1/*
   2 * linux/fs/nfs/pagelist.c
   3 *
   4 * A set of helper functions for managing NFS read and write requests.
   5 * The main purpose of these routines is to provide support for the
   6 * coalescing of several requests into a single RPC call.
   7 *
   8 * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
   9 *
  10 */
  11
  12#include <linux/slab.h>
  13#include <linux/file.h>
  14#include <linux/sched.h>
  15#include <linux/sunrpc/clnt.h>
  16#include <linux/nfs.h>
  17#include <linux/nfs3.h>
  18#include <linux/nfs4.h>
  19#include <linux/nfs_page.h>
  20#include <linux/nfs_fs.h>
  21#include <linux/nfs_mount.h>
  22#include <linux/export.h>
  23
  24#include "internal.h"
  25#include "pnfs.h"
  26
  27#define NFSDBG_FACILITY		NFSDBG_PAGECACHE
  28
  29static struct kmem_cache *nfs_page_cachep;
  30static const struct rpc_call_ops nfs_pgio_common_ops;
  31
  32static bool nfs_pgarray_set(struct nfs_page_array *p, unsigned int pagecount)
  33{
  34	p->npages = pagecount;
  35	if (pagecount <= ARRAY_SIZE(p->page_array))
  36		p->pagevec = p->page_array;
  37	else {
  38		p->pagevec = kcalloc(pagecount, sizeof(struct page *), GFP_KERNEL);
  39		if (!p->pagevec)
  40			p->npages = 0;
  41	}
  42	return p->pagevec != NULL;
  43}
  44
  45struct nfs_pgio_mirror *
  46nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
  47{
  48	return nfs_pgio_has_mirroring(desc) ?
  49		&desc->pg_mirrors[desc->pg_mirror_idx] :
  50		&desc->pg_mirrors[0];
  51}
  52EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
  53
  54void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
  55		       struct nfs_pgio_header *hdr,
  56		       void (*release)(struct nfs_pgio_header *hdr))
  57{
  58	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
  59
  60
  61	hdr->req = nfs_list_entry(mirror->pg_list.next);
  62	hdr->inode = desc->pg_inode;
  63	hdr->cred = hdr->req->wb_context->cred;
  64	hdr->io_start = req_offset(hdr->req);
  65	hdr->good_bytes = mirror->pg_count;
  66	hdr->dreq = desc->pg_dreq;
  67	hdr->layout_private = desc->pg_layout_private;
  68	hdr->release = release;
  69	hdr->completion_ops = desc->pg_completion_ops;
  70	if (hdr->completion_ops->init_hdr)
  71		hdr->completion_ops->init_hdr(hdr);
  72
  73	hdr->pgio_mirror_idx = desc->pg_mirror_idx;
  74}
  75EXPORT_SYMBOL_GPL(nfs_pgheader_init);
  76
  77void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
  78{
  79	spin_lock(&hdr->lock);
  80	if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags)
  81	    || pos < hdr->io_start + hdr->good_bytes) {
  82		clear_bit(NFS_IOHDR_EOF, &hdr->flags);
  83		hdr->good_bytes = pos - hdr->io_start;
  84		hdr->error = error;
  85	}
  86	spin_unlock(&hdr->lock);
  87}
  88
  89static inline struct nfs_page *
  90nfs_page_alloc(void)
  91{
  92	struct nfs_page	*p = kmem_cache_zalloc(nfs_page_cachep, GFP_NOIO);
  93	if (p)
  94		INIT_LIST_HEAD(&p->wb_list);
  95	return p;
  96}
  97
  98static inline void
  99nfs_page_free(struct nfs_page *p)
 100{
 101	kmem_cache_free(nfs_page_cachep, p);
 102}
 103
 104/**
 105 * nfs_iocounter_wait - wait for i/o to complete
 106 * @l_ctx: nfs_lock_context with io_counter to use
 107 *
 108 * returns -ERESTARTSYS if interrupted by a fatal signal.
 109 * Otherwise returns 0 once the io_count hits 0.
 110 */
 111int
 112nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
 113{
 114	return wait_on_atomic_t(&l_ctx->io_count, nfs_wait_atomic_killable,
 115			TASK_KILLABLE);
 116}
 117
 118/*
 119 * nfs_page_group_lock - lock the head of the page group
 120 * @req - request in group that is to be locked
 121 * @nonblock - if true don't block waiting for lock
 122 *
 123 * this lock must be held if modifying the page group list
 124 *
 125 * return 0 on success, < 0 on error: -EDELAY if nonblocking or the
 126 * result from wait_on_bit_lock
 127 *
 128 * NOTE: calling with nonblock=false should always have set the
 129 *       lock bit (see fs/buffer.c and other uses of wait_on_bit_lock
 130 *       with TASK_UNINTERRUPTIBLE), so there is no need to check the result.
 131 */
 132int
 133nfs_page_group_lock(struct nfs_page *req, bool nonblock)
 134{
 135	struct nfs_page *head = req->wb_head;
 136
 137	WARN_ON_ONCE(head != head->wb_head);
 138
 139	if (!test_and_set_bit(PG_HEADLOCK, &head->wb_flags))
 140		return 0;
 141
 142	if (!nonblock)
 143		return wait_on_bit_lock(&head->wb_flags, PG_HEADLOCK,
 144				TASK_UNINTERRUPTIBLE);
 145
 146	return -EAGAIN;
 147}
 148
 149/*
 150 * nfs_page_group_lock_wait - wait for the lock to clear, but don't grab it
 151 * @req - a request in the group
 152 *
 153 * This is a blocking call to wait for the group lock to be cleared.
 154 */
 155void
 156nfs_page_group_lock_wait(struct nfs_page *req)
 157{
 158	struct nfs_page *head = req->wb_head;
 159
 160	WARN_ON_ONCE(head != head->wb_head);
 161
 162	wait_on_bit(&head->wb_flags, PG_HEADLOCK,
 163		TASK_UNINTERRUPTIBLE);
 164}
 165
 166/*
 167 * nfs_page_group_unlock - unlock the head of the page group
 168 * @req - request in group that is to be unlocked
 169 */
 170void
 171nfs_page_group_unlock(struct nfs_page *req)
 172{
 173	struct nfs_page *head = req->wb_head;
 174
 175	WARN_ON_ONCE(head != head->wb_head);
 176
 177	smp_mb__before_atomic();
 178	clear_bit(PG_HEADLOCK, &head->wb_flags);
 179	smp_mb__after_atomic();
 180	wake_up_bit(&head->wb_flags, PG_HEADLOCK);
 181}
 182
 183/*
 184 * nfs_page_group_sync_on_bit_locked
 185 *
 186 * must be called with page group lock held
 187 */
 188static bool
 189nfs_page_group_sync_on_bit_locked(struct nfs_page *req, unsigned int bit)
 190{
 191	struct nfs_page *head = req->wb_head;
 192	struct nfs_page *tmp;
 193
 194	WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &head->wb_flags));
 195	WARN_ON_ONCE(test_and_set_bit(bit, &req->wb_flags));
 196
 197	tmp = req->wb_this_page;
 198	while (tmp != req) {
 199		if (!test_bit(bit, &tmp->wb_flags))
 200			return false;
 201		tmp = tmp->wb_this_page;
 202	}
 203
 204	/* true! reset all bits */
 205	tmp = req;
 206	do {
 207		clear_bit(bit, &tmp->wb_flags);
 208		tmp = tmp->wb_this_page;
 209	} while (tmp != req);
 210
 211	return true;
 212}
 213
 214/*
 215 * nfs_page_group_sync_on_bit - set bit on current request, but only
 216 *   return true if the bit is set for all requests in page group
 217 * @req - request in page group
 218 * @bit - PG_* bit that is used to sync page group
 219 */
 220bool nfs_page_group_sync_on_bit(struct nfs_page *req, unsigned int bit)
 221{
 222	bool ret;
 223
 224	nfs_page_group_lock(req, false);
 225	ret = nfs_page_group_sync_on_bit_locked(req, bit);
 226	nfs_page_group_unlock(req);
 227
 
