.stripeoffset % plex->stripesize;
|
||
|
||
/* The offset of the stripe start relative to this subdisk */
|
||
m.sdbase = m.stripebase / (plex->subdisks - 1);
|
||
|
||
m.useroffset = *diskaddr - m.diskstart; /* The offset of the start in the user buffer */
|
||
|
||
/*
|
||
* The number of sectors to transfer in the
|
||
* current (first) subdisk.
|
||
*/
|
||
m.initlen = min(diskend - *diskaddr, /* the amount remaining to transfer */
|
||
plex->stripesize - m.initoffset); /* and the amount left in this block */
|
||
|
||
/*
|
||
* The number of sectors to transfer in this stripe
|
||
* is the minumum of the amount remaining to transfer
|
||
* and the amount left in this stripe.
|
||
*/
|
||
m.stripesectors = min(diskend - *diskaddr,
|
||
plex->stripesize * (plex->subdisks - 1) - m.stripeoffset);
|
||
|
||
/* The number of data subdisks involved in this request */
|
||
m.sdcount = (m.stripesectors + m.initoffset + plex->stripesize - 1) / plex->stripesize;
|
||
|
||
/* Part B: decide what kind of transfer this will be.
|
||
|
||
* start and end addresses of the transfer in
|
||
* the current block.
|
||
*
|
||
* There are a number of different kinds of
|
||
* transfer, each of which relates to a
|
||
* specific subdisk:
|
||
*
|
||
* 1. Normal read. All participating subdisks
|
||
* are up, and the transfer can be made
|
||
* directly to the user buffer. The bounds
|
||
* of the transfer are described by
|
||
* m.dataoffset and m.datalen. We have
|
||
* already calculated m.initoffset and
|
||
* m.initlen, which define the parameters
|
||
* for the first data block.
|
||
*
|
||
* 2. Recovery read. One participating
|
||
* subdisk is down. To recover data, all
|
||
* the other subdisks, including the parity
|
||
* subdisk, must be read. The data is
|
||
* recovered by exclusive-oring all the
|
||
* other blocks. The bounds of the
|
||
* transfer are described by m.groupoffset
|
||
* and m.grouplen.
|
||
*
|
||
* 3. A read request may request reading both
|
||
* available data (normal read) and
|
||
* non-available data (recovery read).
|
||
* This can be a problem if the address
|
||
* ranges of the two reads do not coincide:
|
||
* in this case, the normal read needs to
|
||
* be extended to cover the address range
|
||
* of the recovery read, and must thus be
|
||
* performed out of malloced memory.
|
||
*
|
||
* 4. Normal write. All the participating
|
||
* subdisks are up. The bounds of the
|
||
* transfer are described by m.dataoffset
|
||
* and m.datalen. Since these values
|
||
* differ for each block, we calculate the
|
||
* bounds for the parity block
|
||
* independently as the maximum of the
|
||
* individual blocks and store these values
|
||
* in m.writeoffset and m.writelen. This
|
||
* write proceeds in four phases:
|
||
*
|
||
* i. Read the old contents of each block
|
||
* and the parity block.
|
||
* ii. ``Remove'' the old contents from
|
||
* the parity block with exclusive or.
|
||
* iii. ``Insert'' the new contents of the
|
||
* block in the parity block, again
|
||
* with exclusive or.
|
||
*
|
||
* iv. Write the new contents of the data
|
||
* blocks and the parity block. The data
|
||
* block transfers can be made directly from
|
||
* the user buffer.
|
||
*
|
||
* 5. Degraded write where the data block is
|
||
* not available. The bounds of the
|
||
* transfer are described by m.groupoffset
|
||
* and m.grouplen. This requires the
|
||
* following steps:
|
||
*
|
||
* i. Read in all the other data blocks,
|
||
* excluding the parity block.
|
||
*
|
||
* ii. Recreate the parity block from the
|
||
* other data blocks and the data to be
|
||
* written.
|
||
*
|
||
* iii. Write the parity block.
|
||
*
|
||
* 6. Parityless write, a write where the
|
||
* parity block is not available. This is
|
||
* in fact the simplest: just write the
|
||
* data blocks. This can proceed directly
|
||
* from the user buffer. The bounds of the
|
||
* transfer are described by m.dataoffset
|
||
* and m.datalen.
