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Linux/fs/nfs/pagelist.c

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  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 
 29 static struct kmem_cache *nfs_page_cachep;
 30 static const struct rpc_call_ops nfs_pgio_common_ops;
 31 
 32 static 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 
 45 struct nfs_pgio_mirror *
 46 nfs_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 }
 52 EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);
 53 
 54 void 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 }
 75 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
 76 
 77 void 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 
 89 static inline struct nfs_page *
 90 nfs_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 
 98 static inline void
 99 nfs_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  */
111 int
112 nfs_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  */
132 int
133 nfs_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  */
155 void
156 nfs_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  */
170 void
171 nfs_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  */
188 static bool
189 nfs_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  */
220 bool 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  */
237 static inline void
238 nfs_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  */
280 static void
281 nfs_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  */
316 struct nfs_page *
317 nfs_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_file_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  */
361 void 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  */
377 void 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  */
390 static 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  */
418 void 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 
434 void 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  */
446 int
447 nfs_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  */
462 size_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 }
484 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
485 
486 struct 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 }
497 EXPORT_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  */
503 void nfs_pgio_header_free(struct nfs_pgio_header *hdr)
504 {
505         hdr->rw_ops->rw_free_header(hdr);
506 }
507 EXPORT_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  */
517 void 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 }
524 EXPORT_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  */
534 static 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  */
575 static 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 
584 int 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);
625 out:
626         return ret;
627 }
628 EXPORT_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  */
635 static 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  */
646 static 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 
653 static 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  */
674 void 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 }
716 EXPORT_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  */
723 static 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  */
747 int 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 }
797 EXPORT_SYMBOL_GPL(nfs_generic_pgio);
798 
799 static 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  */
825 static 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  */
852 void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
853 {
854         pgio->pg_mirror_count = 1;
855         pgio->pg_mirror_idx = 0;
856 }
857 
858 static 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 
867 static bool nfs_match_lock_context(const struct nfs_lock_context *l1,
868                 const struct nfs_lock_context *l2)
869 {
870         return l1->lockowner.l_owner == l2->lockowner.l_owner
871                 && l1->lockowner.l_pid == l2->lockowner.l_pid;
872 }
873 
874 /**
875  * nfs_can_coalesce_requests - test two requests for compatibility
876  * @prev: pointer to nfs_page
877  * @req: pointer to nfs_page
878  *
879  * The nfs_page structures 'prev' and 'req' are compared to ensure that the
880  * page data area they describe is contiguous, and that their RPC
881  * credentials, NFSv4 open state, and lockowners are the same.
882  *
883  * Return 'true' if this is the case, else return 'false'.
884  */
885 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
886                                       struct nfs_page *req,
887                                       struct nfs_pageio_descriptor *pgio)
888 {
889         size_t size;
890         struct file_lock_context *flctx;
891 
892         if (prev) {
893                 if (!nfs_match_open_context(req->wb_context, prev->wb_context))
894                         return false;
895                 flctx = d_inode(req->wb_context->dentry)->i_flctx;
896                 if (flctx != NULL &&
897                     !(list_empty_careful(&flctx->flc_posix) &&
898                       list_empty_careful(&flctx->flc_flock)) &&
899                     !nfs_match_lock_context(req->wb_lock_context,
900                                             prev->wb_lock_context))
901                         return false;
902                 if (req_offset(req) != req_offset(prev) + prev->wb_bytes)
903                         return false;
904                 if (req->wb_page == prev->wb_page) {
905                         if (req->wb_pgbase != prev->wb_pgbase + prev->wb_bytes)
906                                 return false;
907                 } else {
908                         if (req->wb_pgbase != 0 ||
909                             prev->wb_pgbase + prev->wb_bytes != PAGE_SIZE)
910                                 return false;
911                 }
912         }
913         size = pgio->pg_ops->pg_test(pgio, prev, req);
914         WARN_ON_ONCE(size > req->wb_bytes);
915         if (size && size < req->wb_bytes)
916                 req->wb_bytes = size;
917         return size > 0;
918 }
919 
920 /**
921  * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
922  * @desc: destination io descriptor
923  * @req: request
924  *
925  * Returns true if the request 'req' was successfully coalesced into the
926  * existing list of pages 'desc'.
