1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   4 * All Rights Reserved.
   5 */
   6#include "xfs.h"
   7#include <linux/backing-dev.h>
   8#include <linux/dax.h>
   9
  10#include "xfs_shared.h"
  11#include "xfs_format.h"
  12#include "xfs_log_format.h"
  13#include "xfs_trans_resv.h"
  14#include "xfs_mount.h"
  15#include "xfs_trace.h"
  16#include "xfs_log.h"
  17#include "xfs_log_recover.h"
  18#include "xfs_log_priv.h"
  19#include "xfs_trans.h"
  20#include "xfs_buf_item.h"
  21#include "xfs_errortag.h"
  22#include "xfs_error.h"
  23#include "xfs_ag.h"
  24#include "xfs_buf_mem.h"
  25
  26struct kmem_cache *xfs_buf_cache;
  27
  28/*
  29 * Locking orders
  30 *
  31 * xfs_buf_ioacct_inc:
  32 * xfs_buf_ioacct_dec:
  33 *	b_sema (caller holds)
  34 *	  b_lock
  35 *
  36 * xfs_buf_stale:
  37 *	b_sema (caller holds)
  38 *	  b_lock
  39 *	    lru_lock
  40 *
  41 * xfs_buf_rele:
  42 *	b_lock
  43 *	  pag_buf_lock
  44 *	    lru_lock
  45 *
  46 * xfs_buftarg_drain_rele
  47 *	lru_lock
  48 *	  b_lock (trylock due to inversion)
  49 *
  50 * xfs_buftarg_isolate
  51 *	lru_lock
  52 *	  b_lock (trylock due to inversion)
  53 */
  54
  55static int __xfs_buf_submit(struct xfs_buf *bp, bool wait);
  56
  57static inline int
  58xfs_buf_submit(
  59	struct xfs_buf		*bp)
  60{
  61	return __xfs_buf_submit(bp, !(bp->b_flags & XBF_ASYNC));
  62}
  63
  64static inline bool xfs_buf_is_uncached(struct xfs_buf *bp)
  65{
  66	return bp->b_rhash_key == XFS_BUF_DADDR_NULL;
  67}
  68
  69static inline int
  70xfs_buf_is_vmapped(
  71	struct xfs_buf	*bp)
  72{
  73	/*
  74	 * Return true if the buffer is vmapped.
  75	 *
  76	 * b_addr is null if the buffer is not mapped, but the code is clever
  77	 * enough to know it doesn't have to map a single page, so the check has
  78	 * to be both for b_addr and bp->b_page_count > 1.
  79	 */
  80	return bp->b_addr && bp->b_page_count > 1;
  81}
  82
  83static inline int
  84xfs_buf_vmap_len(
  85	struct xfs_buf	*bp)
  86{
  87	return (bp->b_page_count * PAGE_SIZE);
  88}
  89
  90/*
  91 * Bump the I/O in flight count on the buftarg if we haven't yet done so for
  92 * this buffer. The count is incremented once per buffer (per hold cycle)
  93 * because the corresponding decrement is deferred to buffer release. Buffers
  94 * can undergo I/O multiple times in a hold-release cycle and per buffer I/O
  95 * tracking adds unnecessary overhead. This is used for sychronization purposes
  96 * with unmount (see xfs_buftarg_drain()), so all we really need is a count of
  97 * in-flight buffers.
  98 *
  99 * Buffers that are never released (e.g., superblock, iclog buffers) must set
 100 * the XBF_NO_IOACCT flag before I/O submission. Otherwise, the buftarg count
 101 * never reaches zero and unmount hangs indefinitely.
 102 */
 103static inline void
 104xfs_buf_ioacct_inc(
 105	struct xfs_buf	*bp)
 106{
 107	if (bp->b_flags & XBF_NO_IOACCT)
 108		return;
 109
 110	ASSERT(bp->b_flags & XBF_ASYNC);
 111	spin_lock(&bp->b_lock);
 112	if (!(bp->b_state & XFS_BSTATE_IN_FLIGHT)) {
 113		bp->b_state |= XFS_BSTATE_IN_FLIGHT;
 114		percpu_counter_inc(&bp->b_target->bt_io_count);
 115	}
 116	spin_unlock(&bp->b_lock);
 117}
 118
 119/*
 120 * Clear the in-flight state on a buffer about to be released to the LRU or
 121 * freed and unaccount from the buftarg.
 122 */
 123static inline void
 124__xfs_buf_ioacct_dec(
 125	struct xfs_buf	*bp)
 126{
 127	lockdep_assert_held(&bp->b_lock);
 128
 129	if (bp->b_state & XFS_BSTATE_IN_FLIGHT) {
 130		bp->b_state &= ~XFS_BSTATE_IN_FLIGHT;
 131		percpu_counter_dec(&bp->b_target->bt_io_count);
 132	}
 133}
 134
 135static inline void
 136xfs_buf_ioacct_dec(
 137	struct xfs_buf	*bp)
 138{
 139	spin_lock(&bp->b_lock);
 140	__xfs_buf_ioacct_dec(bp);
 141	spin_unlock(&bp->b_lock);
 142}
 143
 144/*
 145 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
 146 * b_lru_ref count so that the buffer is freed immediately when the buffer
 147 * reference count falls to zero. If the buffer is already on the LRU, we need
 148 * to remove the reference that LRU holds on the buffer.
 149 *
 150 * This prevents build-up of stale buffers on the LRU.
 151 */
 152void
 153xfs_buf_stale(
 154	struct xfs_buf	*bp)
 155{
 156	ASSERT(xfs_buf_islocked(bp));
 157
 158	bp->b_flags |= XBF_STALE;
 159
 160	/*
 161	 * Clear the delwri status so that a delwri queue walker will not
 162	 * flush this buffer to disk now that it is stale. The delwri queue has
 163	 * a reference to the buffer, so this is safe to do.
 164	 */
 165	bp->b_flags &= ~_XBF_DELWRI_Q;
 166
 167	/*
 168	 * Once the buffer is marked stale and unlocked, a subsequent lookup
 169	 * could reset b_flags. There is no guarantee that the buffer is
 170	 * unaccounted (released to LRU) before that occurs. Drop in-flight
 171	 * status now to preserve accounting consistency.
 172	 */
 173	spin_lock(&bp->b_lock);
 174	__xfs_buf_ioacct_dec(bp);
 175
 176	atomic_set(&bp->b_lru_ref, 0);
 177	if (!(bp->b_state & XFS_BSTATE_DISPOSE) &&
 178	    (list_lru_del_obj(&bp->b_target->bt_lru, &bp->b_lru)))
 179		atomic_dec(&bp->b_hold);
 180
 181	ASSERT(atomic_read(&bp->b_hold) >= 1);
 182	spin_unlock(&bp->b_lock);
 183}
 184
 185static int
 186xfs_buf_get_maps(
 187	struct xfs_buf		*bp,
 188	int			map_count)
 189{
 190	ASSERT(bp->b_maps == NULL);
 191	bp->b_map_count = map_count;
 192
 193	if (map_count == 1) {
 194		bp->b_maps = &bp->__b_map;
 195		return 0;
 196	}
 197
 198	bp->b_maps = kzalloc(map_count * sizeof(struct xfs_buf_map),
 199			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
 200	if (!bp->b_maps)
 201		return -ENOMEM;
 202	return 0;
 203}
 204
 205/*
 206 *	Frees b_pages if it was allocated.
 207 */
 208static void
 209xfs_buf_free_maps(
 210	struct xfs_buf	*bp)
 211{
 212	if (bp->b_maps != &bp->__b_map) {
 213		kfree(bp->b_maps);
 214		bp->b_maps = NULL;
 215	}
 216}
 217
 218static int
 219_xfs_buf_alloc(
 220	struct xfs_buftarg	*target,
 221	struct xfs_buf_map	*map,
 222	int			nmaps,
 223	xfs_buf_flags_t		flags,
 224	struct xfs_buf		**bpp)
 225{
 226	struct xfs_buf		*bp;
 227	int			error;
 228	int			i;
 229
 230	*bpp = NULL;
 231	bp = kmem_cache_zalloc(xfs_buf_cache,
 232			GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
 233
 234	/*
 235	 * We don't want certain flags to appear in b_flags unless they are
 236	 * specifically set by later operations on the buffer.
 237	 */
 238	flags &= ~(XBF_UNMAPPED | XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD);
 239
 240	atomic_set(&bp->b_hold, 1);
 241	atomic_set(&bp->b_lru_ref, 1);
 242	init_completion(&bp->b_iowait);
 243	INIT_LIST_HEAD(&bp->b_lru);
 244	INIT_LIST_HEAD(&bp->b_list);
 245	INIT_LIST_HEAD(&bp->b_li_list);
 246	sema_init(&bp->b_sema, 0); /* held, no waiters */
 247	spin_lock_init(&bp->b_lock);
 248	bp->b_target = target;
 249	bp->b_mount = target->bt_mount;
 250	bp->b_flags = flags;
 251
 252	/*
 253	 * Set length and io_length to the same value initially.
 254	 * I/O routines should use io_length, which will be the same in
 255	 * most cases but may be reset (e.g. XFS recovery).
 256	 */
 257	error = xfs_buf_get_maps(bp, nmaps);
 258	if (error)  {
 259		kmem_cache_free(xfs_buf_cache, bp);
 260		return error;
 261	}
 262
 263	bp->b_rhash_key = map[0].bm_bn;
 264	bp->b_length = 0;
 265	for (i = 0; i < nmaps; i++) {
 266		bp->b_maps[i].bm_bn = map[i].bm_bn;
 267		bp->b_maps[i].bm_len = map[i].bm_len;
 268		bp->b_length += map[i].bm_len;
 269	}
 270
 271	atomic_set(&bp->b_pin_count, 0);
 272	init_waitqueue_head(&bp->b_waiters);
 273
 274	XFS_STATS_INC(bp->b_mount, xb_create);
 275	trace_xfs_buf_init(bp, _RET_IP_);
 276
 277	*bpp = bp;
 278	return 0;
 279}
 280
 281static void
 282xfs_buf_free_pages(
 283	struct xfs_buf	*bp)
 284{
 285	uint		i;
 286
 287	ASSERT(bp->b_flags & _XBF_PAGES);
 288
 289	if (xfs_buf_is_vmapped(bp))
 290		vm_unmap_ram(bp->b_addr, bp->b_page_count);
 291
 292	for (i = 0; i < bp->b_page_count; i++) {
 293		if (bp->b_pages[i])
 294			__free_page(bp->b_pages[i]);
 295	}
 296	mm_account_reclaimed_pages(bp->b_page_count);
 
