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1da177e4 LT |
1 | /* |
2 | * linux/fs/nfs/direct.c | |
3 | * | |
4 | * Copyright (C) 2003 by Chuck Lever <cel@netapp.com> | |
5 | * | |
6 | * High-performance uncached I/O for the Linux NFS client | |
7 | * | |
8 | * There are important applications whose performance or correctness | |
9 | * depends on uncached access to file data. Database clusters | |
10 | * (multiple copies of the same instance running on separate hosts) | |
11 | * implement their own cache coherency protocol that subsumes file | |
12 | * system cache protocols. Applications that process datasets | |
13 | * considerably larger than the client's memory do not always benefit | |
14 | * from a local cache. A streaming video server, for instance, has no | |
15 | * need to cache the contents of a file. | |
16 | * | |
17 | * When an application requests uncached I/O, all read and write requests | |
18 | * are made directly to the server; data stored or fetched via these | |
19 | * requests is not cached in the Linux page cache. The client does not | |
20 | * correct unaligned requests from applications. All requested bytes are | |
21 | * held on permanent storage before a direct write system call returns to | |
22 | * an application. | |
23 | * | |
24 | * Solaris implements an uncached I/O facility called directio() that | |
25 | * is used for backups and sequential I/O to very large files. Solaris | |
26 | * also supports uncaching whole NFS partitions with "-o forcedirectio," | |
27 | * an undocumented mount option. | |
28 | * | |
29 | * Designed by Jeff Kimmel, Chuck Lever, and Trond Myklebust, with | |
30 | * help from Andrew Morton. | |
31 | * | |
32 | * 18 Dec 2001 Initial implementation for 2.4 --cel | |
33 | * 08 Jul 2002 Version for 2.4.19, with bug fixes --trondmy | |
34 | * 08 Jun 2003 Port to 2.5 APIs --cel | |
35 | * 31 Mar 2004 Handle direct I/O without VFS support --cel | |
36 | * 15 Sep 2004 Parallel async reads --cel | |
37 | * | |
38 | */ | |
39 | ||
40 | #include <linux/config.h> | |
41 | #include <linux/errno.h> | |
42 | #include <linux/sched.h> | |
43 | #include <linux/kernel.h> | |
44 | #include <linux/smp_lock.h> | |
45 | #include <linux/file.h> | |
46 | #include <linux/pagemap.h> | |
47 | #include <linux/kref.h> | |
48 | ||
49 | #include <linux/nfs_fs.h> | |
50 | #include <linux/nfs_page.h> | |
51 | #include <linux/sunrpc/clnt.h> | |
52 | ||
53 | #include <asm/system.h> | |
54 | #include <asm/uaccess.h> | |
55 | #include <asm/atomic.h> | |
56 | ||
91d5b470 CL |
57 | #include "iostat.h" |
58 | ||
1da177e4 LT |
59 | #define NFSDBG_FACILITY NFSDBG_VFS |
60 | #define MAX_DIRECTIO_SIZE (4096UL << PAGE_SHIFT) | |
61 | ||
143f412e | 62 | static void nfs_free_user_pages(struct page **pages, int npages, int do_dirty); |
1da177e4 LT |
63 | static kmem_cache_t *nfs_direct_cachep; |
64 | ||
65 | /* | |
66 | * This represents a set of asynchronous requests that we're waiting on | |
67 | */ | |
68 | struct nfs_direct_req { | |
69 | struct kref kref; /* release manager */ | |
70 | struct list_head list; /* nfs_read_data structs */ | |
71 | wait_queue_head_t wait; /* wait for i/o completion */ | |
91d5b470 | 72 | struct inode * inode; /* target file of I/O */ |
1da177e4 LT |
73 | struct page ** pages; /* pages in our buffer */ |
