xref: /linux/fs/xfs/xfs_iomap.c (revision 3fd6c59042dbba50391e30862beac979491145fe)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (c) 2000-2006 Silicon Graphics, Inc.
4  * Copyright (c) 2016-2018 Christoph Hellwig.
5  * All Rights Reserved.
6  */
7 #include "xfs.h"
8 #include "xfs_fs.h"
9 #include "xfs_shared.h"
10 #include "xfs_format.h"
11 #include "xfs_log_format.h"
12 #include "xfs_trans_resv.h"
13 #include "xfs_mount.h"
14 #include "xfs_inode.h"
15 #include "xfs_btree.h"
16 #include "xfs_bmap_btree.h"
17 #include "xfs_bmap.h"
18 #include "xfs_bmap_util.h"
19 #include "xfs_errortag.h"
20 #include "xfs_error.h"
21 #include "xfs_trans.h"
22 #include "xfs_trans_space.h"
23 #include "xfs_inode_item.h"
24 #include "xfs_iomap.h"
25 #include "xfs_trace.h"
26 #include "xfs_quota.h"
27 #include "xfs_rtgroup.h"
28 #include "xfs_dquot_item.h"
29 #include "xfs_dquot.h"
30 #include "xfs_reflink.h"
31 #include "xfs_health.h"
32 #include "xfs_rtbitmap.h"
33 
34 #define XFS_ALLOC_ALIGN(mp, off) \
35 	(((off) >> mp->m_allocsize_log) << mp->m_allocsize_log)
36 
37 static int
xfs_alert_fsblock_zero(xfs_inode_t * ip,xfs_bmbt_irec_t * imap)38 xfs_alert_fsblock_zero(
39 	xfs_inode_t	*ip,
40 	xfs_bmbt_irec_t	*imap)
41 {
42 	xfs_alert_tag(ip->i_mount, XFS_PTAG_FSBLOCK_ZERO,
43 			"Access to block zero in inode %llu "
44 			"start_block: %llx start_off: %llx "
45 			"blkcnt: %llx extent-state: %x",
46 		(unsigned long long)ip->i_ino,
47 		(unsigned long long)imap->br_startblock,
48 		(unsigned long long)imap->br_startoff,
49 		(unsigned long long)imap->br_blockcount,
50 		imap->br_state);
51 	xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
52 	return -EFSCORRUPTED;
53 }
54 
55 u64
xfs_iomap_inode_sequence(struct xfs_inode * ip,u16 iomap_flags)56 xfs_iomap_inode_sequence(
57 	struct xfs_inode	*ip,
58 	u16			iomap_flags)
59 {
60 	u64			cookie = 0;
61 
62 	if (iomap_flags & IOMAP_F_XATTR)
63 		return READ_ONCE(ip->i_af.if_seq);
64 	if ((iomap_flags & IOMAP_F_SHARED) && ip->i_cowfp)
65 		cookie = (u64)READ_ONCE(ip->i_cowfp->if_seq) << 32;
66 	return cookie | READ_ONCE(ip->i_df.if_seq);
67 }
68 
69 /*
70  * Check that the iomap passed to us is still valid for the given offset and
71  * length.
72  */
73 static bool
xfs_iomap_valid(struct inode * inode,const struct iomap * iomap)74 xfs_iomap_valid(
75 	struct inode		*inode,
76 	const struct iomap	*iomap)
77 {
78 	struct xfs_inode	*ip = XFS_I(inode);
79 
80 	if (iomap->validity_cookie !=
81 			xfs_iomap_inode_sequence(ip, iomap->flags)) {
82 		trace_xfs_iomap_invalid(ip, iomap);
83 		return false;
84 	}
85 
86 	XFS_ERRORTAG_DELAY(ip->i_mount, XFS_ERRTAG_WRITE_DELAY_MS);
87 	return true;
88 }
89 
90 static const struct iomap_folio_ops xfs_iomap_folio_ops = {
91 	.iomap_valid		= xfs_iomap_valid,
92 };
93 
94 int
xfs_bmbt_to_iomap(struct xfs_inode * ip,struct iomap * iomap,struct xfs_bmbt_irec * imap,unsigned int mapping_flags,u16 iomap_flags,u64 sequence_cookie)95 xfs_bmbt_to_iomap(
96 	struct xfs_inode	*ip,
97 	struct iomap		*iomap,
98 	struct xfs_bmbt_irec	*imap,
99 	unsigned int		mapping_flags,
100 	u16			iomap_flags,
101 	u64			sequence_cookie)
102 {
103 	struct xfs_mount	*mp = ip->i_mount;
104 	struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
105 
106 	if (unlikely(!xfs_valid_startblock(ip, imap->br_startblock))) {
107 		xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
108 		return xfs_alert_fsblock_zero(ip, imap);
109 	}
110 
111 	if (imap->br_startblock == HOLESTARTBLOCK) {
112 		iomap->addr = IOMAP_NULL_ADDR;
113 		iomap->type = IOMAP_HOLE;
114 	} else if (imap->br_startblock == DELAYSTARTBLOCK ||
115 		   isnullstartblock(imap->br_startblock)) {
116 		iomap->addr = IOMAP_NULL_ADDR;
117 		iomap->type = IOMAP_DELALLOC;
118 	} else {
119 		xfs_daddr_t	daddr = xfs_fsb_to_db(ip, imap->br_startblock);
120 
121 		iomap->addr = BBTOB(daddr);
122 		if (mapping_flags & IOMAP_DAX)
123 			iomap->addr += target->bt_dax_part_off;
124 
125 		if (imap->br_state == XFS_EXT_UNWRITTEN)
126 			iomap->type = IOMAP_UNWRITTEN;
127 		else
128 			iomap->type = IOMAP_MAPPED;
129 
130 		/*
131 		 * Mark iomaps starting at the first sector of a RTG as merge
132 		 * boundary so that each I/O completions is contained to a
133 		 * single RTG.
134 		 */
135 		if (XFS_IS_REALTIME_INODE(ip) && xfs_has_rtgroups(mp) &&
136 		    xfs_rtbno_is_group_start(mp, imap->br_startblock))
137 			iomap->flags |= IOMAP_F_BOUNDARY;
138 	}
139 	iomap->offset = XFS_FSB_TO_B(mp, imap->br_startoff);
140 	iomap->length = XFS_FSB_TO_B(mp, imap->br_blockcount);
141 	if (mapping_flags & IOMAP_DAX)
142 		iomap->dax_dev = target->bt_daxdev;
143 	else
144 		iomap->bdev = target->bt_bdev;
145 	iomap->flags = iomap_flags;
146 
147 	if (xfs_ipincount(ip) &&
148 	    (ip->i_itemp->ili_fsync_fields & ~XFS_ILOG_TIMESTAMP))
149 		iomap->flags |= IOMAP_F_DIRTY;
150 
151 	iomap->validity_cookie = sequence_cookie;
152 	iomap->folio_ops = &xfs_iomap_folio_ops;
153 	return 0;
154 }
155 
156 static void
xfs_hole_to_iomap(struct xfs_inode * ip,struct iomap * iomap,xfs_fileoff_t offset_fsb,xfs_fileoff_t end_fsb)157 xfs_hole_to_iomap(
158 	struct xfs_inode	*ip,
159 	struct iomap		*iomap,
160 	xfs_fileoff_t		offset_fsb,
161 	xfs_fileoff_t		end_fsb)
162 {
163 	struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
164 
165 	iomap->addr = IOMAP_NULL_ADDR;
166 	iomap->type = IOMAP_HOLE;
167 	iomap->offset = XFS_FSB_TO_B(ip->i_mount, offset_fsb);
168 	iomap->length = XFS_FSB_TO_B(ip->i_mount, end_fsb - offset_fsb);
169 	iomap->bdev = target->bt_bdev;
170 	iomap->dax_dev = target->bt_daxdev;
171 }
172 
173 static inline xfs_fileoff_t
xfs_iomap_end_fsb(struct xfs_mount * mp,loff_t offset,loff_t count)174 xfs_iomap_end_fsb(
175 	struct xfs_mount	*mp,
176 	loff_t			offset,
177 	loff_t			count)
178 {
179 	ASSERT(offset <= mp->m_super->s_maxbytes);
180 	return min(XFS_B_TO_FSB(mp, offset + count),
181 		   XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes));
182 }
183 
184 static xfs_extlen_t
xfs_eof_alignment(struct xfs_inode * ip)185 xfs_eof_alignment(
186 	struct xfs_inode	*ip)
187 {
188 	struct xfs_mount	*mp = ip->i_mount;
189 	xfs_extlen_t		align = 0;
190 
191 	if (!XFS_IS_REALTIME_INODE(ip)) {
192 		/*
193 		 * Round up the allocation request to a stripe unit
194 		 * (m_dalign) boundary if the file size is >= stripe unit
195 		 * size, and we are allocating past the allocation eof.
