[mirror_zfs.git] / module / os / freebsd / zfs / dmu_os.c

/*
 * Copyright (c) 2020 iXsystems, Inc.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS 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 AUTHORS 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.
 *
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/types.h>
#include <sys/param.h>
#include <sys/dmu.h>
#include <sys/dmu_impl.h>
#include <sys/dmu_tx.h>
#include <sys/dbuf.h>
#include <sys/dnode.h>
#include <sys/zfs_context.h>
#include <sys/dmu_objset.h>
#include <sys/dmu_traverse.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_synctask.h>
#include <sys/dsl_prop.h>
#include <sys/dmu_zfetch.h>
#include <sys/zfs_ioctl.h>
#include <sys/zap.h>
#include <sys/zio_checksum.h>
#include <sys/zio_compress.h>
#include <sys/sa.h>
#include <sys/zfeature.h>
#include <sys/abd.h>
#include <sys/zfs_rlock.h>
#include <sys/racct.h>
#include <sys/vm.h>
#include <sys/zfs_znode.h>
#include <sys/zfs_vnops.h>

#include <sys/ccompat.h>

#ifndef IDX_TO_OFF
#define	IDX_TO_OFF(idx) (((vm_ooffset_t)(idx)) << PAGE_SHIFT)
#endif

#if  __FreeBSD_version < 1300051
#define	VM_ALLOC_BUSY_FLAGS VM_ALLOC_NOBUSY
#else
#define	VM_ALLOC_BUSY_FLAGS  VM_ALLOC_SBUSY | VM_ALLOC_IGN_SBUSY
#endif


#if __FreeBSD_version < 1300072
#define	dmu_page_lock(m)	vm_page_lock(m)
#define	dmu_page_unlock(m)	vm_page_unlock(m)
#else
#define	dmu_page_lock(m)
#define	dmu_page_unlock(m)
#endif

static int
dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
    uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp)
{
	dnode_t *dn;
	int err;

	err = dnode_hold(os, object, FTAG, &dn);
	if (err)
		return (err);

	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
	    numbufsp, dbpp, DMU_READ_PREFETCH);

	dnode_rele(dn, FTAG);

	return (err);
}

int
dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
    vm_page_t *ma, dmu_tx_t *tx)
{
	dmu_buf_t **dbp;
	struct sf_buf *sf;
	int numbufs, i;
	int err;

	if (size == 0)
		return (0);

	err = dmu_buf_hold_array(os, object, offset, size,
	    FALSE, FTAG, &numbufs, &dbp);
	if (err)
		return (err);

	for (i = 0; i < numbufs; i++) {
		int tocpy, copied, thiscpy;
		int bufoff;
		dmu_buf_t *db = dbp[i];
		caddr_t va;

		ASSERT(size > 0);
		ASSERT3U(db->db_size, >=, PAGESIZE);

		bufoff = offset - db->db_offset;
		tocpy = (int)MIN(db->db_size - bufoff, size);

		ASSERT(i == 0 || i == numbufs-1 || tocpy == db->db_size);

		if (tocpy == db->db_size)
			dmu_buf_will_fill(db, tx);
		else
			dmu_buf_will_dirty(db, tx);

		for (copied = 0; copied < tocpy; copied += PAGESIZE) {
			ASSERT3U(ptoa((*ma)->pindex), ==,
			    db->db_offset + bufoff);
			thiscpy = MIN(PAGESIZE, tocpy - copied);
			va = zfs_map_page(*ma, &sf);
			bcopy(va, (char *)db->db_data + bufoff, thiscpy);
			zfs_unmap_page(sf);
			ma += 1;
			bufoff += PAGESIZE;
		}

		if (tocpy == db->db_size)
			dmu_buf_fill_done(db, tx);

		offset += tocpy;
		size -= tocpy;
	}
	dmu_buf_rele_array(dbp, numbufs, FTAG);
	return (err);
}

int
dmu_read_pages(objset_t *os, uint64_t object, vm_page_t *ma, int count,
    int *rbehind, int *rahead, int last_size)
{
	struct sf_buf *sf;
	vm_object_t vmobj;
	vm_page_t m;
	dmu_buf_t **dbp;
	dmu_buf_t *db;
	caddr_t va;
	int numbufs, i;
	int bufoff, pgoff, tocpy;
	int mi, di;
	int err;