|
||
*
|
||
* 7. Combination of degraded data block write
|
||
* and normal write. In this case the
|
||
* address ranges of the reads may also
|
||
* need to be extended to cover all
|
||
* participating blocks.
|
||
*
|
||
* All requests in a group transfer transfer
|
||
* the same address range relative to their
|
||
* subdisk. The individual transfers may
|
||
* vary, but since our group of requests is
|
||
* all in a single slice, we can define a
|
||
* range in which they all fall.
|
||
*
|
||
* In the following code section, we determine
|
||
* which kind of transfer we will perform. If
|
||
* there is a group transfer, we also decide
|
||
* its bounds relative to the subdisks. At
|
||
* the end, we have the following values:
|
||
*
|
||
* m.flags indicates the kinds of transfers
|
||
* we will perform.
|
||
* m.initoffset indicates the offset of the
|
||
* beginning of any data operation relative
|
||
* to the beginning of the stripe base.
|
||
* m.initlen specifies the length of any data
|
||
* operation.
|
||
* m.dataoffset contains the same value as
|
||
* m.initoffset.
|
||
* m.datalen contains the same value as
|
||
* m.initlen. Initially dataoffset and
|
||
* datalen describe the parameters for the
|
||
* first data block; while building the data
|
||
* block requests, they are updated for each
|
||
* block.
|
||
* m.groupoffset indicates the offset of any
|
||
* group operation relative to the beginning
|
||
* of the stripe base.
|
||
* m.grouplen specifies the length of any
|
||
* group operation.
|
||
* m.writeoffset indicates the offset of a
|
||
* normal write relative to the beginning of
|
||
* the stripe base. This value differs from
|
||
* m.dataoffset in that it applies to the
|
||
* entire operation, and not just the first
|
||
* block.
|
||
* m.writelen specifies the total span of a
|
||
* normal write operation. writeoffset and
|
||
* writelen are used to define the parity
|
||
* block.
|
||
*/
|
||
m.groupoffset = 0; /* assume no group... */
|
||
m.grouplen = 0; /* until we know we have one */
|
||
m.writeoffset = m.initoffset; /* start offset of transfer */
|
||
m.writelen = 0; /* nothing to write yet */
|
||
m.flags = 0; /* no flags yet */
|
||
rsectors = m.stripesectors; /* remaining sectors to examine */
|
||
m.dataoffset = m.initoffset; /* start at the beginning of the transfer */
|
||
m.datalen = m.initlen;
|
||
|
||
if (m.sdcount > 1) {
|
||
plex->multiblock++; /* more than one block for the request */
|
||
/*
|
||
* If we have two transfers that don't overlap,
|
||
* (one at the end of the first block, the other
|
||
* at the beginning of the second block),
|
||
* it's cheaper to split them.
|
||
*/
|
||
if (rsectors < plex->stripesize) {
|
||
m.sdcount = 1; /* just one subdisk */
|
||
m.stripesectors = m.initlen; /* and just this many sectors */
|
||
rsectors = m.initlen; /* and in the loop counter */
|
||
}
|
||
}
|
||
if (SD[plex->sdnos[m.psdno]].state < sd_reborn) /* is our parity subdisk down? */
|
||
m.badsdno = m.psdno; /* note that it's down */
|
||
if (bp->b_iocmd == BIO_READ) { /* read operation */
|
||
for (mysdno = m.firstsdno; rsectors > 0; mysdno++) {
|
||
if (mysdno == m.psdno) /* ignore parity on read */
|
||
mysdno++;
|
||
if (mysdno == plex->subdisks) /* wraparound */
|
||
mysdno = 0;
|
||
if (mysdno == m.psdno) /* parity, */
|
||
mysdno++; /* we've given already */
|
||
|
||
if (SD[plex->sdnos[mysdno]].state < sd_reborn) { /* got a bad subdisk, */
|
||
if (m.badsdno >= 0) /* we had one already, */
|
||
return REQUEST_DOWN; /* we can't take a second */
|
||
m.badsdno = mysdno; /* got the first */
|
||
m.groupoffset = m.dataoffset; /* define the bounds */
|
||
m.grouplen = m.datalen;
|
||
m.flags |= XFR_RECOVERY_READ; /* we need recovery */
|
||
plex->recovered_reads++; /* count another one */
|
||
} else
|
||
m.flags |= XFR_NORMAL_READ; /* normal read */
|
||
|
||
/* Update the pointers for the next block */