 297
 298	if (bp->b_pages != bp->b_page_array)
 299		kfree(bp->b_pages);
 300	bp->b_pages = NULL;
 301	bp->b_flags &= ~_XBF_PAGES;
 302}
 303
 304static void
 305xfs_buf_free_callback(
 306	struct callback_head	*cb)
 307{
 308	struct xfs_buf		*bp = container_of(cb, struct xfs_buf, b_rcu);
 309
 310	xfs_buf_free_maps(bp);
 311	kmem_cache_free(xfs_buf_cache, bp);
 312}
 313
 314static void
 315xfs_buf_free(
 316	struct xfs_buf		*bp)
 317{
 318	trace_xfs_buf_free(bp, _RET_IP_);
 319
 320	ASSERT(list_empty(&bp->b_lru));
 321
 322	if (xfs_buftarg_is_mem(bp->b_target))
 323		xmbuf_unmap_page(bp);
 324	else if (bp->b_flags & _XBF_PAGES)
 325		xfs_buf_free_pages(bp);
 326	else if (bp->b_flags & _XBF_KMEM)
 327		kfree(bp->b_addr);
 328
 329	call_rcu(&bp->b_rcu, xfs_buf_free_callback);
 330}
 331
 332static int
 333xfs_buf_alloc_kmem(
 334	struct xfs_buf	*bp,
 335	xfs_buf_flags_t	flags)
 336{
 337	gfp_t		gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL;
 338	size_t		size = BBTOB(bp->b_length);
 339
 340	/* Assure zeroed buffer for non-read cases. */
 341	if (!(flags & XBF_READ))
 342		gfp_mask |= __GFP_ZERO;
 343
 344	bp->b_addr = kmalloc(size, gfp_mask);
 345	if (!bp->b_addr)
 346		return -ENOMEM;
 347
 348	if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) !=
 349	    ((unsigned long)bp->b_addr & PAGE_MASK)) {
 350		/* b_addr spans two pages - use alloc_page instead */
 351		kfree(bp->b_addr);
 352		bp->b_addr = NULL;
 353		return -ENOMEM;
 354	}
 355	bp->b_offset = offset_in_page(bp->b_addr);
 356	bp->b_pages = bp->b_page_array;
 357	bp->b_pages[0] = kmem_to_page(bp->b_addr);
 358	bp->b_page_count = 1;
 359	bp->b_flags |= _XBF_KMEM;
 360	return 0;
 361}
 362
 363static int
 364xfs_buf_alloc_pages(
 365	struct xfs_buf	*bp,
 366	xfs_buf_flags_t	flags)
 367{
 368	gfp_t		gfp_mask = GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOWARN;
 369	long		filled = 0;
 370
 371	if (flags & XBF_READ_AHEAD)
 372		gfp_mask |= __GFP_NORETRY;
 
 
 373
 374	/* Make sure that we have a page list */
 375	bp->b_page_count = DIV_ROUND_UP(BBTOB(bp->b_length), PAGE_SIZE);
 376	if (bp->b_page_count <= XB_PAGES) {
 377		bp->b_pages = bp->b_page_array;
 378	} else {
 379		bp->b_pages = kzalloc(sizeof(struct page *) * bp->b_page_count,
 380					gfp_mask);
 381		if (!bp->b_pages)
 382			return -ENOMEM;
 383	}
 384	bp->b_flags |= _XBF_PAGES;
 385
 386	/* Assure zeroed buffer for non-read cases. */
 387	if (!(flags & XBF_READ))
 388		gfp_mask |= __GFP_ZERO;
 389
 390	/*
 391	 * Bulk filling of pages can take multiple calls. Not filling the entire
 392	 * array is not an allocation failure, so don't back off if we get at
 393	 * least one extra page.
 394	 */
 395	for (;;) {
 396		long	last = filled;
 397
 398		filled = alloc_pages_bulk_array(gfp_mask, bp->b_page_count,
 399						bp->b_pages);
 400		if (filled == bp->b_page_count) {
 401			XFS_STATS_INC(bp->b_mount, xb_page_found);
 402			break;
 403		}
 404
 405		if (filled != last)
 406			continue;
 407
 408		if (flags & XBF_READ_AHEAD) {
 409			xfs_buf_free_pages(bp);
 410			return -ENOMEM;
 411		}
 412
 413		XFS_STATS_INC(bp->b_mount, xb_page_retries);
 414		memalloc_retry_wait(gfp_mask);
 415	}
 416	return 0;
 417}
 418
 419/*
 420 *	Map buffer into kernel address-space if necessary.
 421 */
 422STATIC int
 423_xfs_buf_map_pages(
 424	struct xfs_buf		*bp,
 425	xfs_buf_flags_t		flags)
 426{
 427	ASSERT(bp->b_flags & _XBF_PAGES);
 428	if (bp->b_page_count == 1) {
 429		/* A single page buffer is always mappable */
 430		bp->b_addr = page_address(bp->b_pages[0]);
 431	} else if (flags & XBF_UNMAPPED) {
 432		bp->b_addr = NULL;
 433	} else {
 434		int retried = 0;
 435		unsigned nofs_flag;
 436
 437		/*
 438		 * vm_map_ram() will allocate auxiliary structures (e.g.
 439		 * pagetables) with GFP_KERNEL, yet we often under a scoped nofs
 440		 * context here. Mixing GFP_KERNEL with GFP_NOFS allocations
 441		 * from the same call site that can be run from both above and
 442		 * below memory reclaim causes lockdep false positives. Hence we
 443		 * always need to force this allocation to nofs context because
 444		 * we can't pass __GFP_NOLOCKDEP down to auxillary structures to
 445		 * prevent false positive lockdep reports.
 446		 *
 447		 * XXX(dgc): I think dquot reclaim is the only place we can get
 448		 * to this function from memory reclaim context now. If we fix
 449		 * that like we've fixed inode reclaim to avoid writeback from
 450		 * reclaim, this nofs wrapping can go away.
 451		 */
 452		nofs_flag = memalloc_nofs_save();
 453		do {
 454			bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
 455						-1);
 456			if (bp->b_addr)
 457				break;
 458			vm_unmap_aliases();
 459		} while (retried++ <= 1);
 460		memalloc_nofs_restore(nofs_flag);
 461
 462		if (!bp->b_addr)
 463			return -ENOMEM;
 464	}
 465
 466	return 0;
 467}
 468
 469/*
 470 *	Finding and Reading Buffers
 471 */
 472static int
 473_xfs_buf_obj_cmp(
 474	struct rhashtable_compare_arg	*arg,
 475	const void			*obj)
 476{
 477	const struct xfs_buf_map	*map = arg->key;
 478	const struct xfs_buf		*bp = obj;
 479
 480	/*
 481	 * The key hashing in the lookup path depends on the key being the
 482	 * first element of the compare_arg, make sure to assert this.
 483	 */
 484	BUILD_BUG_ON(offsetof(struct xfs_buf_map, bm_bn) != 0);
 485
 486	if (bp->b_rhash_key != map->bm_bn)
 487		return 1;
 488
 489	if (unlikely(bp->b_length != map->bm_len)) {
 490		/*
 491		 * found a block number match. If the range doesn't
 492		 * match, the only way this is allowed is if the buffer
 493		 * in the cache is stale and the transaction that made
 494		 * it stale has not yet committed. i.e. we are
 495		 * reallocating a busy extent. Skip this buffer and
 496		 * continue searching for an exact match.
 497		 *
 498		 * Note: If we're scanning for incore buffers to stale, don't
 499		 * complain if we find non-stale buffers.
 500		 */
 501		if (!(map->bm_flags & XBM_LIVESCAN))
 502			ASSERT(bp->b_flags & XBF_STALE);
 503		return 1;
 504	}
 505	return 0;
 506}
 507
 508static const struct rhashtable_params xfs_buf_hash_params = {
 509	.min_size		= 32,	/* empty AGs have minimal footprint */
 510	.nelem_hint		= 16,
 511	.key_len		= sizeof(xfs_daddr_t),
 512	.key_offset		= offsetof(struct xfs_buf, b_rhash_key),
 513	.head_offset		= offsetof(struct xfs_buf, b_rhash_head),
 514	.automatic_shrinking	= true,
 515	.obj_cmpfn		= _xfs_buf_obj_cmp,
 516};
 517
 518int
 519xfs_buf_cache_init(
 520	struct xfs_buf_cache	*bch)
 521{
 522	spin_lock_init(&bch->bc_lock);
 523	return rhashtable_init(&bch->bc_hash, &xfs_buf_hash_params);
 524}
 525
 526void
 527xfs_buf_cache_destroy(
 528	struct xfs_buf_cache	*bch)
 529{
 530	rhashtable_destroy(&bch->bc_hash);
 531}
 532
 533static int
 534xfs_buf_map_verify(
 535	struct xfs_buftarg	*btp,
 536	struct xfs_buf_map	*map)
 537{
 538	xfs_daddr_t		eofs;
 539
 540	/* Check for IOs smaller than the sector size / not sector aligned */
 541	ASSERT(!(BBTOB(map->bm_len) < btp->bt_meta_sectorsize));
 542	ASSERT(!(BBTOB(map->bm_bn) & (xfs_off_t)btp->bt_meta_sectormask));
 543
 544	/*
 545	 * Corrupted block numbers can get through to here, unfortunately, so we
 546	 * have to check that the buffer falls within the filesystem bounds.
 547	 */
 548	eofs = XFS_FSB_TO_BB(btp->bt_mount, btp->bt_mount->m_sb.sb_dblocks);
 549	if (map->bm_bn < 0 || map->bm_bn >= eofs) {
 550		xfs_alert(btp->bt_mount,
 551			  "%s: daddr 0x%llx out of range, EOFS 0x%llx",
 552			  __func__, map->bm_bn, eofs);
 553		WARN_ON(1);
 554		return -EFSCORRUPTED;
 555	}
 556	return 0;
 557}
 558
 559static int
 560xfs_buf_find_lock(
 561	struct xfs_buf          *bp,
 562	xfs_buf_flags_t		flags)
 563{
 564	if (flags & XBF_TRYLOCK) {
 565		if (!xfs_buf_trylock(bp)) {
 566			XFS_STATS_INC(bp->b_mount, xb_busy_locked);
 567			return -EAGAIN;
 568		}
 569	} else {
 570		xfs_buf_lock(bp);
 571		XFS_STATS_INC(bp->b_mount, xb_get_locked_waited);
 572	}
 573
 574	/*
 575	 * if the buffer is stale, clear all the external state associated with
 576	 * it. We need to keep flags such as how we allocated the buffer memory
 577	 * intact here.
 578	 */
 579	if (bp->b_flags & XBF_STALE) {
 580		if (flags & XBF_LIVESCAN) {
 581			xfs_buf_unlock(bp);
 582			return -ENOENT;
 583		}
 584		ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
 585		bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
 586		bp->b_ops = NULL;
 587	}
 588	return 0;
 589}
 590
 591static inline int
 592xfs_buf_lookup(
 593	struct xfs_buf_cache	*bch,
 594	struct xfs_buf_map	*map,
 595	xfs_buf_flags_t		flags,
 596	struct xfs_buf		**bpp)
 597{
 598	struct xfs_buf          *bp;
 599	int			error;
 600
 601	rcu_read_lock();
 602	bp = rhashtable_lookup(&bch->bc_hash, map, xfs_buf_hash_params);
 603	if (!bp || !atomic_inc_not_zero(&bp->b_hold)) {
 604		rcu_read_unlock();
 605		return -ENOENT;
 606	}
 607	rcu_read_unlock();
 608
 609	error = xfs_buf_find_lock(bp, flags);
 610	if (error) {
 611		xfs_buf_rele(bp);
 612		return error;
 613	}
 614
 615	trace_xfs_buf_find(bp, flags, _RET_IP_);
 616	*bpp = bp;
 617	return 0;
 618}
 619
 620/*
 621 * Insert the new_bp into the hash table. This consumes the perag reference
 622 * taken for the lookup regardless of the result of the insert.
 623 */
 624static int
 625xfs_buf_find_insert(
 626	struct xfs_buftarg	*btp,
 627	struct xfs_buf_cache	*bch,
 628	struct xfs_perag	*pag,
 629	struct xfs_buf_map	*cmap,
 630	struct xfs_buf_map	*map,
 631	int			nmaps,
 632	xfs_buf_flags_t		flags,
 633	struct xfs_buf		**bpp)
 634{
 635	struct xfs_buf		*new_bp;
 636	struct xfs_buf		*bp;
 637	int			error;
 638
 639	error = _xfs_buf_alloc(btp, map, nmaps, flags, &new_bp);
 640	if (error)
 641		goto out_drop_pag;
 642
 643	if (xfs_buftarg_is_mem(new_bp->b_target)) {
 644		error = xmbuf_map_page(new_bp);
 645	} else if (BBTOB(new_bp->b_length) >= PAGE_SIZE ||
 646		   xfs_buf_alloc_kmem(new_bp, flags) < 0) {
 647		/*
 648		 * For buffers that fit entirely within a single page, first
 649		 * attempt to allocate the memory from the heap to minimise
 650		 * memory usage. If we can't get heap memory for these small
 651		 * buffers, we fall back to using the page allocator.
 652		 */
 653		error = xfs_buf_alloc_pages(new_bp, flags);
 
