160 lines
7.1 KiB
C
160 lines
7.1 KiB
C
/*-
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* Copyright (c) 1997, 1998
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* Nan Yang Computer Services Limited. All rights reserved.
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*
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* This software is distributed under the so-called ``Berkeley
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* License'':
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Nan Yang Computer
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* Services Limited.
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* 4. Neither the name of the Company nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* This software is provided ``as is'', and any express or implied
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* warranties, including, but not limited to, the implied warranties of
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* merchantability and fitness for a particular purpose are disclaimed.
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* In no event shall the company or contributors be liable for any
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* direct, indirect, incidental, special, exemplary, or consequential
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* damages (including, but not limited to, procurement of substitute
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* goods or services; loss of use, data, or profits; or business
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* interruption) however caused and on any theory of liability, whether
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* in contract, strict liability, or tort (including negligence or
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* otherwise) arising in any way out of the use of this software, even if
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* advised of the possibility of such damage.
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*
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* $Id: request.h,v 1.10 1998/08/03 07:15:26 grog Exp grog $
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*/
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/* Information needed to set up a transfer */
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/* struct buf is surprisingly big (about 300
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* bytes), and it's part of the request, so this
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* value is really important. Most requests
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* don't need more than 2 subrequests per
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* plex. The table is automatically extended if
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* this value is too small. */
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#define RQELTS 2 /* default of 2 requests per transfer */
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enum xferinfo {
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XFR_NORMAL_READ = 1,
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XFR_NORMAL_WRITE = 2, /* write request in normal mode */
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XFR_RECOVERY_READ = 4,
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XFR_DEGRADED_WRITE = 8,
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XFR_PARITYLESS_WRITE = 0x10,
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XFR_NO_PARITY_STRIPE = 0x20, /* parity stripe is not available */
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XFR_DATA_BLOCK = 0x40, /* data block in request */
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XFR_PARITY_BLOCK = 0x80, /* parity block in request */
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XFR_BAD_SUBDISK = 0x100, /* this subdisk is dead */
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XFR_MALLOCED = 0x200, /* this buffer is malloced */
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#if DEBUG
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XFR_PHASE2 = 0x800, /* documentation only: 2nd phase write */
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#endif
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XFR_REVIVECONFLICT = 0x1000, /* possible conflict with a revive operation */
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/* operations that need a parity block */
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XFR_PARITYOP = (XFR_NORMAL_WRITE | XFR_RECOVERY_READ | XFR_DEGRADED_WRITE),
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/* operations that use the group parameters */
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XFR_GROUPOP = (XFR_DEGRADED_WRITE | XFR_RECOVERY_READ),
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/* operations that that use the data parameters */
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XFR_DATAOP = (XFR_NORMAL_READ | XFR_NORMAL_WRITE | XFR_PARITYLESS_WRITE),
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/* operations requiring read before write */
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XFR_RBW = (XFR_NORMAL_WRITE | XFR_DEGRADED_WRITE),
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/* operations that need a malloced buffer */
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XFR_NEEDS_MALLOC = (XFR_NORMAL_WRITE | XFR_RECOVERY_READ | XFR_DEGRADED_WRITE)
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};
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/* Describe one low-level request, part
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* of a high-level request. This is an
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* extended struct buf buffer, and the first
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* element *must* be a struct buf. We pass this structure
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* to the I/O routines instead of a struct buf in oder
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* to be able to locate the high-level request when it
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* completes.
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*
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* All offsets and lengths are in "blocks", i.e. sectors */
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struct rqelement {
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struct buf b; /* buf structure */
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struct rqgroup *rqg; /* pointer to our group */
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/* Information about the transfer */
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daddr_t sdoffset; /* offset in subdisk */
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int useroffset; /* offset in user buffer of normal data */
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/* dataoffset and datalen refer to "individual"
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* data transfers (normal read, parityless write)
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* and also degraded write.
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*
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* groupoffset and grouplen refer to the other
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* "group" operations (normal write, recovery read)
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* Both the offsets are relative to the start of the
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* local buffer */
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int dataoffset; /* offset in buffer of the normal data */
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int groupoffset; /* offset in buffer of group data */
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short datalen; /* length of normal data (sectors) */
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short grouplen; /* length of group data (sectors) */
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short buflen; /* total buffer length to allocate */
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short flags; /* really enum xferinfo (see above) */
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/* Ways to find other components */
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short sdno; /* subdisk number */
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short driveno; /* drive number */
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};
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/* A group of requests built to satisfy a certain
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* component of a user request */
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struct rqgroup {
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struct rqgroup *next; /* pointer to next group */
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struct request *rq; /* pointer to the request */
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short count; /* number of requests in this group */
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short active; /* and number active */
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short plexno; /* index of plex */
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int badsdno; /* index of bad subdisk or -1 */
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enum xferinfo flags; /* description of transfer */
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struct rqelement rqe[0]; /* and the elements of this request */
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};
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/* Describe one high-level request and the
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* work we have to do to satisfy it */
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struct request {
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struct buf *bp; /* pointer to the high-level request */
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int flags;
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union {
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int volno; /* volume index */
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int plexno; /* or plex index */
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} volplex;
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int error; /* current error indication */
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short isplex; /* set if this is a plex request */
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short active; /* number of subrequests still active */
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struct rqgroup *rqg; /* pointer to the first group of requests */
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struct rqgroup *lrqg; /* and to the first group of requests */
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struct request *next; /* link of waiting requests */
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};
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/* Extended buffer header for subdisk I/O. Includes
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* a pointer to the user I/O request. */
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struct sdbuf {
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struct buf b; /* our buffer */
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struct buf *bp; /* and pointer to parent */
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short driveno; /* drive index */
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short sdno; /* and subdisk index */
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};
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/* Values returned by rqe and friends.
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* Be careful with these: they are in order of increasing
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* seriousness. Some routines check for > REQUEST_RECOVERED
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* to indicate a completely failed request. */
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enum requeststatus {
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REQUEST_OK, /* request built OK */
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REQUEST_RECOVERED, /* request OK, but involves RAID5 recovery */
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REQUEST_EOF, /* request failed: outside plex */
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REQUEST_DOWN, /* request failed: subdisk down */
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REQUEST_ENOMEM /* ran out of memory */
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};
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