196 		 *
197 		 * If mounted with the "-o swalloc" option the alignment is
198 		 * increased from the strip unit size to the stripe width.
199 		 */
200 		if (mp->m_swidth && xfs_has_swalloc(mp))
201 			align = mp->m_swidth;
202 		else if (mp->m_dalign)
203 			align = mp->m_dalign;
204 
205 		if (align && XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, align))
206 			align = 0;
207 	}
208 
209 	return align;
210 }
211 
212 /*
213  * Check if last_fsb is outside the last extent, and if so grow it to the next
214  * stripe unit boundary.
215  */
216 xfs_fileoff_t
xfs_iomap_eof_align_last_fsb(struct xfs_inode * ip,xfs_fileoff_t end_fsb)217 xfs_iomap_eof_align_last_fsb(
218 	struct xfs_inode	*ip,
219 	xfs_fileoff_t		end_fsb)
220 {
221 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, XFS_DATA_FORK);
222 	xfs_extlen_t		extsz = xfs_get_extsz_hint(ip);
223 	xfs_extlen_t		align = xfs_eof_alignment(ip);
224 	struct xfs_bmbt_irec	irec;
225 	struct xfs_iext_cursor	icur;
226 
227 	ASSERT(!xfs_need_iread_extents(ifp));
228 
229 	/*
230 	 * Always round up the allocation request to the extent hint boundary.
231 	 */
232 	if (extsz) {
233 		if (align)
234 			align = roundup_64(align, extsz);
235 		else
236 			align = extsz;
237 	}
238 
239 	if (align) {
240 		xfs_fileoff_t	aligned_end_fsb = roundup_64(end_fsb, align);
241 
242 		xfs_iext_last(ifp, &icur);
243 		if (!xfs_iext_get_extent(ifp, &icur, &irec) ||
244 		    aligned_end_fsb >= irec.br_startoff + irec.br_blockcount)
245 			return aligned_end_fsb;
246 	}
247 
248 	return end_fsb;
249 }
250 
251 int
xfs_iomap_write_direct(struct xfs_inode * ip,xfs_fileoff_t offset_fsb,xfs_fileoff_t count_fsb,unsigned int flags,struct xfs_bmbt_irec * imap,u64 * seq)252 xfs_iomap_write_direct(
253 	struct xfs_inode	*ip,
254 	xfs_fileoff_t		offset_fsb,
255 	xfs_fileoff_t		count_fsb,
256 	unsigned int		flags,
257 	struct xfs_bmbt_irec	*imap,
258 	u64			*seq)
259 {
260 	struct xfs_mount	*mp = ip->i_mount;
261 	struct xfs_trans	*tp;
262 	xfs_filblks_t		resaligned;
263 	int			nimaps;
264 	unsigned int		dblocks, rblocks;
265 	bool			force = false;
266 	int			error;
267 	int			bmapi_flags = XFS_BMAPI_PREALLOC;
268 	int			nr_exts = XFS_IEXT_ADD_NOSPLIT_CNT;
269 
270 	ASSERT(count_fsb > 0);
271 
272 	resaligned = xfs_aligned_fsb_count(offset_fsb, count_fsb,
273 					   xfs_get_extsz_hint(ip));
274 	if (unlikely(XFS_IS_REALTIME_INODE(ip))) {
275 		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
276 		rblocks = resaligned;
277 	} else {
278 		dblocks = XFS_DIOSTRAT_SPACE_RES(mp, resaligned);
279 		rblocks = 0;
280 	}
281 
282 	error = xfs_qm_dqattach(ip);
283 	if (error)
284 		return error;
285 
286 	/*
287 	 * For DAX, we do not allocate unwritten extents, but instead we zero
288 	 * the block before we commit the transaction.  Ideally we'd like to do
289 	 * this outside the transaction context, but if we commit and then crash
290 	 * we may not have zeroed the blocks and this will be exposed on
291 	 * recovery of the allocation. Hence we must zero before commit.
292 	 *
293 	 * Further, if we are mapping unwritten extents here, we need to zero
294 	 * and convert them to written so that we don't need an unwritten extent
295 	 * callback for DAX. This also means that we need to be able to dip into
296 	 * the reserve block pool for bmbt block allocation if there is no space
297 	 * left but we need to do unwritten extent conversion.
298 	 */
299 	if (flags & IOMAP_DAX) {
300 		bmapi_flags = XFS_BMAPI_CONVERT | XFS_BMAPI_ZERO;
301 		if (imap->br_state == XFS_EXT_UNWRITTEN) {
302 			force = true;
303 			nr_exts = XFS_IEXT_WRITE_UNWRITTEN_CNT;
304 			dblocks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
305 		}
306 	}
307 
308 	error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, dblocks,
309 			rblocks, force, &tp);
310 	if (error)
311 		return error;
312 
313 	error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK, nr_exts);
314 	if (error)
315 		goto out_trans_cancel;
316 
317 	/*
318 	 * From this point onwards we overwrite the imap pointer that the
319 	 * caller gave to us.
320 	 */
321 	nimaps = 1;
322 	error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb, bmapi_flags, 0,
323 				imap, &nimaps);
324 	if (error)
325 		goto out_trans_cancel;
326 
327 	/*
328 	 * Complete the transaction
329 	 */
330 	error = xfs_trans_commit(tp);
331 	if (error)
332 		goto out_unlock;
333 
334 	if (unlikely(!xfs_valid_startblock(ip, imap->br_startblock))) {
335 		xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
336 		error = xfs_alert_fsblock_zero(ip, imap);
337 	}
338 
339 out_unlock:
340 	*seq = xfs_iomap_inode_sequence(ip, 0);
341 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
342 	return error;
343 
344 out_trans_cancel:
345 	xfs_trans_cancel(tp);
346 	goto out_unlock;
347 }
348 
349 STATIC bool
xfs_quota_need_throttle(struct xfs_inode * ip,xfs_dqtype_t type,xfs_fsblock_t alloc_blocks)350 xfs_quota_need_throttle(
351 	struct xfs_inode	*ip,
352 	xfs_dqtype_t		type,
353 	xfs_fsblock_t		alloc_blocks)
354 {
355 	struct xfs_dquot	*dq = xfs_inode_dquot(ip, type);
356 	struct xfs_dquot_res	*res;
357 	struct xfs_dquot_pre	*pre;
358 
359 	if (!dq || !xfs_this_quota_on(ip->i_mount, type))
360 		return false;
361 
362 	if (XFS_IS_REALTIME_INODE(ip)) {
363 		res = &dq->q_rtb;
364 		pre = &dq->q_rtb_prealloc;
365 	} else {
366 		res = &dq->q_blk;
367 		pre = &dq->q_blk_prealloc;
368 	}
369 
370 	/* no hi watermark, no throttle */
371 	if (!pre->q_prealloc_hi_wmark)
372 		return false;
373 
374 	/* under the lo watermark, no throttle */
375 	if (res->reserved + alloc_blocks < pre->q_prealloc_lo_wmark)
376 		return false;
377 
378 	return true;
379 }
380 
381 STATIC void
xfs_quota_calc_throttle(struct xfs_inode * ip,xfs_dqtype_t type,xfs_fsblock_t * qblocks,int * qshift,int64_t * qfreesp)382 xfs_quota_calc_throttle(
383 	struct xfs_inode	*ip,
384 	xfs_dqtype_t		type,
385 	xfs_fsblock_t		*qblocks,
386 	int			*qshift,
387 	int64_t			*qfreesp)
388 {
389 	struct xfs_dquot	*dq = xfs_inode_dquot(ip, type);
390 	struct xfs_dquot_res	*res;
391 	struct xfs_dquot_pre	*pre;
392 	int64_t			freesp;
393 	int			shift = 0;
394 
395 	if (!dq) {
396 		res = NULL;
397 		pre = NULL;
398 	} else if (XFS_IS_REALTIME_INODE(ip)) {
399 		res = &dq->q_rtb;
400 		pre = &dq->q_rtb_prealloc;
