Import RAID-5 code.
Add Cybernet copyright. OK'd-by: Chuck Jacobus <chuck@cybernet.com>
This commit is contained in:
Greg Lehey
parent
4426dd567f
commit
1943d3438c
|
|
@ -0,0 +1,638 @@
|
|||
/*-
|
||||
* 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: raid5.c,v 1.15 1999/07/07 03:46:01 grog Exp grog $
|
||||
*/
|
||||
/*
|
||||
* XXX To do:
|
||||
*
|
||||
* lock ranges while calculating parity
|
||||
*/
|
||||
|
||||
#include <dev/vinum/vinumhdr.h>
|
||||
#include <dev/vinum/request.h>
|
||||
#include <miscfs/specfs/specdev.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 */
|
||||
|
||||
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 */
|
||||
struct rqelement *prqe = NULL; /* XXX */
|
||||
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 */
|
||||
m.psdno = plex->subdisks - 1 - (*diskaddr / (plex->stripesize * (plex->subdisks - 1))) % plex->subdisks;
|
||||
|
||||
/*
|
||||
* 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_flags & B_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, */
|
||||
/*
|
||||
* XXX be cleverer here. We can still
|
||||
* read what we can read.
|
||||
*/
|
||||
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.
|
||||
*
|
||||
* XXX be cleverer here. We should
|
||||
* still write what we can write.
|
||||
*/
|
||||
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;
|
||||
|
||||
/*
|
||||
* XXX see if we can satisfy a recovery_read from a
|
||||
* different plex. If so, return from here with no requests WRITEME
|
||||
*/
|
||||
|
||||
/* 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_flags |= B_ERROR;
|
||||
bp->b_error = ENOMEM;
|
||||
biodone(bp);
|
||||
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;
|
||||
prqe = rqe; /* debug XXX */
|
||||
if (build_rq_buffer(rqe, plex)) /* build the buffer */
|
||||
return REQUEST_ENOMEM; /* can't do it */
|
||||
rqe->b.b_flags |= B_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 */
|
||||
#if VINUMDEBUG
|
||||
if (prqe
|
||||
&& (rqe->groupoffset + rqe->sdoffset) < prqe->sdoffset) /* XXX */
|
||||
Debugger("Low data block"); /* XXX */
|
||||
#endif
|
||||
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_flags |= B_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) & ~XFR_DATAOP; /* transfer flags without data op stuf */
|
||||
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_flags |= B_READ; /* we must read first */
|
||||
}
|
||||
}
|
||||
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 rôle. 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);
|
||||
}
|
||||
Loading…
Reference in New Issue