/* $NetBSD: subr_disk.c,v 1.52 2003/04/13 09:08:04 dsl Exp $ */ /*- * Copyright (c) 1996, 1997, 1999, 2000 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, * NASA Ames Research Center. * * 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 the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation 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 BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``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 FOUNDATION 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. */ /* * Copyright (c) 1982, 1986, 1988, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * 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 the University of * California, Berkeley and its contributors. * 4. Neither the name of the University 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 BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS 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. * * @(#)ufs_disksubr.c 8.5 (Berkeley) 1/21/94 */ #include __KERNEL_RCSID(0, "$NetBSD: subr_disk.c,v 1.52 2003/04/13 09:08:04 dsl Exp $"); #include "opt_compat_netbsd.h" #include #include #include #include #include #include #include #include #include /* * A global list of all disks attached to the system. May grow or * shrink over time. */ struct disklist_head disklist; /* TAILQ_HEAD */ int disk_count; /* number of drives in global disklist */ struct simplelock disklist_slock = SIMPLELOCK_INITIALIZER; /* * Compute checksum for disk label. */ u_int dkcksum(struct disklabel *lp) { u_short *start, *end; u_short sum = 0; start = (u_short *)lp; end = (u_short *)&lp->d_partitions[lp->d_npartitions]; while (start < end) sum ^= *start++; return (sum); } /* * Disk error is the preface to plaintive error messages * about failing disk transfers. It prints messages of the form hp0g: hard error reading fsbn 12345 of 12344-12347 (hp0 bn %d cn %d tn %d sn %d) * if the offset of the error in the transfer and a disk label * are both available. blkdone should be -1 if the position of the error * is unknown; the disklabel pointer may be null from drivers that have not * been converted to use them. The message is printed with printf * if pri is LOG_PRINTF, otherwise it uses log at the specified priority. * The message should be completed (with at least a newline) with printf * or addlog, respectively. There is no trailing space. */ #ifndef PRIdaddr #define PRIdaddr PRId64 #endif void diskerr(const struct buf *bp, const char *dname, const char *what, int pri, int blkdone, const struct disklabel *lp) { int unit = DISKUNIT(bp->b_dev), part = DISKPART(bp->b_dev); void (*pr)(const char *, ...); char partname = 'a' + part; daddr_t sn; if (/*CONSTCOND*/0) /* Compiler will error this is the format is wrong... */ printf("%" PRIdaddr, bp->b_blkno); if (pri != LOG_PRINTF) { static const char fmt[] = ""; log(pri, fmt); pr = addlog; } else pr = printf; (*pr)("%s%d%c: %s %sing fsbn ", dname, unit, partname, what, bp->b_flags & B_READ ? "read" : "writ"); sn = bp->b_blkno; if (bp->b_bcount <= DEV_BSIZE) (*pr)("%" PRIdaddr, sn); else { if (blkdone >= 0) { sn += blkdone; (*pr)("%" PRIdaddr " of ", sn); } (*pr)("%" PRIdaddr "-%" PRIdaddr "", bp->b_blkno, bp->b_blkno + (bp->b_bcount - 1) / DEV_BSIZE); } if (lp && (blkdone >= 0 || bp->b_bcount <= lp->d_secsize)) { sn += lp->d_partitions[part].p_offset; (*pr)(" (%s%d bn %" PRIdaddr "; cn %" PRIdaddr "", dname, unit, sn, sn / lp->d_secpercyl); sn %= lp->d_secpercyl; (*pr)(" tn %" PRIdaddr " sn %" PRIdaddr ")", sn / lp->d_nsectors, sn % lp->d_nsectors); } } /* * Initialize the disklist. Called by main() before autoconfiguration. */ void disk_init(void) { TAILQ_INIT(&disklist); disk_count = 0; } /* * Searches the disklist for the disk corresponding to the * name provided. */ struct disk * disk_find(char *name) { struct disk *diskp; if ((name == NULL) || (disk_count <= 0)) return (NULL); simple_lock(&disklist_slock); for (diskp = TAILQ_FIRST(&disklist); diskp != NULL; diskp = TAILQ_NEXT(diskp, dk_link)) if (strcmp(diskp->dk_name, name) == 0) { simple_unlock(&disklist_slock); return (diskp); } simple_unlock(&disklist_slock); return (NULL); } /* * Attach a disk. */ void disk_attach(struct disk *diskp) { int s; /* * Allocate and initialize the disklabel structures. Note that * it's not safe to sleep here, since we're probably going to be * called during autoconfiguration. */ diskp->dk_label = malloc(sizeof(struct disklabel), M_DEVBUF, M_NOWAIT); diskp->dk_cpulabel = malloc(sizeof(struct cpu_disklabel), M_DEVBUF, M_NOWAIT); if ((diskp->dk_label == NULL) || (diskp->dk_cpulabel == NULL)) panic("disk_attach: can't allocate storage for disklabel"); memset(diskp->dk_label, 0, sizeof(struct disklabel)); memset(diskp->dk_cpulabel, 0, sizeof(struct cpu_disklabel)); /* * Set the attached timestamp. */ s = splclock(); diskp->dk_attachtime = mono_time; splx(s); /* * Link into the disklist. */ simple_lock(&disklist_slock); TAILQ_INSERT_TAIL(&disklist, diskp, dk_link); simple_unlock(&disklist_slock); ++disk_count; } /* * Detach a disk. */ void disk_detach(struct disk *diskp) { /* * Remove from the disklist. */ if (--disk_count < 0) panic("disk_detach: disk_count < 0"); simple_lock(&disklist_slock); TAILQ_REMOVE(&disklist, diskp, dk_link); simple_unlock(&disklist_slock); /* * Free the space used by the disklabel structures. */ free(diskp->dk_label, M_DEVBUF); free(diskp->dk_cpulabel, M_DEVBUF); } /* * Increment a disk's busy counter. If the counter is going from * 0 to 1, set the timestamp. */ void disk_busy(struct disk *diskp) { int s; /* * XXX We'd like to use something as accurate as microtime(), * but that doesn't depend on the system TOD clock. */ if (diskp->dk_busy++ == 0) { s = splclock(); diskp->dk_timestamp = mono_time; splx(s); } } /* * Decrement a disk's busy counter, increment the byte count, total busy * time, and reset the timestamp. */ void disk_unbusy(struct disk *diskp, long bcount, int read) { int s; struct timeval dv_time, diff_time; if (diskp->dk_busy-- == 0) { printf("%s: dk_busy < 0\n", diskp->dk_name); panic("disk_unbusy"); } s = splclock(); dv_time = mono_time; splx(s); timersub(&dv_time, &diskp->dk_timestamp, &diff_time); timeradd(&diskp->dk_time, &diff_time, &diskp->dk_time); diskp->dk_timestamp = dv_time; if (bcount > 0) { if (read) { diskp->dk_rbytes += bcount; diskp->dk_rxfer++; } else { diskp->dk_wbytes += bcount; diskp->dk_wxfer++; } } } /* * Reset the metrics counters on the given disk. Note that we cannot * reset the busy counter, as it may case a panic in disk_unbusy(). * We also must avoid playing with the timestamp information, as it * may skew any pending transfer results. */ void disk_resetstat(struct disk *diskp) { int s = splbio(), t; diskp->dk_rxfer = 0; diskp->dk_rbytes = 0; diskp->dk_wxfer = 0; diskp->dk_wbytes = 0; t = splclock(); diskp->dk_attachtime = mono_time; splx(t); timerclear(&diskp->dk_time); splx(s); } int sysctl_disknames(void *vwhere, size_t *sizep) { char buf[DK_DISKNAMELEN + 1]; char *where = vwhere; struct disk *diskp; size_t needed, left, slen; int error, first; first = 1; error = 0; needed = 0; left = *sizep; simple_lock(&disklist_slock); for (diskp = TAILQ_FIRST(&disklist); diskp != NULL; diskp = TAILQ_NEXT(diskp, dk_link)) { if (where == NULL) needed += strlen(diskp->dk_name) + 1; else { memset(buf, 0, sizeof(buf)); if (first) { strncpy(buf, diskp->dk_name, sizeof(buf)); first = 0; } else { buf[0] = ' '; strncpy(buf + 1, diskp->dk_name, sizeof(buf) - 1); } buf[DK_DISKNAMELEN] = '\0'; slen = strlen(buf); if (left < slen + 1) break; /* +1 to copy out the trailing NUL byte */ error = copyout(buf, where, slen + 1); if (error) break; where += slen; needed += slen; left -= slen; } } simple_unlock(&disklist_slock); *sizep = needed; return (error); } int sysctl_diskstats(int *name, u_int namelen, void *vwhere, size_t *sizep) { struct disk_sysctl sdisk; struct disk *diskp; char *where = vwhere; size_t tocopy, left; int error; /* * The original hw.diskstats call was broken and did not require * the userland to pass in it's size of struct disk_sysctl. This * was fixed after NetBSD 1.6 was released, and any applications * that do not pass in the size are given an error only, unless * we care about 1.6 compatibility. */ if (namelen == 0) #ifdef COMPAT_16 tocopy = offsetof(struct disk_sysctl, dk_rxfer); #else return (EINVAL); #endif else tocopy = name[0]; if (where == NULL) { *sizep = disk_count * tocopy; return (0); } error = 0; left = *sizep; memset(&sdisk, 0, sizeof(sdisk)); *sizep = 0; simple_lock(&disklist_slock); TAILQ_FOREACH(diskp, &disklist, dk_link) { if (left < tocopy) break; strncpy(sdisk.dk_name, diskp->dk_name, sizeof(sdisk.dk_name)); sdisk.dk_xfer = diskp->dk_rxfer + diskp->dk_wxfer; sdisk.dk_rxfer = diskp->dk_rxfer; sdisk.dk_wxfer = diskp->dk_wxfer; sdisk.dk_seek = diskp->dk_seek; sdisk.dk_bytes = diskp->dk_rbytes + diskp->dk_wbytes; sdisk.dk_rbytes = diskp->dk_rbytes; sdisk.dk_wbytes = diskp->dk_wbytes; sdisk.dk_attachtime_sec = diskp->dk_attachtime.tv_sec; sdisk.dk_attachtime_usec = diskp->dk_attachtime.tv_usec; sdisk.dk_timestamp_sec = diskp->dk_timestamp.tv_sec; sdisk.dk_timestamp_usec = diskp->dk_timestamp.tv_usec; sdisk.dk_time_sec = diskp->dk_time.tv_sec; sdisk.dk_time_usec = diskp->dk_time.tv_usec; sdisk.dk_busy = diskp->dk_busy; error = copyout(&sdisk, where, min(tocopy, sizeof(sdisk))); if (error) break; where += tocopy; *sizep += tocopy; left -= tocopy; } simple_unlock(&disklist_slock); return (error); } struct bufq_fcfs { TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */ }; struct bufq_disksort { TAILQ_HEAD(, buf) bq_head; /* actual list of buffers */ }; #define PRIO_READ_BURST 48 #define PRIO_WRITE_REQ 16 struct bufq_prio { TAILQ_HEAD(, buf) bq_read, bq_write; /* actual list of buffers */ struct buf *bq_write_next; /* next request in bq_write */ struct buf *bq_next; /* current request */ int bq_read_burst; /* # of consecutive reads */ }; /* * Check if two buf's are in ascending order. */ static __inline int buf_inorder(struct buf *bp, struct buf *bq, int sortby) { int r; if (bp == NULL || bq == NULL) return (bq == NULL); if (sortby == BUFQ_SORT_CYLINDER) r = bp->b_cylinder - bq->b_cylinder; else r = 0; if (r == 0) r = bp->b_rawblkno - bq->b_rawblkno; return (r <= 0); } /* * First-come first-served sort for disks. * * Requests are appended to the queue without any reordering. */ static void bufq_fcfs_put(struct bufq_state *bufq, struct buf *bp) { struct bufq_fcfs *fcfs = bufq->bq_private; TAILQ_INSERT_TAIL(&fcfs->bq_head, bp, b_actq); } static struct buf * bufq_fcfs_get(struct bufq_state *bufq, int remove) { struct bufq_fcfs *fcfs = bufq->bq_private; struct buf *bp; bp = TAILQ_FIRST(&fcfs->bq_head); if (bp != NULL && remove) TAILQ_REMOVE(&fcfs->bq_head, bp, b_actq); return (bp); } /* * Seek sort for disks. * * There are actually two queues, sorted in ascendening order. The first * queue holds those requests which are positioned after the current block; * the second holds requests which came in after their position was passed. * Thus we implement