|
||
m.dataoffset = 0; /* back to the start of the stripe */
|
||
rsectors -= m.datalen; /* remaining sectors to examine */
|
||
m.datalen = min(rsectors, plex->stripesize); /* amount that will fit in this block */
|
||
}
|
||
} else { /* write operation */
|
||
for (mysdno = m.firstsdno; rsectors > 0; mysdno++) {
|
||
if (mysdno == m.psdno) /* parity stripe, we've dealt with that */
|
||
mysdno++;
|
||
if (mysdno == plex->subdisks) /* wraparound */
|
||
mysdno = 0;
|
||
if (mysdno == m.psdno) /* parity, */
|
||
mysdno++; /* we've given already */
|
||
|
||
sd = &SD[plex->sdnos[mysdno]];
|
||
if (sd->state != sd_up) {
|
||
enum requeststatus s;
|
||
|
||
s = checksdstate(sd, rq, *diskaddr, diskend); /* do we need to change state? */
|
||
if (s && (m.badsdno >= 0)) { /* second bad disk, */
|
||
int sdno;
|
||
/*
|
||
* If the parity disk is down, there's
|
||
* no recovery. We make all involved
|
||
* subdisks stale. Otherwise, we
|
||
* should be able to recover, but it's
|
||
* like pulling teeth. Fix it later.
|
||
*/
|
||
for (sdno = 0; sdno < m.sdcount; sdno++) {
|
||
struct sd *sd = &SD[plex->sdnos[sdno]];
|
||
if (sd->state >= sd_reborn) /* sort of up, */
|
||
set_sd_state(sd->sdno, sd_stale, setstate_force); /* make it stale */
|
||
}
|
||
return s; /* and crap out */
|
||
}
|
||
m.badsdno = mysdno; /* note which one is bad */
|
||
m.flags |= XFR_DEGRADED_WRITE; /* we need recovery */
|
||
plex->degraded_writes++; /* count another one */
|
||
m.groupoffset = m.dataoffset; /* define the bounds */
|
||
m.grouplen = m.datalen;
|
||
} else {
|
||
m.flags |= XFR_NORMAL_WRITE; /* normal write operation */
|
||
if (m.writeoffset > m.dataoffset) { /* move write operation lower */
|
||
m.writelen = max(m.writeoffset + m.writelen,
|
||
m.dataoffset + m.datalen)
|
||
- m.dataoffset;
|
||
m.writeoffset = m.dataoffset;
|
||
} else
|
||
m.writelen = max(m.writeoffset + m.writelen,
|
||
m.dataoffset + m.datalen)
|
||
- m.writeoffset;
|
||
}
|
||
|
||
/* Update the pointers for the next block */
|
||
m.dataoffset = 0; /* back to the start of the stripe */
|
||
rsectors -= m.datalen; /* remaining sectors to examine */
|
||
m.datalen = min(rsectors, plex->stripesize); /* amount that will fit in this block */
|
||
}
|
||
if (m.badsdno == m.psdno) { /* got a bad parity block, */
|
||
struct sd *psd = &SD[plex->sdnos[m.psdno]];
|
||
|
||
if (psd->state == sd_down)
|
||
set_sd_state(psd->sdno, sd_obsolete, setstate_force); /* it's obsolete now */
|
||
else if (psd->state == sd_crashed)
|
||
set_sd_state(psd->sdno, sd_stale, setstate_force); /* it's stale now */
|
||
m.flags &= ~XFR_NORMAL_WRITE; /* this write isn't normal, */
|
||
m.flags |= XFR_PARITYLESS_WRITE; /* it's parityless */
|
||
plex->parityless_writes++; /* count another one */
|
||
}
|
||
}
|
||
|
||
/* reset the initial transfer values */
|
||
m.dataoffset = m.initoffset; /* start at the beginning of the transfer */
|
||
m.datalen = m.initlen;
|
||
|
||
/* decide how many requests we need */
|
||
if (m.flags & (XFR_RECOVERY_READ | XFR_DEGRADED_WRITE))
|
||
/* doing a recovery read or degraded write, */
|
||
m.rqcount = plex->subdisks; /* all subdisks */
|
||
else if (m.flags & XFR_NORMAL_WRITE) /* normal write, */
|
||
m.rqcount = m.sdcount + 1; /* all data blocks and the parity block */
|
||
else /* parityless write or normal read */
|
||
m.rqcount = m.sdcount; /* just the data blocks */
|
||
|
||
/* Part C: build the requests */
|
||
rqg = allocrqg(rq, m.rqcount); /* get a request group */
|
||
if (rqg == NULL) { /* malloc failed */
|
||
bp->b_error = ENOMEM;
|
||
bp->b_ioflags |= BIO_ERROR;
|
||
return REQUEST_ENOMEM;
|
||
}
|
||
rqg->plexno = plexno;
|
||
rqg->flags = m.flags;
|
||
rqno = 0; /* index in the request group */
|
||
|
||
/* 1: PARITY BLOCK */
|
||
/*
|
||
* Are we performing an operation which requires parity? In that case,
|
||
* work out the parameters and define the parity block.