74 | unsigned int npages; /* count of pages */ | |
75 | atomic_t complete, /* i/os we're waiting for */ | |
76 | count, /* bytes actually processed */ | |
77 | error; /* any reported error */ | |
78 | }; | |
79 | ||
80 | ||
b8a32e2b CL |
81 | /** |
82 | * nfs_direct_IO - NFS address space operation for direct I/O | |
83 | * @rw: direction (read or write) | |
84 | * @iocb: target I/O control block | |
85 | * @iov: array of vectors that define I/O buffer | |
86 | * @pos: offset in file to begin the operation | |
87 | * @nr_segs: size of iovec array | |
88 | * | |
89 | * The presence of this routine in the address space ops vector means | |
90 | * the NFS client supports direct I/O. However, we shunt off direct | |
91 | * read and write requests before the VFS gets them, so this method | |
92 | * should never be called. | |
93 | */ | |
94 | ssize_t nfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, loff_t pos, unsigned long nr_segs) | |
95 | { | |
96 | struct dentry *dentry = iocb->ki_filp->f_dentry; | |
97 | ||
98 | dprintk("NFS: nfs_direct_IO (%s) off/no(%Ld/%lu) EINVAL\n", | |
99 | dentry->d_name.name, (long long) pos, nr_segs); | |
100 | ||
101 | return -EINVAL; | |
102 | } | |
103 | ||
d4cc948b | 104 | static inline int nfs_get_user_pages(int rw, unsigned long user_addr, size_t size, struct page ***pages) |
1da177e4 LT |
105 | { |
106 | int result = -ENOMEM; | |
107 | unsigned long page_count; | |
108 | size_t array_size; | |
109 | ||
110 | /* set an arbitrary limit to prevent type overflow */ | |
111 | /* XXX: this can probably be as large as INT_MAX */ | |
112 | if (size > MAX_DIRECTIO_SIZE) { | |
113 | *pages = NULL; | |
114 | return -EFBIG; | |
115 | } | |
116 | ||
117 | page_count = (user_addr + size + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
118 | page_count -= user_addr >> PAGE_SHIFT; | |
119 | ||
120 | array_size = (page_count * sizeof(struct page *)); | |
121 | *pages = kmalloc(array_size, GFP_KERNEL); | |
122 | if (*pages) { | |
123 | down_read(¤t->mm->mmap_sem); | |
124 | result = get_user_pages(current, current->mm, user_addr, | |
125 | page_count, (rw == READ), 0, | |
126 | *pages, NULL); | |
127 | up_read(¤t->mm->mmap_sem); | |
143f412e TM |
128 | /* |
129 | * If we got fewer pages than expected from get_user_pages(), | |
130 | * the user buffer runs off the end of a mapping; return EFAULT. | |
131 | */ | |
132 | if (result >= 0 && result < page_count) { | |
133 | nfs_free_user_pages(*pages, result, 0); | |
134 | *pages = NULL; | |
135 | result = -EFAULT; | |
136 | } | |
1da177e4 LT |
137 | } |
138 | return result; | |
139 | } | |
140 | ||
d4cc948b | 141 | static void nfs_free_user_pages(struct page **pages, int npages, int do_dirty) |
1da177e4 LT |
142 | { |
143 | int i; | |
144 | for (i = 0; i < npages; i++) { | |
566dd606 TM |
145 | struct page *page = pages[i]; |
146 | if (do_dirty && !PageCompound(page)) | |
147 | set_page_dirty_lock(page); | |
148 | page_cache_release(page); | |
1da177e4 LT |
149 | } |
150 | kfree(pages); | |
151 | } | |
152 | ||
1da177e4 LT |
153 | static void nfs_direct_req_release(struct kref *kref) |
154 | { | |
155 | struct nfs_direct_req *dreq = container_of(kref, struct nfs_direct_req, kref); | |
156 | kmem_cache_free(nfs_direct_cachep, dreq); | |
157 | } | |
158 | ||
d4cc948b | 159 | /* |
1da177e4 LT |