a one-way scan, retracting after reaching the end of * the drive to the first request on the second queue, at which time it * becomes the first queue. * * A one-way scan is natural because of the way UNIX read-ahead blocks are * allocated. */ static void bufq_disksort_put(struct bufq_state *bufq, struct buf *bp) { struct bufq_disksort *disksort = bufq->bq_private; struct buf *bq, *nbq; int sortby; sortby = bufq->bq_flags & BUFQ_SORT_MASK; bq = TAILQ_FIRST(&disksort->bq_head); /* * If the queue is empty it's easy; we just go on the end. */ if (bq == NULL) { TAILQ_INSERT_TAIL(&disksort->bq_head, bp, b_actq); return; } /* * If we lie before the currently active request, then we * must locate the second request list and add ourselves to it. */ if (buf_inorder(bp, bq, sortby)) { while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) { /* * Check for an ``inversion'' in the normally ascending * block numbers, indicating the start of the second * request list. */ if (buf_inorder(nbq, bq, sortby)) { /* * Search the second request list for the first * request at a larger block number. We go * after that; if there is no such request, we * go at the end. */ do { if (buf_inorder(bp, nbq, sortby)) goto insert; bq = nbq; } while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL); goto insert; /* after last */ } bq = nbq; } /* * No inversions... we will go after the last, and * be the first request in the second request list. */ goto insert; } /* * Request is at/after the current request... * sort in the first request list. */ while ((nbq = TAILQ_NEXT(bq, b_actq)) != NULL) { /* * We want to go after the current request if there is an * inversion after it (i.e. it is the end of the first * request list), or if the next request is a larger cylinder * than our request. */ if (buf_inorder(nbq, bq, sortby) || buf_inorder(bp, nbq, sortby)) goto insert; bq = nbq; } /* * Neither a second list nor a larger request... we go at the end of * the first list, which is the same as the end of the whole schebang. */ insert: TAILQ_INSERT_AFTER(&disksort->bq_head, bq, bp, b_actq); } static struct buf * bufq_disksort_get(struct bufq_state *bufq, int remove) { struct bufq_disksort *disksort = bufq->bq_private; struct buf *bp; bp = TAILQ_FIRST(&disksort->bq_head); if (bp != NULL && remove) TAILQ_REMOVE(&disksort->bq_head, bp, b_actq); return (bp); } /* * Seek sort for disks. * * There are two queues. The first queue holds read requests; the second * holds write requests. The read queue is first-come first-served; the * write queue is sorted in ascendening block order. * The read queue is processed first. After PRIO_READ_BURST consecutive * read requests with non-empty write queue PRIO_WRITE_REQ requests from * the write queue will be processed. */ static void bufq_prio_put(struct bufq_state *bufq, struct buf *bp) { struct bufq_prio *prio = bufq->bq_private; struct buf *bq; int sortby; sortby = bufq->bq_flags & BUFQ_SORT_MASK; /* * If it's a read request append it to the list. */ if ((bp->b_flags & B_READ) == B_READ) { TAILQ_INSERT_TAIL(&prio->bq_read, bp, b_actq); return; } bq = TAILQ_FIRST(&prio->bq_write); /* * If the write list is empty, simply append it to the list. */ if (bq == NULL) { TAILQ_INSERT_TAIL(&prio->bq_write, bp, b_actq); prio->bq_write_next = bp; return; } /* * If we lie after the next request, insert after this request. */ if (buf_inorder(prio->bq_write_next, bp, sortby)) bq = prio->bq_write_next; /* * Search for the first request at a larger block number. * We go before this request if it exists. */ while (bq != NULL && buf_inorder(bq, bp, sortby)) bq = TAILQ_NEXT(bq, b_actq); if (bq != NULL) TAILQ_INSERT_BEFORE(bq, bp, b_actq); else