|
||
* XFR_PARITYOP is XFR_NORMAL_WRITE | XFR_RECOVERY_READ | XFR_DEGRADED_WRITE
|
||
*/
|
||
if (m.flags & XFR_PARITYOP) { /* need parity */
|
||
rqe = &rqg->rqe[rqno]; /* point to element */
|
||
sd = &SD[plex->sdnos[m.psdno]]; /* the subdisk in question */
|
||
rqe->rqg = rqg; /* point back to group */
|
||
rqe->flags = (m.flags | XFR_PARITY_BLOCK | XFR_MALLOCED) /* always malloc parity block */
|
||
&~(XFR_NORMAL_READ | XFR_PARITYLESS_WRITE); /* transfer flags without data op stuf */
|
||
setrqebounds(rqe, &m); /* set up the bounds of the transfer */
|
||
rqe->sdno = sd->sdno; /* subdisk number */
|
||
rqe->driveno = sd->driveno;
|
||
if (build_rq_buffer(rqe, plex)) /* build the buffer */
|
||
return REQUEST_ENOMEM; /* can't do it */
|
||
rqe->b.b_iocmd = BIO_READ; /* we must read first */
|
||
m.sdcount++; /* adjust the subdisk count */
|
||
rqno++; /* and point to the next request */
|
||
}
|
||
/*
|
||
* 2: DATA BLOCKS
|
||
* Now build up requests for the blocks required
|
||
* for individual transfers
|
||
*/
|
||
for (mysdno = m.firstsdno; rqno < m.sdcount; mysdno++, rqno++) {
|
||
if (mysdno == m.psdno) /* parity, */
|
||
mysdno++; /* we've given already */
|
||
if (mysdno == plex->subdisks) /* got to the end, */
|
||
mysdno = 0; /* wrap around */
|
||
if (mysdno == m.psdno) /* parity, */
|
||
mysdno++; /* we've given already */
|
||
|
||
rqe = &rqg->rqe[rqno]; /* point to element */
|
||
sd = &SD[plex->sdnos[mysdno]]; /* the subdisk in question */
|
||
rqe->rqg = rqg; /* point to group */
|
||
if (m.flags & XFR_NEEDS_MALLOC) /* we need a malloced buffer first */
|
||
rqe->flags = m.flags | XFR_DATA_BLOCK | XFR_MALLOCED; /* transfer flags */
|
||
else
|
||
rqe->flags = m.flags | XFR_DATA_BLOCK; /* transfer flags */
|
||
if (mysdno == m.badsdno) { /* this is the bad subdisk */
|
||
rqg->badsdno = rqno; /* note which one */
|
||
rqe->flags |= XFR_BAD_SUBDISK; /* note that it's dead */
|
||
/*
|
||
* we can't read or write from/to it,
|
||
* but we don't need to malloc
|
||
*/
|
||
rqe->flags &= ~(XFR_MALLOCED | XFR_NORMAL_READ | XFR_NORMAL_WRITE);
|
||
}
|
||
setrqebounds(rqe, &m); /* set up the bounds of the transfer */
|
||
rqe->useroffset = m.useroffset; /* offset in user buffer */
|
||
rqe->sdno = sd->sdno; /* subdisk number */
|
||
rqe->driveno = sd->driveno;
|
||
if (build_rq_buffer(rqe, plex)) /* build the buffer */
|
||
return REQUEST_ENOMEM; /* can't do it */
|
||
if ((m.flags & XFR_PARITYOP) /* parity operation, */
|
||
&&((m.flags & XFR_BAD_SUBDISK) == 0)) /* and not the bad subdisk, */
|
||
rqe->b.b_iocmd = BIO_READ; /* we must read first */
|
||
|
||
/* Now update pointers for the next block */
|
||
*diskaddr += m.datalen; /* skip past what we've done */
|
||
m.stripesectors -= m.datalen; /* deduct from what's left */
|
||
m.useroffset += m.datalen; /* and move on in the user buffer */
|
||
m.datalen = min(m.stripesectors, plex->stripesize); /* and recalculate */
|
||
m.dataoffset = 0; /* start at the beginning of next block */
|
||
}
|
||
|
||
/*
|
||
* 3: REMAINING BLOCKS FOR RECOVERY
|
||
* Finally, if we have a recovery operation, build
|
||
* up transfers for the other subdisks. Follow the
|
||
* subdisks around until we get to where we started.
