read.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * linux/fs/nfs/read.c
  4 *
  5 * Block I/O for NFS
  6 *
  7 * Partial copy of Linus' read cache modifications to fs/nfs/file.c
  8 * modified for async RPC by okir@monad.swb.de
  9 */
 10
 11#include <linux/time.h>
 12#include <linux/kernel.h>
 13#include <linux/errno.h>
 14#include <linux/fcntl.h>
 15#include <linux/stat.h>
 16#include <linux/mm.h>
 17#include <linux/slab.h>
 18#include <linux/task_io_accounting_ops.h>
 19#include <linux/pagemap.h>
 20#include <linux/sunrpc/clnt.h>
 21#include <linux/nfs_fs.h>
 22#include <linux/nfs_page.h>
 23#include <linux/module.h>
 24
 25#include "nfs4_fs.h"
 26#include "internal.h"
 27#include "iostat.h"
 28#include "fscache.h"
 29#include "pnfs.h"
 30#include "nfstrace.h"
 31#include "delegation.h"
 32
 33#define NFSDBG_FACILITY		NFSDBG_PAGECACHE
 34
 35const struct nfs_pgio_completion_ops nfs_async_read_completion_ops;
 36static const struct nfs_rw_ops nfs_rw_read_ops;
 37
 38static struct kmem_cache *nfs_rdata_cachep;
 39
 40static struct nfs_pgio_header *nfs_readhdr_alloc(void)
 41{
 42	struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL);
 43
 44	if (p)
 45		p->rw_mode = FMODE_READ;
 46	return p;
 47}
 48
 49static void nfs_readhdr_free(struct nfs_pgio_header *rhdr)
 50{
 51	kfree(rhdr->res.scratch);
 52	kmem_cache_free(nfs_rdata_cachep, rhdr);
 53}
 54
 55static int nfs_return_empty_folio(struct folio *folio)
 56{
 57	folio_zero_segment(folio, 0, folio_size(folio));
 58	folio_mark_uptodate(folio);
 59	if (nfs_netfs_folio_unlock(folio))
 60		folio_unlock(folio);
 61	return 0;
 62}
 63
 64void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio,
 65			      struct inode *inode, bool force_mds,
 66			      const struct nfs_pgio_completion_ops *compl_ops)
 67{
 68	struct nfs_server *server = NFS_SERVER(inode);
 69	const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops;
 70
 71#ifdef CONFIG_NFS_V4_1
 72	if (server->pnfs_curr_ld && !force_mds)
 73		pg_ops = server->pnfs_curr_ld->pg_read_ops;
 74#endif
 75	nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops,
 76			server->rsize, 0);
 77}
 78EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
 79
 80void nfs_pageio_complete_read(struct nfs_pageio_descriptor *pgio)
 81{
 82	struct nfs_pgio_mirror *pgm;
 83	unsigned long npages;
 84
 85	nfs_pageio_complete(pgio);
 86
 87	/* It doesn't make sense to do mirrored reads! */
 88	WARN_ON_ONCE(pgio->pg_mirror_count != 1);
 89
 90	pgm = &pgio->pg_mirrors[0];
 91	NFS_I(pgio->pg_inode)->read_io += pgm->pg_bytes_written;
 92	npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> PAGE_SHIFT;
 93	nfs_add_stats(pgio->pg_inode, NFSIOS_READPAGES, npages);
 94}
 95
 96
 97void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
 98{
 99	struct nfs_pgio_mirror *mirror;
100
101	if (pgio->pg_ops && pgio->pg_ops->pg_cleanup)
102		pgio->pg_ops->pg_cleanup(pgio);
103
104	pgio->pg_ops = &nfs_pgio_rw_ops;
105
106	/* read path should never have more than one mirror */
107	WARN_ON_ONCE(pgio->pg_mirror_count != 1);
108
109	mirror = &pgio->pg_mirrors[0];
110	mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
111}
112EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
