[unix-history] / sys / ufs / ufs_bmap.c

/*
 * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
 * All rights reserved.
 *
 * 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.
 *
 *	from: @(#)ufs_bmap.c	7.13 (Berkeley) 5/8/91
 *	$Id: ufs_bmap.c,v 1.2 1993/10/16 18:17:51 rgrimes Exp $
 */

#include "param.h"
#include "systm.h"
#include "buf.h"
#include "proc.h"
#include "file.h"
#include "vnode.h"

#include "quota.h"
#include "inode.h"
#include "fs.h"

/*
 * Bmap converts a the logical block number of a file
 * to its physical block number on the disk. The conversion
 * is done by using the logical block number to index into
 * the array of block pointers described by the dinode.
 */
int
bmap(ip, bn, bnp)
	register struct inode *ip;
	register daddr_t bn;
	daddr_t	*bnp;
{
	register struct fs *fs;
	register daddr_t nb;
	struct buf *bp;
	daddr_t *bap;
	int i, j, sh;
	int error;

	if (bn < 0)
		return (EFBIG);
	fs = ip->i_fs;

	/*
	 * The first NDADDR blocks are direct blocks
	 */
	if (bn < NDADDR) {
		nb = ip->i_db[bn];
		if (nb == 0) {
			*bnp = (daddr_t)-1;
			return (0);
		}
		*bnp = fsbtodb(fs, nb);
		return (0);
	}
	/*
	 * Determine the number of levels of indirection.
	 */
	sh = 1;
	bn -= NDADDR;
	for (j = NIADDR; j > 0; j--) {
		sh *= NINDIR(fs);
		if (bn < sh)
			break;
		bn -= sh;
	}
	if (j == 0)
		return (EFBIG);
	/*
	 * Fetch through the indirect blocks.
	 */
	nb = ip->i_ib[NIADDR - j];
	if (nb == 0) {
		*bnp = (daddr_t)-1;
		return (0);
	}
	for (; j <= NIADDR; j++) {
		if (error = bread(ip->i_devvp, fsbtodb(fs, nb),
		    (int)fs->fs_bsize, NOCRED, &bp)) {
			brelse(bp);
			return (error);
		}
		bap = bp->b_un.b_daddr;
		sh /= NINDIR(fs);
		i = (bn / sh) % NINDIR(fs);
		nb = bap[i];
		if (nb == 0) {
			*bnp = (daddr_t)-1;
			brelse(bp);
			return (0);
		}
		brelse(bp);
	}
	*bnp = fsbtodb(fs, nb);
	return (0);
}

/*
 * Balloc defines the structure of file system storage
 * by allocating the physical blocks on a device given
 * the inode and the logical block number in a file.
 */
int
balloc(ip, bn, size, bpp, flags)
	register struct inode *ip;
	register daddr_t bn;
	int size;
	struct buf **bpp;
	int flags;
{
	register struct fs *fs;
	register daddr_t nb;
	struct buf *bp, *nbp;
	struct vnode *vp = ITOV(ip);
	int osize, nsize, i, j, sh, error;
	daddr_t newb, lbn, *bap, pref, blkpref();

	*bpp = (struct buf *)0;
	if (bn < 0)
		return (EFBIG);
	fs = ip->i_fs;