|
||
* These requests use only the group parameters.
|
||
*/
|
||
if ((rqno < m.rqcount) /* haven't done them all already */
|
||
&&(m.flags & (XFR_RECOVERY_READ | XFR_DEGRADED_WRITE))) {
|
||
for (; rqno < m.rqcount; rqno++, mysdno++) {
|
||
if (mysdno == m.psdno) /* parity, */
|
||
mysdno++; /* we've given already */
|
||
if (mysdno == plex->subdisks) /* got to the end, */
|
||
mysdno = 0; /* wrap around */
|
||
if (mysdno == m.psdno) /* parity, */
|
||
mysdno++; /* we've given already */
|
||
|
||
rqe = &rqg->rqe[rqno]; /* point to element */
|
||
sd = &SD[plex->sdnos[mysdno]]; /* the subdisk in question */
|
||
rqe->rqg = rqg; /* point to group */
|
||
|
||
rqe->sdoffset = m.sdbase + m.groupoffset; /* start of transfer */
|
||
rqe->dataoffset = 0; /* for tidiness' sake */
|
||
rqe->groupoffset = 0; /* group starts at the beginining */
|
||
rqe->datalen = 0;
|
||
rqe->grouplen = m.grouplen;
|
||
rqe->buflen = m.grouplen;
|
||
rqe->flags = (m.flags | XFR_MALLOCED) /* transfer flags without data op stuf */
|
||
&~XFR_DATAOP;
|
||
rqe->sdno = sd->sdno; /* subdisk number */
|
||
rqe->driveno = sd->driveno;
|
||
if (build_rq_buffer(rqe, plex)) /* build the buffer */
|
||
return REQUEST_ENOMEM; /* can't do it */
|
||
rqe->b.b_iocmd = BIO_READ; /* we must read first */
|
||
}
|
||
}
|
||
/*
|
||
* We need to lock the address range before
|
||
* doing anything. We don't have to be
|
||
* performing a recovery operation: somebody
|
||
* else could be doing so, and the results could
|
||
* influence us. Note the fact here, we'll perform
|
||
* the lock in launch_requests.
|
||
*/
|
||
rqg->lockbase = m.stripebase;
|
||
if (*diskaddr < diskend) /* didn't finish the request on this stripe */
|
||
plex->multistripe++; /* count another one */
|
||
}
|
||
return REQUEST_OK;
|
||
}
|
||
|
||
/*
|
||
* Helper function for rqe5: adjust the bounds of
|
||
* the transfers to minimize the buffer
|
||
* allocation.
|
||
*
|
||
* Each request can handle two of three different
|
||
* data ranges:
|
||
*
|
||
* 1. The range described by the parameters
|
||
* dataoffset and datalen, for normal read or
|
||
* parityless write.
|
||
* 2. The range described by the parameters
|
||
* groupoffset and grouplen, for recovery read
|
||
* and degraded write.
|
||
* 3. For normal write, the range depends on the
|
||
* kind of block. For data blocks, the range
|
||
* is defined by dataoffset and datalen. For
|
||
* parity blocks, it is defined by writeoffset
|
||
* and writelen.
|
||
*
|
||
* In order not to allocate more memory than
|
||
* necessary, this function adjusts the bounds
|
||
* parameter for each request to cover just the
|
||
* minimum necessary for the function it performs.
|
||
* This will normally vary from one request to the
|
||
* next.
|
||
*
|
||
* Things are slightly different for the parity
|
||
* block. In this case, the bounds defined by
|
||
* mp->writeoffset and mp->writelen also play a
|
||
* r<>le. Select this case by setting the
|
||
* parameter forparity != 0.