	ASSERT3U(ma[0]->pindex + count - 1, ==, ma[count - 1]->pindex);
	ASSERT(last_size <= PAGE_SIZE);

	err = dmu_buf_hold_array(os, object, IDX_TO_OFF(ma[0]->pindex),
	    IDX_TO_OFF(count - 1) + last_size, TRUE, FTAG, &numbufs, &dbp);
	if (err != 0)
		return (err);

#ifdef ZFS_DEBUG
	IMPLY(last_size < PAGE_SIZE, *rahead == 0);
	if (dbp[0]->db_offset != 0 || numbufs > 1) {
		for (i = 0; i < numbufs; i++) {
			ASSERT(ISP2(dbp[i]->db_size));
			ASSERT((dbp[i]->db_offset % dbp[i]->db_size) == 0);
			ASSERT3U(dbp[i]->db_size, ==, dbp[0]->db_size);
		}
	}
#endif

	vmobj = ma[0]->object;
	zfs_vmobject_wlock_12(vmobj);

	db = dbp[0];
	for (i = 0; i < *rbehind; i++) {
		m = vm_page_grab_unlocked(vmobj, ma[0]->pindex - 1 - i,
		    VM_ALLOC_NORMAL | VM_ALLOC_NOWAIT | VM_ALLOC_BUSY_FLAGS);
		if (m == NULL)
			break;
		if (!vm_page_none_valid(m)) {
			ASSERT3U(m->valid, ==, VM_PAGE_BITS_ALL);
			vm_page_do_sunbusy(m);
			break;
		}
		ASSERT(m->dirty == 0);
		ASSERT(!pmap_page_is_write_mapped(m));

		ASSERT(db->db_size > PAGE_SIZE);
		bufoff = IDX_TO_OFF(m->pindex) % db->db_size;
		va = zfs_map_page(m, &sf);
		bcopy((char *)db->db_data + bufoff, va, PAGESIZE);
		zfs_unmap_page(sf);
		vm_page_valid(m);
		dmu_page_lock(m);
		if ((m->busy_lock & VPB_BIT_WAITERS) != 0)
			vm_page_activate(m);
		else
			vm_page_deactivate(m);
		dmu_page_unlock(m);
		vm_page_do_sunbusy(m);
	}
	*rbehind = i;

	bufoff = IDX_TO_OFF(ma[0]->pindex) % db->db_size;
	pgoff = 0;
	for (mi = 0, di = 0; mi < count && di < numbufs; ) {
		if (pgoff == 0) {
			m = ma[mi];
			if (m != bogus_page) {
				vm_page_assert_xbusied(m);
				ASSERT(vm_page_none_valid(m));
				ASSERT(m->dirty == 0);
				ASSERT(!pmap_page_is_write_mapped(m));
				va = zfs_map_page(m, &sf);
			}
		}
		if (bufoff == 0)
			db = dbp[di];

		if (m != bogus_page) {
			ASSERT3U(IDX_TO_OFF(m->pindex) + pgoff, ==,
			    db->db_offset + bufoff);
		}

		/*
		 * We do not need to clamp the copy size by the file
		 * size as the last block is zero-filled beyond the
		 * end of file anyway.
		 */
		tocpy = MIN(db->db_size - bufoff, PAGESIZE - pgoff);
		if (m != bogus_page)
			bcopy((char *)db->db_data + bufoff, va + pgoff, tocpy);

		pgoff += tocpy;
		ASSERT(pgoff <= PAGESIZE);
		if (pgoff == PAGESIZE) {
			if (m != bogus_page) {
				zfs_unmap_page(sf);
				vm_page_valid(m);
			}
			ASSERT(mi < count);
			mi++;
			pgoff = 0;
		}

		bufoff += tocpy;
		ASSERT(bufoff <= db->db_size);
		if (bufoff == db->db_size) {
			ASSERT(di < numbufs);
			di++;
			bufoff = 0;
		}
	}

