Merge branch 'timers-cleanup-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / nfs / pagelist.c
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/nfs3.h>
17 #include <linux/nfs4.h>
18 #include <linux/nfs_page.h>
19 #include <linux/nfs_fs.h>
20 #include <linux/nfs_mount.h>
21
22 #include "internal.h"
23 #include "pnfs.h"
24
25 static struct kmem_cache *nfs_page_cachep;
26
27 static inline struct nfs_page *
28 nfs_page_alloc(void)
29 {
30 struct nfs_page *p = kmem_cache_zalloc(nfs_page_cachep, GFP_KERNEL);
31 if (p)
32 INIT_LIST_HEAD(&p->wb_list);
33 return p;
34 }
35
36 static inline void
37 nfs_page_free(struct nfs_page *p)
38 {
39 kmem_cache_free(nfs_page_cachep, p);
40 }
41
42 /**
43 * nfs_create_request - Create an NFS read/write request.
44 * @file: file descriptor to use
45 * @inode: inode to which the request is attached
46 * @page: page to write
47 * @offset: starting offset within the page for the write
48 * @count: number of bytes to read/write
49 *
50 * The page must be locked by the caller. This makes sure we never
51 * create two different requests for the same page.
52 * User should ensure it is safe to sleep in this function.
53 */
54 struct nfs_page *
55 nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
56 struct page *page,
57 unsigned int offset, unsigned int count)
58 {
59 struct nfs_page *req;
60
61 /* try to allocate the request struct */
62 req = nfs_page_alloc();
63 if (req == NULL)
64 return ERR_PTR(-ENOMEM);
65
66 /* get lock context early so we can deal with alloc failures */
67 req->wb_lock_context = nfs_get_lock_context(ctx);
68 if (req->wb_lock_context == NULL) {
69 nfs_page_free(req);
70 return ERR_PTR(-ENOMEM);
71 }
72
73 /* Initialize the request struct. Initially, we assume a
74 * long write-back delay. This will be adjusted in
75 * update_nfs_request below if the region is not locked. */
76 req->wb_page = page;
77 atomic_set(&req->wb_complete, 0);
78 req->wb_index = page->index;
79 page_cache_get(page);
80 BUG_ON(PagePrivate(page));
81 BUG_ON(!PageLocked(page));
82 BUG_ON(page->mapping->host != inode);
83 req->wb_offset = offset;
84 req->wb_pgbase = offset;
85 req->wb_bytes = count;
86 req->wb_context = get_nfs_open_context(ctx);
87 kref_init(&req->wb_kref);
88 return req;
89 }
90
91 /**
92 * nfs_unlock_request - Unlock request and wake up sleepers.
93 * @req:
94 */
95 void nfs_unlock_request(struct nfs_page *req)
96 {
97 if (!NFS_WBACK_BUSY(req)) {
98 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
99 BUG();
100 }
101 smp_mb__before_clear_bit();
102 clear_bit(PG_BUSY, &req->wb_flags);
103 smp_mb__after_clear_bit();
104 wake_up_bit(&req->wb_flags, PG_BUSY);
105 nfs_release_request(req);
106 }
107
108 /**
109 * nfs_set_page_tag_locked - Tag a request as locked
110 * @req:
111 */
112 int nfs_set_page_tag_locked(struct nfs_page *req)
113 {
114 if (!nfs_lock_request_dontget(req))
115 return 0;
116 if (test_bit(PG_MAPPED, &req->wb_flags))
117 radix_tree_tag_set(&NFS_I(req->wb_context->path.dentry->d_inode)->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
118 return 1;
119 }
120
121 /**
122 * nfs_clear_page_tag_locked - Clear request tag and wake up sleepers
123 */
124 void nfs_clear_page_tag_locked(struct nfs_page *req)
125 {
126 if (test_bit(PG_MAPPED, &req->wb_flags)) {
127 struct inode *inode = req->wb_context->path.dentry->d_inode;
128 struct nfs_inode *nfsi = NFS_I(inode);
129
130 spin_lock(&inode->i_lock);
131 radix_tree_tag_clear(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED);
132 nfs_unlock_request(req);
133 spin_unlock(&inode->i_lock);
134 } else
135 nfs_unlock_request(req);
136 }
137
138 /*
139 * nfs_clear_request - Free up all resources allocated to the request
140 * @req:
141 *
142 * Release page and open context resources associated with a read/write
143 * request after it has completed.
144 */
145 static void nfs_clear_request(struct nfs_page *req)
146 {
147 struct page *page = req->wb_page;
148 struct nfs_open_context *ctx = req->wb_context;
149 struct nfs_lock_context *l_ctx = req->wb_lock_context;
150
151 if (page != NULL) {
152 page_cache_release(page);
153 req->wb_page = NULL;
154 }
155 if (l_ctx != NULL) {
156 nfs_put_lock_context(l_ctx);
157 req->wb_lock_context = NULL;
158 }
159 if (ctx != NULL) {
160 put_nfs_open_context(ctx);
161 req->wb_context = NULL;
162 }
163 }
164
165
166 /**
167 * nfs_release_request - Release the count on an NFS read/write request
168 * @req: request to release
169 *
170 * Note: Should never be called with the spinlock held!