	/*
	 * If the next write will extend the file into a new block,
	 * and the file is currently composed of a fragment
	 * this fragment has to be extended to be a full block.
	 */
	nb = lblkno(fs, ip->i_size);
	if (nb < NDADDR && nb < bn) {
		osize = blksize(fs, ip, nb);
		if (osize < fs->fs_bsize && osize > 0) {
			error = realloccg(ip, nb,
				blkpref(ip, nb, (int)nb, &ip->i_db[0]),
				osize, (int)fs->fs_bsize, &bp);
			if (error)
				return (error);
			ip->i_size = (nb + 1) * fs->fs_bsize;
			vnode_pager_setsize(ITOV(ip), (u_long)ip->i_size);
			ip->i_db[nb] = dbtofsb(fs, bp->b_blkno);
			ip->i_flag |= IUPD|ICHG;
			if (flags & B_SYNC)
				bwrite(bp);
			else
				bawrite(bp);
		}
	}
	/*
	 * The first NDADDR blocks are direct blocks
	 */
	if (bn < NDADDR) {
		nb = ip->i_db[bn];
		if (nb != 0 && ip->i_size >= (bn + 1) * fs->fs_bsize) {
			error = bread(vp, bn, fs->fs_bsize, NOCRED, &bp);
			if (error) {
				brelse(bp);
				return (error);
			}
			*bpp = bp;
			return (0);
		}
		if (nb != 0) {
			/*
			 * Consider need to reallocate a fragment.
			 */
			osize = fragroundup(fs, blkoff(fs, ip->i_size));
			nsize = fragroundup(fs, size);
			if (nsize <= osize) {
				error = bread(vp, bn, osize, NOCRED, &bp);
				if (error) {
					brelse(bp);
					return (error);
				}
			} else {
				error = realloccg(ip, bn,
					blkpref(ip, bn, (int)bn, &ip->i_db[0]),
					osize, nsize, &bp);
				if (error)
					return (error);
			}
		} else {
			if (ip->i_size < (bn + 1) * fs->fs_bsize)
				nsize = fragroundup(fs, size);
			else
				nsize = fs->fs_bsize;
			error = alloc(ip, bn,
				blkpref(ip, bn, (int)bn, &ip->i_db[0]),
				nsize, &newb);
			if (error)
				return (error);
			bp = getblk(vp, bn, nsize);
			bp->b_blkno = fsbtodb(fs, newb);
			if (flags & B_CLRBUF)
				clrbuf(bp);
		}
		ip->i_db[bn] = dbtofsb(fs, bp->b_blkno);
		ip->i_flag |= IUPD|ICHG;
		*bpp = bp;
		return (0);
	}
	/*
	 * Determine the number of levels of indirection.
	 */
	pref = 0;
	sh = 1;
	lbn = bn;
	bn -= NDADDR;
	for (j = NIADDR; j > 0; j--) {
		sh *= NINDIR(fs);
		if (bn < sh)
			break;
		bn -= sh;
	}
	if (j == 0)
		return (EFBIG);
	/*
	 * Fetch the first indirect block allocating if necessary.
	 */
	nb = ip->i_ib[NIADDR - j];
	if (nb == 0) {
		pref = blkpref(ip, lbn, 0, (daddr_t *)0);
	        if (error = alloc(ip, lbn, pref, (int)fs->fs_bsize, &newb))
			return (error);
		nb = newb;
		bp = getblk(ip->i_devvp, fsbtodb(fs, nb), fs->fs_bsize);
		clrbuf(bp);
		/*
		 * Write synchronously so that indirect blocks
		 * never point at garbage.
		 */
		if (error = bwrite(bp)) {
			blkfree(ip, nb, fs->fs_bsize);
			return (error);
		}
		ip->i_ib[NIADDR - j] = nb;
		ip->i_flag |= IUPD|ICHG;
	}
	/*
	 * Fetch through the indirect blocks, allocating as necessary.
	 */
	for (; ; j++) {
		error = bread(ip->i_devvp, fsbtodb(fs, nb),
		    (int)fs->fs_bsize, NOCRED, &bp);
		if (error) {
			brelse(bp);
			return (error);
		}
		bap = bp->b_un.b_daddr;
		sh /= NINDIR(fs);
		i = (bn / sh) % NINDIR(fs);
		nb = bap[i];
		if (j == NIADDR)
			break;
		if (nb != 0) {
			brelse(bp);
			continue;
		}
		if (pref == 0)
			pref = blkpref(ip, lbn, 0, (daddr_t *)0);
		if (error = alloc(ip, lbn, pref, (int)fs->fs_bsize, &newb)) {
			brelse(bp);
			return (error);
		}
		nb = newb;
		nbp = getblk(ip->i_devvp, fsbtodb(fs, nb), fs->fs_bsize);
		clrbuf(nbp);
		/*
		 * Write synchronously so that indirect blocks
		 * never point at garbage.
		 */
		if (error = bwrite(nbp)) {
			blkfree(ip, nb, fs->fs_bsize);
			brelse(bp);
			return (error);
		}