 
 
 
 
 
 
 
 228	return ret;
 229}
 230
 231/*
 232 * nfs_page_group_init - Initialize the page group linkage for @req
 233 * @req - a new nfs request
 234 * @prev - the previous request in page group, or NULL if @req is the first
 235 *         or only request in the group (the head).
 236 */
 237static inline void
 238nfs_page_group_init(struct nfs_page *req, struct nfs_page *prev)
 239{
 240	struct inode *inode;
 241	WARN_ON_ONCE(prev == req);
 242
 243	if (!prev) {
 244		/* a head request */
 245		req->wb_head = req;
 246		req->wb_this_page = req;
 247	} else {
 248		/* a subrequest */
 249		WARN_ON_ONCE(prev->wb_this_page != prev->wb_head);
 250		WARN_ON_ONCE(!test_bit(PG_HEADLOCK, &prev->wb_head->wb_flags));
 251		req->wb_head = prev->wb_head;
 252		req->wb_this_page = prev->wb_this_page;
 253		prev->wb_this_page = req;
 254
 255		/* All subrequests take a ref on the head request until
 256		 * nfs_page_group_destroy is called */
 257		kref_get(&req->wb_head->wb_kref);
 258
 259		/* grab extra ref and bump the request count if head request
 260		 * has extra ref from the write/commit path to handle handoff
 261		 * between write and commit lists. */
 262		if (test_bit(PG_INODE_REF, &prev->wb_head->wb_flags)) {
 263			inode = page_file_mapping(req->wb_page)->host;
 264			set_bit(PG_INODE_REF, &req->wb_flags);
 265			kref_get(&req->wb_kref);
 266			spin_lock(&inode->i_lock);
 267			NFS_I(inode)->nrequests++;
 268			spin_unlock(&inode->i_lock);
 269		}
 270	}
 271}
 272
 273/*
 274 * nfs_page_group_destroy - sync the destruction of page groups
 275 * @req - request that no longer needs the page group
 276 *
 277 * releases the page group reference from each member once all
 278 * members have called this function.
 279 */
 280static void
 281nfs_page_group_destroy(struct kref *kref)
 282{
 283	struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
 284	struct nfs_page *tmp, *next;
 285
 286	/* subrequests must release the ref on the head request */
 287	if (req->wb_head != req)
 288		nfs_release_request(req->wb_head);
 289
 290	if (!nfs_page_group_sync_on_bit(req, PG_TEARDOWN))
 291		return;
 292
 293	tmp = req;
 294	do {
 295		next = tmp->wb_this_page;
 296		/* unlink and free */
 297		tmp->wb_this_page = tmp;
 298		tmp->wb_head = tmp;
 299		nfs_free_request(tmp);
 300		tmp = next;
 301	} while (tmp != req);
 302}
 303
 304/**
 305 * nfs_create_request - Create an NFS read/write request.
 306 * @ctx: open context to use
 