401 	} else {
402 		res = &dq->q_blk;
403 		pre = &dq->q_blk_prealloc;
404 	}
405 
406 	/* no dq, or over hi wmark, squash the prealloc completely */
407 	if (!res || res->reserved >= pre->q_prealloc_hi_wmark) {
408 		*qblocks = 0;
409 		*qfreesp = 0;
410 		return;
411 	}
412 
413 	freesp = pre->q_prealloc_hi_wmark - res->reserved;
414 	if (freesp < pre->q_low_space[XFS_QLOWSP_5_PCNT]) {
415 		shift = 2;
416 		if (freesp < pre->q_low_space[XFS_QLOWSP_3_PCNT])
417 			shift += 2;
418 		if (freesp < pre->q_low_space[XFS_QLOWSP_1_PCNT])
419 			shift += 2;
420 	}
421 
422 	if (freesp < *qfreesp)
423 		*qfreesp = freesp;
424 
425 	/* only overwrite the throttle values if we are more aggressive */
426 	if ((freesp >> shift) < (*qblocks >> *qshift)) {
427 		*qblocks = freesp;
428 		*qshift = shift;
429 	}
430 }
431 
432 static int64_t
xfs_iomap_freesp(struct percpu_counter * counter,uint64_t low_space[XFS_LOWSP_MAX],int * shift)433 xfs_iomap_freesp(
434 	struct percpu_counter	*counter,
435 	uint64_t		low_space[XFS_LOWSP_MAX],
436 	int			*shift)
437 {
438 	int64_t			freesp;
439 
440 	freesp = percpu_counter_read_positive(counter);
441 	if (freesp < low_space[XFS_LOWSP_5_PCNT]) {
442 		*shift = 2;
443 		if (freesp < low_space[XFS_LOWSP_4_PCNT])
444 			(*shift)++;
445 		if (freesp < low_space[XFS_LOWSP_3_PCNT])
446 			(*shift)++;
447 		if (freesp < low_space[XFS_LOWSP_2_PCNT])
448 			(*shift)++;
449 		if (freesp < low_space[XFS_LOWSP_1_PCNT])
450 			(*shift)++;
451 	}
452 	return freesp;
453 }
454 
455 /*
456  * If we don't have a user specified preallocation size, dynamically increase
457  * the preallocation size as the size of the file grows.  Cap the maximum size
458  * at a single extent or less if the filesystem is near full. The closer the
459  * filesystem is to being full, the smaller the maximum preallocation.
460  */
461 STATIC xfs_fsblock_t
xfs_iomap_prealloc_size(struct xfs_inode * ip,int whichfork,loff_t offset,loff_t count,struct xfs_iext_cursor * icur)462 xfs_iomap_prealloc_size(
463 	struct xfs_inode	*ip,
464 	int			whichfork,
465 	loff_t			offset,
466 	loff_t			count,
467 	struct xfs_iext_cursor	*icur)
468 {
469 	struct xfs_iext_cursor	ncur = *icur;
470 	struct xfs_bmbt_irec	prev, got;
471 	struct xfs_mount	*mp = ip->i_mount;
472 	struct xfs_ifork	*ifp = xfs_ifork_ptr(ip, whichfork);
473 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
474 	int64_t			freesp;
475 	xfs_fsblock_t		qblocks;
476 	xfs_fsblock_t		alloc_blocks = 0;
477 	xfs_extlen_t		plen;
478 	int			shift = 0;
479 	int			qshift = 0;
480 
481 	/*
482 	 * As an exception we don't do any preallocation at all if the file is
483 	 * smaller than the minimum preallocation and we are using the default
484 	 * dynamic preallocation scheme, as it is likely this is the only write
485 	 * to the file that is going to be done.
486 	 */
487 	if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_allocsize_blocks))
488 		return 0;
489 
490 	/*
491 	 * Use the minimum preallocation size for small files or if we are
492 	 * writing right after a hole.
493 	 */
494 	if (XFS_ISIZE(ip) < XFS_FSB_TO_B(mp, mp->m_dalign) ||
495 	    !xfs_iext_prev_extent(ifp, &ncur, &prev) ||
496 	    prev.br_startoff + prev.br_blockcount < offset_fsb)
497 		return mp->m_allocsize_blocks;
498 
499 	/*
500 	 * Take the size of the preceding data extents as the basis for the
501 	 * preallocation size. Note that we don't care if the previous extents
502 	 * are written or not.
503 	 */
504 	plen = prev.br_blockcount;
505 	while (xfs_iext_prev_extent(ifp, &ncur, &got)) {
506 		if (plen > XFS_MAX_BMBT_EXTLEN / 2 ||
507 		    isnullstartblock(got.br_startblock) ||
508 		    got.br_startoff + got.br_blockcount != prev.br_startoff ||
509 		    got.br_startblock + got.br_blockcount != prev.br_startblock)
510 			break;
511 		plen += got.br_blockcount;
512 		prev = got;
513 	}
514 
515 	/*
516 	 * If the size of the extents is greater than half the maximum extent
517 	 * length, then use the current offset as the basis.  This ensures that
518 	 * for large files the preallocation size always extends to
519 	 * XFS_BMBT_MAX_EXTLEN rather than falling short due to things like stripe
520 	 * unit/width alignment of real extents.
521 	 */
522 	alloc_blocks = plen * 2;
523 	if (alloc_blocks > XFS_MAX_BMBT_EXTLEN)
524 		alloc_blocks = XFS_B_TO_FSB(mp, offset);
525 	qblocks = alloc_blocks;
526 
527 	/*
528 	 * XFS_BMBT_MAX_EXTLEN is not a power of two value but we round the prealloc
529 	 * down to the nearest power of two value after throttling. To prevent
530 	 * the round down from unconditionally reducing the maximum supported
531 	 * prealloc size, we round up first, apply appropriate throttling, round
532 	 * down and cap the value to XFS_BMBT_MAX_EXTLEN.
533 	 */
534 	alloc_blocks = XFS_FILEOFF_MIN(roundup_pow_of_two(XFS_MAX_BMBT_EXTLEN),
535 				       alloc_blocks);
536 
537 	if (unlikely(XFS_IS_REALTIME_INODE(ip)))
538 		freesp = xfs_rtbxlen_to_blen(mp,
539 				xfs_iomap_freesp(&mp->m_frextents,
540 					mp->m_low_rtexts, &shift));
541 	else
542 		freesp = xfs_iomap_freesp(&mp->m_fdblocks, mp->m_low_space,
543 				&shift);
544 
545 	/*
546 	 * Check each quota to cap the prealloc size, provide a shift value to
547 	 * throttle with and adjust amount of available space.
548 	 */
549 	if (xfs_quota_need_throttle(ip, XFS_DQTYPE_USER, alloc_blocks))
550 		xfs_quota_calc_throttle(ip, XFS_DQTYPE_USER, &qblocks, &qshift,
551 					&freesp);
552 	if (xfs_quota_need_throttle(ip, XFS_DQTYPE_GROUP, alloc_blocks))
553 		xfs_quota_calc_throttle(ip, XFS_DQTYPE_GROUP, &qblocks, &qshift,
554 					&freesp);
555 	if (xfs_quota_need_throttle(ip, XFS_DQTYPE_PROJ, alloc_blocks))
556 		xfs_quota_calc_throttle(ip, XFS_DQTYPE_PROJ, &qblocks, &qshift,
557 					&freesp);
558 
559 	/*
560 	 * The final prealloc size is set to the minimum of free space available
561 	 * in each of the quotas and the overall filesystem.
562 	 *
563 	 * The shift throttle value is set to the maximum value as determined by
564 	 * the global low free space values and per-quota low free space values.
565 	 */
566 	alloc_blocks = min(alloc_blocks, qblocks);
567 	shift = max(shift, qshift);
568 
569 	if (shift)
570 		alloc_blocks >>= shift;
571 	/*
572 	 * rounddown_pow_of_two() returns an undefined result if we pass in
573 	 * alloc_blocks = 0.