113
114bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size)
115{
116	WARN_ON(hdr->res.scratch != NULL);
117	hdr->res.scratch = kmalloc(size, GFP_KERNEL);
118	return hdr->res.scratch != NULL;
119}
120EXPORT_SYMBOL_GPL(nfs_read_alloc_scratch);
121
122static void nfs_readpage_release(struct nfs_page *req, int error)
123{
124	struct folio *folio = nfs_page_to_folio(req);
125
126	if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE))
127		if (nfs_netfs_folio_unlock(folio))
128			folio_unlock(folio);
129
130	nfs_release_request(req);
131}
132
133static void nfs_page_group_set_uptodate(struct nfs_page *req)
134{
135	if (nfs_page_group_sync_on_bit(req, PG_UPTODATE))
136		folio_mark_uptodate(nfs_page_to_folio(req));
137}
138
139static void nfs_read_completion(struct nfs_pgio_header *hdr)
140{
141	unsigned long bytes = 0;
142	int error;
143
144	if (test_bit(NFS_IOHDR_REDO, &hdr->flags))
145		goto out;
146	while (!list_empty(&hdr->pages)) {
147		struct nfs_page *req = nfs_list_entry(hdr->pages.next);
148		struct folio *folio = nfs_page_to_folio(req);
149		unsigned long start = req->wb_pgbase;
150		unsigned long end = req->wb_pgbase + req->wb_bytes;
151
152		if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) {
153			/* note: regions of the page not covered by a
154			 * request are zeroed in nfs_read_add_folio
155			 */
156			if (bytes > hdr->good_bytes) {
157				/* nothing in this request was good, so zero
158				 * the full extent of the request */
159				folio_zero_segment(folio, start, end);
160
161			} else if (hdr->good_bytes - bytes < req->wb_bytes) {
162				/* part of this request has good bytes, but
163				 * not all. zero the bad bytes */
164				start += hdr->good_bytes - bytes;
165				WARN_ON(start < req->wb_pgbase);
166				folio_zero_segment(folio, start, end);
167			}
168		}
169		error = 0;
170		bytes += req->wb_bytes;
171		if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) {
172			if (bytes <= hdr->good_bytes)
173				nfs_page_group_set_uptodate(req);
174			else {
175				error = hdr->error;
176				xchg(&nfs_req_openctx(req)->error, error);
177			}
178		} else
179			nfs_page_group_set_uptodate(req);
180		nfs_list_remove_request(req);
181		nfs_readpage_release(req, error);
182	}
183	nfs_netfs_read_completion(hdr);
184
185out:
186	hdr->release(hdr);
187}
188
189static void nfs_initiate_read(struct nfs_pgio_header *hdr,
190			      struct rpc_message *msg,
191			      const struct nfs_rpc_ops *rpc_ops,
192			      struct rpc_task_setup *task_setup_data, int how)
193{
194	rpc_ops->read_setup(hdr, msg);
195	nfs_netfs_initiate_read(hdr);
196	trace_nfs_initiate_read(hdr);
197}
198
199static void
200nfs_async_read_error(struct list_head *head, int error)
201{
202	struct nfs_page	*req;
203
204	while (!list_empty(head)) {
205		req = nfs_list_entry(head->next);
206		nfs_list_remove_request(req);
207		nfs_readpage_release(req, error);
208	}
209}
210
211const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = {
212	.error_cleanup = nfs_async_read_error,
213	.completion = nfs_read_completion,
214};
215
216/*
217 * This is the callback from RPC telling us whether a reply was
218 * received or some error occurred (timeout or socket shutdown).