160 | * Note we also set the number of requests we have in the dreq when we are |
161 | * done. This prevents races with I/O completion so we will always wait | |
162 | * until all requests have been dispatched and completed. | |
163 | */ | |
5dd602f2 | 164 | static struct nfs_direct_req *nfs_direct_read_alloc(size_t nbytes, size_t rsize) |
1da177e4 LT |
165 | { |
166 | struct list_head *list; | |
167 | struct nfs_direct_req *dreq; | |
168 | unsigned int reads = 0; | |
40859d7e | 169 | unsigned int rpages = (rsize + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
1da177e4 LT |
170 | |
171 | dreq = kmem_cache_alloc(nfs_direct_cachep, SLAB_KERNEL); | |
172 | if (!dreq) | |
173 | return NULL; | |
174 | ||
175 | kref_init(&dreq->kref); | |
176 | init_waitqueue_head(&dreq->wait); | |
177 | INIT_LIST_HEAD(&dreq->list); | |
178 | atomic_set(&dreq->count, 0); | |
179 | atomic_set(&dreq->error, 0); | |
180 | ||
181 | list = &dreq->list; | |
182 | for(;;) { | |
40859d7e | 183 | struct nfs_read_data *data = nfs_readdata_alloc(rpages); |
1da177e4 LT |
184 | |
185 | if (unlikely(!data)) { | |
186 | while (!list_empty(list)) { | |
187 | data = list_entry(list->next, | |
188 | struct nfs_read_data, pages); | |
189 | list_del(&data->pages); | |
190 | nfs_readdata_free(data); | |
191 | } | |
192 | kref_put(&dreq->kref, nfs_direct_req_release); | |
193 | return NULL; | |
194 | } | |
195 | ||
196 | INIT_LIST_HEAD(&data->pages); | |
197 | list_add(&data->pages, list); | |
198 | ||
199 | data->req = (struct nfs_page *) dreq; | |
200 | reads++; | |
201 | if (nbytes <= rsize) | |
202 | break; | |
203 | nbytes -= rsize; | |
204 | } | |
205 | kref_get(&dreq->kref); | |
206 | atomic_set(&dreq->complete, reads); | |
207 | return dreq; | |
208 | } | |
209 | ||
d4cc948b | 210 | /* |
1da177e4 LT |
211 | * We must hold a reference to all the pages in this direct read request |
212 | * until the RPCs complete. This could be long *after* we are woken up in | |
213 | * nfs_direct_read_wait (for instance, if someone hits ^C on a slow server). | |
214 | */ | |
ec06c096 | 215 | static void nfs_direct_read_result(struct rpc_task *task, void *calldata) |
1da177e4 | 216 | { |
ec06c096 | 217 | struct nfs_read_data *data = calldata; |
1da177e4 LT |
218 | struct nfs_direct_req *dreq = (struct nfs_direct_req *) data->req; |
219 | ||
ec06c096 TM |
220 | if (nfs_readpage_result(task, data) != 0) |
221 | return; | |
222 | if (likely(task->tk_status >= 0)) | |
1da177e4 LT |
223 | atomic_add(data->res.count, &dreq->count); |
224 | else | |
ec06c096 | 225 | atomic_set(&dreq->error, task->tk_status); |
1da177e4 LT |
226 | |
227 | if (unlikely(atomic_dec_and_test(&dreq->complete))) { | |
228 | nfs_free_user_pages(dreq->pages, dreq->npages, 1); | |
229 | wake_up(&dreq->wait); | |
230 | kref_put(&dreq->kref, nfs_direct_req_release); | |
231 | } | |
232 | } | |
233 | ||
ec06c096 TM |
234 | static const struct rpc_call_ops nfs_read_direct_ops = { |
235 | .rpc_call_done = nfs_direct_read_result, | |
236 | .rpc_release = nfs_readdata_release, | |
237 | }; | |
238 | ||
d4cc948b | 239 | /* |
1da177e4 LT |
240 | * For each nfs_read_data struct that was allocated on the list, dispatch |
241 | * an NFS READ operation | |
242 | */ | |
d4cc948b | 243 | static void nfs_direct_read_schedule(struct nfs_direct_req *dreq, struct inode *inode, struct nfs_open_context *ctx, unsigned long user_addr, size_t count, loff_t file_offset) |