TAILQ_INSERT_TAIL(&prio->bq_write, bp, b_actq); } static struct buf * bufq_prio_get(struct bufq_state *bufq, int remove) { struct bufq_prio *prio = bufq->bq_private; struct buf *bp; /* * If no current request, get next from the lists. */ if (prio->bq_next == NULL) { /* * If at least one list is empty, select the other. */ if (TAILQ_FIRST(&prio->bq_read) == NULL) { prio->bq_next = prio->bq_write_next; prio->bq_read_burst = 0; } else if (prio->bq_write_next == NULL) { prio->bq_next = TAILQ_FIRST(&prio->bq_read); prio->bq_read_burst = 0; } else { /* * Both list have requests. Select the read list up * to PRIO_READ_BURST times, then select the write * list PRIO_WRITE_REQ times. */ if (prio->bq_read_burst++ < PRIO_READ_BURST) prio->bq_next = TAILQ_FIRST(&prio->bq_read); else if (prio->bq_read_burst < PRIO_READ_BURST + PRIO_WRITE_REQ) prio->bq_next = prio->bq_write_next; else { prio->bq_next = TAILQ_FIRST(&prio->bq_read); prio->bq_read_burst = 0; } } } bp = prio->bq_next; if (bp != NULL && remove) { if ((bp->b_flags & B_READ) == B_READ) TAILQ_REMOVE(&prio->bq_read, bp, b_actq); else { /* * Advance the write pointer before removing * bp since it is actually prio->bq_write_next. */ prio->bq_write_next = TAILQ_NEXT(prio->bq_write_next, b_actq); TAILQ_REMOVE(&prio->bq_write, bp, b_actq); if (prio->bq_write_next == NULL) prio->bq_write_next = TAILQ_FIRST(&prio->bq_write); } prio->bq_next = NULL; } return (bp); } /* * Create a device buffer queue. */ void bufq_alloc(struct bufq_state *bufq, int flags) { struct bufq_fcfs *fcfs; struct bufq_disksort *disksort; struct bufq_prio *prio; bufq->bq_flags = flags; switch (flags & BUFQ_SORT_MASK) { case BUFQ_SORT_RAWBLOCK: case BUFQ_SORT_CYLINDER: break; case 0: if ((flags & BUFQ_METHOD_MASK) == BUFQ_FCFS) break; /* FALLTHROUGH */ default: panic("bufq_alloc: sort out of range"); } switch (flags & BUFQ_METHOD_MASK) { case BUFQ_FCFS: bufq->bq_get = bufq_fcfs_get; bufq->bq_put = bufq_fcfs_put; MALLOC(bufq->bq_private, struct bufq_fcfs *, sizeof(struct bufq_fcfs), M_DEVBUF, M_ZERO); fcfs = (struct bufq_fcfs *)bufq->bq_private; TAILQ_INIT(&fcfs->bq_head); break; case BUFQ_DISKSORT: bufq->bq_get = bufq_disksort_get; bufq->bq_put = bufq_disksort_put; MALLOC(bufq->bq_private, struct bufq_disksort *, sizeof(struct bufq_disksort), M_DEVBUF, M_ZERO); disksort = (struct bufq_disksort *)bufq->bq_private; TAILQ_INIT(&disksort->bq_head); break; case BUFQ_READ_PRIO: bufq->bq_get = bufq_prio_get; bufq->bq_put = bufq_prio_put; MALLOC(bufq->bq_private, struct bufq_prio *, sizeof(struct bufq_prio), M_DEVBUF, M_ZERO); prio = (struct bufq_prio *)bufq->bq_private; TAILQ_INIT(&prio->bq_read); TAILQ_INIT(&prio->bq_write); break; default: panic("bufq_alloc: method out of range"); } } /* * Destroy a device buffer queue. */ void bufq_free(struct bufq_state *bufq) { KASSERT(bufq->bq_private != NULL); KASSERT(BUFQ_PEEK(bufq) == NULL); FREE(bufq->bq_private, M_DEVBUF); bufq->bq_get = NULL; bufq->bq_put = NULL; } /* * Bounds checking against the media size, used for the raw partition. * The sector size passed in should currently always be DEV_BSIZE, * and the media size the size of the device in DEV_BSIZE sectors. */ int bounds_check_with_mediasize(struct buf *bp, int secsize, u_int64_t mediasize) { int sz; sz = howmany(bp->b_bcount, secsize); if (bp->b_blkno + sz > mediasize) { sz = mediasize - bp->b_blkno; if (sz == 0) { /* If exactly at end of disk, return EOF. */ bp->b_resid = bp->b_bcount; goto done; } if (sz < 0) { /* If past end of disk, return EINVAL. */ bp->b_error = EINVAL; goto bad; } /* Otherwise, truncate request. */ bp->b_bcount = sz << DEV_BSHIFT; } return 1; bad: bp->b_flags |= B_ERROR; done: return 0; }