1/*
   2 * Copyright (c) 2000-2006 Silicon Graphics, Inc.
   3 * All Rights Reserved.
   4 *
   5 * This program is free software; you can redistribute it and/or
   6 * modify it under the terms of the GNU General Public License as
   7 * published by the Free Software Foundation.
   8 *
   9 * This program is distributed in the hope that it would be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, write the Free Software Foundation,
  16 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18#include "xfs.h"
  19#include <linux/stddef.h>
  20#include <linux/errno.h>
  21#include <linux/gfp.h>
  22#include <linux/pagemap.h>
  23#include <linux/init.h>
  24#include <linux/vmalloc.h>
  25#include <linux/bio.h>
  26#include <linux/sysctl.h>
  27#include <linux/proc_fs.h>
  28#include <linux/workqueue.h>
  29#include <linux/percpu.h>
  30#include <linux/blkdev.h>
  31#include <linux/hash.h>
  32#include <linux/kthread.h>
  33#include <linux/migrate.h>
  34#include <linux/backing-dev.h>
  35#include <linux/freezer.h>
  36
 
 
 
  37#include "xfs_sb.h"
  38#include "xfs_inum.h"
  39#include "xfs_log.h"
  40#include "xfs_ag.h"
  41#include "xfs_mount.h"
  42#include "xfs_trace.h"
 
  43
  44static kmem_zone_t *xfs_buf_zone;
  45STATIC int xfsbufd(void *);
  46STATIC void xfs_buf_delwri_queue(xfs_buf_t *, int);
  47
  48static struct workqueue_struct *xfslogd_workqueue;
  49struct workqueue_struct *xfsdatad_workqueue;
  50struct workqueue_struct *xfsconvertd_workqueue;
  51
  52#ifdef XFS_BUF_LOCK_TRACKING
  53# define XB_SET_OWNER(bp)	((bp)->b_last_holder = current->pid)
  54# define XB_CLEAR_OWNER(bp)	((bp)->b_last_holder = -1)
  55# define XB_GET_OWNER(bp)	((bp)->b_last_holder)
  56#else
  57# define XB_SET_OWNER(bp)	do { } while (0)
  58# define XB_CLEAR_OWNER(bp)	do { } while (0)
  59# define XB_GET_OWNER(bp)	do { } while (0)
  60#endif
  61
  62#define xb_to_gfp(flags) \
  63	((((flags) & XBF_READ_AHEAD) ? __GFP_NORETRY : \
  64	  ((flags) & XBF_DONT_BLOCK) ? GFP_NOFS : GFP_KERNEL) | __GFP_NOWARN)
  65
  66#define xb_to_km(flags) \
  67	 (((flags) & XBF_DONT_BLOCK) ? KM_NOFS : KM_SLEEP)
  68
  69#define xfs_buf_allocate(flags) \
  70	kmem_zone_alloc(xfs_buf_zone, xb_to_km(flags))
  71#define xfs_buf_deallocate(bp) \
  72	kmem_zone_free(xfs_buf_zone, (bp));
  73
  74static inline int
  75xfs_buf_is_vmapped(
  76	struct xfs_buf	*bp)
  77{
  78	/*
  79	 * Return true if the buffer is vmapped.
  80	 *
  81	 * The XBF_MAPPED flag is set if the buffer should be mapped, but the
  82	 * code is clever enough to know it doesn't have to map a single page,
  83	 * so the check has to be both for XBF_MAPPED and bp->b_page_count > 1.
  84	 */
  85	return (bp->b_flags & XBF_MAPPED) && bp->b_page_count > 1;
  86}
  87
  88static inline int
  89xfs_buf_vmap_len(
  90	struct xfs_buf	*bp)
  91{
  92	return (bp->b_page_count * PAGE_SIZE) - bp->b_offset;
  93}
  94
  95/*
  96 * xfs_buf_lru_add - add a buffer to the LRU.
 
 
 
  97 *
  98 * The LRU takes a new reference to the buffer so that it will only be freed
  99 * once the shrinker takes the buffer off the LRU.
 100 */
 101STATIC void
 102xfs_buf_lru_add(
 103	struct xfs_buf	*bp)
 104{
 105	struct xfs_buftarg *btp = bp->b_target;
 106
 107	spin_lock(&btp->bt_lru_lock);
 108	if (list_empty(&bp->b_lru)) {
 109		atomic_inc(&bp->b_hold);
 110		list_add_tail(&bp->b_lru, &btp->bt_lru);
 111		btp->bt_lru_nr++;
 112	}
 113	spin_unlock(&btp->bt_lru_lock);
 
 
 
 
 
 
 
 
 
 
 114}
 115
 116/*
 117 * xfs_buf_lru_del - remove a buffer from the LRU
 118 *
 119 * The unlocked check is safe here because it only occurs when there are not
 120 * b_lru_ref counts left on the inode under the pag->pag_buf_lock. it is there
 121 * to optimise the shrinker removing the buffer from the LRU and calling
 122 * xfs_buf_free(). i.e. it removes an unnecessary round trip on the
 123 * bt_lru_lock.
 124 */
 125STATIC void
 126xfs_buf_lru_del(
 127	struct xfs_buf	*bp)
 128{
 129	struct xfs_buftarg *btp = bp->b_target;
 
 130
 131	if (list_empty(&bp->b_lru))
 132		return;
 133
 134	spin_lock(&btp->bt_lru_lock);
 135	if (!list_empty(&bp->b_lru)) {
 136		list_del_init(&bp->b_lru);
 137		btp->bt_lru_nr--;
 138	}
 139	spin_unlock(&btp->bt_lru_lock);
 
 
 
 
 
 140}
 141
 142/*
 143 * When we mark a buffer stale, we remove the buffer from the LRU and clear the
 144 * b_lru_ref count so that the buffer is freed immediately when the buffer
 145 * reference count falls to zero. If the buffer is already on the LRU, we need
 146 * to remove the reference that LRU holds on the buffer.
 147 *
 148 * This prevents build-up of stale buffers on the LRU.
 149 */
 150void
 151xfs_buf_stale(
 152	struct xfs_buf	*bp)
 153{
 154	bp->b_flags |= XBF_STALE;
 155	atomic_set(&(bp)->b_lru_ref, 0);
 156	if (!list_empty(&bp->b_lru)) {
 157		struct xfs_buftarg *btp = bp->b_target;
 158
 159		spin_lock(&btp->bt_lru_lock);
 160		if (!list_empty(&bp->b_lru)) {
 161			list_del_init(&bp->b_lru);
 162			btp->bt_lru_nr--;
 163			atomic_dec(&bp->b_hold);
 164		}
 165		spin_unlock(&btp->bt_lru_lock);
 166	}
 167	ASSERT(atomic_read(&bp->b_hold) >= 1);
 168}
 169
 170STATIC void
 171_xfs_buf_initialize(
 172	xfs_buf_t		*bp,
 173	xfs_buftarg_t		*target,
 174	xfs_off_t		range_base,
 175	size_t			range_length,
 176	xfs_buf_flags_t		flags)
 177{
 
 
 
 
 
 
 
 
 178	/*
 179	 * We don't want certain flags to appear in b_flags.
 
 180	 */
 181	flags &= ~(XBF_LOCK|XBF_MAPPED|XBF_DONT_BLOCK|XBF_READ_AHEAD);
 182
 183	memset(bp, 0, sizeof(xfs_buf_t));
 184	atomic_set(&bp->b_hold, 1);
 185	atomic_set(&bp->b_lru_ref, 1);
 186	init_completion(&bp->b_iowait);
 187	INIT_LIST_HEAD(&bp->b_lru);
 188	INIT_LIST_HEAD(&bp->b_list);
 189	RB_CLEAR_NODE(&bp->b_rbnode);
 190	sema_init(&bp->b_sema, 0); /* held, no waiters */
 
 191	XB_SET_OWNER(bp);
 192	bp->b_target = target;
 193	bp->b_file_offset = range_base;
 
 194	/*
 195	 * Set buffer_length and count_desired to the same value initially.
 196	 * I/O routines should use count_desired, which will be the same in
 197	 * most cases but may be reset (e.g. XFS recovery).
 198	 */
 199	bp->b_buffer_length = bp->b_count_desired = range_length;
 200	bp->b_flags = flags;
 201	bp->b_bn = XFS_BUF_DADDR_NULL;
 
 
 
 
 
 
 
 
 
 
 
 
 202	atomic_set(&bp->b_pin_count, 0);
 203	init_waitqueue_head(&bp->b_waiters);
 204
 205	XFS_STATS_INC(xb_create);
 206
 207	trace_xfs_buf_init(bp, _RET_IP_);
 