#ifdef ZFS_DEBUG
	/*
	 * Three possibilities:
	 * - last requested page ends at a buffer boundary and , thus,
	 *   all pages and buffers have been iterated;
	 * - all requested pages are filled, but the last buffer
	 *   has not been exhausted;
	 *   the read-ahead is possible only in this case;
	 * - all buffers have been read, but the last page has not been
	 *   fully filled;
	 *   this is only possible if the file has only a single buffer
	 *   with a size that is not a multiple of the page size.
	 */
	if (mi == count) {
		ASSERT(di >= numbufs - 1);
		IMPLY(*rahead != 0, di == numbufs - 1);
		IMPLY(*rahead != 0, bufoff != 0);
		ASSERT(pgoff == 0);
	}
	if (di == numbufs) {
		ASSERT(mi >= count - 1);
		ASSERT(*rahead == 0);
		IMPLY(pgoff == 0, mi == count);
		if (pgoff != 0) {
			ASSERT(mi == count - 1);
			ASSERT((dbp[0]->db_size & PAGE_MASK) != 0);
		}
	}
#endif
	if (pgoff != 0) {
		ASSERT(m != bogus_page);
		bzero(va + pgoff, PAGESIZE - pgoff);
		zfs_unmap_page(sf);
		vm_page_valid(m);
	}

	for (i = 0; i < *rahead; i++) {
		m = vm_page_grab_unlocked(vmobj, ma[count - 1]->pindex + 1 + i,
		    VM_ALLOC_NORMAL | VM_ALLOC_NOWAIT | VM_ALLOC_BUSY_FLAGS);
		if (m == NULL)
			break;
		if (!vm_page_none_valid(m)) {
			ASSERT3U(m->valid, ==, VM_PAGE_BITS_ALL);
			vm_page_do_sunbusy(m);
			break;
		}
		ASSERT(m->dirty == 0);
		ASSERT(!pmap_page_is_mapped(m));

		ASSERT(db->db_size > PAGE_SIZE);
		bufoff = IDX_TO_OFF(m->pindex) % db->db_size;
		tocpy = MIN(db->db_size - bufoff, PAGESIZE);
		va = zfs_map_page(m, &sf);
		bcopy((char *)db->db_data + bufoff, va, tocpy);
		if (tocpy < PAGESIZE) {
			ASSERT(i == *rahead - 1);
			ASSERT((db->db_size & PAGE_MASK) != 0);
			bzero(va + tocpy, PAGESIZE - tocpy);
		}
		zfs_unmap_page(sf);
		vm_page_valid(m);
		dmu_page_lock(m);
		if ((m->busy_lock & VPB_BIT_WAITERS) != 0)
			vm_page_activate(m);
		else
			vm_page_deactivate(m);
		dmu_page_unlock(m);
		vm_page_do_sunbusy(m);
	}
	*rahead = i;
	zfs_vmobject_wunlock_12(vmobj);