		bap[i] = nb;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write. If this is the first instance of
		 * the delayed write, reassociate the buffer with the
		 * file so it will be written if the file is sync'ed.
		 */
		if (flags & B_SYNC) {
			bwrite(bp);
		} else if (bp->b_flags & B_DELWRI) {
			bdwrite(bp);
		} else {
			bdwrite(bp);
			reassignbuf(bp, vp);
		}
	}
	/*
	 * Get the data block, allocating if necessary.
	 */
	if (nb == 0) {
		pref = blkpref(ip, lbn, i, &bap[0]);
		if (error = alloc(ip, lbn, pref, (int)fs->fs_bsize, &newb)) {
			brelse(bp);
			return (error);
		}
		nb = newb;
		nbp = getblk(vp, lbn, fs->fs_bsize);
		nbp->b_blkno = fsbtodb(fs, nb);
		if (flags & B_CLRBUF)
			clrbuf(nbp);
		bap[i] = nb;
		/*
		 * If required, write synchronously, otherwise use
		 * delayed write. If this is the first instance of
		 * the delayed write, reassociate the buffer with the
		 * file so it will be written if the file is sync'ed.
		 */
		if (flags & B_SYNC) {
			bwrite(bp);
		} else if (bp->b_flags & B_DELWRI) {
			bdwrite(bp);
		} else {
			bdwrite(bp);
			reassignbuf(bp, vp);
		}
		*bpp = nbp;
		return (0);
	}
	brelse(bp);
	if (flags & B_CLRBUF) {
		error = bread(vp, lbn, (int)fs->fs_bsize, NOCRED, &nbp);
		if (error) {
			brelse(nbp);
			return (error);
		}
	} else {
		nbp = getblk(vp, lbn, fs->fs_bsize);
		nbp->b_blkno = fsbtodb(fs, nb);
	}
	*bpp = nbp;
	return (0);
}
Commit	Line	Data
15637ed4 RG	1	/*
	2	* Copyright (c) 1982, 1986, 1989 Regents of the University of California.
	3	* All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. All advertising materials mentioning features or use of this software
	14	* must display the following acknowledgement:
	15	* This product includes software developed by the University of
	16	* California, Berkeley and its contributors.
	17	* 4. Neither the name of the University nor the names of its contributors
	18	* may be used to endorse or promote products derived from this software
	19	* without specific prior written permission.
	20	*
	21	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	22	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	23	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	24	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	25	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	26	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	27	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	28	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	29	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	30	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	31	* SUCH DAMAGE.
	32	*
1eb58e01	33	* from: @(#)ufs_bmap.c 7.13 (Berkeley) 5/8/91
4c45483e	34	* $Id: ufs_bmap.c,v 1.2 1993/10/16 18:17:51 rgrimes Exp $
15637ed4 RG	35	*/
	36
	37	#include "param.h"
	38	#include "systm.h"
	39	#include "buf.h"
	40	#include "proc.h"
	41	#include "file.h"
	42	#include "vnode.h"
	43
	44	#include "quota.h"
	45	#include "inode.h"
	46	#include "fs.h"
	47
	48	/*
	49	* Bmap converts a the logical block number of a file
	50	* to its physical block number on the disk. The conversion
	51	* is done by using the logical block number to index into
	52	* the array of block pointers described by the dinode.
	53	*/
4c45483e	54	int
15637ed4 RG	55	bmap(ip, bn, bnp)
	56	register struct inode *ip;
	57	register daddr_t bn;
	58	daddr_t *bnp;
	59	{
	60	register struct fs *fs;
	61	register daddr_t nb;
	62	struct buf *bp;
	63	daddr_t *bap;
	64	int i, j, sh;
	65	int error;
	66
	67	if (bn < 0)
	68	return (EFBIG);