 307 * @page: page to write
 308 * @last: last nfs request created for this page group or NULL if head
 309 * @offset: starting offset within the page for the write
 310 * @count: number of bytes to read/write
 311 *
 312 * The page must be locked by the caller. This makes sure we never
 313 * create two different requests for the same page.
 314 * User should ensure it is safe to sleep in this function.
 315 */
 316struct nfs_page *
 317nfs_create_request(struct nfs_open_context *ctx, struct page *page,
 318		   struct nfs_page *last, unsigned int offset,
 319		   unsigned int count)
 320{
 321	struct nfs_page		*req;
 322	struct nfs_lock_context *l_ctx;
 323
 324	if (test_bit(NFS_CONTEXT_BAD, &ctx->flags))
 325		return ERR_PTR(-EBADF);
 326	/* try to allocate the request struct */
 327	req = nfs_page_alloc();
 328	if (req == NULL)
 329		return ERR_PTR(-ENOMEM);
 330
 331	/* get lock context early so we can deal with alloc failures */
 332	l_ctx = nfs_get_lock_context(ctx);
 333	if (IS_ERR(l_ctx)) {
 334		nfs_page_free(req);
 335		return ERR_CAST(l_ctx);
 336	}
 337	req->wb_lock_context = l_ctx;
 338	atomic_inc(&l_ctx->io_count);
 339
 340	/* Initialize the request struct. Initially, we assume a
 341	 * long write-back delay. This will be adjusted in
 342	 * update_nfs_request below if the region is not locked. */
 343	req->wb_page    = page;
 344	if (page) {
 345		req->wb_index = page_index(page);
 346		get_page(page);
 347	}
 348	req->wb_offset  = offset;
 349	req->wb_pgbase	= offset;
 350	req->wb_bytes   = count;
 351	req->wb_context = get_nfs_open_context(ctx);
 352	kref_init(&req->wb_kref);
 353	nfs_page_group_init(req, last);
 354	return req;
 355}
 356
 357/**
 358 * nfs_unlock_request - Unlock request and wake up sleepers.
 359 * @req:
 360 */
 361void nfs_unlock_request(struct nfs_page *req)
 362{
 363	if (!NFS_WBACK_BUSY(req)) {
 364		printk(KERN_ERR "NFS: Invalid unlock attempted\n");
 365		BUG();
 366	}
 367	smp_mb__before_atomic();
 368	clear_bit(PG_BUSY, &req->wb_flags);
 369	smp_mb__after_atomic();
 370	wake_up_bit(&req->wb_flags, PG_BUSY);
 371}
 372
 373/**
 374 * nfs_unlock_and_release_request - Unlock request and release the nfs_page
 375 * @req:
 376 */
 377void nfs_unlock_and_release_request(struct nfs_page *req)
 378{
 379	nfs_unlock_request(req);
 380	nfs_release_request(req);
 381}
 382
 383/*
 384 * nfs_clear_request - Free up all resources allocated to the request
 385 * @req:
 386 *
 387 * Release page and open context resources associated with a read/write
 388 * request after it has completed.
 389 */
 390static void nfs_clear_request(struct nfs_page *req)
 391{
 392	struct page *page = req->wb_page;
 393	struct nfs_open_context *ctx = req->wb_context;
 394	struct nfs_lock_context *l_ctx = req->wb_lock_context;
 395
 396	if (page != NULL) {
 397		put_page(page);
 398		req->wb_page = NULL;
 399	}
 400	if (l_ctx != NULL) {
 401		if (atomic_dec_and_test(&l_ctx->io_count))
 402			wake_up_atomic_t(&l_ctx->io_count);
 403		nfs_put_lock_context(l_ctx);
 404		req->wb_lock_context = NULL;
 405	}
 406	if (ctx != NULL) {
 407		put_nfs_open_context(ctx);
 408		req->wb_context = NULL;
 409	}
 410}
 411
 
 412/**
 413 * nfs_release_request - Release the count on an NFS read/write request
 414 * @req: request to release
 415 *
 416 * Note: Should never be called with the spinlock held!
 417 */
 418void nfs_free_request(struct nfs_page *req)
 419{
 420	WARN_ON_ONCE(req->wb_this_page != req);
 421
 422	/* extra debug: make sure no sync bits are still set */
 423	WARN_ON_ONCE(test_bit(PG_TEARDOWN, &req->wb_flags));
 424	WARN_ON_ONCE(test_bit(PG_UNLOCKPAGE, &req->wb_flags));
 425	WARN_ON_ONCE(test_bit(PG_UPTODATE, &req->wb_flags));
 426	WARN_ON_ONCE(test_bit(PG_WB_END, &req->wb_flags));
 427	WARN_ON_ONCE(test_bit(PG_REMOVE, &req->wb_flags));
 428
 429	/* Release struct file and open context */
 430	nfs_clear_request(req);
 431	nfs_page_free(req);
 432}
 433
 434void nfs_release_request(struct nfs_page *req)
 435{
 436	kref_put(&req->wb_kref, nfs_page_group_destroy);
 
 
 
 
 
 
 437}
 438
 439/**
 440 * nfs_wait_on_request - Wait for a request to complete.
 441 * @req: request to wait upon.
 442 *
 443 * Interruptible by fatal signals only.
 444 * The user is responsible for holding a count on the request.
 445 */
 446int
 447nfs_wait_on_request(struct nfs_page *req)
 448{
 449	return wait_on_bit_io(&req->wb_flags, PG_BUSY,
 450			      TASK_UNINTERRUPTIBLE);
 
 451}
 452
 453/*
 454 * nfs_generic_pg_test - determine if requests can be coalesced
 455 * @desc: pointer to descriptor
 456 * @prev: previous request in desc, or NULL
 457 * @req: this request
 458 *
 459 * Returns zero if @req can be coalesced into @desc, otherwise it returns
 460 * the size of the request.
 461 */
 462size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
 463			   struct nfs_page *prev, struct nfs_page *req)
 464{
 465	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 466
 467
 468	if (mirror->pg_count > mirror->pg_bsize) {
 469		/* should never happen */
 470		WARN_ON_ONCE(1);
 471		return 0;
 472	}
 473
 474	/*
 475	 * Limit the request size so that we can still allocate a page array
 476	 * for it without upsetting the slab allocator.
 