 
 208}
 209
 210/*
 211 *	Allocate a page array capable of holding a specified number
 212 *	of pages, and point the page buf at it.
 213 */
 214STATIC int
 215_xfs_buf_get_pages(
 216	xfs_buf_t		*bp,
 217	int			page_count,
 218	xfs_buf_flags_t		flags)
 219{
 220	/* Make sure that we have a page list */
 221	if (bp->b_pages == NULL) {
 222		bp->b_offset = xfs_buf_poff(bp->b_file_offset);
 223		bp->b_page_count = page_count;
 224		if (page_count <= XB_PAGES) {
 225			bp->b_pages = bp->b_page_array;
 226		} else {
 227			bp->b_pages = kmem_alloc(sizeof(struct page *) *
 228					page_count, xb_to_km(flags));
 229			if (bp->b_pages == NULL)
 230				return -ENOMEM;
 231		}
 232		memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
 233	}
 234	return 0;
 235}
 236
 237/*
 238 *	Frees b_pages if it was allocated.
 239 */
 240STATIC void
 241_xfs_buf_free_pages(
 242	xfs_buf_t	*bp)
 243{
 244	if (bp->b_pages != bp->b_page_array) {
 245		kmem_free(bp->b_pages);
 246		bp->b_pages = NULL;
 247	}
 248}
 249
 250/*
 251 *	Releases the specified buffer.
 252 *
 253 * 	The modification state of any associated pages is left unchanged.
 254 * 	The buffer most not be on any hash - use xfs_buf_rele instead for
 255 * 	hashed and refcounted buffers
 256 */
 257void
 258xfs_buf_free(
 259	xfs_buf_t		*bp)
 260{
 261	trace_xfs_buf_free(bp, _RET_IP_);
 262
 263	ASSERT(list_empty(&bp->b_lru));
 264
 265	if (bp->b_flags & _XBF_PAGES) {
 266		uint		i;
 267
 268		if (xfs_buf_is_vmapped(bp))
 269			vm_unmap_ram(bp->b_addr - bp->b_offset,
 270					bp->b_page_count);
 271
 272		for (i = 0; i < bp->b_page_count; i++) {
 273			struct page	*page = bp->b_pages[i];
 274
 275			__free_page(page);
 276		}
 277	} else if (bp->b_flags & _XBF_KMEM)
 278		kmem_free(bp->b_addr);
 279	_xfs_buf_free_pages(bp);
 280	xfs_buf_deallocate(bp);
 
 281}
 282
 283/*
 284 * Allocates all the pages for buffer in question and builds it's page list.
 285 */
 286STATIC int
 287xfs_buf_allocate_memory(
 288	xfs_buf_t		*bp,
 289	uint			flags)
 290{
 291	size_t			size = bp->b_count_desired;
 292	size_t			nbytes, offset;
 293	gfp_t			gfp_mask = xb_to_gfp(flags);
 294	unsigned short		page_count, i;
 295	xfs_off_t		end;
 296	int			error;
 297
 298	/*
 299	 * for buffers that are contained within a single page, just allocate
 300	 * the memory from the heap - there's no need for the complexity of
 301	 * page arrays to keep allocation down to order 0.
 302	 */
 303	if (bp->b_buffer_length < PAGE_SIZE) {
 304		bp->b_addr = kmem_alloc(bp->b_buffer_length, xb_to_km(flags));
 
 305		if (!bp->b_addr) {
 306			/* low memory - use alloc_page loop instead */
 307			goto use_alloc_page;
 308		}
 309
 310		if (((unsigned long)(bp->b_addr + bp->b_buffer_length - 1) &
 311								PAGE_MASK) !=
 312		    ((unsigned long)bp->b_addr & PAGE_MASK)) {
 313			/* b_addr spans two pages - use alloc_page instead */
 314			kmem_free(bp->b_addr);
 315			bp->b_addr = NULL;
 316			goto use_alloc_page;
 317		}
 318		bp->b_offset = offset_in_page(bp->b_addr);
 319		bp->b_pages = bp->b_page_array;
 320		bp->b_pages[0] = virt_to_page(bp->b_addr);
 321		bp->b_page_count = 1;
 322		bp->b_flags |= XBF_MAPPED | _XBF_KMEM;
 323		return 0;
 324	}
 325
 326use_alloc_page:
 327	end = bp->b_file_offset + bp->b_buffer_length;
 328	page_count = xfs_buf_btoc(end) - xfs_buf_btoct(bp->b_file_offset);
 329	error = _xfs_buf_get_pages(bp, page_count, flags);
 
 
 330	if (unlikely(error))
 331		return error;
 332
 333	offset = bp->b_offset;
 334	bp->b_flags |= _XBF_PAGES;
 335
 336	for (i = 0; i < bp->b_page_count; i++) {
 337		struct page	*page;
 338		uint		retries = 0;
 339retry:
 340		page = alloc_page(gfp_mask);
 341		if (unlikely(page == NULL)) {
 342			if (flags & XBF_READ_AHEAD) {
 343				bp->b_page_count = i;
 344				error = ENOMEM;
 345				goto out_free_pages;
 346			}
 347
 348			/*
 349			 * This could deadlock.
 350			 *
 351			 * But until all the XFS lowlevel code is revamped to
 352			 * handle buffer allocation failures we can't do much.
 353			 */
 354			if (!(++retries % 100))
 355				xfs_err(NULL,
 356		"possible memory allocation deadlock in %s (mode:0x%x)",
 
 357					__func__, gfp_mask);
 358
 359			XFS_STATS_INC(xb_page_retries);
 360			congestion_wait(BLK_RW_ASYNC, HZ/50);
 361			goto retry;
 362		}
 363
 364		XFS_STATS_INC(xb_page_found);
 365
 366		nbytes = min_t(size_t, size, PAGE_SIZE - offset);
 367		size -= nbytes;
 368		bp->b_pages[i] = page;
 369		offset = 0;
 370	}
 371	return 0;
 372
 373out_free_pages:
 374	for (i = 0; i < bp->b_page_count; i++)
 375		__free_page(bp->b_pages[i]);
 376	return error;
 377}
 378
 379/*
 380 *	Map buffer into kernel address-space if necessary.
 381 */
 382STATIC int
 383_xfs_buf_map_pages(
 384	xfs_buf_t		*bp,
 385	uint			flags)
 386{
 387	ASSERT(bp->b_flags & _XBF_PAGES);
 388	if (bp->b_page_count == 1) {
 389		/* A single page buffer is always mappable */
 390		bp->b_addr = page_address(bp->b_pages[0]) + bp->b_offset;
 391		bp->b_flags |= XBF_MAPPED;
 392	} else if (flags & XBF_MAPPED) {
 
 393		int retried = 0;
 
 394
 
 
 
 
 
 
 
 
 
 395		do {
 396			bp->b_addr = vm_map_ram(bp->b_pages, bp->b_page_count,
 397						-1, PAGE_KERNEL);
 398			if (bp->b_addr)
 399				break;
 400			vm_unmap_aliases();
 401		} while (retried++ <= 1);
 
 402
 403		if (!bp->b_addr)
 404			return -ENOMEM;
 405		bp->b_addr += bp->b_offset;
 406		bp->b_flags |= XBF_MAPPED;
 407	}
 408
 409	return 0;
 410}
 411
 412/*
 413 *	Finding and Reading Buffers
 414 */
 415
 416/*
 417 *	Look up, and creates if absent, a lockable buffer for
 418 *	a given range of an inode.  The buffer is returned
 419 *	locked.	 If other overlapping buffers exist, they are
 420 *	released before the new buffer is created and locked,
 421 *	which may imply that this call will block until those buffers
 422 *	are unlocked.  No I/O is implied by this call.
 423 */
 424xfs_buf_t *
 425_xfs_buf_find(
 426	xfs_buftarg_t		*btp,	/* block device target		*/
 427	xfs_off_t		ioff,	/* starting offset of range	*/
 428	size_t			isize,	/* length of range		*/
 429	xfs_buf_flags_t		flags,
 430	xfs_buf_t		*new_bp)
 431{
 432	xfs_off_t		range_base;
 433	size_t			range_length;
 434	struct xfs_perag	*pag;
 435	struct rb_node		**rbp;
 436	struct rb_node		*parent;
 437	xfs_buf_t		*bp;
 
 
 