|
||
*/
|
||
void
|
||
setrqebounds(struct rqelement *rqe, struct metrics *mp)
|
||
{
|
||
/* parity block of a normal write */
|
||
if ((rqe->flags & (XFR_NORMAL_WRITE | XFR_PARITY_BLOCK))
|
||
== (XFR_NORMAL_WRITE | XFR_PARITY_BLOCK)) { /* case 3 */
|
||
if (rqe->flags & XFR_DEGRADED_WRITE) { /* also degraded write */
|
||
/*
|
||
* With a combined normal and degraded write, we
|
||
* will zero out the area of the degraded write
|
||
* in the second phase, so we don't need to read
|
||
* it in. Unfortunately, we need a way to tell
|
||
* build_request_buffer the size of the buffer,
|
||
* and currently that's the length of the read.
|
||
* As a result, we read everything, even the stuff
|
||
* that we're going to nuke.
|
||
* FIXME XXX
|
||
*/
|
||
if (mp->groupoffset < mp->writeoffset) { /* group operation starts lower */
|
||
rqe->sdoffset = mp->sdbase + mp->groupoffset; /* start of transfer */
|
||
rqe->dataoffset = mp->writeoffset - mp->groupoffset; /* data starts here */
|
||
rqe->groupoffset = 0; /* and the group at the beginning */
|
||
} else { /* individual data starts first */
|
||
rqe->sdoffset = mp->sdbase + mp->writeoffset; /* start of transfer */
|
||
rqe->dataoffset = 0; /* individual data starts at the beginning */
|
||
rqe->groupoffset = mp->groupoffset - mp->writeoffset; /* group starts here */
|
||
}
|
||
rqe->datalen = mp->writelen;
|
||
rqe->grouplen = mp->grouplen;
|
||
} else { /* just normal write (case 3) */
|
||
rqe->sdoffset = mp->sdbase + mp->writeoffset; /* start of transfer */
|
||
rqe->dataoffset = 0; /* degradation starts at the beginning */
|
||
rqe->groupoffset = 0; /* for tidiness' sake */
|
||
rqe->datalen = mp->writelen;
|
||
rqe->grouplen = 0;
|
||
}
|
||
} else if (rqe->flags & XFR_DATAOP) { /* data operation (case 1 or 3) */
|
||
if (rqe->flags & XFR_GROUPOP) { /* also a group operation (case 2) */
|
||
if (mp->groupoffset < mp->dataoffset) { /* group operation starts lower */
|
||
rqe->sdoffset = mp->sdbase + mp->groupoffset; /* start of transfer */
|
||
rqe->dataoffset = mp->dataoffset - mp->groupoffset; /* data starts here */
|
||
rqe->groupoffset = 0; /* and the group at the beginning */
|
||
} else { /* individual data starts first */
|
||
rqe->sdoffset = mp->sdbase + mp->dataoffset; /* start of transfer */
|
||
rqe->dataoffset = 0; /* individual data starts at the beginning */
|
||
rqe->groupoffset = mp->groupoffset - mp->dataoffset; /* group starts here */
|
||
}
|
||
rqe->datalen = mp->datalen;
|
||
rqe->grouplen = mp->grouplen;
|
||
} else { /* just data operation (case 1) */
|
||
rqe->sdoffset = mp->sdbase + mp->dataoffset; /* start of transfer */
|
||
rqe->dataoffset = 0; /* degradation starts at the beginning */
|
||
rqe->groupoffset = 0; /* for tidiness' sake */
|
||
rqe->datalen = mp->datalen;
|
||
rqe->grouplen = 0;
|
||
}
|
||
} else { /* just group operations (case 2) */
|
||
rqe->sdoffset = mp->sdbase + mp->groupoffset; /* start of transfer */
|
||
rqe->dataoffset = 0; /* for tidiness' sake */
|
||
rqe->groupoffset = 0; /* group starts at the beginining */
|
||
rqe->datalen = 0;
|
||
rqe->grouplen = mp->grouplen;
|
||
}
|
||
rqe->buflen = max(rqe->dataoffset + rqe->datalen, /* total buffer length */
|
||
rqe->groupoffset + rqe->grouplen);
|
||
}
|
||
/* Local Variables: */
|
||
/* fill-column: 50 */
|
||
/* End: */
|