	dmu_buf_rele_array(dbp, numbufs, FTAG);
	return (0);
}
Commit	Line	Data
9f0a21e6 MM	1	/*
	2	* Copyright (c) 2020 iXsystems, Inc.
	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	*
	14	* THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
	15	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	16	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	17	* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
	18	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	19	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	20	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	21	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	22	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	23	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	24	* SUCH DAMAGE.
	25	*
	26	*/
	27
	28	#include <sys/cdefs.h>
	29	__FBSDID("$FreeBSD$");
	30
e64cc495 MM	31	#include <sys/types.h>
e64cc495 MM	32	#include <sys/param.h>
9f0a21e6 MM	33	#include <sys/dmu.h>
	34	#include <sys/dmu_impl.h>
	35	#include <sys/dmu_tx.h>
	36	#include <sys/dbuf.h>
	37	#include <sys/dnode.h>
	38	#include <sys/zfs_context.h>
	39	#include <sys/dmu_objset.h>
	40	#include <sys/dmu_traverse.h>
	41	#include <sys/dsl_dataset.h>
	42	#include <sys/dsl_dir.h>
	43	#include <sys/dsl_pool.h>
	44	#include <sys/dsl_synctask.h>
	45	#include <sys/dsl_prop.h>
	46	#include <sys/dmu_zfetch.h>
	47	#include <sys/zfs_ioctl.h>
	48	#include <sys/zap.h>
	49	#include <sys/zio_checksum.h>
	50	#include <sys/zio_compress.h>
	51	#include <sys/sa.h>
	52	#include <sys/zfeature.h>
	53	#include <sys/abd.h>
	54	#include <sys/zfs_rlock.h>
	55	#include <sys/racct.h>
	56	#include <sys/vm.h>
	57	#include <sys/zfs_znode.h>
	58	#include <sys/zfs_vnops.h>
	59
e64cc495	60	#include <sys/ccompat.h>
9f0a21e6 MM	61
	62	#ifndef IDX_TO_OFF
	63	#define IDX_TO_OFF(idx) (((vm_ooffset_t)(idx)) << PAGE_SHIFT)
	64	#endif
	65
	66	#if __FreeBSD_version < 1300051
	67	#define VM_ALLOC_BUSY_FLAGS VM_ALLOC_NOBUSY
	68	#else
	69	#define VM_ALLOC_BUSY_FLAGS VM_ALLOC_SBUSY \| VM_ALLOC_IGN_SBUSY
	70	#endif
	71
	72
	73	#if __FreeBSD_version < 1300072
	74	#define dmu_page_lock(m) vm_page_lock(m)
	75	#define dmu_page_unlock(m) vm_page_unlock(m)
	76	#else
	77	#define dmu_page_lock(m)
	78	#define dmu_page_unlock(m)
	79	#endif
	80
	81	static int
	82	dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
	83	uint64_t length, int read, void tag, int numbufsp, dmu_buf_t ***dbpp)
	84	{
	85	dnode_t *dn;
	86	int err;
	87
	88	err = dnode_hold(os, object, FTAG, &dn);
	89	if (err)
	90	return (err);
	91
	92	err = dmu_buf_hold_array_by_dnode(dn, offset, length, read, tag,
	93	numbufsp, dbpp, DMU_READ_PREFETCH);
	94
	95	dnode_rele(dn, FTAG);
	96
	97	return (err);
	98	}
	99
	100	int
	101	dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
	102	vm_page_t ma, dmu_tx_t tx)
	103	{
	104	dmu_buf_t **dbp;
	105	struct sf_buf *sf;
	106	int numbufs, i;
	107	int err;
	108
	109	if (size == 0)
	110	return (0);
	111
	112	err = dmu_buf_hold_array(os, object, offset, size,
	113	FALSE, FTAG, &numbufs, &dbp);
	114	if (err)
	115	return (err);
	116
	117	for (i = 0; i < numbufs; i++) {
	118	int tocpy, copied, thiscpy;
	119	int bufoff;
	120	dmu_buf_t *db = dbp[i];
	121	caddr_t va;