 
 438
 439	range_base = (ioff << BBSHIFT);
 440	range_length = (isize << BBSHIFT);
 441
 442	/* Check for IOs smaller than the sector size / not sector aligned */
 443	ASSERT(!(range_length < (1 << btp->bt_sshift)));
 444	ASSERT(!(range_base & (xfs_off_t)btp->bt_smask));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 445
 446	/* get tree root */
 447	pag = xfs_perag_get(btp->bt_mount,
 448				xfs_daddr_to_agno(btp->bt_mount, ioff));
 449
 450	/* walk tree */
 451	spin_lock(&pag->pag_buf_lock);
 452	rbp = &pag->pag_buf_tree.rb_node;
 453	parent = NULL;
 454	bp = NULL;
 455	while (*rbp) {
 456		parent = *rbp;
 457		bp = rb_entry(parent, struct xfs_buf, b_rbnode);
 458
 459		if (range_base < bp->b_file_offset)
 460			rbp = &(*rbp)->rb_left;
 461		else if (range_base > bp->b_file_offset)
 462			rbp = &(*rbp)->rb_right;
 463		else {
 464			/*
 465			 * found a block offset match. If the range doesn't
 466			 * match, the only way this is allowed is if the buffer
 467			 * in the cache is stale and the transaction that made
 468			 * it stale has not yet committed. i.e. we are
 469			 * reallocating a busy extent. Skip this buffer and
 470			 * continue searching to the right for an exact match.
 471			 */
 472			if (bp->b_buffer_length != range_length) {
 473				ASSERT(bp->b_flags & XBF_STALE);
 474				rbp = &(*rbp)->rb_right;
 475				continue;
 476			}
 477			atomic_inc(&bp->b_hold);
 478			goto found;
 479		}
 480	}
 481
 482	/* No match found */
 483	if (new_bp) {
 484		_xfs_buf_initialize(new_bp, btp, range_base,
 485				range_length, flags);
 486		rb_link_node(&new_bp->b_rbnode, parent, rbp);
 487		rb_insert_color(&new_bp->b_rbnode, &pag->pag_buf_tree);
 488		/* the buffer keeps the perag reference until it is freed */
 489		new_bp->b_pag = pag;
 490		spin_unlock(&pag->pag_buf_lock);
 491	} else {
 492		XFS_STATS_INC(xb_miss_locked);
 493		spin_unlock(&pag->pag_buf_lock);
 494		xfs_perag_put(pag);
 495	}
 496	return new_bp;
 497
 498found:
 499	spin_unlock(&pag->pag_buf_lock);
 500	xfs_perag_put(pag);
 501
 502	if (!xfs_buf_trylock(bp)) {
 503		if (flags & XBF_TRYLOCK) {
 504			xfs_buf_rele(bp);
 505			XFS_STATS_INC(xb_busy_locked);
 506			return NULL;
 507		}
 508		xfs_buf_lock(bp);
 509		XFS_STATS_INC(xb_get_locked_waited);
 510	}
 511
 512	/*
 513	 * if the buffer is stale, clear all the external state associated with
 514	 * it. We need to keep flags such as how we allocated the buffer memory
 515	 * intact here.
 516	 */
 517	if (bp->b_flags & XBF_STALE) {
 518		ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
 519		bp->b_flags &= XBF_MAPPED | _XBF_KMEM | _XBF_PAGES;
 
 
 520	}
 521
 522	trace_xfs_buf_find(bp, flags, _RET_IP_);
 523	XFS_STATS_INC(xb_get_locked);
 524	return bp;
 525}
 526
 527/*
 528 *	Assembles a buffer covering the specified range.
 529 *	Storage in memory for all portions of the buffer will be allocated,
 530 *	although backing storage may not be.
 531 */
 532xfs_buf_t *
 533xfs_buf_get(
 534	xfs_buftarg_t		*target,/* target for buffer		*/
 535	xfs_off_t		ioff,	/* starting offset of range	*/
 536	size_t			isize,	/* length of range		*/
 537	xfs_buf_flags_t		flags)
 538{
 539	xfs_buf_t		*bp, *new_bp;
 
 540	int			error = 0;
 541
 542	new_bp = xfs_buf_allocate(flags);
 
 
 
 
 543	if (unlikely(!new_bp))
 544		return NULL;
 545
 546	bp = _xfs_buf_find(target, ioff, isize, flags, new_bp);
 547	if (bp == new_bp) {
 548		error = xfs_buf_allocate_memory(bp, flags);
 549		if (error)
 550			goto no_buffer;
 551	} else {
 552		xfs_buf_deallocate(new_bp);
 553		if (unlikely(bp == NULL))
 554			return NULL;
 
 555	}
 556
 557	if (!(bp->b_flags & XBF_MAPPED)) {
 
 
 
 
 558		error = _xfs_buf_map_pages(bp, flags);
 559		if (unlikely(error)) {
 560			xfs_warn(target->bt_mount,
 561				"%s: failed to map pages\n", __func__);
 562			goto no_buffer;
 
 563		}
 564	}
 565
 566	XFS_STATS_INC(xb_get);
 567
 568	/*
 569	 * Always fill in the block number now, the mapped cases can do
 570	 * their own overlay of this later.
 571	 */
 572	bp->b_bn = ioff;
 573	bp->b_count_desired = bp->b_buffer_length;
 574
 
 575	trace_xfs_buf_get(bp, flags, _RET_IP_);
 576	return bp;
 577
 578 no_buffer:
 579	if (flags & (XBF_LOCK | XBF_TRYLOCK))
 580		xfs_buf_unlock(bp);
 581	xfs_buf_rele(bp);
 582	return NULL;
 583}
 584
 585STATIC int
 586_xfs_buf_read(
 587	xfs_buf_t		*bp,
 588	xfs_buf_flags_t		flags)
 589{
 590	int			status;
 591
 592	ASSERT(!(flags & (XBF_DELWRI|XBF_WRITE)));
 593	ASSERT(bp->b_bn != XFS_BUF_DADDR_NULL);
 594
 595	bp->b_flags &= ~(XBF_WRITE | XBF_ASYNC | XBF_DELWRI | XBF_READ_AHEAD);
 596	bp->b_flags |= flags & (XBF_READ | XBF_ASYNC | XBF_READ_AHEAD);
 597
 598	status = xfs_buf_iorequest(bp);
 599	if (status || bp->b_error || (flags & XBF_ASYNC))
 600		return status;
 601	return xfs_buf_iowait(bp);
 
 602}
 603
 604xfs_buf_t *
 605xfs_buf_read(
 606	xfs_buftarg_t		*target,
 607	xfs_off_t		ioff,
 608	size_t			isize,
 609	xfs_buf_flags_t		flags)
 
 610{
 611	xfs_buf_t		*bp;
 612
 613	flags |= XBF_READ;
 614
 615	bp = xfs_buf_get(target, ioff, isize, flags);
 616	if (bp) {
 617		trace_xfs_buf_read(bp, flags, _RET_IP_);
 618
 619		if (!XFS_BUF_ISDONE(bp)) {
 620			XFS_STATS_INC(xb_get_read);
 
 621			_xfs_buf_read(bp, flags);
 622		} else if (flags & XBF_ASYNC) {
 623			/*
 624			 * Read ahead call which is already satisfied,
 625			 * drop the buffer
 626			 */
 627			goto no_buffer;
 
 628		} else {
 629			/* We do not want read in the flags */
 630			bp->b_flags &= ~XBF_READ;
 631		}
 632	}
 633
 634	return bp;
 635
 636 no_buffer:
 637	if (flags & (XBF_LOCK | XBF_TRYLOCK))
 638		xfs_buf_unlock(bp);
 639	xfs_buf_rele(bp);
 640	return NULL;
 641}
 642
 643/*
 644 *	If we are not low on memory then do the readahead in a deadlock
 645 *	safe manner.
 646 */
 647void
 648xfs_buf_readahead(
 649	xfs_buftarg_t		*target,
 650	xfs_off_t		ioff,
 651	size_t			isize)
 
 652{
 653	if (bdi_read_congested(target->bt_bdi))
 654		return;
 655
 656	xfs_buf_read(target, ioff, isize,
 657		     XBF_TRYLOCK|XBF_ASYNC|XBF_READ_AHEAD|XBF_DONT_BLOCK);
 658}
 659
 660/*
 661 * Read an uncached buffer from disk. Allocates and returns a locked
 662 * buffer containing the disk contents or nothing.
 663 */
 664struct xfs_buf *
 665xfs_buf_read_uncached(
 666	struct xfs_mount	*mp,
 667	struct xfs_buftarg	*target,
 668	xfs_daddr_t		daddr,
 669	size_t			length,
 670	int			flags)
 
 
 671{
 672	xfs_buf_t		*bp;
 673	int			error;
 
 674
 675	bp = xfs_buf_get_uncached(target, length, flags);
 676	if (!bp)
 677		return NULL;
 678
 679	/* set up the buffer for a read IO */
 680	XFS_BUF_SET_ADDR(bp, daddr);
 681	XFS_BUF_READ(bp);
 682
 683	xfsbdstrat(mp, bp);
 684	error = xfs_buf_iowait(bp);
 685	if (error || bp->b_error) {
 