1da177e4 LT |
244 | { |
245 | struct list_head *list = &dreq->list; | |
246 | struct page **pages = dreq->pages; | |
5dd602f2 | 247 | size_t rsize = NFS_SERVER(inode)->rsize; |
1da177e4 | 248 | unsigned int curpage, pgbase; |
1da177e4 LT |
249 | |
250 | curpage = 0; | |
251 | pgbase = user_addr & ~PAGE_MASK; | |
252 | do { | |
253 | struct nfs_read_data *data; | |
5dd602f2 | 254 | size_t bytes; |
1da177e4 LT |
255 | |
256 | bytes = rsize; | |
257 | if (count < rsize) | |
258 | bytes = count; | |
259 | ||
260 | data = list_entry(list->next, struct nfs_read_data, pages); | |
261 | list_del_init(&data->pages); | |
262 | ||
263 | data->inode = inode; | |
264 | data->cred = ctx->cred; | |
265 | data->args.fh = NFS_FH(inode); | |
266 | data->args.context = ctx; | |
267 | data->args.offset = file_offset; | |
268 | data->args.pgbase = pgbase; | |
269 | data->args.pages = &pages[curpage]; | |
270 | data->args.count = bytes; | |
271 | data->res.fattr = &data->fattr; | |
272 | data->res.eof = 0; | |
273 | data->res.count = bytes; | |
274 | ||
ec06c096 TM |
275 | rpc_init_task(&data->task, NFS_CLIENT(inode), RPC_TASK_ASYNC, |
276 | &nfs_read_direct_ops, data); | |
1da177e4 LT |
277 | NFS_PROTO(inode)->read_setup(data); |
278 | ||
279 | data->task.tk_cookie = (unsigned long) inode; | |
1da177e4 LT |
280 | |
281 | lock_kernel(); | |
282 | rpc_execute(&data->task); | |
283 | unlock_kernel(); | |
284 | ||
285 | dfprintk(VFS, "NFS: %4d initiated direct read call (req %s/%Ld, %u bytes @ offset %Lu)\n", | |
286 | data->task.tk_pid, | |
287 | inode->i_sb->s_id, | |
288 | (long long)NFS_FILEID(inode), | |
289 | bytes, | |
290 | (unsigned long long)data->args.offset); | |
291 | ||
292 | file_offset += bytes; | |
293 | pgbase += bytes; | |
294 | curpage += pgbase >> PAGE_SHIFT; | |
295 | pgbase &= ~PAGE_MASK; | |
296 | ||
297 | count -= bytes; | |
298 | } while (count != 0); | |
299 | } | |
300 | ||
d4cc948b | 301 | /* |
1da177e4 LT |
302 | * Collects and returns the final error value/byte-count. |
303 | */ | |
304 | static ssize_t nfs_direct_read_wait(struct nfs_direct_req *dreq, int intr) | |
305 | { | |
306 | int result = 0; | |
307 | ||
308 | if (intr) { | |
309 | result = wait_event_interruptible(dreq->wait, | |
310 | (atomic_read(&dreq->complete) == 0)); | |
311 | } else { | |
312 | wait_event(dreq->wait, (atomic_read(&dreq->complete) == 0)); | |
313 | } | |
314 | ||
315 | if (!result) | |
316 | result = atomic_read(&dreq->error); | |
317 | if (!result) | |
318 | result = atomic_read(&dreq->count); | |
319 | ||
320 | kref_put(&dreq->kref, nfs_direct_req_release); | |
321 | return (ssize_t) result; | |
322 | } | |
323 | ||
d4cc948b | 324 | static ssize_t nfs_direct_read_seg(struct inode *inode, struct nfs_open_context *ctx, unsigned long user_addr, size_t count, loff_t file_offset, struct page **pages, unsigned int nr_pages) |
1da177e4 LT |
325 | { |
326 | ssize_t result; | |
327 | sigset_t oldset; | |
328 | struct rpc_clnt *clnt = NFS_CLIENT(inode); | |
329 | struct nfs_direct_req *dreq; | |
330 | ||
331 | dreq = nfs_direct_read_alloc(count, NFS_SERVER(inode)->rsize); | |
332 | if (!dreq) | |
333 | return -ENOMEM; | |
334 | ||
335 | dreq->pages = pages; | |
336 | dreq->npages = nr_pages; | |