 
 654	}
 655	if (error)
 656		goto out_free_buf;
 657
 658	spin_lock(&bch->bc_lock);
 659	bp = rhashtable_lookup_get_insert_fast(&bch->bc_hash,
 660			&new_bp->b_rhash_head, xfs_buf_hash_params);
 661	if (IS_ERR(bp)) {
 662		error = PTR_ERR(bp);
 663		spin_unlock(&bch->bc_lock);
 664		goto out_free_buf;
 665	}
 666	if (bp && atomic_inc_not_zero(&bp->b_hold)) {
 667		/* found an existing buffer */
 668		spin_unlock(&bch->bc_lock);
 
 669		error = xfs_buf_find_lock(bp, flags);
 670		if (error)
 671			xfs_buf_rele(bp);
 672		else
 673			*bpp = bp;
 674		goto out_free_buf;
 675	}
 676
 677	/* The new buffer keeps the perag reference until it is freed. */
 678	new_bp->b_pag = pag;
 679	spin_unlock(&bch->bc_lock);
 680	*bpp = new_bp;
 681	return 0;
 682
 683out_free_buf:
 684	xfs_buf_free(new_bp);
 685out_drop_pag:
 686	if (pag)
 687		xfs_perag_put(pag);
 688	return error;
 689}
 690
 691static inline struct xfs_perag *
 692xfs_buftarg_get_pag(
 693	struct xfs_buftarg		*btp,
 694	const struct xfs_buf_map	*map)
 695{
 696	struct xfs_mount		*mp = btp->bt_mount;
 697
 698	if (xfs_buftarg_is_mem(btp))
 699		return NULL;
 700	return xfs_perag_get(mp, xfs_daddr_to_agno(mp, map->bm_bn));
 701}
 702
 703static inline struct xfs_buf_cache *
 704xfs_buftarg_buf_cache(
 705	struct xfs_buftarg		*btp,
 706	struct xfs_perag		*pag)
 707{
 708	if (pag)
 709		return &pag->pag_bcache;
 710	return btp->bt_cache;
 711}
 712
 713/*
 714 * Assembles a buffer covering the specified range. The code is optimised for
 715 * cache hits, as metadata intensive workloads will see 3 orders of magnitude
 716 * more hits than misses.
 717 */
 718int
 719xfs_buf_get_map(
 720	struct xfs_buftarg	*btp,
 721	struct xfs_buf_map	*map,
 722	int			nmaps,
 723	xfs_buf_flags_t		flags,
 724	struct xfs_buf		**bpp)
 725{
 726	struct xfs_buf_cache	*bch;
 727	struct xfs_perag	*pag;
 728	struct xfs_buf		*bp = NULL;
 729	struct xfs_buf_map	cmap = { .bm_bn = map[0].bm_bn };
 730	int			error;
 731	int			i;
 732
 733	if (flags & XBF_LIVESCAN)
 734		cmap.bm_flags |= XBM_LIVESCAN;
 735	for (i = 0; i < nmaps; i++)
 736		cmap.bm_len += map[i].bm_len;
 737
 738	error = xfs_buf_map_verify(btp, &cmap);
 739	if (error)
 740		return error;
 741
 742	pag = xfs_buftarg_get_pag(btp, &cmap);
 743	bch = xfs_buftarg_buf_cache(btp, pag);
 744
 745	error = xfs_buf_lookup(bch, &cmap, flags, &bp);
 746	if (error && error != -ENOENT)
 747		goto out_put_perag;
 748
 749	/* cache hits always outnumber misses by at least 10:1 */
 750	if (unlikely(!bp)) {
 751		XFS_STATS_INC(btp->bt_mount, xb_miss_locked);
 752
 753		if (flags & XBF_INCORE)
 754			goto out_put_perag;
 755
 756		/* xfs_buf_find_insert() consumes the perag reference. */
 757		error = xfs_buf_find_insert(btp, bch, pag, &cmap, map, nmaps,
 758				flags, &bp);
 759		if (error)
 760			return error;
 761	} else {
 762		XFS_STATS_INC(btp->bt_mount, xb_get_locked);
 763		if (pag)
 764			xfs_perag_put(pag);
 765	}
 766
 767	/* We do not hold a perag reference anymore. */
 768	if (!bp->b_addr) {
 769		error = _xfs_buf_map_pages(bp, flags);
 770		if (unlikely(error)) {
 771			xfs_warn_ratelimited(btp->bt_mount,
 772				"%s: failed to map %u pages", __func__,
 773				bp->b_page_count);
 774			xfs_buf_relse(bp);
 775			return error;
 776		}
 777	}
 778
 779	/*
 780	 * Clear b_error if this is a lookup from a caller that doesn't expect
 781	 * valid data to be found in the buffer.
 782	 */
 783	if (!(flags & XBF_READ))
 784		xfs_buf_ioerror(bp, 0);
 785
 786	XFS_STATS_INC(btp->bt_mount, xb_get);
 787	trace_xfs_buf_get(bp, flags, _RET_IP_);
 788	*bpp = bp;
 789	return 0;
 790
 791out_put_perag:
 792	if (pag)
 793		xfs_perag_put(pag);
 794	return error;
 795}
 796
 797int
 798_xfs_buf_read(
 799	struct xfs_buf		*bp,
 800	xfs_buf_flags_t		flags)
 801{
 802	ASSERT(!(flags & XBF_WRITE));
 803	ASSERT(bp->b_maps[0].bm_bn != XFS_BUF_DADDR_NULL);
 804
 805	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_READ_AHEAD | XBF_DONE);
 806	bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
 807
 808	return xfs_buf_submit(bp);
 809}
 810
 811/*
 812 * Reverify a buffer found in cache without an attached ->b_ops.
 813 *
 814 * If the caller passed an ops structure and the buffer doesn't have ops
 815 * assigned, set the ops and use it to verify the contents. If verification
 816 * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is
 817 * already in XBF_DONE state on entry.
 818 *
 819 * Under normal operations, every in-core buffer is verified on read I/O
 820 * completion. There are two scenarios that can lead to in-core buffers without
 821 * an assigned ->b_ops. The first is during log recovery of buffers on a V4
 822 * filesystem, though these buffers are purged at the end of recovery. The
 823 * other is online repair, which intentionally reads with a NULL buffer ops to
 824 * run several verifiers across an in-core buffer in order to establish buffer
 825 * type.  If repair can't establish that, the buffer will be left in memory
 826 * with NULL buffer ops.
 827 */
 828int
 829xfs_buf_reverify(
 830	struct xfs_buf		*bp,
 831	const struct xfs_buf_ops *ops)
 832{
 833	ASSERT(bp->b_flags & XBF_DONE);
 834	ASSERT(bp->b_error == 0);
 835
 836	if (!ops || bp->b_ops)
 837		return 0;
 838
 839	bp->b_ops = ops;
 840	bp->b_ops->verify_read(bp);
 841	if (bp->b_error)
 842		bp->b_flags &= ~XBF_DONE;
 843	return bp->b_error;
 844}
 845
 846int
 847xfs_buf_read_map(
 848	struct xfs_buftarg	*target,
 849	struct xfs_buf_map	*map,
 850	int			nmaps,
 851	xfs_buf_flags_t		flags,
 852	struct xfs_buf		**bpp,
 853	const struct xfs_buf_ops *ops,
 854	xfs_failaddr_t		fa)
 855{
 856	struct xfs_buf		*bp;
 857	int			error;
 858
 859	flags |= XBF_READ;
 860	*bpp = NULL;
 861
 862	error = xfs_buf_get_map(target, map, nmaps, flags, &bp);
 863	if (error)
 864		return error;
 865
 866	trace_xfs_buf_read(bp, flags, _RET_IP_);
 867
 868	if (!(bp->b_flags & XBF_DONE)) {
 869		/* Initiate the buffer read and wait. */
 870		XFS_STATS_INC(target->bt_mount, xb_get_read);
 871		bp->b_ops = ops;
 872		error = _xfs_buf_read(bp, flags);
 873
 874		/* Readahead iodone already dropped the buffer, so exit. */
 875		if (flags & XBF_ASYNC)
 876			return 0;
 877	} else {
 878		/* Buffer already read; all we need to do is check it. */
 879		error = xfs_buf_reverify(bp, ops);
 880
 881		/* Readahead already finished; drop the buffer and exit. */
 882		if (flags & XBF_ASYNC) {
 883			xfs_buf_relse(bp);
 884			return 0;
 885		}
 886
 887		/* We do not want read in the flags */
 888		bp->b_flags &= ~XBF_READ;
 889		ASSERT(bp->b_ops != NULL || ops == NULL);
 890	}
 891
 892	/*
 893	 * If we've had a read error, then the contents of the buffer are
 894	 * invalid and should not be used. To ensure that a followup read tries
 895	 * to pull the buffer from disk again, we clear the XBF_DONE flag and
 896	 * mark the buffer stale. This ensures that anyone who has a current
 897	 * reference to the buffer will interpret it's contents correctly and
 898	 * future cache lookups will also treat it as an empty, uninitialised
 899	 * buffer.
 900	 */
 901	if (error) {
 902		/*
 903		 * Check against log shutdown for error reporting because
 904		 * metadata writeback may require a read first and we need to
 905		 * report errors in metadata writeback until the log is shut
 906		 * down. High level transaction read functions already check
 907		 * against mount shutdown, anyway, so we only need to be
 908		 * concerned about low level IO interactions here.
 909		 */
 910		if (!xlog_is_shutdown(target->bt_mount->m_log))
 911			xfs_buf_ioerror_alert(bp, fa);
 912
 913		bp->b_flags &= ~XBF_DONE;
 914		xfs_buf_stale(bp);
 915		xfs_buf_relse(bp);
 916
 917		/* bad CRC means corrupted metadata */
 918		if (error == -EFSBADCRC)
 919			error = -EFSCORRUPTED;
 920		return error;
 921	}
 922
 923	*bpp = bp;
 924	return 0;
 925}
 926
 927/*
 928 *	If we are not low on memory then do the readahead in a deadlock
 929 *	safe manner.
 930 */
 931void
 932xfs_buf_readahead_map(
 933	struct xfs_buftarg	*target,
 934	struct xfs_buf_map	*map,
 935	int			nmaps,
 936	const struct xfs_buf_ops *ops)
 937{
 938	struct xfs_buf		*bp;
 939
 940	/*
 941	 * Currently we don't have a good means or justification for performing
 942	 * xmbuf_map_page asynchronously, so we don't do readahead.
 943	 */
 944	if (xfs_buftarg_is_mem(target))
 945		return;
 946
 947	xfs_buf_read_map(target, map, nmaps,
 948		     XBF_TRYLOCK | XBF_ASYNC | XBF_READ_AHEAD, &bp, ops,
 949		     __this_address);
 950}
 951
 952/*
 953 * Read an uncached buffer from disk. Allocates and returns a locked
 954 * buffer containing the disk contents or nothing. Uncached buffers always have
 955 * a cache index of XFS_BUF_DADDR_NULL so we can easily determine if the buffer
 956 * is cached or uncached during fault diagnosis.
 957 */
 958int
 959xfs_buf_read_uncached(
 960	struct xfs_buftarg	*target,
 961	xfs_daddr_t		daddr,
 962	size_t			numblks,
 963	xfs_buf_flags_t		flags,
 964	struct xfs_buf		**bpp,
 965	const struct xfs_buf_ops *ops)
 966{
 967	struct xfs_buf		*bp;
 968	int			error;
 969
 970	*bpp = NULL;
 971
 972	error = xfs_buf_get_uncached(target, numblks, flags, &bp);
 973	if (error)
 974		return error;
 975
 976	/* set up the buffer for a read IO */
 977	ASSERT(bp->b_map_count == 1);
 978	bp->b_rhash_key = XFS_BUF_DADDR_NULL;
 979	bp->b_maps[0].bm_bn = daddr;
 980	bp->b_flags |= XBF_READ;
 981	bp->b_ops = ops;
 982
 983	xfs_buf_submit(bp);
 984	if (bp->b_error) {
 985		error = bp->b_error;
 986		xfs_buf_relse(bp);
 987		return error;
 988	}
 989
 990	*bpp = bp;
 991	return 0;
 992}
 993
 994int
 995xfs_buf_get_uncached(
 996	struct xfs_buftarg	*target,
 997	size_t			numblks,
 998	xfs_buf_flags_t		flags,
 999	struct xfs_buf		**bpp)
1000{
1001	int			error;
1002	struct xfs_buf		*bp;
1003	DEFINE_SINGLE_BUF_MAP(map, XFS_BUF_DADDR_NULL, numblks);
1004
1005	*bpp = NULL;
1006
1007	/* flags might contain irrelevant bits, pass only what we care about */
1008	error = _xfs_buf_alloc(target, &map, 1, flags & XBF_NO_IOACCT, &bp);
1009	if (error)
1010		return error;
1011
1012	if (xfs_buftarg_is_mem(bp->b_target))
1013		error = xmbuf_map_page(bp);
1014	else
1015		error = xfs_buf_alloc_pages(bp, flags);
1016	if (error)
1017		goto fail_free_buf;
1018
1019	error = _xfs_buf_map_pages(bp, 0);
1020	if (unlikely(error)) {
1021		xfs_warn(target->bt_mount,
1022			"%s: failed to map pages", __func__);
1023		goto fail_free_buf;
1024	}
1025
1026	trace_xfs_buf_get_uncached(bp, _RET_IP_);
1027	*bpp = bp;
1028	return 0;
1029
1030fail_free_buf:
1031	xfs_buf_free(bp);
1032	return error;
1033}
1034
1035/*
1036 *	Increment reference count on buffer, to hold the buffer concurrently
1037 *	with another thread which may release (free) the buffer asynchronously.
1038 *	Must hold the buffer already to call this function.
1039 */
1040void
1041xfs_buf_hold(
1042	struct xfs_buf		*bp)
1043{
1044	trace_xfs_buf_hold(bp, _RET_IP_);
1045	atomic_inc(&bp->b_hold);
1046}
1047
1048static void
1049xfs_buf_rele_uncached(
1050	struct xfs_buf		*bp)
1051{
1052	ASSERT(list_empty(&bp->b_lru));
1053	if (atomic_dec_and_test(&bp->b_hold)) {
1054		xfs_buf_ioacct_dec(bp);
1055		xfs_buf_free(bp);
1056	}
1057}
1058
1059static void
1060xfs_buf_rele_cached(
1061	struct xfs_buf		*bp)
1062{
1063	struct xfs_buftarg	*btp = bp->b_target;
1064	struct xfs_perag	*pag = bp->b_pag;
1065	struct xfs_buf_cache	*bch = xfs_buftarg_buf_cache(btp, pag);
1066	bool			release;
1067	bool			freebuf = false;
1068
1069	trace_xfs_buf_rele(bp, _RET_IP_);
1070
 