 
 
 686		xfs_buf_relse(bp);
 687		return NULL;
 688	}
 689	return bp;
 690}
 691
 692xfs_buf_t *
 693xfs_buf_get_empty(
 694	size_t			len,
 695	xfs_buftarg_t		*target)
 696{
 697	xfs_buf_t		*bp;
 698
 699	bp = xfs_buf_allocate(0);
 700	if (bp)
 701		_xfs_buf_initialize(bp, target, 0, len, 0);
 702	return bp;
 703}
 704
 705/*
 706 * Return a buffer allocated as an empty buffer and associated to external
 707 * memory via xfs_buf_associate_memory() back to it's empty state.
 708 */
 709void
 710xfs_buf_set_empty(
 711	struct xfs_buf		*bp,
 712	size_t			len)
 713{
 714	if (bp->b_pages)
 715		_xfs_buf_free_pages(bp);
 716
 717	bp->b_pages = NULL;
 718	bp->b_page_count = 0;
 719	bp->b_addr = NULL;
 720	bp->b_file_offset = 0;
 721	bp->b_buffer_length = bp->b_count_desired = len;
 
 
 722	bp->b_bn = XFS_BUF_DADDR_NULL;
 723	bp->b_flags &= ~XBF_MAPPED;
 
 724}
 725
 726static inline struct page *
 727mem_to_page(
 728	void			*addr)
 729{
 730	if ((!is_vmalloc_addr(addr))) {
 731		return virt_to_page(addr);
 732	} else {
 733		return vmalloc_to_page(addr);
 734	}
 735}
 736
 737int
 738xfs_buf_associate_memory(
 739	xfs_buf_t		*bp,
 740	void			*mem,
 741	size_t			len)
 742{
 743	int			rval;
 744	int			i = 0;
 745	unsigned long		pageaddr;
 746	unsigned long		offset;
 747	size_t			buflen;
 748	int			page_count;
 749
 750	pageaddr = (unsigned long)mem & PAGE_MASK;
 751	offset = (unsigned long)mem - pageaddr;
 752	buflen = PAGE_ALIGN(len + offset);
 753	page_count = buflen >> PAGE_SHIFT;
 754
 755	/* Free any previous set of page pointers */
 756	if (bp->b_pages)
 757		_xfs_buf_free_pages(bp);
 758
 759	bp->b_pages = NULL;
 760	bp->b_addr = mem;
 761
 762	rval = _xfs_buf_get_pages(bp, page_count, XBF_DONT_BLOCK);
 763	if (rval)
 764		return rval;
 765
 766	bp->b_offset = offset;
 767
 768	for (i = 0; i < bp->b_page_count; i++) {
 769		bp->b_pages[i] = mem_to_page((void *)pageaddr);
 770		pageaddr += PAGE_SIZE;
 771	}
 772
 773	bp->b_count_desired = len;
 774	bp->b_buffer_length = buflen;
 775	bp->b_flags |= XBF_MAPPED;
 776
 777	return 0;
 778}
 779
 780xfs_buf_t *
 781xfs_buf_get_uncached(
 782	struct xfs_buftarg	*target,
 783	size_t			len,
 784	int			flags)
 785{
 786	unsigned long		page_count = PAGE_ALIGN(len) >> PAGE_SHIFT;
 787	int			error, i;
 788	xfs_buf_t		*bp;
 
 789
 790	bp = xfs_buf_allocate(0);
 791	if (unlikely(bp == NULL))
 792		goto fail;
 793	_xfs_buf_initialize(bp, target, 0, len, 0);
 794
 795	error = _xfs_buf_get_pages(bp, page_count, 0);
 
 796	if (error)
 797		goto fail_free_buf;
 798
 799	for (i = 0; i < page_count; i++) {
 800		bp->b_pages[i] = alloc_page(xb_to_gfp(flags));
 801		if (!bp->b_pages[i])
 802			goto fail_free_mem;
 803	}
 804	bp->b_flags |= _XBF_PAGES;
 805
 806	error = _xfs_buf_map_pages(bp, XBF_MAPPED);
 807	if (unlikely(error)) {
 808		xfs_warn(target->bt_mount,
 809			"%s: failed to map pages\n", __func__);
 810		goto fail_free_mem;
 811	}
 812
 813	trace_xfs_buf_get_uncached(bp, _RET_IP_);
 814	return bp;
 815
 816 fail_free_mem:
 817	while (--i >= 0)
 818		__free_page(bp->b_pages[i]);
 819	_xfs_buf_free_pages(bp);
 820 fail_free_buf:
 821	xfs_buf_deallocate(bp);
 
 822 fail:
 823	return NULL;
 824}
 825
 826/*
 827 *	Increment reference count on buffer, to hold the buffer concurrently
 828 *	with another thread which may release (free) the buffer asynchronously.
 829 *	Must hold the buffer already to call this function.
 830 */
 831void
 832xfs_buf_hold(
 833	xfs_buf_t		*bp)
 834{
 835	trace_xfs_buf_hold(bp, _RET_IP_);
 836	atomic_inc(&bp->b_hold);
 837}
 838
 839/*
 840 *	Releases a hold on the specified buffer.  If the
 841 *	the hold count is 1, calls xfs_buf_free.
 842 */
 843void
 844xfs_buf_rele(
 845	xfs_buf_t		*bp)
 846{
 847	struct xfs_perag	*pag = bp->b_pag;
 848
 849	trace_xfs_buf_rele(bp, _RET_IP_);
 850
 851	if (!pag) {
 852		ASSERT(list_empty(&bp->b_lru));
 853		ASSERT(RB_EMPTY_NODE(&bp->b_rbnode));
 854		if (atomic_dec_and_test(&bp->b_hold))
 855			xfs_buf_free(bp);
 856		return;
 857	}
 858
 859	ASSERT(!RB_EMPTY_NODE(&bp->b_rbnode));
 860
 861	ASSERT(atomic_read(&bp->b_hold) > 0);
 862	if (atomic_dec_and_lock(&bp->b_hold, &pag->pag_buf_lock)) {
 863		if (!(bp->b_flags & XBF_STALE) &&
 864			   atomic_read(&bp->b_lru_ref)) {
 865			xfs_buf_lru_add(bp);
 
 
 
 
 
 
 
 
 
 866			spin_unlock(&pag->pag_buf_lock);
 867		} else {
 868			xfs_buf_lru_del(bp);
 869			ASSERT(!(bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)));
 
 
 
 
 
 
 
 
 
 
 
 
 870			rb_erase(&bp->b_rbnode, &pag->pag_buf_tree);
 871			spin_unlock(&pag->pag_buf_lock);
 872			xfs_perag_put(pag);
 873			xfs_buf_free(bp);
 874		}
 875	}
 876}
 877
 878
 879/*
 880 *	Lock a buffer object, if it is not already locked.
 881 *
 882 *	If we come across a stale, pinned, locked buffer, we know that we are
 883 *	being asked to lock a buffer that has been reallocated. Because it is
 884 *	pinned, we know that the log has not been pushed to disk and hence it
 885 *	will still be locked.  Rather than continuing to have trylock attempts
 886 *	fail until someone else pushes the log, push it ourselves before
 887 *	returning.  This means that the xfsaild will not get stuck trying
 888 *	to push on stale inode buffers.
 889 */
 890int
 891xfs_buf_trylock(
 892	struct xfs_buf		*bp)
 893{
 894	int			locked;
 895
 896	locked = down_trylock(&bp->b_sema) == 0;
 897	if (locked)
 898		XB_SET_OWNER(bp);
 899	else if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
 900		xfs_log_force(bp->b_target->bt_mount, 0);
 901
 902	trace_xfs_buf_trylock(bp, _RET_IP_);
 903	return locked;
 904}
 905
 906/*
 907 *	Lock a buffer object.
 908 *
 909 *	If we come across a stale, pinned, locked buffer, we know that we
 910 *	are being asked to lock a buffer that has been reallocated. Because
 911 *	it is pinned, we know that the log has not been pushed to disk and
 912 *	hence it will still be locked. Rather than sleeping until someone
 913 *	else pushes the log, push it ourselves before trying to get the lock.
 914 */
 915void
 916xfs_buf_lock(
 917	struct xfs_buf		*bp)
 918{
 919	trace_xfs_buf_lock(bp, _RET_IP_);
 920
 921	if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
 922		xfs_log_force(bp->b_target->bt_mount, 0);
 923	down(&bp->b_sema);
 924	XB_SET_OWNER(bp);
 925
 926	trace_xfs_buf_lock_done(bp, _RET_IP_);
 927}
 928
 929/*
 930 *	Releases the lock on the buffer object.
 931 *	If the buffer is marked delwri but is not queued, do so before we
 932 *	unlock the buffer as we need to set flags correctly.  We also need to
 933 *	take a reference for the delwri queue because the unlocker is going to
 934 *	drop their's and they don't know we just queued it.
 935 */
 936void
 937xfs_buf_unlock(
 938	struct xfs_buf		*bp)
 939{
 940	if ((bp->b_flags & (XBF_DELWRI|_XBF_DELWRI_Q)) == XBF_DELWRI) {
 941		atomic_inc(&bp->b_hold);
 942		bp->b_flags |= XBF_ASYNC;
 943		xfs_buf_delwri_queue(bp, 0);
 944	}
 945
 946	XB_CLEAR_OWNER(bp);
 947	up(&bp->b_sema);
 948
 949	trace_xfs_buf_unlock(bp, _RET_IP_);
 950}
 951
 952STATIC void
 953xfs_buf_wait_unpin(
 954	xfs_buf_t		*bp)
 955{
 956	DECLARE_WAITQUEUE	(wait, current);
 957
 958	if (atomic_read(&bp->b_pin_count) == 0)
 959		return;
 960
 961	add_wait_queue(&bp->b_waiters, &wait);
 962	for (;;) {
 963		set_current_state(TASK_UNINTERRUPTIBLE);
 964		if (atomic_read(&bp->b_pin_count) == 0)
 965			break;
 966		io_schedule();
 967	}
 968	remove_wait_queue(&bp->b_waiters, &wait);
 969	set_current_state(TASK_RUNNING);
 970}
 971
 972/*
 973 *	Buffer Utility Routines
 974 */
 975
 976STATIC void
 977xfs_buf_iodone_work(
 978	struct work_struct	*work)
 979{
 980	xfs_buf_t		*bp =
 981		container_of(work, xfs_buf_t, b_iodone_work);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 982
 983	if (bp->b_iodone)
 984		(*(bp->b_iodone))(bp);
 985	else if (bp->b_flags & XBF_ASYNC)
 986		xfs_buf_relse(bp);
 