574 	 */
575 	if (alloc_blocks)
576 		alloc_blocks = rounddown_pow_of_two(alloc_blocks);
577 	if (alloc_blocks > XFS_MAX_BMBT_EXTLEN)
578 		alloc_blocks = XFS_MAX_BMBT_EXTLEN;
579 
580 	/*
581 	 * If we are still trying to allocate more space than is
582 	 * available, squash the prealloc hard. This can happen if we
583 	 * have a large file on a small filesystem and the above
584 	 * lowspace thresholds are smaller than XFS_BMBT_MAX_EXTLEN.
585 	 */
586 	while (alloc_blocks && alloc_blocks >= freesp)
587 		alloc_blocks >>= 4;
588 	if (alloc_blocks < mp->m_allocsize_blocks)
589 		alloc_blocks = mp->m_allocsize_blocks;
590 	trace_xfs_iomap_prealloc_size(ip, alloc_blocks, shift,
591 				      mp->m_allocsize_blocks);
592 	return alloc_blocks;
593 }
594 
595 int
xfs_iomap_write_unwritten(xfs_inode_t * ip,xfs_off_t offset,xfs_off_t count,bool update_isize)596 xfs_iomap_write_unwritten(
597 	xfs_inode_t	*ip,
598 	xfs_off_t	offset,
599 	xfs_off_t	count,
600 	bool		update_isize)
601 {
602 	xfs_mount_t	*mp = ip->i_mount;
603 	xfs_fileoff_t	offset_fsb;
604 	xfs_filblks_t	count_fsb;
605 	xfs_filblks_t	numblks_fsb;
606 	int		nimaps;
607 	xfs_trans_t	*tp;
608 	xfs_bmbt_irec_t imap;
609 	struct inode	*inode = VFS_I(ip);
610 	xfs_fsize_t	i_size;
611 	uint		resblks;
612 	int		error;
613 
614 	trace_xfs_unwritten_convert(ip, offset, count);
615 
616 	offset_fsb = XFS_B_TO_FSBT(mp, offset);
617 	count_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
618 	count_fsb = (xfs_filblks_t)(count_fsb - offset_fsb);
619 
620 	/*
621 	 * Reserve enough blocks in this transaction for two complete extent
622 	 * btree splits.  We may be converting the middle part of an unwritten
623 	 * extent and in this case we will insert two new extents in the btree
624 	 * each of which could cause a full split.
625 	 *
626 	 * This reservation amount will be used in the first call to
627 	 * xfs_bmbt_split() to select an AG with enough space to satisfy the
628 	 * rest of the operation.
629 	 */
630 	resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0) << 1;
631 
632 	/* Attach dquots so that bmbt splits are accounted correctly. */
633 	error = xfs_qm_dqattach(ip);
634 	if (error)
635 		return error;
636 
637 	do {
638 		/*
639 		 * Set up a transaction to convert the range of extents
640 		 * from unwritten to real. Do allocations in a loop until
641 		 * we have covered the range passed in.
642 		 *
643 		 * Note that we can't risk to recursing back into the filesystem
644 		 * here as we might be asked to write out the same inode that we
645 		 * complete here and might deadlock on the iolock.
646 		 */
647 		error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, resblks,
648 				0, true, &tp);
649 		if (error)
650 			return error;
651 
652 		error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK,
653 				XFS_IEXT_WRITE_UNWRITTEN_CNT);
654 		if (error)
655 			goto error_on_bmapi_transaction;
656 
657 		/*
658 		 * Modify the unwritten extent state of the buffer.
659 		 */
660 		nimaps = 1;
661 		error = xfs_bmapi_write(tp, ip, offset_fsb, count_fsb,
662 					XFS_BMAPI_CONVERT, resblks, &imap,
663 					&nimaps);
664 		if (error)
665 			goto error_on_bmapi_transaction;
666 
667 		/*
668 		 * Log the updated inode size as we go.  We have to be careful
669 		 * to only log it up to the actual write offset if it is
670 		 * halfway into a block.
671 		 */
672 		i_size = XFS_FSB_TO_B(mp, offset_fsb + count_fsb);
673 		if (i_size > offset + count)
674 			i_size = offset + count;
675 		if (update_isize && i_size > i_size_read(inode))
676 			i_size_write(inode, i_size);
677 		i_size = xfs_new_eof(ip, i_size);
678 		if (i_size) {
679 			ip->i_disk_size = i_size;
680 			xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
681 		}
682 
683 		error = xfs_trans_commit(tp);
684 		xfs_iunlock(ip, XFS_ILOCK_EXCL);
685 		if (error)
686 			return error;
687 
688 		if (unlikely(!xfs_valid_startblock(ip, imap.br_startblock))) {
689 			xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
690 			return xfs_alert_fsblock_zero(ip, &imap);
691 		}
692 
693 		if ((numblks_fsb = imap.br_blockcount) == 0) {
694 			/*
695 			 * The numblks_fsb value should always get
696 			 * smaller, otherwise the loop is stuck.
697 			 */
698 			ASSERT(imap.br_blockcount);
699 			break;
700 		}
701 		offset_fsb += numblks_fsb;
702 		count_fsb -= numblks_fsb;
703 	} while (count_fsb > 0);
704 
705 	return 0;
706 
707 error_on_bmapi_transaction:
708 	xfs_trans_cancel(tp);
709 	xfs_iunlock(ip, XFS_ILOCK_EXCL);
710 	return error;
711 }
712 
713 static inline bool
imap_needs_alloc(struct inode * inode,unsigned flags,struct xfs_bmbt_irec * imap,int nimaps)714 imap_needs_alloc(
715 	struct inode		*inode,
716 	unsigned		flags,
717 	struct xfs_bmbt_irec	*imap,
718 	int			nimaps)
719 {
720 	/* don't allocate blocks when just zeroing */
721 	if (flags & IOMAP_ZERO)
722 		return false;
723 	if (!nimaps ||
724 	    imap->br_startblock == HOLESTARTBLOCK ||
725 	    imap->br_startblock == DELAYSTARTBLOCK)
726 		return true;
727 	/* we convert unwritten extents before copying the data for DAX */
728 	if ((flags & IOMAP_DAX) && imap->br_state == XFS_EXT_UNWRITTEN)
729 		return true;
730 	return false;
731 }
732 
733 static inline bool
imap_needs_cow(struct xfs_inode * ip,unsigned int flags,struct xfs_bmbt_irec * imap,int nimaps)734 imap_needs_cow(
735 	struct xfs_inode	*ip,
736 	unsigned int		flags,
737 	struct xfs_bmbt_irec	*imap,
738 	int			nimaps)
739 {
740 	if (!xfs_is_cow_inode(ip))
741 		return false;
742 
743 	/* when zeroing we don't have to COW holes or unwritten extents */
744 	if (flags & (IOMAP_UNSHARE | IOMAP_ZERO)) {
745 		if (!nimaps ||
746 		    imap->br_startblock == HOLESTARTBLOCK ||
747 		    imap->br_state == XFS_EXT_UNWRITTEN)
748 			return false;
749 	}
750 
751 	return true;
752 }
753 
754 /*
755  * Extents not yet cached requires exclusive access, don't block for
756  * IOMAP_NOWAIT.
757  *
758  * This is basically an opencoded xfs_ilock_data_map_shared() call, but with
759  * support for IOMAP_NOWAIT.
760  */
761 static int
xfs_ilock_for_iomap(struct xfs_inode * ip,unsigned flags,unsigned * lockmode)762 xfs_ilock_for_iomap(
763 	struct xfs_inode	*ip,
764 	unsigned		flags,
765 	unsigned		*lockmode)
766 {
767 	if (flags & IOMAP_NOWAIT) {
768 		if (xfs_need_iread_extents(&ip->i_df))
769 			return -EAGAIN;
770 		if (!xfs_ilock_nowait(ip, *lockmode))
771 			return -EAGAIN;
772 	} else {
773 		if (xfs_need_iread_extents(&ip->i_df))
774 			*lockmode = XFS_ILOCK_EXCL;
775 		xfs_ilock(ip, *lockmode);
776 	}
777 
778 	return 0;
779 }
780 
781 /*
782  * Check that the imap we are going to return to the caller spans the entire
783  * range that the caller requested for the IO.