 
 
 477	 */
 478	if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
 479			sizeof(struct page *) > PAGE_SIZE)
 480		return 0;
 481
 482	return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 483}
 484EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 485
 486struct nfs_pgio_header *nfs_pgio_header_alloc(const struct nfs_rw_ops *ops)
 487{
 488	struct nfs_pgio_header *hdr = ops->rw_alloc_header();
 489
 490	if (hdr) {
 491		INIT_LIST_HEAD(&hdr->pages);
 492		spin_lock_init(&hdr->lock);
 493		hdr->rw_ops = ops;
 494	}
 495	return hdr;
 496}
 497EXPORT_SYMBOL_GPL(nfs_pgio_header_alloc);
 498
 499/*
 500 * nfs_pgio_header_free - Free a read or write header
 501 * @hdr: The header to free
 502 */
 503void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
 504{
 505	hdr->rw_ops->rw_free_header(hdr);
 506}
 507EXPORT_SYMBOL_GPL(nfs_pgio_header_free);
 508
 509/**
 510 * nfs_pgio_data_destroy - make @hdr suitable for reuse
 511 *
 512 * Frees memory and releases refs from nfs_generic_pgio, so that it may
 513 * be called again.
 514 *
 515 * @hdr: A header that has had nfs_generic_pgio called
 516 */
 517void nfs_pgio_data_destroy(struct nfs_pgio_header *hdr)
 518{
 519	if (hdr->args.context)
 520		put_nfs_open_context(hdr->args.context);
 521	if (hdr->page_array.pagevec != hdr->page_array.page_array)
 522		kfree(hdr->page_array.pagevec);
 523}
 524EXPORT_SYMBOL_GPL(nfs_pgio_data_destroy);
 525
 526/**
 527 * nfs_pgio_rpcsetup - Set up arguments for a pageio call
 528 * @hdr: The pageio hdr
 529 * @count: Number of bytes to read
 530 * @offset: Initial offset
 531 * @how: How to commit data (writes only)
 532 * @cinfo: Commit information for the call (writes only)
 533 */
 534static void nfs_pgio_rpcsetup(struct nfs_pgio_header *hdr,
 535			      unsigned int count, unsigned int offset,
 536			      int how, struct nfs_commit_info *cinfo)
 537{
 538	struct nfs_page *req = hdr->req;
 539
 540	/* Set up the RPC argument and reply structs
 541	 * NB: take care not to mess about with hdr->commit et al. */
 542
 543	hdr->args.fh     = NFS_FH(hdr->inode);
 544	hdr->args.offset = req_offset(req) + offset;
 545	/* pnfs_set_layoutcommit needs this */
 546	hdr->mds_offset = hdr->args.offset;
 547	hdr->args.pgbase = req->wb_pgbase + offset;
 548	hdr->args.pages  = hdr->page_array.pagevec;
 549	hdr->args.count  = count;
 550	hdr->args.context = get_nfs_open_context(req->wb_context);
 551	hdr->args.lock_context = req->wb_lock_context;
 552	hdr->args.stable  = NFS_UNSTABLE;
 553	switch (how & (FLUSH_STABLE | FLUSH_COND_STABLE)) {
 554	case 0:
 555		break;
 556	case FLUSH_COND_STABLE:
 557		if (nfs_reqs_to_commit(cinfo))
 558			break;
 559	default:
 560		hdr->args.stable = NFS_FILE_SYNC;
 561	}
 562
 563	hdr->res.fattr   = &hdr->fattr;
 564	hdr->res.count   = count;
 565	hdr->res.eof     = 0;
 566	hdr->res.verf    = &hdr->verf;
 567	nfs_fattr_init(&hdr->fattr);
 568}
 569
 570/**
 571 * nfs_pgio_prepare - Prepare pageio hdr to go over the wire
 572 * @task: The current task
 573 * @calldata: pageio header to prepare
 574 */
 575static void nfs_pgio_prepare(struct rpc_task *task, void *calldata)
 576{
 577	struct nfs_pgio_header *hdr = calldata;
 578	int err;
 579	err = NFS_PROTO(hdr->inode)->pgio_rpc_prepare(task, hdr);
 580	if (err)
 581		rpc_exit(task, err);
 582}
 583
 584int nfs_initiate_pgio(struct rpc_clnt *clnt, struct nfs_pgio_header *hdr,
 585		      struct rpc_cred *cred, const struct nfs_rpc_ops *rpc_ops,
 586		      const struct rpc_call_ops *call_ops, int how, int flags)
 587{
 588	struct rpc_task *task;
 589	struct rpc_message msg = {
 590		.rpc_argp = &hdr->args,
 591		.rpc_resp = &hdr->res,
 592		.rpc_cred = cred,
 593	};
 594	struct rpc_task_setup task_setup_data = {
 595		.rpc_client = clnt,
 596		.task = &hdr->task,
 597		.rpc_message = &msg,
 598		.callback_ops = call_ops,
 599		.callback_data = hdr,
 600		.workqueue = nfsiod_workqueue,
 601		.flags = RPC_TASK_ASYNC | flags,
 602	};
 603	int ret = 0;
 604
 605	hdr->rw_ops->rw_initiate(hdr, &msg, rpc_ops, &task_setup_data, how);
 606
 607	dprintk("NFS: initiated pgio call "
 608		"(req %s/%llu, %u bytes @ offset %llu)\n",
 609		hdr->inode->i_sb->s_id,
 610		(unsigned long long)NFS_FILEID(hdr->inode),
 611		hdr->args.count,
 612		(unsigned long long)hdr->args.offset);
 613
 614	task = rpc_run_task(&task_setup_data);
 615	if (IS_ERR(task)) {
 616		ret = PTR_ERR(task);
 617		goto out;
 618	}
 619	if (how & FLUSH_SYNC) {
 620		ret = rpc_wait_for_completion_task(task);
 621		if (ret == 0)
 622			ret = task->tk_status;
 623	}
 624	rpc_put_task(task);
 625out:
 626	return ret;
 627}
 628EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 629
 630/**
 631 * nfs_pgio_error - Clean up from a pageio error
 632 * @desc: IO descriptor
 633 * @hdr: pageio header
 634 */
 635static void nfs_pgio_error(struct nfs_pgio_header *hdr)
 636{
 637	set_bit(NFS_IOHDR_REDO, &hdr->flags);
 638	nfs_pgio_data_destroy(hdr);
 639	hdr->completion_ops->completion(hdr);
 640}
 641
 642/**
 643 * nfs_pgio_release - Release pageio data
 644 * @calldata: The pageio header to release
 645 */
 646static void nfs_pgio_release(void *calldata)
 647{
 648	struct nfs_pgio_header *hdr = calldata;
 649	nfs_pgio_data_destroy(hdr);
 650	hdr->completion_ops->completion(hdr);
 651}
 652
 653static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
 654				   unsigned int bsize)
 655{
 656	INIT_LIST_HEAD(&mirror->pg_list);
 657	mirror->pg_bytes_written = 0;
 658	mirror->pg_count = 0;
 659	mirror->pg_bsize = bsize;
 660	mirror->pg_base = 0;
 661	mirror->pg_recoalesce = 0;
 662}
 663
 664/**
 665 * nfs_pageio_init - initialise a page io descriptor
 666 * @desc: pointer to descriptor
 667 * @inode: pointer to inode
 668 * @pg_ops: pointer to pageio operations
 669 * @compl_ops: pointer to pageio completion operations
 670 * @rw_ops: pointer to nfs read/write operations
 671 * @bsize: io block size
 672 * @io_flags: extra parameters for the io function
 673 */
 674void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
 675		     struct inode *inode,
 676		     const struct nfs_pageio_ops *pg_ops,
 677		     const struct nfs_pgio_completion_ops *compl_ops,
 678		     const struct nfs_rw_ops *rw_ops,
 679		     size_t bsize,
 680		     int io_flags)
 681{
 682	struct nfs_pgio_mirror *new;
 683	int i;
 684
 