91d5b470 | 337 | dreq->inode = inode; |
1da177e4 | 338 | |
91d5b470 | 339 | nfs_add_stats(inode, NFSIOS_DIRECTREADBYTES, count); |
1da177e4 LT |
340 | rpc_clnt_sigmask(clnt, &oldset); |
341 | nfs_direct_read_schedule(dreq, inode, ctx, user_addr, count, | |
342 | file_offset); | |
343 | result = nfs_direct_read_wait(dreq, clnt->cl_intr); | |
344 | rpc_clnt_sigunmask(clnt, &oldset); | |
345 | ||
346 | return result; | |
347 | } | |
348 | ||
d4cc948b | 349 | /* |
1da177e4 LT |
350 | * We've already pushed out any non-direct writes so that this read |
351 | * will see them when we read from the server. | |
352 | */ | |
d4cc948b | 353 | static ssize_t nfs_direct_read(struct inode *inode, struct nfs_open_context *ctx, const struct iovec *iov, loff_t file_offset, unsigned long nr_segs) |
1da177e4 LT |
354 | { |
355 | ssize_t tot_bytes = 0; | |
356 | unsigned long seg = 0; | |
357 | ||
358 | while ((seg < nr_segs) && (tot_bytes >= 0)) { | |
359 | ssize_t result; | |
360 | int page_count; | |
361 | struct page **pages; | |
362 | const struct iovec *vec = &iov[seg++]; | |
363 | unsigned long user_addr = (unsigned long) vec->iov_base; | |
364 | size_t size = vec->iov_len; | |
365 | ||
366 | page_count = nfs_get_user_pages(READ, user_addr, size, &pages); | |
367 | if (page_count < 0) { | |
368 | nfs_free_user_pages(pages, 0, 0); | |
369 | if (tot_bytes > 0) | |
370 | break; | |
371 | return page_count; | |
372 | } | |
373 | ||
374 | result = nfs_direct_read_seg(inode, ctx, user_addr, size, | |
375 | file_offset, pages, page_count); | |
376 | ||
377 | if (result <= 0) { | |
378 | if (tot_bytes > 0) | |
379 | break; | |
380 | return result; | |
381 | } | |
382 | tot_bytes += result; | |
383 | file_offset += result; | |
384 | if (result < size) | |
385 | break; | |
386 | } | |
387 | ||
388 | return tot_bytes; | |
389 | } | |
390 | ||
d4cc948b | 391 | static ssize_t nfs_direct_write_seg(struct inode *inode, struct nfs_open_context *ctx, unsigned long user_addr, size_t count, loff_t file_offset, struct page **pages, int nr_pages) |
1da177e4 LT |
392 | { |
393 | const unsigned int wsize = NFS_SERVER(inode)->wsize; | |
394 | size_t request; | |
395 | int curpage, need_commit; | |
396 | ssize_t result, tot_bytes; | |
397 | struct nfs_writeverf first_verf; | |
398 | struct nfs_write_data *wdata; | |
399 | ||
40859d7e | 400 | wdata = nfs_writedata_alloc(NFS_SERVER(inode)->wpages); |
1da177e4 LT |
401 | if (!wdata) |
402 | return -ENOMEM; | |
403 | ||
404 | wdata->inode = inode; | |
405 | wdata->cred = ctx->cred; | |
406 | wdata->args.fh = NFS_FH(inode); | |
407 | wdata->args.context = ctx; | |
408 | wdata->args.stable = NFS_UNSTABLE; | |
409 | if (IS_SYNC(inode) || NFS_PROTO(inode)->version == 2 || count <= wsize) | |
410 | wdata->args.stable = NFS_FILE_SYNC; | |
411 | wdata->res.fattr = &wdata->fattr; | |
412 | wdata->res.verf = &wdata->verf; | |
413 | ||
414 | nfs_begin_data_update(inode); | |
415 | retry: | |
416 | need_commit = 0; | |
417 | tot_bytes = 0; | |
418 | curpage = 0; | |
419 | request = count; | |
420 | wdata->args.pgbase = user_addr & ~PAGE_MASK; | |
421 | wdata->args.offset = file_offset; | |
422 | do { | |
423 | wdata->args.count = request; | |
424 | if (wdata->args.count > wsize) | |
425 | wdata->args.count = wsize; | |
426 | wdata->args.pages = &pages[curpage]; | |
427 | ||