784  */
785 static bool
imap_spans_range(struct xfs_bmbt_irec * imap,xfs_fileoff_t offset_fsb,xfs_fileoff_t end_fsb)786 imap_spans_range(
787 	struct xfs_bmbt_irec	*imap,
788 	xfs_fileoff_t		offset_fsb,
789 	xfs_fileoff_t		end_fsb)
790 {
791 	if (imap->br_startoff > offset_fsb)
792 		return false;
793 	if (imap->br_startoff + imap->br_blockcount < end_fsb)
794 		return false;
795 	return true;
796 }
797 
798 static int
xfs_direct_write_iomap_begin(struct inode * inode,loff_t offset,loff_t length,unsigned flags,struct iomap * iomap,struct iomap * srcmap)799 xfs_direct_write_iomap_begin(
800 	struct inode		*inode,
801 	loff_t			offset,
802 	loff_t			length,
803 	unsigned		flags,
804 	struct iomap		*iomap,
805 	struct iomap		*srcmap)
806 {
807 	struct xfs_inode	*ip = XFS_I(inode);
808 	struct xfs_mount	*mp = ip->i_mount;
809 	struct xfs_bmbt_irec	imap, cmap;
810 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
811 	xfs_fileoff_t		end_fsb = xfs_iomap_end_fsb(mp, offset, length);
812 	int			nimaps = 1, error = 0;
813 	bool			shared = false;
814 	u16			iomap_flags = 0;
815 	unsigned int		lockmode;
816 	u64			seq;
817 
818 	ASSERT(flags & (IOMAP_WRITE | IOMAP_ZERO));
819 
820 	if (xfs_is_shutdown(mp))
821 		return -EIO;
822 
823 	/*
824 	 * Writes that span EOF might trigger an IO size update on completion,
825 	 * so consider them to be dirty for the purposes of O_DSYNC even if
826 	 * there is no other metadata changes pending or have been made here.
827 	 */
828 	if (offset + length > i_size_read(inode))
829 		iomap_flags |= IOMAP_F_DIRTY;
830 
831 	/*
832 	 * COW writes may allocate delalloc space or convert unwritten COW
833 	 * extents, so we need to make sure to take the lock exclusively here.
834 	 */
835 	if (xfs_is_cow_inode(ip))
836 		lockmode = XFS_ILOCK_EXCL;
837 	else
838 		lockmode = XFS_ILOCK_SHARED;
839 
840 relock:
841 	error = xfs_ilock_for_iomap(ip, flags, &lockmode);
842 	if (error)
843 		return error;
844 
845 	/*
846 	 * The reflink iflag could have changed since the earlier unlocked
847 	 * check, check if it again and relock if needed.
848 	 */
849 	if (xfs_is_cow_inode(ip) && lockmode == XFS_ILOCK_SHARED) {
850 		xfs_iunlock(ip, lockmode);
851 		lockmode = XFS_ILOCK_EXCL;
852 		goto relock;
853 	}
854 
855 	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
856 			       &nimaps, 0);
857 	if (error)
858 		goto out_unlock;
859 
860 	if (imap_needs_cow(ip, flags, &imap, nimaps)) {
861 		error = -EAGAIN;
862 		if (flags & IOMAP_NOWAIT)
863 			goto out_unlock;
864 
865 		/* may drop and re-acquire the ilock */
866 		error = xfs_reflink_allocate_cow(ip, &imap, &cmap, &shared,
867 				&lockmode,
868 				(flags & IOMAP_DIRECT) || IS_DAX(inode));
869 		if (error)
870 			goto out_unlock;
871 		if (shared)
872 			goto out_found_cow;
873 		end_fsb = imap.br_startoff + imap.br_blockcount;
874 		length = XFS_FSB_TO_B(mp, end_fsb) - offset;
875 	}
876 
877 	if (imap_needs_alloc(inode, flags, &imap, nimaps))
878 		goto allocate_blocks;
879 
880 	/*
881 	 * NOWAIT and OVERWRITE I/O needs to span the entire requested I/O with
882 	 * a single map so that we avoid partial IO failures due to the rest of
883 	 * the I/O range not covered by this map triggering an EAGAIN condition
884 	 * when it is subsequently mapped and aborting the I/O.
885 	 */
886 	if (flags & (IOMAP_NOWAIT | IOMAP_OVERWRITE_ONLY)) {
887 		error = -EAGAIN;
888 		if (!imap_spans_range(&imap, offset_fsb, end_fsb))
889 			goto out_unlock;
890 	}
891 
892 	/*
893 	 * For overwrite only I/O, we cannot convert unwritten extents without
894 	 * requiring sub-block zeroing.  This can only be done under an
895 	 * exclusive IOLOCK, hence return -EAGAIN if this is not a written
896 	 * extent to tell the caller to try again.
897 	 */
898 	if (flags & IOMAP_OVERWRITE_ONLY) {
899 		error = -EAGAIN;
900 		if (imap.br_state != XFS_EXT_NORM &&
901 	            ((offset | length) & mp->m_blockmask))
902 			goto out_unlock;
903 	}
904 
905 	seq = xfs_iomap_inode_sequence(ip, iomap_flags);
906 	xfs_iunlock(ip, lockmode);
907 	trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);
908 	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags, iomap_flags, seq);
909 
910 allocate_blocks:
911 	error = -EAGAIN;
912 	if (flags & (IOMAP_NOWAIT | IOMAP_OVERWRITE_ONLY))
913 		goto out_unlock;
914 
915 	/*
916 	 * We cap the maximum length we map to a sane size  to keep the chunks
917 	 * of work done where somewhat symmetric with the work writeback does.
918 	 * This is a completely arbitrary number pulled out of thin air as a
919 	 * best guess for initial testing.
920 	 *
921 	 * Note that the values needs to be less than 32-bits wide until the
922 	 * lower level functions are updated.