	122
	123	ASSERT(size > 0);
	124	ASSERT3U(db->db_size, >=, PAGESIZE);
125
126	bufoff = offset - db->db_offset;
127	tocpy = (int)MIN(db->db_size - bufoff, size);
128
129	ASSERT(i == 0 \|\| i == numbufs-1 \|\| tocpy == db->db_size);
130
131	if (tocpy == db->db_size)
132	dmu_buf_will_fill(db, tx);
133	else
134	dmu_buf_will_dirty(db, tx);
135
136	for (copied = 0; copied < tocpy; copied += PAGESIZE) {
137	ASSERT3U(ptoa((*ma)->pindex), ==,
138	db->db_offset + bufoff);
139	thiscpy = MIN(PAGESIZE, tocpy - copied);
140	va = zfs_map_page(*ma, &sf);
141	bcopy(va, (char *)db->db_data + bufoff, thiscpy);
142	zfs_unmap_page(sf);
143	ma += 1;
144	bufoff += PAGESIZE;
145	}
146
147	if (tocpy == db->db_size)
148	dmu_buf_fill_done(db, tx);
149
150	offset += tocpy;
151	size -= tocpy;
152	}
153	dmu_buf_rele_array(dbp, numbufs, FTAG);
154	return (err);
155	}
156
157	int
158	dmu_read_pages(objset_t os, uint64_t object, vm_page_t ma, int count,
159	int rbehind, int rahead, int last_size)
160	{
161	struct sf_buf *sf;
162	vm_object_t vmobj;
163	vm_page_t m;
164	dmu_buf_t **dbp;
165	dmu_buf_t *db;
166	caddr_t va;
167	int numbufs, i;
168	int bufoff, pgoff, tocpy;
169	int mi, di;
170	int err;
171
172	ASSERT3U(ma[0]->pindex + count - 1, ==, ma[count - 1]->pindex);
173	ASSERT(last_size <= PAGE_SIZE);
174
175	err = dmu_buf_hold_array(os, object, IDX_TO_OFF(ma[0]->pindex),
176	IDX_TO_OFF(count - 1) + last_size, TRUE, FTAG, &numbufs, &dbp);
177	if (err != 0)
178	return (err);
179
6d8da841	180	#ifdef ZFS_DEBUG
9f0a21e6 MM	181	IMPLY(last_size < PAGE_SIZE, *rahead == 0);
	182	if (dbp[0]->db_offset != 0 \|\| numbufs > 1) {
	183	for (i = 0; i < numbufs; i++) {
	184	ASSERT(ISP2(dbp[i]->db_size));
	185	ASSERT((dbp[i]->db_offset % dbp[i]->db_size) == 0);
	186	ASSERT3U(dbp[i]->db_size, ==, dbp[0]->db_size);
	187	}
	188	}
	189	#endif
	190
	191	vmobj = ma[0]->object;
c614fd6e	192	zfs_vmobject_wlock_12(vmobj);
9f0a21e6 MM	193
	194	db = dbp[0];
	195	for (i = 0; i < *rbehind; i++) {
c614fd6e	196	m = vm_page_grab_unlocked(vmobj, ma[0]->pindex - 1 - i,
9f0a21e6 MM	197	VM_ALLOC_NORMAL \| VM_ALLOC_NOWAIT \| VM_ALLOC_BUSY_FLAGS);
	198	if (m == NULL)
	199	break;
	200	if (!vm_page_none_valid(m)) {
	201	ASSERT3U(m->valid, ==, VM_PAGE_BITS_ALL);
	202	vm_page_do_sunbusy(m);
	203	break;
	204	}
	205	ASSERT(m->dirty == 0);
c614fd6e	206	ASSERT(!pmap_page_is_write_mapped(m));
9f0a21e6 MM	207
	208	ASSERT(db->db_size > PAGE_SIZE);
	209	bufoff = IDX_TO_OFF(m->pindex) % db->db_size;
	210	va = zfs_map_page(m, &sf);
	211	bcopy((char *)db->db_data + bufoff, va, PAGESIZE);
	212	zfs_unmap_page(sf);
	213	vm_page_valid(m);
	214	dmu_page_lock(m);
	215	if ((m->busy_lock & VPB_BIT_WAITERS) != 0)
	216	vm_page_activate(m);
	217	else
	218	vm_page_deactivate(m);
	219	dmu_page_unlock(m);
	220	vm_page_do_sunbusy(m);
	221	}
	222	*rbehind = i;
	223
	224	bufoff = IDX_TO_OFF(ma[0]->pindex) % db->db_size;
	225	pgoff = 0;
	226	for (mi = 0, di = 0; mi < count && di < numbufs; ) {
	227	if (pgoff == 0) {
	228	m = ma[mi];
	229	if (m != bogus_page) {
	230	vm_page_assert_xbusied(m);
	231	ASSERT(vm_page_none_valid(m));
	232	ASSERT(m->dirty == 0);
c614fd6e	233	ASSERT(!pmap_page_is_write_mapped(m));
9f0a21e6 MM	234	va = zfs_map_page(m, &sf);