 
 685	desc->pg_moreio = 0;
 
 686	desc->pg_inode = inode;
 687	desc->pg_ops = pg_ops;
 688	desc->pg_completion_ops = compl_ops;
 689	desc->pg_rw_ops = rw_ops;
 690	desc->pg_ioflags = io_flags;
 691	desc->pg_error = 0;
 692	desc->pg_lseg = NULL;
 693	desc->pg_dreq = NULL;
 694	desc->pg_layout_private = NULL;
 695	desc->pg_bsize = bsize;
 696
 697	desc->pg_mirror_count = 1;
 698	desc->pg_mirror_idx = 0;
 699
 700	if (pg_ops->pg_get_mirror_count) {
 701		/* until we have a request, we don't have an lseg and no
 702		 * idea how many mirrors there will be */
 703		new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
 704			      sizeof(struct nfs_pgio_mirror), GFP_KERNEL);
 705		desc->pg_mirrors_dynamic = new;
 706		desc->pg_mirrors = new;
 707
 708		for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
 709			nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
 710	} else {
 711		desc->pg_mirrors_dynamic = NULL;
 712		desc->pg_mirrors = desc->pg_mirrors_static;
 713		nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
 714	}
 715}
 716EXPORT_SYMBOL_GPL(nfs_pageio_init);
 717
 718/**
 719 * nfs_pgio_result - Basic pageio error handling
 720 * @task: The task that ran
 721 * @calldata: Pageio header to check
 722 */
 723static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 724{
 725	struct nfs_pgio_header *hdr = calldata;
 726	struct inode *inode = hdr->inode;
 727
 728	dprintk("NFS: %s: %5u, (status %d)\n", __func__,
 729		task->tk_pid, task->tk_status);
 730
 731	if (hdr->rw_ops->rw_done(task, hdr, inode) != 0)
 732		return;
 733	if (task->tk_status < 0)
 734		nfs_set_pgio_error(hdr, task->tk_status, hdr->args.offset);
 735	else
 736		hdr->rw_ops->rw_result(task, hdr);
 737}
 738
 739/*
 740 * Create an RPC task for the given read or write request and kick it.
 741 * The page must have been locked by the caller.
 742 *
 743 * It may happen that the page we're passed is not marked dirty.
 744 * This is the case if nfs_updatepage detects a conflicting request
 745 * that has been written but not committed.
 746 */
 747int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
 748		     struct nfs_pgio_header *hdr)
 749{
 750	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 751
 752	struct nfs_page		*req;
 753	struct page		**pages,
 754				*last_page;
 755	struct list_head *head = &mirror->pg_list;
 756	struct nfs_commit_info cinfo;
 757	unsigned int pagecount, pageused;
 758
 759	pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
 760	if (!nfs_pgarray_set(&hdr->page_array, pagecount)) {
 761		nfs_pgio_error(hdr);
 762		desc->pg_error = -ENOMEM;
 763		return desc->pg_error;
 764	}
 765
 766	nfs_init_cinfo(&cinfo, desc->pg_inode, desc->pg_dreq);
 767	pages = hdr->page_array.pagevec;
 768	last_page = NULL;
 769	pageused = 0;
 770	while (!list_empty(head)) {
 771		req = nfs_list_entry(head->next);
 772		nfs_list_remove_request(req);
 773		nfs_list_add_request(req, &hdr->pages);
 774
 775		if (!last_page || last_page != req->wb_page) {
 776			pageused++;
 777			if (pageused > pagecount)
 778				break;
 779			*pages++ = last_page = req->wb_page;
 780		}
 781	}
 782	if (WARN_ON_ONCE(pageused != pagecount)) {
 783		nfs_pgio_error(hdr);
 784		desc->pg_error = -EINVAL;
 785		return desc->pg_error;
 786	}
 787
 788	if ((desc->pg_ioflags & FLUSH_COND_STABLE) &&
 789	    (desc->pg_moreio || nfs_reqs_to_commit(&cinfo)))
 790		desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 791
 792	/* Set up the argument struct */
 793	nfs_pgio_rpcsetup(hdr, mirror->pg_count, 0, desc->pg_ioflags, &cinfo);
 794	desc->pg_rpc_callops = &nfs_pgio_common_ops;
 795	return 0;
 796}
 797EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 798
 799static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 800{
 801	struct nfs_pgio_header *hdr;
 802	int ret;
 803
 804	hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
 805	if (!hdr) {
 806		desc->pg_error = -ENOMEM;