 
 
 
 
 
 
 
 
1071	ASSERT(atomic_read(&bp->b_hold) > 0);
1072
1073	/*
1074	 * We grab the b_lock here first to serialise racing xfs_buf_rele()
1075	 * calls. The pag_buf_lock being taken on the last reference only
1076	 * serialises against racing lookups in xfs_buf_find(). IOWs, the second
1077	 * to last reference we drop here is not serialised against the last
1078	 * reference until we take bp->b_lock. Hence if we don't grab b_lock
1079	 * first, the last "release" reference can win the race to the lock and
1080	 * free the buffer before the second-to-last reference is processed,
1081	 * leading to a use-after-free scenario.
1082	 */
1083	spin_lock(&bp->b_lock);
1084	release = atomic_dec_and_lock(&bp->b_hold, &bch->bc_lock);
1085	if (!release) {
1086		/*
1087		 * Drop the in-flight state if the buffer is already on the LRU
1088		 * and it holds the only reference. This is racy because we
1089		 * haven't acquired the pag lock, but the use of _XBF_IN_FLIGHT
1090		 * ensures the decrement occurs only once per-buf.
1091		 */
1092		if ((atomic_read(&bp->b_hold) == 1) && !list_empty(&bp->b_lru))
1093			__xfs_buf_ioacct_dec(bp);
1094		goto out_unlock;
1095	}
1096
1097	/* the last reference has been dropped ... */
1098	__xfs_buf_ioacct_dec(bp);
1099	if (!(bp->b_flags & XBF_STALE) && atomic_read(&bp->b_lru_ref)) {
1100		/*
1101		 * If the buffer is added to the LRU take a new reference to the
1102		 * buffer for the LRU and clear the (now stale) dispose list
1103		 * state flag
1104		 */
1105		if (list_lru_add_obj(&btp->bt_lru, &bp->b_lru)) {
1106			bp->b_state &= ~XFS_BSTATE_DISPOSE;
1107			atomic_inc(&bp->b_hold);
1108		}
1109		spin_unlock(&bch->bc_lock);
1110	} else {
1111		/*
1112		 * most of the time buffers will already be removed from the
1113		 * LRU, so optimise that case by checking for the
1114		 * XFS_BSTATE_DISPOSE flag indicating the last list the buffer
1115		 * was on was the disposal list
1116		 */
1117		if (!(bp->b_state & XFS_BSTATE_DISPOSE)) {
1118			list_lru_del_obj(&btp->bt_lru, &bp->b_lru);
1119		} else {
1120			ASSERT(list_empty(&bp->b_lru));
1121		}
1122
1123		ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1124		rhashtable_remove_fast(&bch->bc_hash, &bp->b_rhash_head,
1125				xfs_buf_hash_params);
1126		spin_unlock(&bch->bc_lock);
1127		if (pag)
1128			xfs_perag_put(pag);
1129		freebuf = true;
1130	}
1131
1132out_unlock:
1133	spin_unlock(&bp->b_lock);
1134
1135	if (freebuf)
1136		xfs_buf_free(bp);
1137}
1138
1139/*
1140 * Release a hold on the specified buffer.
1141 */
1142void
1143xfs_buf_rele(
1144	struct xfs_buf		*bp)
1145{
1146	trace_xfs_buf_rele(bp, _RET_IP_);
1147	if (xfs_buf_is_uncached(bp))
1148		xfs_buf_rele_uncached(bp);
1149	else
1150		xfs_buf_rele_cached(bp);
1151}
1152
1153/*
1154 *	Lock a buffer object, if it is not already locked.
1155 *
1156 *	If we come across a stale, pinned, locked buffer, we know that we are
1157 *	being asked to lock a buffer that has been reallocated. Because it is
1158 *	pinned, we know that the log has not been pushed to disk and hence it
1159 *	will still be locked.  Rather than continuing to have trylock attempts
1160 *	fail until someone else pushes the log, push it ourselves before
1161 *	returning.  This means that the xfsaild will not get stuck trying
1162 *	to push on stale inode buffers.
1163 */
1164int
1165xfs_buf_trylock(
1166	struct xfs_buf		*bp)
1167{
1168	int			locked;
1169
1170	locked = down_trylock(&bp->b_sema) == 0;
1171	if (locked)
1172		trace_xfs_buf_trylock(bp, _RET_IP_);
1173	else
1174		trace_xfs_buf_trylock_fail(bp, _RET_IP_);
1175	return locked;
1176}
1177
1178/*
1179 *	Lock a buffer object.
1180 *
1181 *	If we come across a stale, pinned, locked buffer, we know that we
1182 *	are being asked to lock a buffer that has been reallocated. Because
1183 *	it is pinned, we know that the log has not been pushed to disk and
1184 *	hence it will still be locked. Rather than sleeping until someone
1185 *	else pushes the log, push it ourselves before trying to get the lock.
1186 */
1187void
1188xfs_buf_lock(
1189	struct xfs_buf		*bp)
1190{
1191	trace_xfs_buf_lock(bp, _RET_IP_);
1192
1193	if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
1194		xfs_log_force(bp->b_mount, 0);
1195	down(&bp->b_sema);
1196
1197	trace_xfs_buf_lock_done(bp, _RET_IP_);
1198}
1199
1200void
1201xfs_buf_unlock(
1202	struct xfs_buf		*bp)
1203{
1204	ASSERT(xfs_buf_islocked(bp));
1205
1206	up(&bp->b_sema);
1207	trace_xfs_buf_unlock(bp, _RET_IP_);
1208}
1209
1210STATIC void
1211xfs_buf_wait_unpin(
1212	struct xfs_buf		*bp)
1213{
1214	DECLARE_WAITQUEUE	(wait, current);
1215
1216	if (atomic_read(&bp->b_pin_count) == 0)
1217		return;
1218
1219	add_wait_queue(&bp->b_waiters, &wait);
1220	for (;;) {
1221		set_current_state(TASK_UNINTERRUPTIBLE);
1222		if (atomic_read(&bp->b_pin_count) == 0)
1223			break;
1224		io_schedule();
1225	}
1226	remove_wait_queue(&bp->b_waiters, &wait);
1227	set_current_state(TASK_RUNNING);
1228}
1229
1230static void
1231xfs_buf_ioerror_alert_ratelimited(
1232	struct xfs_buf		*bp)
1233{
1234	static unsigned long	lasttime;
1235	static struct xfs_buftarg *lasttarg;
1236
1237	if (bp->b_target != lasttarg ||
1238	    time_after(jiffies, (lasttime + 5*HZ))) {
1239		lasttime = jiffies;
1240		xfs_buf_ioerror_alert(bp, __this_address);
1241	}
1242	lasttarg = bp->b_target;
1243}
1244
1245/*
1246 * Account for this latest trip around the retry handler, and decide if
1247 * we've failed enough times to constitute a permanent failure.
1248 */
1249static bool
1250xfs_buf_ioerror_permanent(
1251	struct xfs_buf		*bp,
1252	struct xfs_error_cfg	*cfg)
1253{
1254	struct xfs_mount	*mp = bp->b_mount;
1255
1256	if (cfg->max_retries != XFS_ERR_RETRY_FOREVER &&
1257	    ++bp->b_retries > cfg->max_retries)
1258		return true;
1259	if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1260	    time_after(jiffies, cfg->retry_timeout + bp->b_first_retry_time))
1261		return true;
1262
1263	/* At unmount we may treat errors differently */
1264	if (xfs_is_unmounting(mp) && mp->m_fail_unmount)
1265		return true;
1266
1267	return false;
1268}
1269
1270/*
1271 * On a sync write or shutdown we just want to stale the buffer and let the
1272 * caller handle the error in bp->b_error appropriately.
1273 *
1274 * If the write was asynchronous then no one will be looking for the error.  If
1275 * this is the first failure of this type, clear the error state and write the
1276 * buffer out again. This means we always retry an async write failure at least
1277 * once, but we also need to set the buffer up to behave correctly now for
1278 * repeated failures.
1279 *
1280 * If we get repeated async write failures, then we take action according to the
1281 * error configuration we have been set up to use.
1282 *
1283 * Returns true if this function took care of error handling and the caller must
1284 * not touch the buffer again.  Return false if the caller should proceed with
1285 * normal I/O completion handling.
1286 */
1287static bool
1288xfs_buf_ioend_handle_error(
1289	struct xfs_buf		*bp)
1290{
1291	struct xfs_mount	*mp = bp->b_mount;
1292	struct xfs_error_cfg	*cfg;
1293
1294	/*
1295	 * If we've already shutdown the journal because of I/O errors, there's
1296	 * no point in giving this a retry.
1297	 */
1298	if (xlog_is_shutdown(mp->m_log))
1299		goto out_stale;
1300
1301	xfs_buf_ioerror_alert_ratelimited(bp);
1302
1303	/*
1304	 * We're not going to bother about retrying this during recovery.
1305	 * One strike!
1306	 */
1307	if (bp->b_flags & _XBF_LOGRECOVERY) {
1308		xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1309		return false;
1310	}
1311
1312	/*
1313	 * Synchronous writes will have callers process the error.
1314	 */
1315	if (!(bp->b_flags & XBF_ASYNC))
1316		goto out_stale;
1317
1318	trace_xfs_buf_iodone_async(bp, _RET_IP_);
1319
1320	cfg = xfs_error_get_cfg(mp, XFS_ERR_METADATA, bp->b_error);
1321	if (bp->b_last_error != bp->b_error ||
1322	    !(bp->b_flags & (XBF_STALE | XBF_WRITE_FAIL))) {
1323		bp->b_last_error = bp->b_error;
1324		if (cfg->retry_timeout != XFS_ERR_RETRY_FOREVER &&
1325		    !bp->b_first_retry_time)
1326			bp->b_first_retry_time = jiffies;
1327		goto resubmit;
1328	}
1329
1330	/*
1331	 * Permanent error - we need to trigger a shutdown if we haven't already
1332	 * to indicate that inconsistency will result from this action.
1333	 */
1334	if (xfs_buf_ioerror_permanent(bp, cfg)) {
1335		xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1336		goto out_stale;
1337	}
1338
1339	/* Still considered a transient error. Caller will schedule retries. */
1340	if (bp->b_flags & _XBF_INODES)
1341		xfs_buf_inode_io_fail(bp);
1342	else if (bp->b_flags & _XBF_DQUOTS)
1343		xfs_buf_dquot_io_fail(bp);
1344	else
1345		ASSERT(list_empty(&bp->b_li_list));
1346	xfs_buf_ioerror(bp, 0);
1347	xfs_buf_relse(bp);
1348	return true;
1349
1350resubmit:
1351	xfs_buf_ioerror(bp, 0);
1352	bp->b_flags |= (XBF_DONE | XBF_WRITE_FAIL);
1353	xfs_buf_submit(bp);
1354	return true;
1355out_stale:
1356	xfs_buf_stale(bp);
1357	bp->b_flags |= XBF_DONE;
1358	bp->b_flags &= ~XBF_WRITE;
1359	trace_xfs_buf_error_relse(bp, _RET_IP_);
1360	return false;
1361}
1362
1363static void
1364xfs_buf_ioend(
1365	struct xfs_buf	*bp)
1366{
1367	trace_xfs_buf_iodone(bp, _RET_IP_);
1368
1369	/*
1370	 * Pull in IO completion errors now. We are guaranteed to be running
1371	 * single threaded, so we don't need the lock to read b_io_error.
1372	 */
1373	if (!bp->b_error && bp->b_io_error)
1374		xfs_buf_ioerror(bp, bp->b_io_error);
1375
1376	if (bp->b_flags & XBF_READ) {
1377		if (!bp->b_error && bp->b_ops)
1378			bp->b_ops->verify_read(bp);
1379		if (!bp->b_error)
1380			bp->b_flags |= XBF_DONE;
1381	} else {
1382		if (!bp->b_error) {
1383			bp->b_flags &= ~XBF_WRITE_FAIL;
1384			bp->b_flags |= XBF_DONE;
1385		}
1386
1387		if (unlikely(bp->b_error) && xfs_buf_ioend_handle_error(bp))
1388			return;
1389
1390		/* clear the retry state */
1391		bp->b_last_error = 0;
1392		bp->b_retries = 0;
1393		bp->b_first_retry_time = 0;
1394
1395		/*
1396		 * Note that for things like remote attribute buffers, there may
1397		 * not be a buffer log item here, so processing the buffer log
1398		 * item must remain optional.
1399		 */
1400		if (bp->b_log_item)
1401			xfs_buf_item_done(bp);
1402
1403		if (bp->b_flags & _XBF_INODES)
1404			xfs_buf_inode_iodone(bp);
1405		else if (bp->b_flags & _XBF_DQUOTS)
1406			xfs_buf_dquot_iodone(bp);
1407
1408	}
1409
1410	bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD |
1411			 _XBF_LOGRECOVERY);
1412
1413	if (bp->b_flags & XBF_ASYNC)
1414		xfs_buf_relse(bp);
1415	else
1416		complete(&bp->b_iowait);
1417}
1418
1419static void
1420xfs_buf_ioend_work(
1421	struct work_struct	*work)
1422{
1423	struct xfs_buf		*bp =
1424		container_of(work, struct xfs_buf, b_ioend_work);
1425
1426	xfs_buf_ioend(bp);
1427}
1428
1429static void
1430xfs_buf_ioend_async(
1431	struct xfs_buf	*bp)
1432{
1433	INIT_WORK(&bp->b_ioend_work, xfs_buf_ioend_work);
1434	queue_work(bp->b_mount->m_buf_workqueue, &bp->b_ioend_work);
1435}
1436
1437void
1438__xfs_buf_ioerror(
1439	struct xfs_buf		*bp,
1440	int			error,
1441	xfs_failaddr_t		failaddr)
1442{
1443	ASSERT(error <= 0 && error >= -1000);
1444	bp->b_error = error;
1445	trace_xfs_buf_ioerror(bp, error, failaddr);
1446}
1447
1448void
1449xfs_buf_ioerror_alert(
1450	struct xfs_buf		*bp,
1451	xfs_failaddr_t		func)
1452{
1453	xfs_buf_alert_ratelimited(bp, "XFS: metadata IO error",
1454		"metadata I/O error in \"%pS\" at daddr 0x%llx len %d error %d",
1455				  func, (uint64_t)xfs_buf_daddr(bp),
1456				  bp->b_length, -bp->b_error);