	235	}
	236	}
	237	if (bufoff == 0)
	238	db = dbp[di];
	239
	240	if (m != bogus_page) {
	241	ASSERT3U(IDX_TO_OFF(m->pindex) + pgoff, ==,
	242	db->db_offset + bufoff);
	243	}
	244
	245	/*
	246	* We do not need to clamp the copy size by the file
	247	* size as the last block is zero-filled beyond the
	248	* end of file anyway.
	249	*/
	250	tocpy = MIN(db->db_size - bufoff, PAGESIZE - pgoff);
	251	if (m != bogus_page)
	252	bcopy((char *)db->db_data + bufoff, va + pgoff, tocpy);
	253
	254	pgoff += tocpy;
	255	ASSERT(pgoff <= PAGESIZE);
	256	if (pgoff == PAGESIZE) {
	257	if (m != bogus_page) {
	258	zfs_unmap_page(sf);
	259	vm_page_valid(m);
	260	}
	261	ASSERT(mi < count);
	262	mi++;
	263	pgoff = 0;
	264	}
	265
	266	bufoff += tocpy;
	267	ASSERT(bufoff <= db->db_size);
	268	if (bufoff == db->db_size) {
	269	ASSERT(di < numbufs);
	270	di++;
	271	bufoff = 0;
	272	}
	273	}
	274
6d8da841	275	#ifdef ZFS_DEBUG
9f0a21e6 MM	276	/*
	277	* Three possibilities:
	278	* - last requested page ends at a buffer boundary and , thus,
	279	* all pages and buffers have been iterated;
	280	* - all requested pages are filled, but the last buffer
	281	* has not been exhausted;
	282	* the read-ahead is possible only in this case;
	283	* - all buffers have been read, but the last page has not been
	284	* fully filled;
	285	* this is only possible if the file has only a single buffer
	286	* with a size that is not a multiple of the page size.
	287	*/
	288	if (mi == count) {
	289	ASSERT(di >= numbufs - 1);
	290	IMPLY(*rahead != 0, di == numbufs - 1);
	291	IMPLY(*rahead != 0, bufoff != 0);
	292	ASSERT(pgoff == 0);
	293	}
	294	if (di == numbufs) {
	295	ASSERT(mi >= count - 1);
	296	ASSERT(*rahead == 0);
	297	IMPLY(pgoff == 0, mi == count);
	298	if (pgoff != 0) {
	299	ASSERT(mi == count - 1);
	300	ASSERT((dbp[0]->db_size & PAGE_MASK) != 0);
	301	}
	302	}
	303	#endif
	304	if (pgoff != 0) {
	305	ASSERT(m != bogus_page);
	306	bzero(va + pgoff, PAGESIZE - pgoff);
	307	zfs_unmap_page(sf);
	308	vm_page_valid(m);
	309	}
	310
	311	for (i = 0; i < *rahead; i++) {
c614fd6e	312	m = vm_page_grab_unlocked(vmobj, ma[count - 1]->pindex + 1 + i,
9f0a21e6 MM	313	VM_ALLOC_NORMAL \| VM_ALLOC_NOWAIT \| VM_ALLOC_BUSY_FLAGS);
	314	if (m == NULL)
	315	break;
	316	if (!vm_page_none_valid(m)) {
	317	ASSERT3U(m->valid, ==, VM_PAGE_BITS_ALL);
	318	vm_page_do_sunbusy(m);
	319	break;
	320	}
	321	ASSERT(m->dirty == 0);
	322	ASSERT(!pmap_page_is_mapped(m));
	323
	324	ASSERT(db->db_size > PAGE_SIZE);
	325	bufoff = IDX_TO_OFF(m->pindex) % db->db_size;
	326	tocpy = MIN(db->db_size - bufoff, PAGESIZE);
	327	va = zfs_map_page(m, &sf);
	328	bcopy((char *)db->db_data + bufoff, va, tocpy);
	329	if (tocpy < PAGESIZE) {
	330	ASSERT(i == *rahead - 1);
	331	ASSERT((db->db_size & PAGE_MASK) != 0);
	332	bzero(va + tocpy, PAGESIZE - tocpy);
	333	}
	334	zfs_unmap_page(sf);
	335	vm_page_valid(m);
	336	dmu_page_lock(m);
	337	if ((m->busy_lock & VPB_BIT_WAITERS) != 0)
	338	vm_page_activate(m);
	339	else
	340	vm_page_deactivate(m);
	341	dmu_page_unlock(m);
	342	vm_page_do_sunbusy(m);
	343	}
	344	*rahead = i;
c614fd6e	345	zfs_vmobject_wunlock_12(vmobj);
9f0a21e6 MM	346
	347	dmu_buf_rele_array(dbp, numbufs, FTAG);
	348	return (0);
	349	}