 807		return desc->pg_error;
 808	}
 809	nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
 810	ret = nfs_generic_pgio(desc, hdr);
 811	if (ret == 0)
 812		ret = nfs_initiate_pgio(NFS_CLIENT(hdr->inode),
 813					hdr,
 814					hdr->cred,
 815					NFS_PROTO(hdr->inode),
 816					desc->pg_rpc_callops,
 817					desc->pg_ioflags, 0);
 818	return ret;
 819}
 820
 821/*
 822 * nfs_pageio_setup_mirroring - determine if mirroring is to be used
 823 *				by calling the pg_get_mirror_count op
 824 */
 825static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
 826				       struct nfs_page *req)
 827{
 828	int mirror_count = 1;
 829
 830	if (!pgio->pg_ops->pg_get_mirror_count)
 831		return 0;
 832
 833	mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
 834
 835	if (pgio->pg_error < 0)
 836		return pgio->pg_error;
 837
 838	if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
 839		return -EINVAL;
 840
 841	if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
 842		return -EINVAL;
 843
 844	pgio->pg_mirror_count = mirror_count;
 845
 846	return 0;
 847}
 848
 849/*
 850 * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
 851 */
 852void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
 853{
 854	pgio->pg_mirror_count = 1;
 855	pgio->pg_mirror_idx = 0;
 856}
 857
 858static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
 859{
 860	pgio->pg_mirror_count = 1;
 861	pgio->pg_mirror_idx = 0;
 862	pgio->pg_mirrors = pgio->pg_mirrors_static;
 863	kfree(pgio->pg_mirrors_dynamic);
 864	pgio->pg_mirrors_dynamic = NULL;
 865}
 866
 867static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
 868		const struct nfs_lock_context *l2)
 869{
 870	return l1->lockowner == l2->lockowner;
 
 871}
 872
 873/**
 874 * nfs_can_coalesce_requests - test two requests for compatibility
 875 * @prev: pointer to nfs_page
 876 * @req: pointer to nfs_page
 877 *
 878 * The nfs_page structures 'prev' and 'req' are compared to ensure that the
 879 * page data area they describe is contiguous, and that their RPC
 880 * credentials, NFSv4 open state, and lockowners are the same.
 881 *
 882 * Return 'true' if this is the case, else return 'false'.
 883 */
 884static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 885				      struct nfs_page *req,
 886				      struct nfs_pageio_descriptor *pgio)
 887{
 888	size_t size;
 889	struct file_lock_context *flctx;
 890
 891	if (prev) {
 892		if (!nfs_match_open_context(req->wb_context, prev->wb_context))
 893			return false;
 894		flctx = d_inode(req->wb_context->dentry)->i_flctx;
 895		if (flctx != NULL &&
 896		    !(list_empty_careful(&flctx->flc_posix) &&
 897		      list_empty_careful(&flctx->flc_flock)) &&
 898		    !nfs_match_lock_context(req->wb_lock_context,
 899					    prev->wb_lock_context))
 900			return false;
 901		if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
 902			return false;
 903		if (req->wb_page == prev->wb_page) {
 904			if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
 905				return false;
 906		} else {
 907			if (req->wb_pgbase != 0 ||
 908			    prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
 909				return false;
 910		}
 911	}
 912	size = pgio->pg_ops->pg_test(pgio, prev, req);
 913	WARN_ON_ONCE(size > req->wb_bytes);
 914	if (size && size < req->wb_bytes)
 915		req->wb_bytes = size;
 916	return size > 0;
 917}
 918
 919/**
 920 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
 921 * @desc: destination io descriptor
 922 * @req: request
 923 *
 924 * Returns true if the request 'req' was successfully coalesced into the
 925 * existing list of pages 'desc'.
 926 */
 927static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
 928				     struct nfs_page *req)
 929{
 930	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 931
 932	struct nfs_page *prev = NULL;
 933
 934	if (mirror->pg_count != 0) {
 935		prev = nfs_list_entry(mirror->pg_list.prev);
 