927  */
928 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
929                                      struct nfs_page *req)
930 {
931         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
932 
933         struct nfs_page *prev = NULL;
934 
935         if (mirror->pg_count != 0) {
936                 prev = nfs_list_entry(mirror->pg_list.prev);
937         } else {
938                 if (desc->pg_ops->pg_init)
939                         desc->pg_ops->pg_init(desc, req);
940                 if (desc->pg_error < 0)
941                         return 0;
942                 mirror->pg_base = req->wb_pgbase;
943         }
944         if (!nfs_can_coalesce_requests(prev, req, desc))
945                 return 0;
946         nfs_list_remove_request(req);
947         nfs_list_add_request(req, &mirror->pg_list);
948         mirror->pg_count += req->wb_bytes;
949         return 1;
950 }
951 
952 /*
953  * Helper for nfs_pageio_add_request and nfs_pageio_complete
954  */
955 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
956 {
957         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
958 
959 
960         if (!list_empty(&mirror->pg_list)) {
961                 int error = desc->pg_ops->pg_doio(desc);
962                 if (error < 0)
963                         desc->pg_error = error;
964                 else
965                         mirror->pg_bytes_written += mirror->pg_count;
966         }
967         if (list_empty(&mirror->pg_list)) {
968                 mirror->pg_count = 0;
969                 mirror->pg_base = 0;
970         }
971 }
972 
973 /**
974  * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
975  * @desc: destination io descriptor
976  * @req: request
977  *
978  * This may split a request into subrequests which are all part of the
979  * same page group.
980  *
981  * Returns true if the request 'req' was successfully coalesced into the
982  * existing list of pages 'desc'.
983  */
984 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
985                            struct nfs_page *req)
986 {
987         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
988 
989         struct nfs_page *subreq;
990         unsigned int bytes_left = 0;
991         unsigned int offset, pgbase;
992 
993         nfs_page_group_lock(req, false);
994 
995         subreq = req;
996         bytes_left = subreq->wb_bytes;
997         offset = subreq->wb_offset;
998         pgbase = subreq->wb_pgbase;
999 
1000         do {
1001                 if (!nfs_pageio_do_add_request(desc, subreq)) {
1002                         /* make sure pg_test call(s) did nothing */
1003                         WARN_ON_ONCE(subreq->wb_bytes != bytes_left);
1004                         WARN_ON_ONCE(subreq->wb_offset != offset);
1005                         WARN_ON_ONCE(subreq->wb_pgbase != pgbase);
1006 
1007                         nfs_page_group_unlock(req);
1008                         desc->pg_moreio = 1;
1009                         nfs_pageio_doio(desc);
1010                         if (desc->pg_error < 0)
1011                                 return 0;
1012                         if (mirror->pg_recoalesce)
1013                                 return 0;
1014                         /* retry add_request for this subreq */
1015                         nfs_page_group_lock(req, false);
1016                         continue;
1017                 }
1018 
1019                 /* check for buggy pg_test call(s) */
1020                 WARN_ON_ONCE(subreq->wb_bytes + subreq->wb_pgbase > PAGE_SIZE);
1021                 WARN_ON_ONCE(subreq->wb_bytes > bytes_left);
1022                 WARN_ON_ONCE(subreq->wb_bytes == 0);
1023 
1024                 bytes_left -= subreq->wb_bytes;
1025                 offset += subreq->wb_bytes;
1026                 pgbase += subreq->wb_bytes;
1027 
1028                 if (bytes_left) {
1029                         subreq = nfs_create_request(req->wb_context,
1030                                         req->wb_page,
1031                                         subreq, pgbase, bytes_left);
1032                         if (IS_ERR(subreq))
1033                                 goto err_ptr;
1034                         nfs_lock_request(subreq);
1035                         subreq->wb_offset  = offset;
1036                         subreq->wb_index = req->wb_index;
1037                 }
1038         } while (bytes_left > 0);
1039 
1040         nfs_page_group_unlock(req);
1041         return 1;
1042 err_ptr:
1043         desc->pg_error = PTR_ERR(subreq);
1044         nfs_page_group_unlock(req);
1045         return 0;
1046 }
1047 
1048 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
1049 {
1050         struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);
1051         LIST_HEAD(head);
1052 
1053         do {
1054                 list_splice_init(&mirror->pg_list, &head);
1055                 mirror->pg_bytes_written -= mirror->pg_count;
1056                 mirror->pg_count = 0;
1057                 mirror->pg_base = 0;
1058                 mirror->pg_recoalesce = 0;
1059 
1060                 while (!list_empty(&head)) {
1061                         struct nfs_page *req;
1062 