 
 987}
 988
 989void
 990xfs_buf_ioend(
 991	xfs_buf_t		*bp,
 992	int			schedule)
 993{
 994	trace_xfs_buf_iodone(bp, _RET_IP_);
 
 995
 996	bp->b_flags &= ~(XBF_READ | XBF_WRITE | XBF_READ_AHEAD);
 997	if (bp->b_error == 0)
 998		bp->b_flags |= XBF_DONE;
 999
1000	if ((bp->b_iodone) || (bp->b_flags & XBF_ASYNC)) {
1001		if (schedule) {
1002			INIT_WORK(&bp->b_iodone_work, xfs_buf_iodone_work);
1003			queue_work(xfslogd_workqueue, &bp->b_iodone_work);
1004		} else {
1005			xfs_buf_iodone_work(&bp->b_iodone_work);
1006		}
1007	} else {
1008		complete(&bp->b_iowait);
1009	}
1010}
1011
1012void
1013xfs_buf_ioerror(
1014	xfs_buf_t		*bp,
1015	int			error)
1016{
1017	ASSERT(error >= 0 && error <= 0xffff);
1018	bp->b_error = (unsigned short)error;
1019	trace_xfs_buf_ioerror(bp, error, _RET_IP_);
1020}
1021
1022int
1023xfs_bwrite(
1024	struct xfs_mount	*mp,
1025	struct xfs_buf		*bp)
1026{
1027	int			error;
1028
1029	bp->b_flags |= XBF_WRITE;
1030	bp->b_flags &= ~(XBF_ASYNC | XBF_READ);
1031
1032	xfs_buf_delwri_dequeue(bp);
1033	xfs_bdstrat_cb(bp);
1034
1035	error = xfs_buf_iowait(bp);
1036	if (error)
1037		xfs_force_shutdown(mp, SHUTDOWN_META_IO_ERROR);
1038	xfs_buf_relse(bp);
1039	return error;
1040}
1041
1042void
1043xfs_bdwrite(
1044	void			*mp,
1045	struct xfs_buf		*bp)
1046{
1047	trace_xfs_buf_bdwrite(bp, _RET_IP_);
1048
1049	bp->b_flags &= ~XBF_READ;
1050	bp->b_flags |= (XBF_DELWRI | XBF_ASYNC);
1051
1052	xfs_buf_delwri_queue(bp, 1);
1053}
1054
1055/*
1056 * Called when we want to stop a buffer from getting written or read.
1057 * We attach the EIO error, muck with its flags, and call xfs_buf_ioend
1058 * so that the proper iodone callbacks get called.
1059 */
1060STATIC int
1061xfs_bioerror(
1062	xfs_buf_t *bp)
1063{
1064#ifdef XFSERRORDEBUG
1065	ASSERT(XFS_BUF_ISREAD(bp) || bp->b_iodone);
1066#endif
1067
1068	/*
1069	 * No need to wait until the buffer is unpinned, we aren't flushing it.
1070	 */
1071	xfs_buf_ioerror(bp, EIO);
1072
1073	/*
1074	 * We're calling xfs_buf_ioend, so delete XBF_DONE flag.
1075	 */
1076	XFS_BUF_UNREAD(bp);
1077	XFS_BUF_UNDELAYWRITE(bp);
1078	XFS_BUF_UNDONE(bp);
1079	XFS_BUF_STALE(bp);
1080
1081	xfs_buf_ioend(bp, 0);
1082
1083	return EIO;
1084}
1085
1086/*
1087 * Same as xfs_bioerror, except that we are releasing the buffer
1088 * here ourselves, and avoiding the xfs_buf_ioend call.
1089 * This is meant for userdata errors; metadata bufs come with
1090 * iodone functions attached, so that we can track down errors.
1091 */
1092STATIC int
1093xfs_bioerror_relse(
1094	struct xfs_buf	*bp)
1095{
1096	int64_t		fl = bp->b_flags;
1097	/*
1098	 * No need to wait until the buffer is unpinned.
1099	 * We aren't flushing it.
1100	 *
1101	 * chunkhold expects B_DONE to be set, whether
1102	 * we actually finish the I/O or not. We don't want to
1103	 * change that interface.
1104	 */
1105	XFS_BUF_UNREAD(bp);
1106	XFS_BUF_UNDELAYWRITE(bp);
1107	XFS_BUF_DONE(bp);
1108	XFS_BUF_STALE(bp);
1109	bp->b_iodone = NULL;
1110	if (!(fl & XBF_ASYNC)) {
1111		/*
1112		 * Mark b_error and B_ERROR _both_.
1113		 * Lot's of chunkcache code assumes that.
1114		 * There's no reason to mark error for
1115		 * ASYNC buffers.
1116		 */
1117		xfs_buf_ioerror(bp, EIO);
1118		XFS_BUF_FINISH_IOWAIT(bp);
1119	} else {
1120		xfs_buf_relse(bp);
1121	}
1122
1123	return EIO;
1124}
1125
1126
1127/*
1128 * All xfs metadata buffers except log state machine buffers
1129 * get this attached as their b_bdstrat callback function.
1130 * This is so that we can catch a buffer
1131 * after prematurely unpinning it to forcibly shutdown the filesystem.
1132 */
1133int
1134xfs_bdstrat_cb(
1135	struct xfs_buf	*bp)
1136{
1137	if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
1138		trace_xfs_bdstrat_shut(bp, _RET_IP_);
1139		/*
1140		 * Metadata write that didn't get logged but
1141		 * written delayed anyway. These aren't associated
1142		 * with a transaction, and can be ignored.
1143		 */
1144		if (!bp->b_iodone && !XFS_BUF_ISREAD(bp))
1145			return xfs_bioerror_relse(bp);
1146		else
1147			return xfs_bioerror(bp);
1148	}
1149
1150	xfs_buf_iorequest(bp);
1151	return 0;
1152}
1153
1154/*
1155 * Wrapper around bdstrat so that we can stop data from going to disk in case
1156 * we are shutting down the filesystem.  Typically user data goes thru this
1157 * path; one of the exceptions is the superblock.
1158 */
1159void
1160xfsbdstrat(
1161	struct xfs_mount	*mp,
1162	struct xfs_buf		*bp)
1163{
1164	if (XFS_FORCED_SHUTDOWN(mp)) {
1165		trace_xfs_bdstrat_shut(bp, _RET_IP_);
1166		xfs_bioerror_relse(bp);
1167		return;
1168	}
1169
1170	xfs_buf_iorequest(bp);
1171}
1172
1173STATIC void
1174_xfs_buf_ioend(
1175	xfs_buf_t		*bp,
1176	int			schedule)
1177{
1178	if (atomic_dec_and_test(&bp->b_io_remaining) == 1)
1179		xfs_buf_ioend(bp, schedule);
 
 
 