428 | dprintk("NFS: direct write: c=%u o=%Ld ua=%lu, pb=%u, cp=%u\n", | |
429 | wdata->args.count, (long long) wdata->args.offset, | |
430 | user_addr + tot_bytes, wdata->args.pgbase, curpage); | |
431 | ||
432 | lock_kernel(); | |
433 | result = NFS_PROTO(inode)->write(wdata); | |
434 | unlock_kernel(); | |
435 | ||
436 | if (result <= 0) { | |
437 | if (tot_bytes > 0) | |
438 | break; | |
439 | goto out; | |
440 | } | |
441 | ||
442 | if (tot_bytes == 0) | |
443 | memcpy(&first_verf.verifier, &wdata->verf.verifier, | |
444 | sizeof(first_verf.verifier)); | |
445 | if (wdata->verf.committed != NFS_FILE_SYNC) { | |
446 | need_commit = 1; | |
447 | if (memcmp(&first_verf.verifier, &wdata->verf.verifier, | |
19352456 | 448 | sizeof(first_verf.verifier))) |
1da177e4 LT |
449 | goto sync_retry; |
450 | } | |
451 | ||
452 | tot_bytes += result; | |
453 | ||
454 | /* in case of a short write: stop now, let the app recover */ | |
455 | if (result < wdata->args.count) | |
456 | break; | |
457 | ||
458 | wdata->args.offset += result; | |
459 | wdata->args.pgbase += result; | |
460 | curpage += wdata->args.pgbase >> PAGE_SHIFT; | |
461 | wdata->args.pgbase &= ~PAGE_MASK; | |
462 | request -= result; | |
463 | } while (request != 0); | |
464 | ||
465 | /* | |
466 | * Commit data written so far, even in the event of an error | |
467 | */ | |
468 | if (need_commit) { | |
469 | wdata->args.count = tot_bytes; | |
470 | wdata->args.offset = file_offset; | |
471 | ||
472 | lock_kernel(); | |
473 | result = NFS_PROTO(inode)->commit(wdata); | |
474 | unlock_kernel(); | |
475 | ||
476 | if (result < 0 || memcmp(&first_verf.verifier, | |
477 | &wdata->verf.verifier, | |
478 | sizeof(first_verf.verifier)) != 0) | |
479 | goto sync_retry; | |
480 | } | |
481 | result = tot_bytes; | |
482 | ||
483 | out: | |
951a143b | 484 | nfs_end_data_update(inode); |
1da177e4 LT |
485 | nfs_writedata_free(wdata); |
486 | return result; | |
487 | ||
488 | sync_retry: | |
489 | wdata->args.stable = NFS_FILE_SYNC; | |
490 | goto retry; | |
491 | } | |
492 | ||
d4cc948b | 493 | /* |
1da177e4 LT |
494 | * Upon return, generic_file_direct_IO invalidates any cached pages |
495 | * that non-direct readers might access, so they will pick up these | |
496 | * writes immediately. | |
497 | */ | |
d4cc948b | 498 | static ssize_t nfs_direct_write(struct inode *inode, struct nfs_open_context *ctx, const struct iovec *iov, loff_t file_offset, unsigned long nr_segs) |
1da177e4 LT |
499 | { |
500 | ssize_t tot_bytes = 0; | |
501 | unsigned long seg = 0; | |
502 | ||
503 | while ((seg < nr_segs) && (tot_bytes >= 0)) { | |
504 | ssize_t result; | |
505 | int page_count; | |
506 | struct page **pages; | |
507 | const struct iovec *vec = &iov[seg++]; | |
508 | unsigned long user_addr = (unsigned long) vec->iov_base; | |
509 | size_t size = vec->iov_len; | |
510 | ||
511 | page_count = nfs_get_user_pages(WRITE, user_addr, size, &pages); | |
512 | if (page_count < 0) { | |
513 | nfs_free_user_pages(pages, 0, 0); | |
514 | if (tot_bytes > 0) | |
515 | break; | |
516 | return page_count; | |
517 | } | |
518 | ||
91d5b470 | 519 | nfs_add_stats(inode, NFSIOS_DIRECTWRITTENBYTES, size); |
1da177e4 LT |
520 | result = nfs_direct_write_seg(inode, ctx, user_addr, size, |
521 | file_offset, pages, page_count); | |