1063                         req = list_first_entry(&head, struct nfs_page, wb_list);
1064                         nfs_list_remove_request(req);
1065                         if (__nfs_pageio_add_request(desc, req))
1066                                 continue;
1067                         if (desc->pg_error < 0) {
1068                                 list_splice_tail(&head, &mirror->pg_list);
1069                                 mirror->pg_recoalesce = 1;
1070                                 return 0;
1071                         }
1072                         break;
1073                 }
1074         } while (mirror->pg_recoalesce);
1075         return 1;
1076 }
1077 
1078 static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
1079                 struct nfs_page *req)
1080 {
1081         int ret;
1082 
1083         do {
1084                 ret = __nfs_pageio_add_request(desc, req);
1085                 if (ret)
1086                         break;
1087                 if (desc->pg_error < 0)
1088                         break;
1089                 ret = nfs_do_recoalesce(desc);
1090         } while (ret);
1091 
1092         return ret;
1093 }
1094 
1095 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
1096                            struct nfs_page *req)
1097 {
1098         u32 midx;
1099         unsigned int pgbase, offset, bytes;
1100         struct nfs_page *dupreq, *lastreq;
1101 
1102         pgbase = req->wb_pgbase;
1103         offset = req->wb_offset;
1104         bytes = req->wb_bytes;
1105 
1106         nfs_pageio_setup_mirroring(desc, req);
1107         if (desc->pg_error < 0)
1108                 goto out_failed;
1109 
1110         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1111                 if (midx) {
1112                         nfs_page_group_lock(req, false);
1113 
1114                         /* find the last request */
1115                         for (lastreq = req->wb_head;
1116                              lastreq->wb_this_page != req->wb_head;
1117                              lastreq = lastreq->wb_this_page)
1118                                 ;
1119 
1120                         dupreq = nfs_create_request(req->wb_context,
1121                                         req->wb_page, lastreq, pgbase, bytes);
1122 
1123                         if (IS_ERR(dupreq)) {
1124                                 nfs_page_group_unlock(req);
1125                                 desc->pg_error = PTR_ERR(dupreq);
1126                                 goto out_failed;
1127                         }
1128 
1129                         nfs_lock_request(dupreq);
1130                         nfs_page_group_unlock(req);
1131                         dupreq->wb_offset = offset;
1132                         dupreq->wb_index = req->wb_index;
1133                 } else
1134                         dupreq = req;
1135 
1136                 if (nfs_pgio_has_mirroring(desc))
1137                         desc->pg_mirror_idx = midx;
1138                 if (!nfs_pageio_add_request_mirror(desc, dupreq))
1139                         goto out_failed;
1140         }
1141 
1142         return 1;
1143 
1144 out_failed:
1145         /*
1146          * We might have failed before sending any reqs over wire.
1147          * Clean up rest of the reqs in mirror pg_list.
1148          */
1149         if (desc->pg_error) {
1150                 struct nfs_pgio_mirror *mirror;
1151                 void (*func)(struct list_head *);
1152 
1153                 /* remember fatal errors */
1154                 if (nfs_error_is_fatal(desc->pg_error))
1155                         mapping_set_error(desc->pg_inode->i_mapping,
1156                                           desc->pg_error);
1157 
1158                 func = desc->pg_completion_ops->error_cleanup;
1159                 for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1160                         mirror = &desc->pg_mirrors[midx];
1161                         func(&mirror->pg_list);
1162                 }
1163         }
1164         return 0;
1165 }
1166 
1167 /*
1168  * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
1169  *                              nfs_pageio_descriptor
1170  * @desc: pointer to io descriptor
1171  * @mirror_idx: pointer to mirror index
1172  */
1173 static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
1174                                        u32 mirror_idx)
1175 {
1176         struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
1177         u32 restore_idx = desc->pg_mirror_idx;
1178 
1179         if (nfs_pgio_has_mirroring(desc))
1180                 desc->pg_mirror_idx = mirror_idx;
1181         for (;;) {
1182                 nfs_pageio_doio(desc);
1183                 if (!mirror->pg_recoalesce)
1184                         break;
1185                 if (!nfs_do_recoalesce(desc))
1186                         break;
1187         }
1188         desc->pg_mirror_idx = restore_idx;
1189 }
1190 
1191 /*
1192  * nfs_pageio_resend - Transfer requests to new descriptor and resend
1193  * @hdr - the pgio header to move request from
1194  * @desc - the pageio descriptor to add requests to
1195  *
1196  * Try to move each request (nfs_page) from @hdr to @desc then attempt
1197  * to send them.