1180}
1181
1182STATIC void
1183xfs_buf_bio_end_io(
1184	struct bio		*bio,
1185	int			error)
1186{
1187	xfs_buf_t		*bp = (xfs_buf_t *)bio->bi_private;
1188
1189	xfs_buf_ioerror(bp, -error);
 
 
 
 
 
 
 
 
 
1190
1191	if (!error && xfs_buf_is_vmapped(bp) && (bp->b_flags & XBF_READ))
1192		invalidate_kernel_vmap_range(bp->b_addr, xfs_buf_vmap_len(bp));
1193
1194	_xfs_buf_ioend(bp, 1);
 
1195	bio_put(bio);
1196}
1197
1198STATIC void
1199_xfs_buf_ioapply(
1200	xfs_buf_t		*bp)
1201{
1202	int			rw, map_i, total_nr_pages, nr_pages;
1203	struct bio		*bio;
1204	int			offset = bp->b_offset;
1205	int			size = bp->b_count_desired;
1206	sector_t		sector = bp->b_bn;
 
 
 
 
 
 
1207
1208	total_nr_pages = bp->b_page_count;
1209	map_i = 0;
1210
1211	if (bp->b_flags & XBF_WRITE) {
1212		if (bp->b_flags & XBF_SYNCIO)
1213			rw = WRITE_SYNC;
1214		else
1215			rw = WRITE;
1216		if (bp->b_flags & XBF_FUA)
1217			rw |= REQ_FUA;
1218		if (bp->b_flags & XBF_FLUSH)
1219			rw |= REQ_FLUSH;
1220	} else if (bp->b_flags & XBF_READ_AHEAD) {
1221		rw = READA;
1222	} else {
1223		rw = READ;
1224	}
1225
1226	/* we only use the buffer cache for meta-data */
1227	rw |= REQ_META;
 
 
 
 
 
1228
1229next_chunk:
1230	atomic_inc(&bp->b_io_remaining);
1231	nr_pages = BIO_MAX_SECTORS >> (PAGE_SHIFT - BBSHIFT);
1232	if (nr_pages > total_nr_pages)
1233		nr_pages = total_nr_pages;
1234
1235	bio = bio_alloc(GFP_NOIO, nr_pages);
1236	bio->bi_bdev = bp->b_target->bt_bdev;
1237	bio->bi_sector = sector;
1238	bio->bi_end_io = xfs_buf_bio_end_io;
1239	bio->bi_private = bp;
1240
1241
1242	for (; size && nr_pages; nr_pages--, map_i++) {
1243		int	rbytes, nbytes = PAGE_SIZE - offset;
1244
1245		if (nbytes > size)
1246			nbytes = size;
1247
1248		rbytes = bio_add_page(bio, bp->b_pages[map_i], nbytes, offset);
 
1249		if (rbytes < nbytes)
1250			break;
1251
1252		offset = 0;
1253		sector += nbytes >> BBSHIFT;
1254		size -= nbytes;
1255		total_nr_pages--;
1256	}
1257
1258	if (likely(bio->bi_size)) {
1259		if (xfs_buf_is_vmapped(bp)) {
1260			flush_kernel_vmap_range(bp->b_addr,
1261						xfs_buf_vmap_len(bp));
1262		}
1263		submit_bio(rw, bio);
1264		if (size)
1265			goto next_chunk;
1266	} else {
1267		xfs_buf_ioerror(bp, EIO);
 
 
 
 
 
1268		bio_put(bio);
1269	}
 
1270}
1271
1272int
1273xfs_buf_iorequest(
1274	xfs_buf_t		*bp)
1275{
1276	trace_xfs_buf_iorequest(bp, _RET_IP_);
 
 
 
 
1277
1278	if (bp->b_flags & XBF_DELWRI) {
1279		xfs_buf_delwri_queue(bp, 1);
1280		return 0;
1281	}
 
 
 
 
 
 
 
 
1282
1283	if (bp->b_flags & XBF_WRITE) {
1284		xfs_buf_wait_unpin(bp);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1285	}
1286
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1287	xfs_buf_hold(bp);
1288
1289	/* Set the count to 1 initially, this will stop an I/O
1290	 * completion callout which happens before we have started
1291	 * all the I/O from calling xfs_buf_ioend too early.
 
1292	 */
1293	atomic_set(&bp->b_io_remaining, 1);
1294	_xfs_buf_ioapply(bp);
1295	_xfs_buf_ioend(bp, 0);
 
 
 
 
 
 
 
 
 
 
 
1296
1297	xfs_buf_rele(bp);
1298	return 0;
1299}
1300
1301/*
1302 *	Waits for I/O to complete on the buffer supplied.
1303 *	It returns immediately if no I/O is pending.
1304 *	It returns the I/O error code, if any, or 0 if there was no error.
1305 */
1306int
1307xfs_buf_iowait(
1308	xfs_buf_t		*bp)
1309{
1310	trace_xfs_buf_iowait(bp, _RET_IP_);
1311
1312	wait_for_completion(&bp->b_iowait);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1313
 
 
 
 
 
 
 
 
 
 
1314	trace_xfs_buf_iowait_done(bp, _RET_IP_);
1315	return bp->b_error;
 
 
 
 
 
 
 
1316}
1317
1318xfs_caddr_t
1319xfs_buf_offset(
1320	xfs_buf_t		*bp,
1321	size_t			offset)
1322{
1323	struct page		*page;
1324
1325	if (bp->b_flags & XBF_MAPPED)
1326		return bp->b_addr + offset;
1327
1328	offset += bp->b_offset;
1329	page = bp->b_pages[offset >> PAGE_SHIFT];
1330	return (xfs_caddr_t)page_address(page) + (offset & (PAGE_SIZE-1));
1331}
1332
1333/*
1334 *	Move data into or out of a buffer.
1335 */
1336void
1337xfs_buf_iomove(
1338	xfs_buf_t		*bp,	/* buffer to process		*/
1339	size_t			boff,	/* starting buffer offset	*/
1340	size_t			bsize,	/* length to copy		*/
1341	void			*data,	/* data address			*/
1342	xfs_buf_rw_t		mode)	/* read/write/zero flag		*/
1343{
1344	size_t			bend, cpoff, csize;
1345	struct page		*page;
1346
1347	bend = boff + bsize;
1348	while (boff < bend) {
1349		page = bp->b_pages[xfs_buf_btoct(boff + bp->b_offset)];
1350		cpoff = xfs_buf_poff(boff + bp->b_offset);
1351		csize = min_t(size_t,
1352			      PAGE_SIZE-cpoff, bp->b_count_desired-boff);
 
 
 
 
1353
1354		ASSERT(((csize + cpoff) <= PAGE_SIZE));
1355
1356		switch (mode) {
1357		case XBRW_ZERO:
1358			memset(page_address(page) + cpoff, 0, csize);
1359			break;
1360		case XBRW_READ:
1361			memcpy(data, page_address(page) + cpoff, csize);
1362			break;
1363		case XBRW_WRITE:
1364			memcpy(page_address(page) + cpoff, data, csize);
1365		}
1366
1367		boff += csize;
1368		data += csize;
1369	}
1370}
1371
1372/*
1373 *	Handling of buffer targets (buftargs).
1374 */
1375
1376/*
1377 * Wait for any bufs with callbacks that have been submitted but have not yet
1378 * returned. These buffers will have an elevated hold count, so wait on those
1379 * while freeing all the buffers only held by the LRU.
1380 */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1381void
1382xfs_wait_buftarg(
1383	struct xfs_buftarg	*btp)
1384{
1385	struct xfs_buf		*bp;
 
1386
1387restart:
1388	spin_lock(&btp->bt_lru_lock);
1389	while (!list_empty(&btp->bt_lru)) {
1390		bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru);
1391		if (atomic_read(&bp->b_hold) > 1) {
1392			spin_unlock(&btp->bt_lru_lock);
1393			delay(100);
1394			goto restart;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1395		}
1396		/*
1397		 * clear the LRU reference count so the bufer doesn't get
1398		 * ignored in xfs_buf_rele().
1399		 */
1400		atomic_set(&bp->b_lru_ref, 0);
1401		spin_unlock(&btp->bt_lru_lock);
1402		xfs_buf_rele(bp);
1403		spin_lock(&btp->bt_lru_lock);
1404	}
1405	spin_unlock(&btp->bt_lru_lock);
1406}
1407
1408int
1409xfs_buftarg_shrink(
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1410	struct shrinker		*shrink,
1411	struct shrink_control	*sc)
1412{
1413	struct xfs_buftarg	*btp = container_of(shrink,
1414					struct xfs_buftarg, bt_shrinker);
1415	struct xfs_buf		*bp;
1416	int nr_to_scan = sc->nr_to_scan;
1417	LIST_HEAD(dispose);
 