1457}
1458
1459/*
1460 * To simulate an I/O failure, the buffer must be locked and held with at least
1461 * three references. The LRU reference is dropped by the stale call. The buf
1462 * item reference is dropped via ioend processing. The third reference is owned
1463 * by the caller and is dropped on I/O completion if the buffer is XBF_ASYNC.
1464 */
1465void
1466xfs_buf_ioend_fail(
1467	struct xfs_buf	*bp)
1468{
1469	bp->b_flags &= ~XBF_DONE;
1470	xfs_buf_stale(bp);
1471	xfs_buf_ioerror(bp, -EIO);
1472	xfs_buf_ioend(bp);
1473}
1474
1475int
1476xfs_bwrite(
1477	struct xfs_buf		*bp)
1478{
1479	int			error;
1480
1481	ASSERT(xfs_buf_islocked(bp));
1482
1483	bp->b_flags |= XBF_WRITE;
1484	bp->b_flags &= ~(XBF_ASYNC | XBF_READ | _XBF_DELWRI_Q |
1485			 XBF_DONE);
1486
1487	error = xfs_buf_submit(bp);
1488	if (error)
1489		xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
1490	return error;
1491}
1492
1493static void
1494xfs_buf_bio_end_io(
1495	struct bio		*bio)
1496{
1497	struct xfs_buf		*bp = (struct xfs_buf *)bio->bi_private;
1498
1499	if (!bio->bi_status &&
1500	    (bp->b_flags & XBF_WRITE) && (bp->b_flags & XBF_ASYNC) &&
1501	    XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_IOERROR))
1502		bio->bi_status = BLK_STS_IOERR;
1503
1504	/*
1505	 * don't overwrite existing errors - otherwise we can lose errors on
1506	 * buffers that require multiple bios to complete.
1507	 */
1508	if (bio->bi_status) {
1509		int error = blk_status_to_errno(bio->bi_status);
1510
1511		cmpxchg(&bp->b_io_error, 0, error);
1512	}
1513
1514	if (!bp->b_error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1515		invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1516
1517	if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1518		xfs_buf_ioend_async(bp);
1519	bio_put(bio);
1520}
1521
1522static void
1523xfs_buf_ioapply_map(
1524	struct xfs_buf	*bp,
1525	int		map,
1526	int		*buf_offset,
1527	int		*count,
1528	blk_opf_t	op)
1529{
1530	int		page_index;
1531	unsigned int	total_nr_pages = bp->b_page_count;
1532	int		nr_pages;
1533	struct bio	*bio;
1534	sector_t	sector =  bp->b_maps[map].bm_bn;
1535	int		size;
1536	int		offset;
1537
1538	/* skip the pages in the buffer before the start offset */
1539	page_index = 0;
1540	offset = *buf_offset;
1541	while (offset >= PAGE_SIZE) {
1542		page_index++;
1543		offset -= PAGE_SIZE;
1544	}
1545
1546	/*
1547	 * Limit the IO size to the length of the current vector, and update the
1548	 * remaining IO count for the next time around.
1549	 */
1550	size = min_t(int, BBTOB(bp->b_maps[map].bm_len), *count);
1551	*count -= size;
1552	*buf_offset += size;
1553
1554next_chunk:
1555	atomic_inc(&bp->b_io_remaining);
1556	nr_pages = bio_max_segs(total_nr_pages);
1557
1558	bio = bio_alloc(bp->b_target->bt_bdev, nr_pages, op, GFP_NOIO);
1559	bio->bi_iter.bi_sector = sector;
1560	bio->bi_end_io = xfs_buf_bio_end_io;
1561	bio->bi_private = bp;
1562
1563	for (; size && nr_pages; nr_pages--, page_index++) {
1564		int	rbytes, nbytes = PAGE_SIZE - offset;
1565
1566		if (nbytes > size)
1567			nbytes = size;
1568
1569		rbytes = bio_add_page(bio, bp->b_pages[page_index], nbytes,
1570				      offset);
1571		if (rbytes < nbytes)
1572			break;
1573
1574		offset = 0;
1575		sector += BTOBB(nbytes);
1576		size -= nbytes;
1577		total_nr_pages--;
1578	}
1579
1580	if (likely(bio->bi_iter.bi_size)) {
1581		if (xfs_buf_is_vmapped(bp)) {
1582			flush_kernel_vmap_range(bp->b_addr,
1583						xfs_buf_vmap_len(bp));
1584		}
1585		submit_bio(bio);
1586		if (size)
1587			goto next_chunk;
1588	} else {
1589		/*
1590		 * This is guaranteed not to be the last io reference count
1591		 * because the caller (xfs_buf_submit) holds a count itself.
1592		 */
1593		atomic_dec(&bp->b_io_remaining);
1594		xfs_buf_ioerror(bp, -EIO);
1595		bio_put(bio);
1596	}
1597
1598}
1599
1600STATIC void
1601_xfs_buf_ioapply(
1602	struct xfs_buf	*bp)
1603{
1604	struct blk_plug	plug;
1605	blk_opf_t	op;
1606	int		offset;
1607	int		size;
1608	int		i;
1609
1610	/*
1611	 * Make sure we capture only current IO errors rather than stale errors
1612	 * left over from previous use of the buffer (e.g. failed readahead).
1613	 */
1614	bp->b_error = 0;
1615
1616	if (bp->b_flags & XBF_WRITE) {
1617		op = REQ_OP_WRITE;
1618
1619		/*
1620		 * Run the write verifier callback function if it exists. If
1621		 * this function fails it will mark the buffer with an error and
1622		 * the IO should not be dispatched.
1623		 */
1624		if (bp->b_ops) {
1625			bp->b_ops->verify_write(bp);
1626			if (bp->b_error) {
1627				xfs_force_shutdown(bp->b_mount,
1628						   SHUTDOWN_CORRUPT_INCORE);
1629				return;
1630			}
1631		} else if (bp->b_rhash_key != XFS_BUF_DADDR_NULL) {
1632			struct xfs_mount *mp = bp->b_mount;
1633
1634			/*
1635			 * non-crc filesystems don't attach verifiers during
1636			 * log recovery, so don't warn for such filesystems.
1637			 */
1638			if (xfs_has_crc(mp)) {
1639				xfs_warn(mp,
1640					"%s: no buf ops on daddr 0x%llx len %d",
1641					__func__, xfs_buf_daddr(bp),
1642					bp->b_length);
1643				xfs_hex_dump(bp->b_addr,
1644						XFS_CORRUPTION_DUMP_LEN);
1645				dump_stack();
1646			}
1647		}
1648	} else {
1649		op = REQ_OP_READ;
1650		if (bp->b_flags & XBF_READ_AHEAD)
1651			op |= REQ_RAHEAD;
1652	}
1653
1654	/* we only use the buffer cache for meta-data */
1655	op |= REQ_META;
1656
1657	/* in-memory targets are directly mapped, no IO required. */
1658	if (xfs_buftarg_is_mem(bp->b_target)) {
1659		xfs_buf_ioend(bp);
1660		return;
1661	}
1662
1663	/*
1664	 * Walk all the vectors issuing IO on them. Set up the initial offset
1665	 * into the buffer and the desired IO size before we start -
1666	 * _xfs_buf_ioapply_vec() will modify them appropriately for each
1667	 * subsequent call.
1668	 */
1669	offset = bp->b_offset;
1670	size = BBTOB(bp->b_length);
1671	blk_start_plug(&plug);
1672	for (i = 0; i < bp->b_map_count; i++) {
1673		xfs_buf_ioapply_map(bp, i, &offset, &size, op);
1674		if (bp->b_error)
1675			break;
1676		if (size <= 0)
1677			break;	/* all done */
1678	}
1679	blk_finish_plug(&plug);
1680}
1681
1682/*
1683 * Wait for I/O completion of a sync buffer and return the I/O error code.
1684 */
1685static int
1686xfs_buf_iowait(
1687	struct xfs_buf	*bp)
1688{
1689	ASSERT(!(bp->b_flags & XBF_ASYNC));
1690
1691	trace_xfs_buf_iowait(bp, _RET_IP_);
1692	wait_for_completion(&bp->b_iowait);
1693	trace_xfs_buf_iowait_done(bp, _RET_IP_);
1694
1695	return bp->b_error;
1696}
1697
1698/*
1699 * Buffer I/O submission path, read or write. Asynchronous submission transfers
1700 * the buffer lock ownership and the current reference to the IO. It is not
1701 * safe to reference the buffer after a call to this function unless the caller
1702 * holds an additional reference itself.
1703 */
1704static int
1705__xfs_buf_submit(
1706	struct xfs_buf	*bp,
1707	bool		wait)
1708{
1709	int		error = 0;
1710
1711	trace_xfs_buf_submit(bp, _RET_IP_);
1712
1713	ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
1714
1715	/*
1716	 * On log shutdown we stale and complete the buffer immediately. We can
1717	 * be called to read the superblock before the log has been set up, so
1718	 * be careful checking the log state.
1719	 *
1720	 * Checking the mount shutdown state here can result in the log tail
1721	 * moving inappropriately on disk as the log may not yet be shut down.
1722	 * i.e. failing this buffer on mount shutdown can remove it from the AIL
1723	 * and move the tail of the log forwards without having written this
1724	 * buffer to disk. This corrupts the log tail state in memory, and
1725	 * because the log may not be shut down yet, it can then be propagated
1726	 * to disk before the log is shutdown. Hence we check log shutdown
1727	 * state here rather than mount state to avoid corrupting the log tail
1728	 * on shutdown.
1729	 */
1730	if (bp->b_mount->m_log &&
1731	    xlog_is_shutdown(bp->b_mount->m_log)) {
1732		xfs_buf_ioend_fail(bp);
1733		return -EIO;
1734	}
1735
1736	/*
1737	 * Grab a reference so the buffer does not go away underneath us. For
1738	 * async buffers, I/O completion drops the callers reference, which
1739	 * could occur before submission returns.
1740	 */
1741	xfs_buf_hold(bp);
1742
1743	if (bp->b_flags & XBF_WRITE)
1744		xfs_buf_wait_unpin(bp);
1745
1746	/* clear the internal error state to avoid spurious errors */
1747	bp->b_io_error = 0;
1748
1749	/*
1750	 * Set the count to 1 initially, this will stop an I/O completion
1751	 * callout which happens before we have started all the I/O from calling
1752	 * xfs_buf_ioend too early.
1753	 */
1754	atomic_set(&bp->b_io_remaining, 1);
1755	if (bp->b_flags & XBF_ASYNC)
1756		xfs_buf_ioacct_inc(bp);
1757	_xfs_buf_ioapply(bp);
1758
1759	/*
1760	 * If _xfs_buf_ioapply failed, we can get back here with only the IO
1761	 * reference we took above. If we drop it to zero, run completion so
1762	 * that we don't return to the caller with completion still pending.
1763	 */
1764	if (atomic_dec_and_test(&bp->b_io_remaining) == 1) {
1765		if (bp->b_error || !(bp->b_flags & XBF_ASYNC))
1766			xfs_buf_ioend(bp);
1767		else
1768			xfs_buf_ioend_async(bp);
1769	}
1770
1771	if (wait)
1772		error = xfs_buf_iowait(bp);
1773
1774	/*
1775	 * Release the hold that keeps the buffer referenced for the entire
1776	 * I/O. Note that if the buffer is async, it is not safe to reference
1777	 * after this release.
1778	 */
1779	xfs_buf_rele(bp);
1780	return error;
1781}
1782
1783void *
1784xfs_buf_offset(
1785	struct xfs_buf		*bp,
1786	size_t			offset)
1787{
1788	struct page		*page;
1789
1790	if (bp->b_addr)
1791		return bp->b_addr + offset;
1792
1793	page = bp->b_pages[offset >> PAGE_SHIFT];
1794	return page_address(page) + (offset & (PAGE_SIZE-1));
1795}
1796
1797void
1798xfs_buf_zero(
1799	struct xfs_buf		*bp,
1800	size_t			boff,
1801	size_t			bsize)
1802{
1803	size_t			bend;
1804
1805	bend = boff + bsize;
1806	while (boff < bend) {
1807		struct page	*page;
1808		int		page_index, page_offset, csize;
1809
1810		page_index = (boff + bp->b_offset) >> PAGE_SHIFT;
1811		page_offset = (boff + bp->b_offset) & ~PAGE_MASK;
1812		page = bp->b_pages[page_index];
1813		csize = min_t(size_t, PAGE_SIZE - page_offset,
1814				      BBTOB(bp->b_length) - boff);
1815
1816		ASSERT((csize + page_offset) <= PAGE_SIZE);
1817
1818		memset(page_address(page) + page_offset, 0, csize);
1819
1820		boff += csize;
1821	}
1822}
1823
1824/*
1825 * Log a message about and stale a buffer that a caller has decided is corrupt.
1826 *
1827 * This function should be called for the kinds of metadata corruption that
1828 * cannot be detect from a verifier, such as incorrect inter-block relationship
1829 * data.  Do /not/ call this function from a verifier function.
1830 *
1831 * The buffer must be XBF_DONE prior to the call.  Afterwards, the buffer will
1832 * be marked stale, but b_error will not be set.  The caller is responsible for
1833 * releasing the buffer or fixing it.
1834 */
1835void
1836__xfs_buf_mark_corrupt(
1837	struct xfs_buf		*bp,
1838	xfs_failaddr_t		fa)
1839{
1840	ASSERT(bp->b_flags & XBF_DONE);
1841
1842	xfs_buf_corruption_error(bp, fa);
1843	xfs_buf_stale(bp);
1844}
1845
1846/*
1847 *	Handling of buffer targets (buftargs).
1848 */
1849
1850/*
1851 * Wait for any bufs with callbacks that have been submitted but have not yet
1852 * returned. These buffers will have an elevated hold count, so wait on those
1853 * while freeing all the buffers only held by the LRU.
1854 */
1855static enum lru_status
1856xfs_buftarg_drain_rele(
1857	struct list_head	*item,
1858	struct list_lru_one	*lru,
 