522 | nfs_free_user_pages(pages, page_count, 0); | |
523 | ||
524 | if (result <= 0) { | |
525 | if (tot_bytes > 0) | |
526 | break; | |
527 | return result; | |
528 | } | |
91d5b470 | 529 | nfs_add_stats(inode, NFSIOS_SERVERWRITTENBYTES, result); |
1da177e4 LT |
530 | tot_bytes += result; |
531 | file_offset += result; | |
532 | if (result < size) | |
533 | break; | |
534 | } | |
535 | return tot_bytes; | |
536 | } | |
537 | ||
1da177e4 LT |
538 | /** |
539 | * nfs_file_direct_read - file direct read operation for NFS files | |
540 | * @iocb: target I/O control block | |
541 | * @buf: user's buffer into which to read data | |
542 | * count: number of bytes to read | |
543 | * pos: byte offset in file where reading starts | |
544 | * | |
545 | * We use this function for direct reads instead of calling | |
546 | * generic_file_aio_read() in order to avoid gfar's check to see if | |
547 | * the request starts before the end of the file. For that check | |
548 | * to work, we must generate a GETATTR before each direct read, and | |
549 | * even then there is a window between the GETATTR and the subsequent | |
550 | * READ where the file size could change. So our preference is simply | |
551 | * to do all reads the application wants, and the server will take | |
552 | * care of managing the end of file boundary. | |
553 | * | |
554 | * This function also eliminates unnecessarily updating the file's | |
555 | * atime locally, as the NFS server sets the file's atime, and this | |
556 | * client must read the updated atime from the server back into its | |
557 | * cache. | |
558 | */ | |
d4cc948b | 559 | ssize_t nfs_file_direct_read(struct kiocb *iocb, char __user *buf, size_t count, loff_t pos) |
1da177e4 LT |
560 | { |
561 | ssize_t retval = -EINVAL; | |
562 | loff_t *ppos = &iocb->ki_pos; | |
563 | struct file *file = iocb->ki_filp; | |
564 | struct nfs_open_context *ctx = | |
565 | (struct nfs_open_context *) file->private_data; | |
1da177e4 LT |
566 | struct address_space *mapping = file->f_mapping; |
567 | struct inode *inode = mapping->host; | |
568 | struct iovec iov = { | |
569 | .iov_base = buf, | |
570 | .iov_len = count, | |
571 | }; | |
572 | ||
ce1a8e67 | 573 | dprintk("nfs: direct read(%s/%s, %lu@%Ld)\n", |
0bbacc40 CL |
574 | file->f_dentry->d_parent->d_name.name, |
575 | file->f_dentry->d_name.name, | |
ce1a8e67 | 576 | (unsigned long) count, (long long) pos); |
1da177e4 LT |
577 | |
578 | if (!is_sync_kiocb(iocb)) | |
579 | goto out; | |
580 | if (count < 0) | |
581 | goto out; | |
582 | retval = -EFAULT; | |
583 | if (!access_ok(VERIFY_WRITE, iov.iov_base, iov.iov_len)) | |
584 | goto out; | |
585 | retval = 0; | |
586 | if (!count) | |
587 | goto out; | |
588 | ||
29884df0 TM |
589 | retval = nfs_sync_mapping(mapping); |
590 | if (retval) | |
591 | goto out; | |
1da177e4 LT |
592 | |
593 | retval = nfs_direct_read(inode, ctx, &iov, pos, 1); | |
594 | if (retval > 0) | |
595 | *ppos = pos + retval; | |
596 | ||
597 | out: | |
598 | return retval; | |
599 | } | |
600 | ||
601 | /** | |
602 | * nfs_file_direct_write - file direct write operation for NFS files | |
603 | * @iocb: target I/O control block | |
604 | * @buf: user's buffer from which to write data | |
605 | * count: number of bytes to write | |
606 | * pos: byte offset in file where writing starts | |
607 | * | |