	69	fs = ip->i_fs;
	70
	71	/*
	72	* The first NDADDR blocks are direct blocks
	73	*/
	74	if (bn < NDADDR) {
	75	nb = ip->i_db[bn];
	76	if (nb == 0) {
	77	*bnp = (daddr_t)-1;
	78	return (0);
	79	}
	80	*bnp = fsbtodb(fs, nb);
	81	return (0);
	82	}
	83	/*
	84	* Determine the number of levels of indirection.
	85	*/
	86	sh = 1;
	87	bn -= NDADDR;
	88	for (j = NIADDR; j > 0; j--) {
	89	sh *= NINDIR(fs);
	90	if (bn < sh)
	91	break;
	92	bn -= sh;
	93	}
	94	if (j == 0)
	95	return (EFBIG);
	96	/*
	97	* Fetch through the indirect blocks.
	98	*/
	99	nb = ip->i_ib[NIADDR - j];
	100	if (nb == 0) {
	101	*bnp = (daddr_t)-1;
	102	return (0);
	103	}
	104	for (; j <= NIADDR; j++) {
	105	if (error = bread(ip->i_devvp, fsbtodb(fs, nb),
	106	(int)fs->fs_bsize, NOCRED, &bp)) {
	107	brelse(bp);
	108	return (error);
	109	}
	110	bap = bp->b_un.b_daddr;
	111	sh /= NINDIR(fs);
	112	i = (bn / sh) % NINDIR(fs);
	113	nb = bap[i];
	114	if (nb == 0) {
	115	*bnp = (daddr_t)-1;
	116	brelse(bp);
	117	return (0);
	118	}
119	brelse(bp);
120	}
121	*bnp = fsbtodb(fs, nb);
122	return (0);
123	}
124
125	/*
126	* Balloc defines the structure of file system storage
127	* by allocating the physical blocks on a device given
128	* the inode and the logical block number in a file.
129	*/
4c45483e	130	int
15637ed4 RG	131	balloc(ip, bn, size, bpp, flags)
	132	register struct inode *ip;
	133	register daddr_t bn;
	134	int size;
	135	struct buf **bpp;
	136	int flags;
	137	{
	138	register struct fs *fs;
	139	register daddr_t nb;
	140	struct buf bp, nbp;
	141	struct vnode *vp = ITOV(ip);
	142	int osize, nsize, i, j, sh, error;
	143	daddr_t newb, lbn, *bap, pref, blkpref();
	144
	145	bpp = (struct buf )0;
	146	if (bn < 0)
	147	return (EFBIG);
	148	fs = ip->i_fs;
	149
	150	/*
	151	* If the next write will extend the file into a new block,
	152	* and the file is currently composed of a fragment
	153	* this fragment has to be extended to be a full block.
	154	*/
	155	nb = lblkno(fs, ip->i_size);
	156	if (nb < NDADDR && nb < bn) {
	157	osize = blksize(fs, ip, nb);
	158	if (osize < fs->fs_bsize && osize > 0) {
	159	error = realloccg(ip, nb,
	160	blkpref(ip, nb, (int)nb, &ip->i_db[0]),
	161	osize, (int)fs->fs_bsize, &bp);
	162	if (error)
	163	return (error);
	164	ip->i_size = (nb + 1) * fs->fs_bsize;
	165	vnode_pager_setsize(ITOV(ip), (u_long)ip->i_size);
	166	ip->i_db[nb] = dbtofsb(fs, bp->b_blkno);
	167	ip->i_flag \|= IUPD\|ICHG;
	168	if (flags & B_SYNC)
	169	bwrite(bp);
	170	else
	171	bawrite(bp);
	172	}
	173	}
	174	/*
	175	* The first NDADDR blocks are direct blocks
	176	*/
	177	if (bn < NDADDR) {
	178	nb = ip->i_db[bn];
	179	if (nb != 0 && ip->i_size >= (bn + 1) * fs->fs_bsize) {
	180	error = bread(vp, bn, fs->fs_bsize, NOCRED, &bp);
	181	if (error) {
	182	brelse(bp);
	183	return (error);
	184	}
	185	*bpp = bp;
	186	return (0);
	187	}
	188	if (nb != 0) {
	189	/*
	190	* Consider need to reallocate a fragment.
	191	*/
	192	osize = fragroundup(fs, blkoff(fs, ip->i_size));
	193	nsize = fragroundup(fs, size);
	194	if (nsize <= osize) {
195	error = bread(vp, bn, osize, NOCRED, &bp);
196	if (error) {
197	brelse(bp);
198	return (error);
199	}
200	} else {
201	error = realloccg(ip, bn,
202	blkpref(ip, bn, (int)bn, &ip->i_db[0]),
203	osize, nsize, &bp);
204	if (error)
205	return (error);
206	}
207	} else {
208	if (ip->i_size < (bn + 1) * fs->fs_bsize)
209	nsize = fragroundup(fs, size);
210	else
211	nsize = fs->fs_bsize;
212	error = alloc(ip, bn,
213	blkpref(ip, bn, (int)bn, &ip->i_db[0]),
214	nsize, &newb);
215	if (error)
216	return (error);