923 	 */
924 	length = min_t(loff_t, length, 1024 * PAGE_SIZE);
925 	end_fsb = xfs_iomap_end_fsb(mp, offset, length);
926 
927 	if (offset + length > XFS_ISIZE(ip))
928 		end_fsb = xfs_iomap_eof_align_last_fsb(ip, end_fsb);
929 	else if (nimaps && imap.br_startblock == HOLESTARTBLOCK)
930 		end_fsb = min(end_fsb, imap.br_startoff + imap.br_blockcount);
931 	xfs_iunlock(ip, lockmode);
932 
933 	error = xfs_iomap_write_direct(ip, offset_fsb, end_fsb - offset_fsb,
934 			flags, &imap, &seq);
935 	if (error)
936 		return error;
937 
938 	trace_xfs_iomap_alloc(ip, offset, length, XFS_DATA_FORK, &imap);
939 	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags,
940 				 iomap_flags | IOMAP_F_NEW, seq);
941 
942 out_found_cow:
943 	length = XFS_FSB_TO_B(mp, cmap.br_startoff + cmap.br_blockcount);
944 	trace_xfs_iomap_found(ip, offset, length - offset, XFS_COW_FORK, &cmap);
945 	if (imap.br_startblock != HOLESTARTBLOCK) {
946 		seq = xfs_iomap_inode_sequence(ip, 0);
947 		error = xfs_bmbt_to_iomap(ip, srcmap, &imap, flags, 0, seq);
948 		if (error)
949 			goto out_unlock;
950 	}
951 	seq = xfs_iomap_inode_sequence(ip, IOMAP_F_SHARED);
952 	xfs_iunlock(ip, lockmode);
953 	return xfs_bmbt_to_iomap(ip, iomap, &cmap, flags, IOMAP_F_SHARED, seq);
954 
955 out_unlock:
956 	if (lockmode)
957 		xfs_iunlock(ip, lockmode);
958 	return error;
959 }
960 
961 const struct iomap_ops xfs_direct_write_iomap_ops = {
962 	.iomap_begin		= xfs_direct_write_iomap_begin,
963 };
964 
965 static int
xfs_dax_write_iomap_end(struct inode * inode,loff_t pos,loff_t length,ssize_t written,unsigned flags,struct iomap * iomap)966 xfs_dax_write_iomap_end(
967 	struct inode		*inode,
968 	loff_t			pos,
969 	loff_t			length,
970 	ssize_t			written,
971 	unsigned		flags,
972 	struct iomap		*iomap)
973 {
974 	struct xfs_inode	*ip = XFS_I(inode);
975 
976 	if (!xfs_is_cow_inode(ip))
977 		return 0;
978 
979 	if (!written) {
980 		xfs_reflink_cancel_cow_range(ip, pos, length, true);
981 		return 0;
982 	}
983 
984 	return xfs_reflink_end_cow(ip, pos, written);
985 }
986 
987 const struct iomap_ops xfs_dax_write_iomap_ops = {
988 	.iomap_begin	= xfs_direct_write_iomap_begin,
989 	.iomap_end	= xfs_dax_write_iomap_end,
990 };
991 
992 static int
xfs_buffered_write_iomap_begin(struct inode * inode,loff_t offset,loff_t count,unsigned flags,struct iomap * iomap,struct iomap * srcmap)993 xfs_buffered_write_iomap_begin(
994 	struct inode		*inode,
995 	loff_t			offset,
996 	loff_t			count,
997 	unsigned		flags,
998 	struct iomap		*iomap,
999 	struct iomap		*srcmap)
1000 {
1001 	struct xfs_inode	*ip = XFS_I(inode);
1002 	struct xfs_mount	*mp = ip->i_mount;
1003 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
1004 	xfs_fileoff_t		end_fsb = xfs_iomap_end_fsb(mp, offset, count);
1005 	struct xfs_bmbt_irec	imap, cmap;
1006 	struct xfs_iext_cursor	icur, ccur;
1007 	xfs_fsblock_t		prealloc_blocks = 0;
1008 	bool			eof = false, cow_eof = false, shared = false;
1009 	int			allocfork = XFS_DATA_FORK;
1010 	int			error = 0;
1011 	unsigned int		lockmode = XFS_ILOCK_EXCL;
1012 	unsigned int		iomap_flags = 0;
1013 	u64			seq;
1014 
1015 	if (xfs_is_shutdown(mp))
1016 		return -EIO;
1017 
1018 	/* we can't use delayed allocations when using extent size hints */
1019 	if (xfs_get_extsz_hint(ip))
1020 		return xfs_direct_write_iomap_begin(inode, offset, count,
1021 				flags, iomap, srcmap);
1022 
1023 	error = xfs_qm_dqattach(ip);
1024 	if (error)
1025 		return error;
1026 
1027 	error = xfs_ilock_for_iomap(ip, flags, &lockmode);
1028 	if (error)
1029 		return error;
1030 
1031 	if (XFS_IS_CORRUPT(mp, !xfs_ifork_has_extents(&ip->i_df)) ||
1032 	    XFS_TEST_ERROR(false, mp, XFS_ERRTAG_BMAPIFORMAT)) {
1033 		xfs_bmap_mark_sick(ip, XFS_DATA_FORK);
1034 		error = -EFSCORRUPTED;
1035 		goto out_unlock;
1036 	}
1037 
1038 	XFS_STATS_INC(mp, xs_blk_mapw);
1039 
1040 	error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
1041 	if (error)
1042 		goto out_unlock;
1043 
1044 	/*
1045 	 * Search the data fork first to look up our source mapping.  We
1046 	 * always need the data fork map, as we have to return it to the
1047 	 * iomap code so that the higher level write code can read data in to
1048 	 * perform read-modify-write cycles for unaligned writes.
1049 	 */
1050 	eof = !xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap);
1051 	if (eof)
1052 		imap.br_startoff = end_fsb; /* fake hole until the end */
1053 
1054 	/* We never need to allocate blocks for zeroing or unsharing a hole. */
1055 	if ((flags & (IOMAP_UNSHARE | IOMAP_ZERO)) &&
1056 	    imap.br_startoff > offset_fsb) {
1057 		xfs_hole_to_iomap(ip, iomap, offset_fsb, imap.br_startoff);
1058 		goto out_unlock;
1059 	}
1060 
1061 	/*
1062 	 * For zeroing, trim a delalloc extent that extends beyond the EOF
1063 	 * block.  If it starts beyond the EOF block, convert it to an
1064 	 * unwritten extent.
1065 	 */
1066 	if ((flags & IOMAP_ZERO) && imap.br_startoff <= offset_fsb &&
1067 	    isnullstartblock(imap.br_startblock)) {
1068 		xfs_fileoff_t eof_fsb = XFS_B_TO_FSB(mp, XFS_ISIZE(ip));
1069 
1070 		if (offset_fsb >= eof_fsb)
1071 			goto convert_delay;
1072 		if (end_fsb > eof_fsb) {
1073 			end_fsb = eof_fsb;
1074 			xfs_trim_extent(&imap, offset_fsb,
1075 					end_fsb - offset_fsb);
1076 		}
1077 	}
1078 
1079 	/*
1080 	 * Search the COW fork extent list even if we did not find a data fork
1081 	 * extent.  This serves two purposes: first this implements the
1082 	 * speculative preallocation using cowextsize, so that we also unshare
1083 	 * block adjacent to shared blocks instead of just the shared blocks
1084 	 * themselves.  Second the lookup in the extent list is generally faster
1085 	 * than going out to the shared extent tree.
1086 	 */
1087 	if (xfs_is_cow_inode(ip)) {
1088 		if (!ip->i_cowfp) {
1089 			ASSERT(!xfs_is_reflink_inode(ip));
1090 			xfs_ifork_init_cow(ip);
1091 		}
1092 		cow_eof = !xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb,
1093 				&ccur, &cmap);
1094 		if (!cow_eof && cmap.br_startoff <= offset_fsb) {
1095 			trace_xfs_reflink_cow_found(ip, &cmap);
1096 			goto found_cow;
1097 		}
1098 	}
1099 
1100 	if (imap.br_startoff <= offset_fsb) {
1101 		/*
1102 		 * For reflink files we may need a delalloc reservation when
1103 		 * overwriting shared extents.   This includes zeroing of
1104 		 * existing extents that contain data.
1105 		 */
1106 		if (!xfs_is_cow_inode(ip) ||
1107 		    ((flags & IOMAP_ZERO) && imap.br_state != XFS_EXT_NORM)) {
1108 			trace_xfs_iomap_found(ip, offset, count, XFS_DATA_FORK,
1109 					&imap);
1110 			goto found_imap;
1111 		}
1112 
1113 		xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
1114 
1115 		/* Trim the mapping to the nearest shared extent boundary. */
1116 		error = xfs_bmap_trim_cow(ip, &imap, &shared);
1117 		if (error)
1118 			goto out_unlock;
1119 
1120 		/* Not shared?  Just report the (potentially capped) extent. */
1121 		if (!shared) {
1122 			trace_xfs_iomap_found(ip, offset, count, XFS_DATA_FORK,
1123 					&imap);
1124 			goto found_imap;
1125 		}
1126 
1127 		/*
1128 		 * Fork all the shared blocks from our write offset until the
1129 		 * end of the extent.
1130 		 */
1131 		allocfork = XFS_COW_FORK;
1132 		end_fsb = imap.br_startoff + imap.br_blockcount;
1133 	} else {
1134 		/*
1135 		 * We cap the maximum length we map here to MAX_WRITEBACK_PAGES
1136 		 * pages to keep the chunks of work done where somewhat
1137 		 * symmetric with the work writeback does.  This is a completely
1138 		 * arbitrary number pulled out of thin air.
1139 		 *
1140 		 * Note that the values needs to be less than 32-bits wide until
1141 		 * the lower level functions are updated.
1142 		 */
1143 		count = min_t(loff_t, count, 1024 * PAGE_SIZE);
1144 		end_fsb = xfs_iomap_end_fsb(mp, offset, count);
1145 
1146 		if (xfs_is_always_cow_inode(ip))
1147 			allocfork = XFS_COW_FORK;
1148 	}
1149 
1150 	if (eof && offset + count > XFS_ISIZE(ip)) {
1151 		/*
1152 		 * Determine the initial size of the preallocation.
1153 		 * We clean up any extra preallocation when the file is closed.