1859	void			*arg)
1860
1861{
1862	struct xfs_buf		*bp = container_of(item, struct xfs_buf, b_lru);
1863	struct list_head	*dispose = arg;
1864
1865	if (atomic_read(&bp->b_hold) > 1) {
1866		/* need to wait, so skip it this pass */
1867		trace_xfs_buf_drain_buftarg(bp, _RET_IP_);
1868		return LRU_SKIP;
1869	}
1870	if (!spin_trylock(&bp->b_lock))
1871		return LRU_SKIP;
1872
1873	/*
1874	 * clear the LRU reference count so the buffer doesn't get
1875	 * ignored in xfs_buf_rele().
1876	 */
1877	atomic_set(&bp->b_lru_ref, 0);
1878	bp->b_state |= XFS_BSTATE_DISPOSE;
1879	list_lru_isolate_move(lru, item, dispose);
1880	spin_unlock(&bp->b_lock);
1881	return LRU_REMOVED;
1882}
1883
1884/*
1885 * Wait for outstanding I/O on the buftarg to complete.
1886 */
1887void
1888xfs_buftarg_wait(
1889	struct xfs_buftarg	*btp)
1890{
1891	/*
1892	 * First wait on the buftarg I/O count for all in-flight buffers to be
1893	 * released. This is critical as new buffers do not make the LRU until
1894	 * they are released.
1895	 *
1896	 * Next, flush the buffer workqueue to ensure all completion processing
1897	 * has finished. Just waiting on buffer locks is not sufficient for
1898	 * async IO as the reference count held over IO is not released until
1899	 * after the buffer lock is dropped. Hence we need to ensure here that
1900	 * all reference counts have been dropped before we start walking the
1901	 * LRU list.
1902	 */
1903	while (percpu_counter_sum(&btp->bt_io_count))
1904		delay(100);
1905	flush_workqueue(btp->bt_mount->m_buf_workqueue);
1906}
1907
1908void
1909xfs_buftarg_drain(
1910	struct xfs_buftarg	*btp)
1911{
1912	LIST_HEAD(dispose);
1913	int			loop = 0;
1914	bool			write_fail = false;
1915
1916	xfs_buftarg_wait(btp);
1917
1918	/* loop until there is nothing left on the lru list. */
1919	while (list_lru_count(&btp->bt_lru)) {
1920		list_lru_walk(&btp->bt_lru, xfs_buftarg_drain_rele,
1921			      &dispose, LONG_MAX);
1922
1923		while (!list_empty(&dispose)) {
1924			struct xfs_buf *bp;
1925			bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1926			list_del_init(&bp->b_lru);
1927			if (bp->b_flags & XBF_WRITE_FAIL) {
1928				write_fail = true;
1929				xfs_buf_alert_ratelimited(bp,
1930					"XFS: Corruption Alert",
1931"Corruption Alert: Buffer at daddr 0x%llx had permanent write failures!",
1932					(long long)xfs_buf_daddr(bp));
1933			}
1934			xfs_buf_rele(bp);
1935		}
1936		if (loop++ != 0)
1937			delay(100);
1938	}
1939
1940	/*
1941	 * If one or more failed buffers were freed, that means dirty metadata
1942	 * was thrown away. This should only ever happen after I/O completion
1943	 * handling has elevated I/O error(s) to permanent failures and shuts
1944	 * down the journal.
1945	 */
1946	if (write_fail) {
1947		ASSERT(xlog_is_shutdown(btp->bt_mount->m_log));
1948		xfs_alert(btp->bt_mount,
1949	      "Please run xfs_repair to determine the extent of the problem.");
1950	}
1951}
1952
1953static enum lru_status
1954xfs_buftarg_isolate(
1955	struct list_head	*item,
1956	struct list_lru_one	*lru,
 