217	bp = getblk(vp, bn, nsize);
218	bp->b_blkno = fsbtodb(fs, newb);
219	if (flags & B_CLRBUF)
220	clrbuf(bp);
221	}
222	ip->i_db[bn] = dbtofsb(fs, bp->b_blkno);
223	ip->i_flag \|= IUPD\|ICHG;
224	*bpp = bp;
225	return (0);
226	}
227	/*
228	* Determine the number of levels of indirection.
229	*/
230	pref = 0;
231	sh = 1;
232	lbn = bn;
233	bn -= NDADDR;
234	for (j = NIADDR; j > 0; j--) {
235	sh *= NINDIR(fs);
236	if (bn < sh)
237	break;
238	bn -= sh;
239	}
240	if (j == 0)
241	return (EFBIG);
242	/*
243	* Fetch the first indirect block allocating if necessary.
244	*/
245	nb = ip->i_ib[NIADDR - j];
246	if (nb == 0) {
247	pref = blkpref(ip, lbn, 0, (daddr_t *)0);
248	if (error = alloc(ip, lbn, pref, (int)fs->fs_bsize, &newb))
249	return (error);
250	nb = newb;
251	bp = getblk(ip->i_devvp, fsbtodb(fs, nb), fs->fs_bsize);
252	clrbuf(bp);
253	/*
254	* Write synchronously so that indirect blocks
255	* never point at garbage.
256	*/
257	if (error = bwrite(bp)) {
258	blkfree(ip, nb, fs->fs_bsize);
259	return (error);
260	}
261	ip->i_ib[NIADDR - j] = nb;
262	ip->i_flag \|= IUPD\|ICHG;
263	}
264	/*
265	* Fetch through the indirect blocks, allocating as necessary.
266	*/
267	for (; ; j++) {
268	error = bread(ip->i_devvp, fsbtodb(fs, nb),
269	(int)fs->fs_bsize, NOCRED, &bp);
270	if (error) {
271	brelse(bp);
272	return (error);
273	}
274	bap = bp->b_un.b_daddr;
275	sh /= NINDIR(fs);
276	i = (bn / sh) % NINDIR(fs);
277	nb = bap[i];
278	if (j == NIADDR)
279	break;
280	if (nb != 0) {
281	brelse(bp);
282	continue;
283	}
284	if (pref == 0)
285	pref = blkpref(ip, lbn, 0, (daddr_t *)0);
286	if (error = alloc(ip, lbn, pref, (int)fs->fs_bsize, &newb)) {
287	brelse(bp);
288	return (error);
289	}
290	nb = newb;
291	nbp = getblk(ip->i_devvp, fsbtodb(fs, nb), fs->fs_bsize);
292	clrbuf(nbp);
293	/*
294	* Write synchronously so that indirect blocks
295	* never point at garbage.
296	*/
297	if (error = bwrite(nbp)) {
298	blkfree(ip, nb, fs->fs_bsize);
299	brelse(bp);
300	return (error);
301	}
302	bap[i] = nb;
303	/*
304	* If required, write synchronously, otherwise use
305	* delayed write. If this is the first instance of
306	* the delayed write, reassociate the buffer with the
307	* file so it will be written if the file is sync'ed.
308	*/
309	if (flags & B_SYNC) {
310	bwrite(bp);
311	} else if (bp->b_flags & B_DELWRI) {
312	bdwrite(bp);
313	} else {
314	bdwrite(bp);
315	reassignbuf(bp, vp);
316	}
317	}
318	/*
319	* Get the data block, allocating if necessary.
320	*/
321	if (nb == 0) {
322	pref = blkpref(ip, lbn, i, &bap[0]);
323	if (error = alloc(ip, lbn, pref, (int)fs->fs_bsize, &newb)) {
324	brelse(bp);
325	return (error);
326	}
327	nb = newb;
328	nbp = getblk(vp, lbn, fs->fs_bsize);
329	nbp->b_blkno = fsbtodb(fs, nb);
330	if (flags & B_CLRBUF)
331	clrbuf(nbp);
332	bap[i] = nb;
333	/*
334	* If required, write synchronously, otherwise use
335	* delayed write. If this is the first instance of
336	* the delayed write, reassociate the buffer with the
337	* file so it will be written if the file is sync'ed.
338	*/
339	if (flags & B_SYNC) {
340	bwrite(bp);
341	} else if (bp->b_flags & B_DELWRI) {
342	bdwrite(bp);
343	} else {
344	bdwrite(bp);
345	reassignbuf(bp, vp);
346	}
347	*bpp = nbp;
348	return (0);
349	}
350	brelse(bp);
351	if (flags & B_CLRBUF) {
352	error = bread(vp, lbn, (int)fs->fs_bsize, NOCRED, &nbp);
353	if (error) {
354	brelse(nbp);
355	return (error);
356	}
357	} else {
358	nbp = getblk(vp, lbn, fs->fs_bsize);
359	nbp->b_blkno = fsbtodb(fs, nb);
360	}
361	*bpp = nbp;
362	return (0);
363	}