1154 		 */
1155 		if (xfs_has_allocsize(mp))
1156 			prealloc_blocks = mp->m_allocsize_blocks;
1157 		else if (allocfork == XFS_DATA_FORK)
1158 			prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork,
1159 						offset, count, &icur);
1160 		else
1161 			prealloc_blocks = xfs_iomap_prealloc_size(ip, allocfork,
1162 						offset, count, &ccur);
1163 		if (prealloc_blocks) {
1164 			xfs_extlen_t	align;
1165 			xfs_off_t	end_offset;
1166 			xfs_fileoff_t	p_end_fsb;
1167 
1168 			end_offset = XFS_ALLOC_ALIGN(mp, offset + count - 1);
1169 			p_end_fsb = XFS_B_TO_FSBT(mp, end_offset) +
1170 					prealloc_blocks;
1171 
1172 			align = xfs_eof_alignment(ip);
1173 			if (align)
1174 				p_end_fsb = roundup_64(p_end_fsb, align);
1175 
1176 			p_end_fsb = min(p_end_fsb,
1177 				XFS_B_TO_FSB(mp, mp->m_super->s_maxbytes));
1178 			ASSERT(p_end_fsb > offset_fsb);
1179 			prealloc_blocks = p_end_fsb - end_fsb;
1180 		}
1181 	}
1182 
1183 	/*
1184 	 * Flag newly allocated delalloc blocks with IOMAP_F_NEW so we punch
1185 	 * them out if the write happens to fail.
1186 	 */
1187 	iomap_flags |= IOMAP_F_NEW;
1188 	if (allocfork == XFS_COW_FORK) {
1189 		error = xfs_bmapi_reserve_delalloc(ip, allocfork, offset_fsb,
1190 				end_fsb - offset_fsb, prealloc_blocks, &cmap,
1191 				&ccur, cow_eof);
1192 		if (error)
1193 			goto out_unlock;
1194 
1195 		trace_xfs_iomap_alloc(ip, offset, count, allocfork, &cmap);
1196 		goto found_cow;
1197 	}
1198 
1199 	error = xfs_bmapi_reserve_delalloc(ip, allocfork, offset_fsb,
1200 			end_fsb - offset_fsb, prealloc_blocks, &imap, &icur,
1201 			eof);
1202 	if (error)
1203 		goto out_unlock;
1204 
1205 	trace_xfs_iomap_alloc(ip, offset, count, allocfork, &imap);
1206 found_imap:
1207 	seq = xfs_iomap_inode_sequence(ip, iomap_flags);
1208 	xfs_iunlock(ip, lockmode);
1209 	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags, iomap_flags, seq);
1210 
1211 convert_delay:
1212 	xfs_iunlock(ip, lockmode);
1213 	truncate_pagecache(inode, offset);
1214 	error = xfs_bmapi_convert_delalloc(ip, XFS_DATA_FORK, offset,
1215 					   iomap, NULL);
1216 	if (error)
1217 		return error;
1218 
1219 	trace_xfs_iomap_alloc(ip, offset, count, XFS_DATA_FORK, &imap);
1220 	return 0;
1221 
1222 found_cow:
1223 	if (imap.br_startoff <= offset_fsb) {
1224 		error = xfs_bmbt_to_iomap(ip, srcmap, &imap, flags, 0,
1225 				xfs_iomap_inode_sequence(ip, 0));
1226 		if (error)
1227 			goto out_unlock;
1228 	} else {
1229 		xfs_trim_extent(&cmap, offset_fsb,
1230 				imap.br_startoff - offset_fsb);
1231 	}
1232 
1233 	iomap_flags |= IOMAP_F_SHARED;
1234 	seq = xfs_iomap_inode_sequence(ip, iomap_flags);
1235 	xfs_iunlock(ip, lockmode);
1236 	return xfs_bmbt_to_iomap(ip, iomap, &cmap, flags, iomap_flags, seq);
1237 
1238 out_unlock:
1239 	xfs_iunlock(ip, lockmode);
1240 	return error;
1241 }
1242 
1243 static void
xfs_buffered_write_delalloc_punch(struct inode * inode,loff_t offset,loff_t length,struct iomap * iomap)1244 xfs_buffered_write_delalloc_punch(
1245 	struct inode		*inode,
1246 	loff_t			offset,
1247 	loff_t			length,
1248 	struct iomap		*iomap)
1249 {
1250 	xfs_bmap_punch_delalloc_range(XFS_I(inode),
1251 			(iomap->flags & IOMAP_F_SHARED) ?
1252 				XFS_COW_FORK : XFS_DATA_FORK,
1253 			offset, offset + length);
1254 }
1255 
1256 static int
xfs_buffered_write_iomap_end(struct inode * inode,loff_t offset,loff_t length,ssize_t written,unsigned flags,struct iomap * iomap)1257 xfs_buffered_write_iomap_end(
1258 	struct inode		*inode,
1259 	loff_t			offset,
1260 	loff_t			length,
1261 	ssize_t			written,
1262 	unsigned		flags,
1263 	struct iomap		*iomap)
1264 {
1265 	loff_t			start_byte, end_byte;
1266 
1267 	/* If we didn't reserve the blocks, we're not allowed to punch them. */
1268 	if (iomap->type != IOMAP_DELALLOC || !(iomap->flags & IOMAP_F_NEW))
1269 		return 0;
1270 
1271 	/*
1272 	 * iomap_page_mkwrite() will never fail in a way that requires delalloc
1273 	 * extents that it allocated to be revoked.  Hence never try to release
1274 	 * them here.
1275 	 */
1276 	if (flags & IOMAP_FAULT)
1277 		return 0;
1278 
1279 	/* Nothing to do if we've written the entire delalloc extent */
1280 	start_byte = iomap_last_written_block(inode, offset, written);
1281 	end_byte = round_up(offset + length, i_blocksize(inode));
1282 	if (start_byte >= end_byte)
1283 		return 0;
1284 
1285 	/* For zeroing operations the callers already hold invalidate_lock. */
1286 	if (flags & (IOMAP_UNSHARE | IOMAP_ZERO)) {
1287 		rwsem_assert_held_write(&inode->i_mapping->invalidate_lock);
1288 		iomap_write_delalloc_release(inode, start_byte, end_byte, flags,
1289 				iomap, xfs_buffered_write_delalloc_punch);
1290 	} else {
1291 		filemap_invalidate_lock(inode->i_mapping);
1292 		iomap_write_delalloc_release(inode, start_byte, end_byte, flags,
1293 				iomap, xfs_buffered_write_delalloc_punch);
1294 		filemap_invalidate_unlock(inode->i_mapping);
1295 	}
1296 
1297 	return 0;
1298 }
1299 
1300 const struct iomap_ops xfs_buffered_write_iomap_ops = {
1301 	.iomap_begin		= xfs_buffered_write_iomap_begin,
1302 	.iomap_end		= xfs_buffered_write_iomap_end,
1303 };
1304 
1305 static int
xfs_read_iomap_begin(struct inode * inode,loff_t offset,loff_t length,unsigned flags,struct iomap * iomap,struct iomap * srcmap)1306 xfs_read_iomap_begin(
1307 	struct inode		*inode,
1308 	loff_t			offset,
1309 	loff_t			length,
1310 	unsigned		flags,
1311 	struct iomap		*iomap,
1312 	struct iomap		*srcmap)
1313 {
1314 	struct xfs_inode	*ip = XFS_I(inode);
1315 	struct xfs_mount	*mp = ip->i_mount;
1316 	struct xfs_bmbt_irec	imap;
1317 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
1318 	xfs_fileoff_t		end_fsb = xfs_iomap_end_fsb(mp, offset, length);
1319 	int			nimaps = 1, error = 0;
1320 	bool			shared = false;
1321 	unsigned int		lockmode = XFS_ILOCK_SHARED;
1322 	u64			seq;
1323 
1324 	ASSERT(!(flags & (IOMAP_WRITE | IOMAP_ZERO)));
1325 
1326 	if (xfs_is_shutdown(mp))
1327 		return -EIO;
1328 
1329 	error = xfs_ilock_for_iomap(ip, flags, &lockmode);
1330 	if (error)
1331 		return error;
1332 	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
1333 			       &nimaps, 0);
1334 	if (!error && ((flags & IOMAP_REPORT) || IS_DAX(inode)))
1335 		error = xfs_reflink_trim_around_shared(ip, &imap, &shared);
1336 	seq = xfs_iomap_inode_sequence(ip, shared ? IOMAP_F_SHARED : 0);
1337 	xfs_iunlock(ip, lockmode);
1338 
1339 	if (error)
1340 		return error;
1341 	trace_xfs_iomap_found(ip, offset, length, XFS_DATA_FORK, &imap);
1342 	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags,
1343 				 shared ? IOMAP_F_SHARED : 0, seq);
1344 }
1345 
1346 const struct iomap_ops xfs_read_iomap_ops = {
1347 	.iomap_begin		= xfs_read_iomap_begin,
1348 };
1349 
1350 static int
xfs_seek_iomap_begin(struct inode * inode,loff_t offset,loff_t length,unsigned flags,struct iomap * iomap,struct iomap * srcmap)1351 xfs_seek_iomap_begin(
1352 	struct inode		*inode,
1353 	loff_t			offset,
1354 	loff_t			length,
1355 	unsigned		flags,
1356 	struct iomap		*iomap,
1357 	struct iomap		*srcmap)
1358 {
1359 	struct xfs_inode	*ip = XFS_I(inode);
1360 	struct xfs_mount	*mp = ip->i_mount;
1361 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
1362 	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + length);
1363 	xfs_fileoff_t		cow_fsb = NULLFILEOFF, data_fsb = NULLFILEOFF;
1364 	struct xfs_iext_cursor	icur;
1365 	struct xfs_bmbt_irec	imap, cmap;
1366 	int			error = 0;
1367 	unsigned		lockmode;
1368 	u64			seq;
1369 
1370 	if (xfs_is_shutdown(mp))
1371 		return -EIO;
1372 
1373 	lockmode = xfs_ilock_data_map_shared(ip);
1374 	error = xfs_iread_extents(NULL, ip, XFS_DATA_FORK);
1375 	if (error)
1376 		goto out_unlock;
1377 
1378 	if (xfs_iext_lookup_extent(ip, &ip->i_df, offset_fsb, &icur, &imap)) {
1379 		/*
1380 		 * If we found a data extent we are done.