1957	void			*arg)
1958{
1959	struct xfs_buf		*bp = container_of(item, struct xfs_buf, b_lru);
1960	struct list_head	*dispose = arg;
1961
1962	/*
1963	 * we are inverting the lru lock/bp->b_lock here, so use a trylock.
1964	 * If we fail to get the lock, just skip it.
1965	 */
1966	if (!spin_trylock(&bp->b_lock))
1967		return LRU_SKIP;
1968	/*
1969	 * Decrement the b_lru_ref count unless the value is already
1970	 * zero. If the value is already zero, we need to reclaim the
1971	 * buffer, otherwise it gets another trip through the LRU.
1972	 */
1973	if (atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1974		spin_unlock(&bp->b_lock);
1975		return LRU_ROTATE;
1976	}
1977
1978	bp->b_state |= XFS_BSTATE_DISPOSE;
1979	list_lru_isolate_move(lru, item, dispose);
1980	spin_unlock(&bp->b_lock);
1981	return LRU_REMOVED;
1982}
1983
1984static unsigned long
1985xfs_buftarg_shrink_scan(
1986	struct shrinker		*shrink,
1987	struct shrink_control	*sc)
1988{
1989	struct xfs_buftarg	*btp = shrink->private_data;
 
1990	LIST_HEAD(dispose);
1991	unsigned long		freed;
1992
1993	freed = list_lru_shrink_walk(&btp->bt_lru, sc,
1994				     xfs_buftarg_isolate, &dispose);
1995
1996	while (!list_empty(&dispose)) {
1997		struct xfs_buf *bp;
1998		bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1999		list_del_init(&bp->b_lru);
2000		xfs_buf_rele(bp);
2001	}
2002
2003	return freed;
2004}
2005
2006static unsigned long
2007xfs_buftarg_shrink_count(
2008	struct shrinker		*shrink,
2009	struct shrink_control	*sc)
2010{
2011	struct xfs_buftarg	*btp = shrink->private_data;
 
2012	return list_lru_shrink_count(&btp->bt_lru, sc);
2013}
2014
2015void
2016xfs_destroy_buftarg(
2017	struct xfs_buftarg	*btp)
2018{
2019	shrinker_free(btp->bt_shrinker);
2020	ASSERT(percpu_counter_sum(&btp->bt_io_count) == 0);
2021	percpu_counter_destroy(&btp->bt_io_count);
2022	list_lru_destroy(&btp->bt_lru);
2023}
2024
2025void
2026xfs_free_buftarg(
2027	struct xfs_buftarg	*btp)
2028{
2029	xfs_destroy_buftarg(btp);
2030	fs_put_dax(btp->bt_daxdev, btp->bt_mount);
2031	/* the main block device is closed by kill_block_super */
2032	if (btp->bt_bdev != btp->bt_mount->m_super->s_bdev)
2033		bdev_fput(btp->bt_bdev_file);
2034	kfree(btp);
2035}
2036
2037int
2038xfs_setsize_buftarg(
2039	struct xfs_buftarg	*btp,
2040	unsigned int		sectorsize)
2041{
2042	/* Set up metadata sector size info */
2043	btp->bt_meta_sectorsize = sectorsize;
2044	btp->bt_meta_sectormask = sectorsize - 1;
2045
2046	if (set_blocksize(btp->bt_bdev_file, sectorsize)) {
2047		xfs_warn(btp->bt_mount,
2048			"Cannot set_blocksize to %u on device %pg",
2049			sectorsize, btp->bt_bdev);
2050		return -EINVAL;
2051	}
2052
2053	return 0;
2054}
2055
2056int
2057xfs_init_buftarg(
2058	struct xfs_buftarg		*btp,
2059	size_t				logical_sectorsize,
2060	const char			*descr)
2061{
2062	/* Set up device logical sector size mask */
2063	btp->bt_logical_sectorsize = logical_sectorsize;
2064	btp->bt_logical_sectormask = logical_sectorsize - 1;
2065
2066	/*
2067	 * Buffer IO error rate limiting. Limit it to no more than 10 messages
2068	 * per 30 seconds so as to not spam logs too much on repeated errors.
2069	 */
2070	ratelimit_state_init(&btp->bt_ioerror_rl, 30 * HZ,
2071			     DEFAULT_RATELIMIT_BURST);
2072
2073	if (list_lru_init(&btp->bt_lru))
2074		return -ENOMEM;
2075	if (percpu_counter_init(&btp->bt_io_count, 0, GFP_KERNEL))
2076		goto out_destroy_lru;
2077
2078	btp->bt_shrinker =
2079		shrinker_alloc(SHRINKER_NUMA_AWARE, "xfs-buf:%s", descr);
2080	if (!btp->bt_shrinker)
2081		goto out_destroy_io_count;
2082	btp->bt_shrinker->count_objects = xfs_buftarg_shrink_count;
2083	btp->bt_shrinker->scan_objects = xfs_buftarg_shrink_scan;
2084	btp->bt_shrinker->private_data = btp;
2085	shrinker_register(btp->bt_shrinker);
2086	return 0;
 
2087
2088out_destroy_io_count:
2089	percpu_counter_destroy(&btp->bt_io_count);
2090out_destroy_lru:
2091	list_lru_destroy(&btp->bt_lru);
2092	return -ENOMEM;
 
 
 
 
 
 
2093}
2094
2095struct xfs_buftarg *
2096xfs_alloc_buftarg(
2097	struct xfs_mount	*mp,
2098	struct file		*bdev_file)
2099{
2100	struct xfs_buftarg	*btp;
2101	const struct dax_holder_operations *ops = NULL;
2102
2103#if defined(CONFIG_FS_DAX) && defined(CONFIG_MEMORY_FAILURE)
2104	ops = &xfs_dax_holder_operations;
2105#endif
2106	btp = kzalloc(sizeof(*btp), GFP_KERNEL | __GFP_NOFAIL);
2107
2108	btp->bt_mount = mp;
2109	btp->bt_bdev_file = bdev_file;
2110	btp->bt_bdev = file_bdev(bdev_file);
2111	btp->bt_dev = btp->bt_bdev->bd_dev;
2112	btp->bt_daxdev = fs_dax_get_by_bdev(btp->bt_bdev, &btp->bt_dax_part_off,
2113					    mp, ops);
2114
2115	if (bdev_can_atomic_write(btp->bt_bdev)) {
2116		btp->bt_bdev_awu_min = bdev_atomic_write_unit_min_bytes(
2117						btp->bt_bdev);
2118		btp->bt_bdev_awu_max = bdev_atomic_write_unit_max_bytes(
2119						btp->bt_bdev);
2120	}
2121
2122	/*
2123	 * When allocating the buftargs we have not yet read the super block and
2124	 * thus don't know the file system sector size yet.
2125	 */
2126	if (xfs_setsize_buftarg(btp, bdev_logical_block_size(btp->bt_bdev)))
 
 
 
2127		goto error_free;
2128	if (xfs_init_buftarg(btp, bdev_logical_block_size(btp->bt_bdev),
2129			mp->m_super->s_id))
2130		goto error_free;
2131
 
 
 
 
 
 
 
 
 
 
2132	return btp;
2133
 
 
 