1418
1419	if (!nr_to_scan)
1420		return btp->bt_lru_nr;
1421
1422	spin_lock(&btp->bt_lru_lock);
1423	while (!list_empty(&btp->bt_lru)) {
1424		if (nr_to_scan-- <= 0)
1425			break;
1426
1427		bp = list_first_entry(&btp->bt_lru, struct xfs_buf, b_lru);
1428
1429		/*
1430		 * Decrement the b_lru_ref count unless the value is already
1431		 * zero. If the value is already zero, we need to reclaim the
1432		 * buffer, otherwise it gets another trip through the LRU.
1433		 */
1434		if (!atomic_add_unless(&bp->b_lru_ref, -1, 0)) {
1435			list_move_tail(&bp->b_lru, &btp->bt_lru);
1436			continue;
1437		}
1438
1439		/*
1440		 * remove the buffer from the LRU now to avoid needing another
1441		 * lock round trip inside xfs_buf_rele().
1442		 */
1443		list_move(&bp->b_lru, &dispose);
1444		btp->bt_lru_nr--;
1445	}
1446	spin_unlock(&btp->bt_lru_lock);
1447
1448	while (!list_empty(&dispose)) {
 
1449		bp = list_first_entry(&dispose, struct xfs_buf, b_lru);
1450		list_del_init(&bp->b_lru);
1451		xfs_buf_rele(bp);
1452	}
1453
1454	return btp->bt_lru_nr;
 
 
 
 
 
 
 
 
 
 
1455}
1456
1457void
1458xfs_free_buftarg(
1459	struct xfs_mount	*mp,
1460	struct xfs_buftarg	*btp)
1461{
1462	unregister_shrinker(&btp->bt_shrinker);
 
1463
1464	xfs_flush_buftarg(btp, 1);
1465	if (mp->m_flags & XFS_MOUNT_BARRIER)
1466		xfs_blkdev_issue_flush(btp);
1467
1468	kthread_stop(btp->bt_task);
1469	kmem_free(btp);
1470}
1471
1472STATIC int
1473xfs_setsize_buftarg_flags(
1474	xfs_buftarg_t		*btp,
1475	unsigned int		blocksize,
1476	unsigned int		sectorsize,
1477	int			verbose)
1478{
1479	btp->bt_bsize = blocksize;
1480	btp->bt_sshift = ffs(sectorsize) - 1;
1481	btp->bt_smask = sectorsize - 1;
1482
1483	if (set_blocksize(btp->bt_bdev, sectorsize)) {
1484		xfs_warn(btp->bt_mount,
1485			"Cannot set_blocksize to %u on device %s\n",
1486			sectorsize, xfs_buf_target_name(btp));
1487		return EINVAL;
1488	}
1489
 
 
 
 
1490	return 0;
1491}
1492
1493/*
1494 *	When allocating the initial buffer target we have not yet
1495 *	read in the superblock, so don't know what sized sectors
1496 *	are being used is at this early stage.  Play safe.
1497 */
1498STATIC int
1499xfs_setsize_buftarg_early(
1500	xfs_buftarg_t		*btp,
1501	struct block_device	*bdev)
1502{
1503	return xfs_setsize_buftarg_flags(btp,
1504			PAGE_SIZE, bdev_logical_block_size(bdev), 0);
1505}
1506
1507int
1508xfs_setsize_buftarg(
1509	xfs_buftarg_t		*btp,
1510	unsigned int		blocksize,
1511	unsigned int		sectorsize)
1512{
1513	return xfs_setsize_buftarg_flags(btp, blocksize, sectorsize, 1);
1514}
1515
1516STATIC int
1517xfs_alloc_delwrite_queue(
1518	xfs_buftarg_t		*btp,
1519	const char		*fsname)
1520{
1521	INIT_LIST_HEAD(&btp->bt_delwrite_queue);
1522	spin_lock_init(&btp->bt_delwrite_lock);
1523	btp->bt_flags = 0;
1524	btp->bt_task = kthread_run(xfsbufd, btp, "xfsbufd/%s", fsname);
1525	if (IS_ERR(btp->bt_task))
1526		return PTR_ERR(btp->bt_task);
1527	return 0;
1528}
1529
1530xfs_buftarg_t *
1531xfs_alloc_buftarg(
1532	struct xfs_mount	*mp,
1533	struct block_device	*bdev,
1534	int			external,
1535	const char		*fsname)
1536{
1537	xfs_buftarg_t		*btp;
1538
1539	btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
1540
1541	btp->bt_mount = mp;
1542	btp->bt_dev =  bdev->bd_dev;
1543	btp->bt_bdev = bdev;
1544	btp->bt_bdi = blk_get_backing_dev_info(bdev);
1545	if (!btp->bt_bdi)
1546		goto error;
1547
1548	INIT_LIST_HEAD(&btp->bt_lru);
1549	spin_lock_init(&btp->bt_lru_lock);
1550	if (xfs_setsize_buftarg_early(btp, bdev))
1551		goto error;
1552	if (xfs_alloc_delwrite_queue(btp, fsname))
 
1553		goto error;
1554	btp->bt_shrinker.shrink = xfs_buftarg_shrink;
 
 
1555	btp->bt_shrinker.seeks = DEFAULT_SEEKS;
 
1556	register_shrinker(&btp->bt_shrinker);
1557	return btp;
1558
1559error:
1560	kmem_free(btp);
1561	return NULL;
1562}
1563
1564
1565/*
1566 *	Delayed write buffer handling
 
 
 
 
 
 
 
 
1567 */
1568STATIC void
1569xfs_buf_delwri_queue(
1570	xfs_buf_t		*bp,
1571	int			unlock)
1572{
1573	struct list_head	*dwq = &bp->b_target->bt_delwrite_queue;
1574	spinlock_t		*dwlk = &bp->b_target->bt_delwrite_lock;
1575
1576	trace_xfs_buf_delwri_queue(bp, _RET_IP_);
1577
1578	ASSERT((bp->b_flags&(XBF_DELWRI|XBF_ASYNC)) == (XBF_DELWRI|XBF_ASYNC));
1579
1580	spin_lock(dwlk);
1581	/* If already in the queue, dequeue and place at tail */
1582	if (!list_empty(&bp->b_list)) {
1583		ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1584		if (unlock)
1585			atomic_dec(&bp->b_hold);
1586		list_del(&bp->b_list);
1587	}
1588
1589	if (list_empty(dwq)) {
1590		/* start xfsbufd as it is about to have something to do */
1591		wake_up_process(bp->b_target->bt_task);
1592	}
1593
1594	bp->b_flags |= _XBF_DELWRI_Q;
1595	list_add_tail(&bp->b_list, dwq);
1596	bp->b_queuetime = jiffies;
1597	spin_unlock(dwlk);
1598
1599	if (unlock)
1600		xfs_buf_unlock(bp);
1601}
1602
1603void
1604xfs_buf_delwri_dequeue(
1605	xfs_buf_t		*bp)
1606{
1607	spinlock_t		*dwlk = &bp->b_target->bt_delwrite_lock;
1608	int			dequeued = 0;
1609
1610	spin_lock(dwlk);
1611	if ((bp->b_flags & XBF_DELWRI) && !list_empty(&bp->b_list)) {
1612		ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1613		list_del_init(&bp->b_list);
1614		dequeued = 1;
 
 
 
1615	}
1616	bp->b_flags &= ~(XBF_DELWRI|_XBF_DELWRI_Q);
1617	spin_unlock(dwlk);
1618
1619	if (dequeued)
1620		xfs_buf_rele(bp);
1621
1622	trace_xfs_buf_delwri_dequeue(bp, _RET_IP_);
1623}
1624
1625/*
1626 * If a delwri buffer needs to be pushed before it has aged out, then promote
1627 * it to the head of the delwri queue so that it will be flushed on the next
1628 * xfsbufd run. We do this by resetting the queuetime of the buffer to be older
1629 * than the age currently needed to flush the buffer. Hence the next time the
1630 * xfsbufd sees it is guaranteed to be considered old enough to flush.
1631 */
1632void
1633xfs_buf_delwri_promote(
1634	struct xfs_buf	*bp)
1635{
1636	struct xfs_buftarg *btp = bp->b_target;
1637	long		age = xfs_buf_age_centisecs * msecs_to_jiffies(10) + 1;
1638
1639	ASSERT(bp->b_flags & XBF_DELWRI);
1640	ASSERT(bp->b_flags & _XBF_DELWRI_Q);
1641
1642	/*
1643	 * Check the buffer age before locking the delayed write queue as we
1644	 * don't need to promote buffers that are already past the flush age.
 