219 */
220static int nfs_readpage_done(struct rpc_task *task,
221			     struct nfs_pgio_header *hdr,
222			     struct inode *inode)
223{
224	int status = NFS_PROTO(inode)->read_done(task, hdr);
225	if (status != 0)
226		return status;
227
228	nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count);
229	trace_nfs_readpage_done(task, hdr);
230
231	if (task->tk_status == -ESTALE) {
232		nfs_set_inode_stale(inode);
233		nfs_mark_for_revalidate(inode);
234	}
235	return 0;
236}
237
238static void nfs_readpage_retry(struct rpc_task *task,
239			       struct nfs_pgio_header *hdr)
240{
241	struct nfs_pgio_args *argp = &hdr->args;
242	struct nfs_pgio_res  *resp = &hdr->res;
243
244	/* This is a short read! */
245	nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD);
246	trace_nfs_readpage_short(task, hdr);
247
248	/* Has the server at least made some progress? */
249	if (resp->count == 0) {
250		nfs_set_pgio_error(hdr, -EIO, argp->offset);
251		return;
252	}
253
254	/* For non rpc-based layout drivers, retry-through-MDS */
255	if (!task->tk_ops) {
256		hdr->pnfs_error = -EAGAIN;
257		return;
258	}
259
260	/* Yes, so retry the read at the end of the hdr */
261	hdr->mds_offset += resp->count;
262	argp->offset += resp->count;
263	argp->pgbase += resp->count;
264	argp->count -= resp->count;
265	resp->count = 0;
266	resp->eof = 0;
267	rpc_restart_call_prepare(task);
268}
269
270static void nfs_readpage_result(struct rpc_task *task,
271				struct nfs_pgio_header *hdr)
272{
273	if (hdr->res.eof) {
274		loff_t pos = hdr->args.offset + hdr->res.count;
275		unsigned int new = pos - hdr->io_start;
276
277		if (hdr->good_bytes > new) {
278			hdr->good_bytes = new;
279			set_bit(NFS_IOHDR_EOF, &hdr->flags);
280			clear_bit(NFS_IOHDR_ERROR, &hdr->flags);
281		}
282	} else if (hdr->res.count < hdr->args.count)
283		nfs_readpage_retry(task, hdr);
284}
285
286int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio,
287		       struct nfs_open_context *ctx,
288		       struct folio *folio)
289{
290	struct inode *inode = folio->mapping->host;
291	struct nfs_server *server = NFS_SERVER(inode);
292	size_t fsize = folio_size(folio);
293	unsigned int rsize = server->rsize;
294	struct nfs_page *new;
295	unsigned int len, aligned_len;
296	int error;
297
298	len = nfs_folio_length(folio);
299	if (len == 0)
300		return nfs_return_empty_folio(folio);
301
302	aligned_len = min_t(unsigned int, ALIGN(len, rsize), fsize);
303
304	new = nfs_page_create_from_folio(ctx, folio, 0, aligned_len);
305	if (IS_ERR(new)) {
306		error = PTR_ERR(new);
307		if (nfs_netfs_folio_unlock(folio))
308			folio_unlock(folio);
309		goto out;
310	}
311
312	if (len < fsize)
313		folio_zero_segment(folio, len, fsize);
314	if (!nfs_pageio_add_request(pgio, new)) {
315		nfs_list_remove_request(new);
316		error = pgio->pg_error;
317		nfs_readpage_release(new, error);
318		goto out;
319	}
320	return 0;
321out:
322	return error;
323}
324
325/*
326 * Actually read a folio over the wire.
327 */
328static int nfs_do_read_folio(struct file *file, struct folio *folio)
329{
330	struct inode *inode = file_inode(file);
331	struct nfs_pageio_descriptor pgio;
332	struct nfs_open_context *ctx;
333	int ret;
334
335	ctx = get_nfs_open_context(nfs_file_open_context(file));
336
337	xchg(&ctx->error, 0);
338	nfs_pageio_init_read(&pgio, inode, false,
339			     &nfs_async_read_completion_ops);
340
341	ret = nfs_read_add_folio(&pgio, ctx, folio);
342	if (ret)
343		goto out_put;
344
345	nfs_pageio_complete_read(&pgio);
346	nfs_update_delegated_atime(inode);
347	if (pgio.pg_error < 0) {
348		ret = pgio.pg_error;
349		goto out_put;
350	}
351
352	ret = folio_wait_locked_killable(folio);
353	if (!folio_test_uptodate(folio) && !ret)
354		ret = xchg(&ctx->error, 0);
355
356out_put:
357	put_nfs_open_context(ctx);
358	return ret;
359}
360
361/*
362 * Synchronously read a folio.