 936	} else {
 937		if (desc->pg_ops->pg_init)
 938			desc->pg_ops->pg_init(desc, req);
 939		if (desc->pg_error < 0)
 940			return 0;
 941		mirror->pg_base = req->wb_pgbase;
 942	}
 943	if (!nfs_can_coalesce_requests(prev, req, desc))
 944		return 0;
 945	nfs_list_remove_request(req);
 946	nfs_list_add_request(req, &mirror->pg_list);
 947	mirror->pg_count += req->wb_bytes;
 948	return 1;
 949}
 950
 951/*
 952 * Helper for nfs_pageio_add_request and nfs_pageio_complete
 953 */
 954static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 955{
 956	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 957
 958
 959	if (!list_empty(&mirror->pg_list)) {
 960		int error = desc->pg_ops->pg_doio(desc);
 961		if (error < 0)
 962			desc->pg_error = error;
 963		else
 964			mirror->pg_bytes_written += mirror->pg_count;
 965	}
 966	if (list_empty(&mirror->pg_list)) {
 967		mirror->pg_count = 0;
 968		mirror->pg_base = 0;
 969	}
 970}
 971
 972/**
 973 * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
 974 * @desc: destination io descriptor
 975 * @req: request
 976 *
 977 * This may split a request into subrequests which are all part of the
 978 * same page group.
 979 *
 980 * Returns true if the request 'req' was successfully coalesced into the
 981 * existing list of pages 'desc'.
 982 */
 983static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
 984			   struct nfs_page *req)
 985{
 986	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
 987
 988	struct nfs_page *subreq;
 989	unsigned int bytes_left = 0;
 990	unsigned int offset, pgbase;
 991
 992	nfs_page_group_lock(req, false);
 993
 994	subreq = req;
 995	bytes_left = subreq->wb_bytes;
 996	offset = subreq->wb_offset;
 997	pgbase = subreq->wb_pgbase;
 998
 999	do {
1000		if (!nfs_pageio_do_add_request(desc, subreq)) {
1001			/* make sure pg_test call(s) did nothing */
1002			WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1003			WARN_ON_ONCE(subreq->wb_offset != offset);
1004			WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1005
1006			nfs_page_group_unlock(req);
1007			desc->pg_moreio = 1;
1008			nfs_pageio_doio(desc);
1009			if (desc->pg_error < 0)
1010				return 0;
1011			if (mirror->pg_recoalesce)
1012				return 0;
1013			/* retry add_request for this subreq */
1014			nfs_page_group_lock(req, false);
1015			continue;
1016		}
1017
1018		/* check for buggy pg_test call(s) */
1019		WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1020		WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1021		WARN_ON_ONCE(subreq->wb_bytes == 0);
1022
1023		bytes_left -= subreq->wb_bytes;
1024		offset += subreq->wb_bytes;
1025		pgbase += subreq->wb_bytes;
1026
1027		if (bytes_left) {
1028			subreq = nfs_create_request(req->wb_context,
1029					req->wb_page,
1030					subreq, pgbase, bytes_left);
1031			if (IS_ERR(subreq))
1032				goto err_ptr;
1033			nfs_lock_request(subreq);
1034			subreq->wb_offset  = offset;
1035			subreq->wb_index = req->wb_index;
1036		}
1037	} while (bytes_left > 0);
1038
1039	nfs_page_group_unlock(req);
1040	return 1;
1041err_ptr:
1042	desc->pg_error = PTR_ERR(subreq);
1043	nfs_page_group_unlock(req);
1044	return 0;
1045}
1046
1047static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1048{
1049	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1050	LIST_HEAD(head);
1051
1052	do {
1053		list_splice_init(&mirror->pg_list, &head);
1054		mirror->pg_bytes_written -= mirror->pg_count;
1055		mirror->pg_count = 0;
1056		mirror->pg_base = 0;
1057		mirror->pg_recoalesce = 0;
1058
1059		while (!list_empty(&head)) {
1060			struct nfs_page *req;
1061
1062			req = list_first_entry(&head, struct nfs_page, wb_list);
1063			nfs_list_remove_request(req);
1064			if (__nfs_pageio_add_request(desc, req))
1065				continue;
1066			if (desc->pg_error < 0) {
1067				list_splice_tail(&head, &mirror->pg_list);
1068				mirror->pg_recoalesce = 1;
1069				return 0;
1070			}
1071			break;
1072		}
1073	} while (mirror->pg_recoalesce);
1074	return 1;
1075}
1076
1077static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1078		struct nfs_page *req)
1079{
1080	int ret;
1081
1082	do {
1083		ret = __nfs_pageio_add_request(desc, req);
1084		if (ret)
1085			break;
1086		if (desc->pg_error < 0)
1087			break;
1088		ret = nfs_do_recoalesce(desc);
1089	} while (ret);
1090
1091	return ret;
1092}
 