1198  *
1199  * Returns 0 on success and < 0 on error.
1200  */
1201 int nfs_pageio_resend(struct nfs_pageio_descriptor *desc,
1202                       struct nfs_pgio_header *hdr)
1203 {
1204         LIST_HEAD(failed);
1205 
1206         desc->pg_dreq = hdr->dreq;
1207         while (!list_empty(&hdr->pages)) {
1208                 struct nfs_page *req = nfs_list_entry(hdr->pages.next);
1209 
1210                 nfs_list_remove_request(req);
1211                 if (!nfs_pageio_add_request(desc, req))
1212                         nfs_list_add_request(req, &failed);
1213         }
1214         nfs_pageio_complete(desc);
1215         if (!list_empty(&failed)) {
1216                 list_move(&failed, &hdr->pages);
1217                 return desc->pg_error < 0 ? desc->pg_error : -EIO;
1218         }
1219         return 0;
1220 }
1221 EXPORT_SYMBOL_GPL(nfs_pageio_resend);
1222 
1223 /**
1224  * nfs_pageio_complete - Complete I/O then cleanup an nfs_pageio_descriptor
1225  * @desc: pointer to io descriptor
1226  */
1227 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
1228 {
1229         u32 midx;
1230 
1231         for (midx = 0; midx < desc->pg_mirror_count; midx++)
1232                 nfs_pageio_complete_mirror(desc, midx);
1233 
1234         if (desc->pg_ops->pg_cleanup)
1235                 desc->pg_ops->pg_cleanup(desc);
1236         nfs_pageio_cleanup_mirroring(desc);
1237 }
1238 
1239 /**
1240  * nfs_pageio_cond_complete - Conditional I/O completion
1241  * @desc: pointer to io descriptor
1242  * @index: page index
1243  *
1244  * It is important to ensure that processes don't try to take locks
1245  * on non-contiguous ranges of pages as that might deadlock. This
1246  * function should be called before attempting to wait on a locked
1247  * nfs_page. It will complete the I/O if the page index 'index'
1248  * is not contiguous with the existing list of pages in 'desc'.
1249  */
1250 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
1251 {
1252         struct nfs_pgio_mirror *mirror;
1253         struct nfs_page *prev;
1254         u32 midx;
1255 
1256         for (midx = 0; midx < desc->pg_mirror_count; midx++) {
1257                 mirror = &desc->pg_mirrors[midx];
1258                 if (!list_empty(&mirror->pg_list)) {
1259                         prev = nfs_list_entry(mirror->pg_list.prev);
1260                         if (index != prev->wb_index + 1)
1261                                 nfs_pageio_complete_mirror(desc, midx);
1262                 }
1263         }
1264 }
1265 
1266 int __init nfs_init_nfspagecache(void)
1267 {
1268         nfs_page_cachep = kmem_cache_create("nfs_page",
1269                                             sizeof(struct nfs_page),
1270                                             0, SLAB_HWCACHE_ALIGN,
1271                                             NULL);
1272         if (nfs_page_cachep == NULL)
1273                 return -ENOMEM;
1274 
1275         return 0;
1276 }
1277 
1278 void nfs_destroy_nfspagecache(void)
1279 {
1280         kmem_cache_destroy(nfs_page_cachep);
1281 }
1282 
1283 static const struct rpc_call_ops nfs_pgio_common_ops = {
1284         .rpc_call_prepare = nfs_pgio_prepare,
1285         .rpc_call_done = nfs_pgio_result,
1286         .rpc_release = nfs_pgio_release,
1287 };
1288 
1289 const struct nfs_pageio_ops nfs_pgio_rw_ops = {
1290         .pg_test = nfs_generic_pg_test,
1291         .pg_doio = nfs_generic_pg_pgios,
1292 };
1293 

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