363 *
364 * This is not heavily used as most users to try an asynchronous
365 * large read through ->readahead first.
366 */
367int nfs_read_folio(struct file *file, struct folio *folio)
368{
369	struct inode *inode = file_inode(file);
370	loff_t pos = folio_pos(folio);
371	size_t len = folio_size(folio);
372	int ret;
373
374	trace_nfs_aop_readpage(inode, pos, len);
375	nfs_inc_stats(inode, NFSIOS_VFSREADPAGE);
376	task_io_account_read(len);
377
378	/*
379	 * Try to flush any pending writes to the file..
380	 *
381	 * NOTE! Because we own the folio lock, there cannot
382	 * be any new pending writes generated at this point
383	 * for this folio (other folios can be written to).
384	 */
385	ret = nfs_wb_folio(inode, folio);
386	if (ret)
387		goto out_unlock;
388	if (folio_test_uptodate(folio))
389		goto out_unlock;
390
391	ret = -ESTALE;
392	if (NFS_STALE(inode))
393		goto out_unlock;
394
395	ret = nfs_netfs_read_folio(file, folio);
396	if (ret)
397		ret = nfs_do_read_folio(file, folio);
398out:
399	trace_nfs_aop_readpage_done(inode, pos, len, ret);
400	return ret;
401out_unlock:
402	folio_unlock(folio);
403	goto out;
404}
405
406void nfs_readahead(struct readahead_control *ractl)
407{
408	struct nfs_pageio_descriptor pgio;
409	struct nfs_open_context *ctx;
410	unsigned int nr_pages = readahead_count(ractl);
411	struct file *file = ractl->file;
412	struct inode *inode = ractl->mapping->host;
413	struct folio *folio;
414	int ret;
415
416	trace_nfs_aop_readahead(inode, readahead_pos(ractl), nr_pages);
417	nfs_inc_stats(inode, NFSIOS_VFSREADPAGES);
418	task_io_account_read(readahead_length(ractl));
419
420	ret = -ESTALE;
421	if (NFS_STALE(inode))
422		goto out;
423
424	ret = nfs_netfs_readahead(ractl);
425	if (!ret)
426		goto out;
427
428	if (file == NULL) {
429		ret = -EBADF;
430		ctx = nfs_find_open_context(inode, NULL, FMODE_READ);
431		if (ctx == NULL)
432			goto out;
433	} else
434		ctx = get_nfs_open_context(nfs_file_open_context(file));
435
436	nfs_pageio_init_read(&pgio, inode, false,
437			     &nfs_async_read_completion_ops);
438
439	while ((folio = readahead_folio(ractl)) != NULL) {
440		ret = nfs_read_add_folio(&pgio, ctx, folio);
441		if (ret)
442			break;
443	}
444
445	nfs_pageio_complete_read(&pgio);
446	nfs_update_delegated_atime(inode);
447
448	put_nfs_open_context(ctx);
449out:
450	trace_nfs_aop_readahead_done(inode, nr_pages, ret);
451}
452
453int __init nfs_init_readpagecache(void)
454{
455	nfs_rdata_cachep = kmem_cache_create("nfs_read_data",
456					     sizeof(struct nfs_pgio_header),
457					     0, SLAB_HWCACHE_ALIGN,
458					     NULL);
459	if (nfs_rdata_cachep == NULL)
460		return -ENOMEM;
461
462	return 0;
463}
464
465void nfs_destroy_readpagecache(void)
466{
467	kmem_cache_destroy(nfs_rdata_cachep);
468}
469
470static const struct nfs_rw_ops nfs_rw_read_ops = {
471	.rw_alloc_header	= nfs_readhdr_alloc,
472	.rw_free_header		= nfs_readhdr_free,
473	.rw_done		= nfs_readpage_done,
474	.rw_result		= nfs_readpage_result,
475	.rw_initiate		= nfs_initiate_read,
476};