 
 
 
1645	 */
1646	if (bp->b_queuetime < jiffies - age)
1647		return;
1648	bp->b_queuetime = jiffies - age;
1649	spin_lock(&btp->bt_delwrite_lock);
1650	list_move(&bp->b_list, &btp->bt_delwrite_queue);
1651	spin_unlock(&btp->bt_delwrite_lock);
1652}
1653
1654STATIC void
1655xfs_buf_runall_queues(
1656	struct workqueue_struct	*queue)
1657{
1658	flush_workqueue(queue);
1659}
1660
1661/*
1662 * Move as many buffers as specified to the supplied list
1663 * idicating if we skipped any buffers to prevent deadlocks.
1664 */
1665STATIC int
1666xfs_buf_delwri_split(
1667	xfs_buftarg_t	*target,
1668	struct list_head *list,
1669	unsigned long	age)
1670{
1671	xfs_buf_t	*bp, *n;
1672	struct list_head *dwq = &target->bt_delwrite_queue;
1673	spinlock_t	*dwlk = &target->bt_delwrite_lock;
1674	int		skipped = 0;
1675	int		force;
1676
1677	force = test_and_clear_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1678	INIT_LIST_HEAD(list);
1679	spin_lock(dwlk);
1680	list_for_each_entry_safe(bp, n, dwq, b_list) {
1681		ASSERT(bp->b_flags & XBF_DELWRI);
1682
1683		if (!xfs_buf_ispinned(bp) && xfs_buf_trylock(bp)) {
1684			if (!force &&
1685			    time_before(jiffies, bp->b_queuetime + age)) {
1686				xfs_buf_unlock(bp);
1687				break;
1688			}
1689
1690			bp->b_flags &= ~(XBF_DELWRI | _XBF_DELWRI_Q);
1691			bp->b_flags |= XBF_WRITE;
1692			list_move_tail(&bp->b_list, list);
1693			trace_xfs_buf_delwri_split(bp, _RET_IP_);
1694		} else
1695			skipped++;
1696	}
1697	spin_unlock(dwlk);
1698
1699	return skipped;
1700
 
1701}
1702
1703/*
1704 * Compare function is more complex than it needs to be because
1705 * the return value is only 32 bits and we are doing comparisons
1706 * on 64 bit values
1707 */
1708static int
1709xfs_buf_cmp(
1710	void		*priv,
1711	struct list_head *a,
1712	struct list_head *b)
1713{
1714	struct xfs_buf	*ap = container_of(a, struct xfs_buf, b_list);
1715	struct xfs_buf	*bp = container_of(b, struct xfs_buf, b_list);
1716	xfs_daddr_t		diff;
1717
1718	diff = ap->b_bn - bp->b_bn;
1719	if (diff < 0)
1720		return -1;
1721	if (diff > 0)
1722		return 1;
1723	return 0;
1724}
1725
1726STATIC int
1727xfsbufd(
1728	void		*data)
1729{
1730	xfs_buftarg_t   *target = (xfs_buftarg_t *)data;
1731
1732	current->flags |= PF_MEMALLOC;
1733
1734	set_freezable();
1735
1736	do {
1737		long	age = xfs_buf_age_centisecs * msecs_to_jiffies(10);
1738		long	tout = xfs_buf_timer_centisecs * msecs_to_jiffies(10);
1739		struct list_head tmp;
1740		struct blk_plug plug;
1741
1742		if (unlikely(freezing(current))) {
1743			set_bit(XBT_FORCE_SLEEP, &target->bt_flags);
1744			refrigerator();
1745		} else {
1746			clear_bit(XBT_FORCE_SLEEP, &target->bt_flags);
 
 
 
 
 
 
 
 
 
 
 
 
1747		}
1748
1749		/* sleep for a long time if there is nothing to do. */
1750		if (list_empty(&target->bt_delwrite_queue))
1751			tout = MAX_SCHEDULE_TIMEOUT;
1752		schedule_timeout_interruptible(tout);
1753
1754		xfs_buf_delwri_split(target, &tmp, age);
1755		list_sort(NULL, &tmp, xfs_buf_cmp);
1756
1757		blk_start_plug(&plug);
1758		while (!list_empty(&tmp)) {
1759			struct xfs_buf *bp;
1760			bp = list_first_entry(&tmp, struct xfs_buf, b_list);
 
 
 
 
 
 
 
 
 
1761			list_del_init(&bp->b_list);
1762			xfs_bdstrat_cb(bp);
1763		}
1764		blk_finish_plug(&plug);
1765	} while (!kthread_should_stop());
1766
1767	return 0;
 
 
 
 
1768}
1769
1770/*
1771 *	Go through all incore buffers, and release buffers if they belong to
1772 *	the given device. This is used in filesystem error handling to
1773 *	preserve the consistency of its metadata.
 
 
 
 
1774 */
1775int
1776xfs_flush_buftarg(
1777	xfs_buftarg_t	*target,
1778	int		wait)
1779{
1780	xfs_buf_t	*bp;
1781	int		pincount = 0;
1782	LIST_HEAD(tmp_list);
1783	LIST_HEAD(wait_list);
1784	struct blk_plug plug;
1785
1786	xfs_buf_runall_queues(xfsconvertd_workqueue);
1787	xfs_buf_runall_queues(xfsdatad_workqueue);
1788	xfs_buf_runall_queues(xfslogd_workqueue);
 
 
 
 
 
 
 
 
 
 
 
 
1789
1790	set_bit(XBT_FORCE_FLUSH, &target->bt_flags);
1791	pincount = xfs_buf_delwri_split(target, &tmp_list, 0);
1792
1793	/*
1794	 * Dropped the delayed write list lock, now walk the temporary list.
1795	 * All I/O is issued async and then if we need to wait for completion
1796	 * we do that after issuing all the IO.
1797	 */
1798	list_sort(NULL, &tmp_list, xfs_buf_cmp);
1799
1800	blk_start_plug(&plug);
1801	while (!list_empty(&tmp_list)) {
1802		bp = list_first_entry(&tmp_list, struct xfs_buf, b_list);
1803		ASSERT(target == bp->b_target);
1804		list_del_init(&bp->b_list);
1805		if (wait) {
1806			bp->b_flags &= ~XBF_ASYNC;
1807			list_add(&bp->b_list, &wait_list);
1808		}
1809		xfs_bdstrat_cb(bp);
1810	}
1811	blk_finish_plug(&plug);
1812
1813	if (wait) {
1814		/* Wait for IO to complete. */
1815		while (!list_empty(&wait_list)) {
1816			bp = list_first_entry(&wait_list, struct xfs_buf, b_list);
1817
1818			list_del_init(&bp->b_list);
1819			xfs_buf_iowait(bp);
1820			xfs_buf_relse(bp);
1821		}
1822	}
1823
1824	return pincount;
1825}
1826
1827int __init
1828xfs_buf_init(void)
1829{
1830	xfs_buf_zone = kmem_zone_init_flags(sizeof(xfs_buf_t), "xfs_buf",
1831						KM_ZONE_HWALIGN, NULL);
1832	if (!xfs_buf_zone)
1833		goto out;
1834
1835	xfslogd_workqueue = alloc_workqueue("xfslogd",
1836					WQ_MEM_RECLAIM | WQ_HIGHPRI, 1);
1837	if (!xfslogd_workqueue)
1838		goto out_free_buf_zone;
1839
1840	xfsdatad_workqueue = alloc_workqueue("xfsdatad", WQ_MEM_RECLAIM, 1);
1841	if (!xfsdatad_workqueue)
1842		goto out_destroy_xfslogd_workqueue;
1843
1844	xfsconvertd_workqueue = alloc_workqueue("xfsconvertd",
1845						WQ_MEM_RECLAIM, 1);
1846	if (!xfsconvertd_workqueue)
1847		goto out_destroy_xfsdatad_workqueue;
1848
1849	return 0;
1850
1851 out_destroy_xfsdatad_workqueue:
1852	destroy_workqueue(xfsdatad_workqueue);
1853 out_destroy_xfslogd_workqueue:
1854	destroy_workqueue(xfslogd_workqueue);
1855 out_free_buf_zone:
1856	kmem_zone_destroy(xfs_buf_zone);
1857 out:
1858	return -ENOMEM;
1859}
1860
1861void
1862xfs_buf_terminate(void)
1863{
1864	destroy_workqueue(xfsconvertd_workqueue);
1865	destroy_workqueue(xfsdatad_workqueue);
1866	destroy_workqueue(xfslogd_workqueue);
1867	kmem_zone_destroy(xfs_buf_zone);
1868}
1869
1870#ifdef CONFIG_KDB_MODULES
1871struct list_head *
1872xfs_get_buftarg_list(void)
1873{
1874	return &xfs_buftarg_list;
1875}
1876#endif