1093
1094int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1095			   struct nfs_page *req)
1096{
1097	u32 midx;
1098	unsigned int pgbase, offset, bytes;
1099	struct nfs_page *dupreq, *lastreq;
1100
1101	pgbase = req->wb_pgbase;
1102	offset = req->wb_offset;
1103	bytes = req->wb_bytes;
1104
1105	nfs_pageio_setup_mirroring(desc, req);
1106	if (desc->pg_error < 0)
1107		goto out_failed;
1108
1109	for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1110		if (midx) {
1111			nfs_page_group_lock(req, false);
1112
1113			/* find the last request */
1114			for (lastreq = req->wb_head;
1115			     lastreq->wb_this_page != req->wb_head;
1116			     lastreq = lastreq->wb_this_page)
1117				;
1118
1119			dupreq = nfs_create_request(req->wb_context,
1120					req->wb_page, lastreq, pgbase, bytes);
1121
1122			if (IS_ERR(dupreq)) {
1123				nfs_page_group_unlock(req);
1124				desc->pg_error = PTR_ERR(dupreq);
1125				goto out_failed;
1126			}
1127
1128			nfs_lock_request(dupreq);
1129			nfs_page_group_unlock(req);
1130			dupreq->wb_offset = offset;
1131			dupreq->wb_index = req->wb_index;
1132		} else
1133			dupreq = req;
1134
1135		if (nfs_pgio_has_mirroring(desc))
1136			desc->pg_mirror_idx = midx;
1137		if (!nfs_pageio_add_request_mirror(desc, dupreq))
1138			goto out_failed;
1139	}
1140
1141	return 1;
1142
1143out_failed:
1144	/*
1145	 * We might have failed before sending any reqs over wire.
1146	 * Clean up rest of the reqs in mirror pg_list.
1147	 */
1148	if (desc->pg_error) {
1149		struct nfs_pgio_mirror *mirror;
1150		void (*func)(struct list_head *);
1151
1152		/* remember fatal errors */
1153		if (nfs_error_is_fatal(desc->pg_error))
1154			mapping_set_error(desc->pg_inode->i_mapping,
1155					  desc->pg_error);
1156
1157		func = desc->pg_completion_ops->error_cleanup;
1158		for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1159			mirror = &desc->pg_mirrors[midx];
1160			func(&mirror->pg_list);
1161		}
1162	}
1163	return 0;
1164}
1165
1166/*
1167 * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1168 *				nfs_pageio_descriptor
1169 * @desc: pointer to io descriptor
1170 * @mirror_idx: pointer to mirror index
1171 */
1172static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1173				       u32 mirror_idx)
1174{
1175	struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1176	u32 restore_idx = desc->pg_mirror_idx;
1177
1178	if (nfs_pgio_has_mirroring(desc))
1179		desc->pg_mirror_idx = mirror_idx;
1180	for (;;) {
1181		nfs_pageio_doio(desc);
1182		if (!mirror->pg_recoalesce)
1183			break;
1184		if (!nfs_do_recoalesce(desc))
1185			break;
1186	}
1187	desc->pg_mirror_idx = restore_idx;
1188}
1189
1190/*
1191 * nfs_pageio_resend - Transfer requests to new descriptor and resend
1192 * @hdr - the pgio header to move request from
1193 * @desc - the pageio descriptor to add requests to
1194 *
1195 * Try to move each request (nfs_page) from @hdr to @desc then attempt
1196 * to send them.
1197 *
1198 * Returns 0 on success and < 0 on error.
1199 */
1200int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1201		      struct nfs_pgio_header *hdr)
1202{
1203	LIST_HEAD(failed);
1204
1205	desc->pg_dreq = hdr->dreq;
1206	while (!list_empty(&hdr->pages)) {
1207		struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1208
1209		nfs_list_remove_request(req);
1210		if (!nfs_pageio_add_request(desc, req))
1211			nfs_list_add_request(req, &failed);
1212	}
1213	nfs_pageio_complete(desc);
1214	if (!list_empty(&failed)) {
1215		list_move(&failed, &hdr->pages);
1216		return desc->pg_error < 0 ? desc->pg_error : -EIO;
1217	}
1218	return 0;
1219}
1220EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1221
1222/**
1223 * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1224 * @desc: pointer to io descriptor
1225 */
1226void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1227{
1228	u32 midx;
1229
1230	for (midx = 0; midx < desc->pg_mirror_count; midx++)
1231		nfs_pageio_complete_mirror(desc, midx);
1232
1233	if (desc->pg_ops->pg_cleanup)
1234		desc->pg_ops->pg_cleanup(desc);
1235	nfs_pageio_cleanup_mirroring(desc);
1236}
 
1237
1238/**
1239 * nfs_pageio_cond_complete - Conditional I/O completion
1240 * @desc: pointer to io descriptor
1241 * @index: page index
1242 *
1243 * It is important to ensure that processes don't try to take locks
1244 * on non-contiguous ranges of pages as that might deadlock. This
1245 * function should be called before attempting to wait on a locked
1246 * nfs_page. It will complete the I/O if the page index 'index'
1247 * is not contiguous with the existing list of pages in 'desc'.
1248 */
1249void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1250{
1251	struct nfs_pgio_mirror *mirror;
1252	struct nfs_page *prev;
1253	u32 midx;
1254
1255	for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1256		mirror = &desc->pg_mirrors[midx];
1257		if (!list_empty(&mirror->pg_list)) {
1258			prev = nfs_list_entry(mirror->pg_list.prev);
1259			if (index != prev->wb_index + 1)
1260				nfs_pageio_complete_mirror(desc, midx);
1261		}
1262	}
1263}
1264
1265int __init nfs_init_nfspagecache(void)
1266{
1267	nfs_page_cachep = kmem_cache_create("nfs_page",
1268					    sizeof(struct nfs_page),
1269					    0, SLAB_HWCACHE_ALIGN,
1270					    NULL);
1271	if (nfs_page_cachep == NULL)
1272		return -ENOMEM;
1273
1274	return 0;
1275}
1276
1277void nfs_destroy_nfspagecache(void)
1278{
1279	kmem_cache_destroy(nfs_page_cachep);
1280}
1281
1282static const struct rpc_call_ops nfs_pgio_common_ops = {
1283	.rpc_call_prepare = nfs_pgio_prepare,
1284	.rpc_call_done = nfs_pgio_result,
1285	.rpc_release = nfs_pgio_release,
1286};
1287
1288const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1289	.pg_test = nfs_generic_pg_test,
1290	.pg_doio = nfs_generic_pg_pgios,
1291};