 
2134error_free:
2135	kfree(btp);
2136	return NULL;
2137}
2138
2139static inline void
2140xfs_buf_list_del(
2141	struct xfs_buf		*bp)
2142{
2143	list_del_init(&bp->b_list);
2144	wake_up_var(&bp->b_list);
2145}
2146
2147/*
2148 * Cancel a delayed write list.
2149 *
2150 * Remove each buffer from the list, clear the delwri queue flag and drop the
2151 * associated buffer reference.
2152 */
2153void
2154xfs_buf_delwri_cancel(
2155	struct list_head	*list)
2156{
2157	struct xfs_buf		*bp;
2158
2159	while (!list_empty(list)) {
2160		bp = list_first_entry(list, struct xfs_buf, b_list);
2161
2162		xfs_buf_lock(bp);
2163		bp->b_flags &= ~_XBF_DELWRI_Q;
2164		xfs_buf_list_del(bp);
2165		xfs_buf_relse(bp);
2166	}
2167}
2168
2169/*
2170 * Add a buffer to the delayed write list.
2171 *
2172 * This queues a buffer for writeout if it hasn't already been.  Note that
2173 * neither this routine nor the buffer list submission functions perform
2174 * any internal synchronization.  It is expected that the lists are thread-local
2175 * to the callers.
2176 *
2177 * Returns true if we queued up the buffer, or false if it already had
2178 * been on the buffer list.
2179 */
2180bool
2181xfs_buf_delwri_queue(
2182	struct xfs_buf		*bp,
2183	struct list_head	*list)
2184{
2185	ASSERT(xfs_buf_islocked(bp));
2186	ASSERT(!(bp->b_flags & XBF_READ));
2187
2188	/*
2189	 * If the buffer is already marked delwri it already is queued up
2190	 * by someone else for imediate writeout.  Just ignore it in that
2191	 * case.
2192	 */
2193	if (bp->b_flags & _XBF_DELWRI_Q) {
2194		trace_xfs_buf_delwri_queued(bp, _RET_IP_);
2195		return false;
2196	}
2197
2198	trace_xfs_buf_delwri_queue(bp, _RET_IP_);
2199
2200	/*
2201	 * If a buffer gets written out synchronously or marked stale while it
2202	 * is on a delwri list we lazily remove it. To do this, the other party
2203	 * clears the  _XBF_DELWRI_Q flag but otherwise leaves the buffer alone.
2204	 * It remains referenced and on the list.  In a rare corner case it
2205	 * might get readded to a delwri list after the synchronous writeout, in
2206	 * which case we need just need to re-add the flag here.
2207	 */
2208	bp->b_flags |= _XBF_DELWRI_Q;
2209	if (list_empty(&bp->b_list)) {
2210		atomic_inc(&bp->b_hold);
2211		list_add_tail(&bp->b_list, list);
2212	}
2213
2214	return true;
2215}
2216
2217/*
2218 * Queue a buffer to this delwri list as part of a data integrity operation.
2219 * If the buffer is on any other delwri list, we'll wait for that to clear
2220 * so that the caller can submit the buffer for IO and wait for the result.
2221 * Callers must ensure the buffer is not already on the list.
2222 */
2223void
2224xfs_buf_delwri_queue_here(
2225	struct xfs_buf		*bp,
2226	struct list_head	*buffer_list)
2227{
2228	/*
2229	 * We need this buffer to end up on the /caller's/ delwri list, not any
2230	 * old list.  This can happen if the buffer is marked stale (which
2231	 * clears DELWRI_Q) after the AIL queues the buffer to its list but
2232	 * before the AIL has a chance to submit the list.
2233	 */
2234	while (!list_empty(&bp->b_list)) {
2235		xfs_buf_unlock(bp);
2236		wait_var_event(&bp->b_list, list_empty(&bp->b_list));
2237		xfs_buf_lock(bp);
2238	}
2239
2240	ASSERT(!(bp->b_flags & _XBF_DELWRI_Q));
2241
2242	xfs_buf_delwri_queue(bp, buffer_list);
2243}
2244
2245/*
2246 * Compare function is more complex than it needs to be because
2247 * the return value is only 32 bits and we are doing comparisons
2248 * on 64 bit values
2249 */
2250static int
2251xfs_buf_cmp(
2252	void			*priv,
2253	const struct list_head	*a,
2254	const struct list_head	*b)
2255{
2256	struct xfs_buf	*ap = container_of(a, struct xfs_buf, b_list);
2257	struct xfs_buf	*bp = container_of(b, struct xfs_buf, b_list);
2258	xfs_daddr_t		diff;
2259
2260	diff = ap->b_maps[0].bm_bn - bp->b_maps[0].bm_bn;
2261	if (diff < 0)
2262		return -1;
2263	if (diff > 0)
2264		return 1;
2265	return 0;
2266}
2267
2268/*
2269 * Submit buffers for write. If wait_list is specified, the buffers are
2270 * submitted using sync I/O and placed on the wait list such that the caller can
2271 * iowait each buffer. Otherwise async I/O is used and the buffers are released
2272 * at I/O completion time. In either case, buffers remain locked until I/O
2273 * completes and the buffer is released from the queue.
2274 */
2275static int
2276xfs_buf_delwri_submit_buffers(
2277	struct list_head	*buffer_list,
2278	struct list_head	*wait_list)
2279{
2280	struct xfs_buf		*bp, *n;
2281	int			pinned = 0;
2282	struct blk_plug		plug;
2283
2284	list_sort(NULL, buffer_list, xfs_buf_cmp);
2285
2286	blk_start_plug(&plug);
2287	list_for_each_entry_safe(bp, n, buffer_list, b_list) {
2288		if (!wait_list) {
2289			if (!xfs_buf_trylock(bp))
2290				continue;
2291			if (xfs_buf_ispinned(bp)) {
2292				xfs_buf_unlock(bp);
2293				pinned++;
2294				continue;
2295			}
2296		} else {
2297			xfs_buf_lock(bp);
2298		}
2299
2300		/*
2301		 * Someone else might have written the buffer synchronously or
2302		 * marked it stale in the meantime.  In that case only the
2303		 * _XBF_DELWRI_Q flag got cleared, and we have to drop the
2304		 * reference and remove it from the list here.
2305		 */
2306		if (!(bp->b_flags & _XBF_DELWRI_Q)) {
2307			xfs_buf_list_del(bp);
2308			xfs_buf_relse(bp);
2309			continue;
2310		}
2311
2312		trace_xfs_buf_delwri_split(bp, _RET_IP_);
2313
2314		/*
2315		 * If we have a wait list, each buffer (and associated delwri
2316		 * queue reference) transfers to it and is submitted
2317		 * synchronously. Otherwise, drop the buffer from the delwri
2318		 * queue and submit async.
2319		 */
2320		bp->b_flags &= ~_XBF_DELWRI_Q;
2321		bp->b_flags |= XBF_WRITE;
2322		if (wait_list) {
2323			bp->b_flags &= ~XBF_ASYNC;
2324			list_move_tail(&bp->b_list, wait_list);
2325		} else {
2326			bp->b_flags |= XBF_ASYNC;
2327			xfs_buf_list_del(bp);
2328		}
2329		__xfs_buf_submit(bp, false);
2330	}
2331	blk_finish_plug(&plug);
2332
2333	return pinned;
2334}
2335
2336/*
2337 * Write out a buffer list asynchronously.
2338 *
2339 * This will take the @buffer_list, write all non-locked and non-pinned buffers
2340 * out and not wait for I/O completion on any of the buffers.  This interface
2341 * is only safely useable for callers that can track I/O completion by higher
2342 * level means, e.g. AIL pushing as the @buffer_list is consumed in this
2343 * function.
2344 *
2345 * Note: this function will skip buffers it would block on, and in doing so
2346 * leaves them on @buffer_list so they can be retried on a later pass. As such,
2347 * it is up to the caller to ensure that the buffer list is fully submitted or
2348 * cancelled appropriately when they are finished with the list. Failure to
2349 * cancel or resubmit the list until it is empty will result in leaked buffers
2350 * at unmount time.
2351 */
2352int
2353xfs_buf_delwri_submit_nowait(
2354	struct list_head	*buffer_list)
2355{
2356	return xfs_buf_delwri_submit_buffers(buffer_list, NULL);
2357}
2358
2359/*
2360 * Write out a buffer list synchronously.
2361 *
2362 * This will take the @buffer_list, write all buffers out and wait for I/O
2363 * completion on all of the buffers. @buffer_list is consumed by the function,
2364 * so callers must have some other way of tracking buffers if they require such
2365 * functionality.
2366 */
2367int
2368xfs_buf_delwri_submit(
2369	struct list_head	*buffer_list)
2370{
2371	LIST_HEAD		(wait_list);
2372	int			error = 0, error2;
2373	struct xfs_buf		*bp;
2374
2375	xfs_buf_delwri_submit_buffers(buffer_list, &wait_list);
2376
2377	/* Wait for IO to complete. */
2378	while (!list_empty(&wait_list)) {
2379		bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
2380
2381		xfs_buf_list_del(bp);
2382
2383		/*
2384		 * Wait on the locked buffer, check for errors and unlock and
2385		 * release the delwri queue reference.
2386		 */
2387		error2 = xfs_buf_iowait(bp);
2388		xfs_buf_relse(bp);
2389		if (!error)
2390			error = error2;
2391	}
2392
2393	return error;
2394}
2395
2396/*
2397 * Push a single buffer on a delwri queue.
2398 *
2399 * The purpose of this function is to submit a single buffer of a delwri queue
2400 * and return with the buffer still on the original queue. The waiting delwri
2401 * buffer submission infrastructure guarantees transfer of the delwri queue
2402 * buffer reference to a temporary wait list. We reuse this infrastructure to
2403 * transfer the buffer back to the original queue.
2404 *
2405 * Note the buffer transitions from the queued state, to the submitted and wait
2406 * listed state and back to the queued state during this call. The buffer
2407 * locking and queue management logic between _delwri_pushbuf() and
2408 * _delwri_queue() guarantee that the buffer cannot be queued to another list
2409 * before returning.
2410 */
2411int
2412xfs_buf_delwri_pushbuf(
2413	struct xfs_buf		*bp,
2414	struct list_head	*buffer_list)
2415{
2416	LIST_HEAD		(submit_list);
2417	int			error;
2418
2419	ASSERT(bp->b_flags & _XBF_DELWRI_Q);
2420
2421	trace_xfs_buf_delwri_pushbuf(bp, _RET_IP_);
2422
2423	/*
2424	 * Isolate the buffer to a new local list so we can submit it for I/O
2425	 * independently from the rest of the original list.
2426	 */
2427	xfs_buf_lock(bp);
2428	list_move(&bp->b_list, &submit_list);
2429	xfs_buf_unlock(bp);
2430
2431	/*
2432	 * Delwri submission clears the DELWRI_Q buffer flag and returns with
2433	 * the buffer on the wait list with the original reference. Rather than
2434	 * bounce the buffer from a local wait list back to the original list
2435	 * after I/O completion, reuse the original list as the wait list.
2436	 */
2437	xfs_buf_delwri_submit_buffers(&submit_list, buffer_list);
2438
2439	/*
2440	 * The buffer is now locked, under I/O and wait listed on the original
2441	 * delwri queue. Wait for I/O completion, restore the DELWRI_Q flag and
2442	 * return with the buffer unlocked and on the original queue.
2443	 */
2444	error = xfs_buf_iowait(bp);
2445	bp->b_flags |= _XBF_DELWRI_Q;
2446	xfs_buf_unlock(bp);
2447
2448	return error;
2449}
2450
2451void xfs_buf_set_ref(struct xfs_buf *bp, int lru_ref)
2452{
2453	/*
2454	 * Set the lru reference count to 0 based on the error injection tag.
2455	 * This allows userspace to disrupt buffer caching for debug/testing
2456	 * purposes.
2457	 */
2458	if (XFS_TEST_ERROR(false, bp->b_mount, XFS_ERRTAG_BUF_LRU_REF))
2459		lru_ref = 0;
2460
2461	atomic_set(&bp->b_lru_ref, lru_ref);
2462}
2463
2464/*
2465 * Verify an on-disk magic value against the magic value specified in the
2466 * verifier structure. The verifier magic is in disk byte order so the caller is
2467 * expected to pass the value directly from disk.
2468 */
2469bool
2470xfs_verify_magic(
2471	struct xfs_buf		*bp,
2472	__be32			dmagic)
2473{
2474	struct xfs_mount	*mp = bp->b_mount;
2475	int			idx;
2476
2477	idx = xfs_has_crc(mp);
2478	if (WARN_ON(!bp->b_ops || !bp->b_ops->magic[idx]))
2479		return false;
2480	return dmagic == bp->b_ops->magic[idx];
2481}
2482/*
2483 * Verify an on-disk magic value against the magic value specified in the
2484 * verifier structure. The verifier magic is in disk byte order so the caller is
2485 * expected to pass the value directly from disk.
2486 */
2487bool
2488xfs_verify_magic16(
2489	struct xfs_buf		*bp,
2490	__be16			dmagic)
2491{
2492	struct xfs_mount	*mp = bp->b_mount;
2493	int			idx;
2494
2495	idx = xfs_has_crc(mp);
2496	if (WARN_ON(!bp->b_ops || !bp->b_ops->magic16[idx]))
2497		return false;
2498	return dmagic == bp->b_ops->magic16[idx];
2499}