1381 		 */
1382 		if (imap.br_startoff <= offset_fsb)
1383 			goto done;
1384 		data_fsb = imap.br_startoff;
1385 	} else {
1386 		/*
1387 		 * Fake a hole until the end of the file.
1388 		 */
1389 		data_fsb = xfs_iomap_end_fsb(mp, offset, length);
1390 	}
1391 
1392 	/*
1393 	 * If a COW fork extent covers the hole, report it - capped to the next
1394 	 * data fork extent:
1395 	 */
1396 	if (xfs_inode_has_cow_data(ip) &&
1397 	    xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &cmap))
1398 		cow_fsb = cmap.br_startoff;
1399 	if (cow_fsb != NULLFILEOFF && cow_fsb <= offset_fsb) {
1400 		if (data_fsb < cow_fsb + cmap.br_blockcount)
1401 			end_fsb = min(end_fsb, data_fsb);
1402 		xfs_trim_extent(&cmap, offset_fsb, end_fsb - offset_fsb);
1403 		seq = xfs_iomap_inode_sequence(ip, IOMAP_F_SHARED);
1404 		error = xfs_bmbt_to_iomap(ip, iomap, &cmap, flags,
1405 				IOMAP_F_SHARED, seq);
1406 		/*
1407 		 * This is a COW extent, so we must probe the page cache
1408 		 * because there could be dirty page cache being backed
1409 		 * by this extent.
1410 		 */
1411 		iomap->type = IOMAP_UNWRITTEN;
1412 		goto out_unlock;
1413 	}
1414 
1415 	/*
1416 	 * Else report a hole, capped to the next found data or COW extent.
1417 	 */
1418 	if (cow_fsb != NULLFILEOFF && cow_fsb < data_fsb)
1419 		imap.br_blockcount = cow_fsb - offset_fsb;
1420 	else
1421 		imap.br_blockcount = data_fsb - offset_fsb;
1422 	imap.br_startoff = offset_fsb;
1423 	imap.br_startblock = HOLESTARTBLOCK;
1424 	imap.br_state = XFS_EXT_NORM;
1425 done:
1426 	seq = xfs_iomap_inode_sequence(ip, 0);
1427 	xfs_trim_extent(&imap, offset_fsb, end_fsb - offset_fsb);
1428 	error = xfs_bmbt_to_iomap(ip, iomap, &imap, flags, 0, seq);
1429 out_unlock:
1430 	xfs_iunlock(ip, lockmode);
1431 	return error;
1432 }
1433 
1434 const struct iomap_ops xfs_seek_iomap_ops = {
1435 	.iomap_begin		= xfs_seek_iomap_begin,
1436 };
1437 
1438 static int
xfs_xattr_iomap_begin(struct inode * inode,loff_t offset,loff_t length,unsigned flags,struct iomap * iomap,struct iomap * srcmap)1439 xfs_xattr_iomap_begin(
1440 	struct inode		*inode,
1441 	loff_t			offset,
1442 	loff_t			length,
1443 	unsigned		flags,
1444 	struct iomap		*iomap,
1445 	struct iomap		*srcmap)
1446 {
1447 	struct xfs_inode	*ip = XFS_I(inode);
1448 	struct xfs_mount	*mp = ip->i_mount;
1449 	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset);
1450 	xfs_fileoff_t		end_fsb = XFS_B_TO_FSB(mp, offset + length);
1451 	struct xfs_bmbt_irec	imap;
1452 	int			nimaps = 1, error = 0;
1453 	unsigned		lockmode;
1454 	int			seq;
1455 
1456 	if (xfs_is_shutdown(mp))
1457 		return -EIO;
1458 
1459 	lockmode = xfs_ilock_attr_map_shared(ip);
1460 
1461 	/* if there are no attribute fork or extents, return ENOENT */
1462 	if (!xfs_inode_has_attr_fork(ip) || !ip->i_af.if_nextents) {
1463 		error = -ENOENT;
1464 		goto out_unlock;
1465 	}
1466 
1467 	ASSERT(ip->i_af.if_format != XFS_DINODE_FMT_LOCAL);
1468 	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb, &imap,
1469 			       &nimaps, XFS_BMAPI_ATTRFORK);
1470 out_unlock:
1471 
1472 	seq = xfs_iomap_inode_sequence(ip, IOMAP_F_XATTR);
1473 	xfs_iunlock(ip, lockmode);
1474 
1475 	if (error)
1476 		return error;
1477 	ASSERT(nimaps);
1478 	return xfs_bmbt_to_iomap(ip, iomap, &imap, flags, IOMAP_F_XATTR, seq);
1479 }
1480 
1481 const struct iomap_ops xfs_xattr_iomap_ops = {
1482 	.iomap_begin		= xfs_xattr_iomap_begin,
1483 };
1484 
1485 int
xfs_zero_range(struct xfs_inode * ip,loff_t pos,loff_t len,bool * did_zero)1486 xfs_zero_range(
1487 	struct xfs_inode	*ip,
1488 	loff_t			pos,
1489 	loff_t			len,
1490 	bool			*did_zero)
1491 {
1492 	struct inode		*inode = VFS_I(ip);
1493 
1494 	xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
1495 
1496 	if (IS_DAX(inode))
1497 		return dax_zero_range(inode, pos, len, did_zero,
1498 				      &xfs_dax_write_iomap_ops);
1499 	return iomap_zero_range(inode, pos, len, did_zero,
1500 				&xfs_buffered_write_iomap_ops);
1501 }
1502 
1503 int
xfs_truncate_page(struct xfs_inode * ip,loff_t pos,bool * did_zero)1504 xfs_truncate_page(
1505 	struct xfs_inode	*ip,
1506 	loff_t			pos,
1507 	bool			*did_zero)
1508 {
1509 	struct inode		*inode = VFS_I(ip);
1510 
1511 	if (IS_DAX(inode))
1512 		return dax_truncate_page(inode, pos, did_zero,
1513 					&xfs_dax_write_iomap_ops);
1514 	return iomap_truncate_page(inode, pos, did_zero,
1515 				   &xfs_buffered_write_iomap_ops);
1516 }
1517