608 | * We use this function for direct writes instead of calling | |
609 | * generic_file_aio_write() in order to avoid taking the inode | |
610 | * semaphore and updating the i_size. The NFS server will set | |
611 | * the new i_size and this client must read the updated size | |
612 | * back into its cache. We let the server do generic write | |
613 | * parameter checking and report problems. | |
614 | * | |
615 | * We also avoid an unnecessary invocation of generic_osync_inode(), | |
616 | * as it is fairly meaningless to sync the metadata of an NFS file. | |
617 | * | |
618 | * We eliminate local atime updates, see direct read above. | |
619 | * | |
620 | * We avoid unnecessary page cache invalidations for normal cached | |
621 | * readers of this file. | |
622 | * | |
623 | * Note that O_APPEND is not supported for NFS direct writes, as there | |
624 | * is no atomic O_APPEND write facility in the NFS protocol. | |
625 | */ | |
d4cc948b | 626 | ssize_t nfs_file_direct_write(struct kiocb *iocb, const char __user *buf, size_t count, loff_t pos) |
1da177e4 | 627 | { |
ce1a8e67 | 628 | ssize_t retval; |
1da177e4 LT |
629 | struct file *file = iocb->ki_filp; |
630 | struct nfs_open_context *ctx = | |
631 | (struct nfs_open_context *) file->private_data; | |
1da177e4 LT |
632 | struct address_space *mapping = file->f_mapping; |
633 | struct inode *inode = mapping->host; | |
634 | struct iovec iov = { | |
635 | .iov_base = (char __user *)buf, | |
1da177e4 LT |
636 | }; |
637 | ||
ce1a8e67 | 638 | dfprintk(VFS, "nfs: direct write(%s/%s, %lu@%Ld)\n", |
0bbacc40 | 639 | file->f_dentry->d_parent->d_name.name, |
ce1a8e67 CL |
640 | file->f_dentry->d_name.name, |
641 | (unsigned long) count, (long long) pos); | |
1da177e4 | 642 | |
ce1a8e67 | 643 | retval = -EINVAL; |
1da177e4 LT |
644 | if (!is_sync_kiocb(iocb)) |
645 | goto out; | |
ce1a8e67 CL |
646 | |
647 | retval = generic_write_checks(file, &pos, &count, 0); | |
648 | if (retval) | |
1da177e4 | 649 | goto out; |
ce1a8e67 CL |
650 | |
651 | retval = -EINVAL; | |
652 | if ((ssize_t) count < 0) | |
1da177e4 | 653 | goto out; |
1da177e4 LT |
654 | retval = 0; |
655 | if (!count) | |
656 | goto out; | |
ce1a8e67 CL |
657 | iov.iov_len = count, |
658 | ||
659 | retval = -EFAULT; | |
660 | if (!access_ok(VERIFY_READ, iov.iov_base, iov.iov_len)) | |
661 | goto out; | |
1da177e4 | 662 | |
29884df0 TM |
663 | retval = nfs_sync_mapping(mapping); |
664 | if (retval) | |
665 | goto out; | |
1da177e4 LT |
666 | |
667 | retval = nfs_direct_write(inode, ctx, &iov, pos, 1); | |
668 | if (mapping->nrpages) | |
669 | invalidate_inode_pages2(mapping); | |
670 | if (retval > 0) | |
ce1a8e67 | 671 | iocb->ki_pos = pos + retval; |
1da177e4 LT |
672 | |
673 | out: | |
674 | return retval; | |
675 | } | |
676 | ||
677 | int nfs_init_directcache(void) | |
678 | { | |
679 | nfs_direct_cachep = kmem_cache_create("nfs_direct_cache", | |
680 | sizeof(struct nfs_direct_req), | |
681 | 0, SLAB_RECLAIM_ACCOUNT, | |
682 | NULL, NULL); | |
683 | if (nfs_direct_cachep == NULL) | |
684 | return -ENOMEM; | |
685 | ||
686 | return 0; | |
687 | } | |
688 | ||
689 | void nfs_destroy_directcache(void) | |
690 | { | |
691 | if (kmem_cache_destroy(nfs_direct_cachep)) | |
692 | printk(KERN_INFO "nfs_direct_cache: not all structures were freed\n"); | |
693 | } |