171 */
172 static void nfs_free_request(struct kref *kref)
173 {
174 struct nfs_page *req = container_of(kref, struct nfs_page, wb_kref);
175
176 /* Release struct file and open context */
177 nfs_clear_request(req);
178 nfs_page_free(req);
179 }
180
181 void nfs_release_request(struct nfs_page *req)
182 {
183 kref_put(&req->wb_kref, nfs_free_request);
184 }
185
186 static int nfs_wait_bit_uninterruptible(void *word)
187 {
188 io_schedule();
189 return 0;
190 }
191
192 /**
193 * nfs_wait_on_request - Wait for a request to complete.
194 * @req: request to wait upon.
195 *
196 * Interruptible by fatal signals only.
197 * The user is responsible for holding a count on the request.
198 */
199 int
200 nfs_wait_on_request(struct nfs_page *req)
201 {
202 return wait_on_bit(&req->wb_flags, PG_BUSY,
203 nfs_wait_bit_uninterruptible,
204 TASK_UNINTERRUPTIBLE);
205 }
206
207 bool nfs_generic_pg_test(struct nfs_pageio_descriptor *desc, struct nfs_page *prev, struct nfs_page *req)
208 {
209 /*
210 * FIXME: ideally we should be able to coalesce all requests
211 * that are not block boundary aligned, but currently this
212 * is problematic for the case of bsize < PAGE_CACHE_SIZE,
213 * since nfs_flush_multi and nfs_pagein_multi assume you
214 * can have only one struct nfs_page.
215 */
216 if (desc->pg_bsize < PAGE_SIZE)
217 return 0;
218
219 return desc->pg_count + req->wb_bytes <= desc->pg_bsize;
220 }
221 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
222
223 /**
224 * nfs_pageio_init - initialise a page io descriptor
225 * @desc: pointer to descriptor
226 * @inode: pointer to inode
227 * @doio: pointer to io function
228 * @bsize: io block size
229 * @io_flags: extra parameters for the io function
230 */
231 void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
232 struct inode *inode,
233 int (*doio)(struct nfs_pageio_descriptor *),
234 size_t bsize,
235 int io_flags)
236 {
237 INIT_LIST_HEAD(&desc->pg_list);
238 desc->pg_bytes_written = 0;
239 desc->pg_count = 0;
240 desc->pg_bsize = bsize;
241 desc->pg_base = 0;
242 desc->pg_moreio = 0;
243 desc->pg_inode = inode;
244 desc->pg_doio = doio;
245 desc->pg_ioflags = io_flags;
246 desc->pg_error = 0;
247 desc->pg_lseg = NULL;
248 desc->pg_test = nfs_generic_pg_test;
249 pnfs_pageio_init(desc, inode);
250 }
251
252 /**
253 * nfs_can_coalesce_requests - test two requests for compatibility
254 * @prev: pointer to nfs_page
255 * @req: pointer to nfs_page
256 *
257 * The nfs_page structures 'prev' and 'req' are compared to ensure that the
258 * page data area they describe is contiguous, and that their RPC
259 * credentials, NFSv4 open state, and lockowners are the same.
260 *
261 * Return 'true' if this is the case, else return 'false'.
262 */
263 static bool nfs_can_coalesce_requests(struct nfs_page *prev,
264 struct nfs_page *req,
265 struct nfs_pageio_descriptor *pgio)
266 {
267 if (req->wb_context->cred != prev->wb_context->cred)
268 return false;
269 if (req->wb_lock_context->lockowner != prev->wb_lock_context->lockowner)
270 return false;
271 if (req->wb_context->state != prev->wb_context->state)
272 return false;
273 if (req->wb_index != (prev->wb_index + 1))
274 return false;
275 if (req->wb_pgbase != 0)
276 return false;
277 if (prev->wb_pgbase + prev->wb_bytes != PAGE_CACHE_SIZE)
278 return false;
279 return pgio->pg_test(pgio, prev, req);
280 }
281
282 /**
283 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
284 * @desc: destination io descriptor
285 * @req: request
286 *
287 * Returns true if the request 'req' was successfully coalesced into the
288 * existing list of pages 'desc'.
289 */
290 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
291 struct nfs_page *req)
292 {
293 if (desc->pg_count != 0) {
294 struct nfs_page *prev;
295
296 prev = nfs_list_entry(desc->pg_list.prev);
297 if (!nfs_can_coalesce_requests(prev, req, desc))
298 return 0;
299 } else {
300 desc->pg_base = req->wb_pgbase;
301 }
302 nfs_list_remove_request(req);
303 nfs_list_add_request(req, &desc->pg_list);
304 desc->pg_count += req->wb_bytes;
305 return 1;
306 }
307
308 /*
309 * Helper for nfs_pageio_add_request and nfs_pageio_complete
310 */
311 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
312 {
313 if (!list_empty(&desc->pg_list)) {
314 int error = desc->pg_doio(desc);
315 if (error < 0)
316 desc->pg_error = error;
317 else
318 desc->pg_bytes_written += desc->pg_count;
319 }
320 if (list_empty(&desc->pg_list)) {
321 desc->pg_count = 0;
322 desc->pg_base = 0;
323 }
324 }
325
326 /**
327 * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
328 * @desc: destination io descriptor
329 * @req: request
330 *
331 * Returns true if the request 'req' was successfully coalesced into the
332 * existing list of pages 'desc'.
333 */
334 int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
335 struct nfs_page *req)
336 {
337 while (!nfs_pageio_do_add_request(desc, req)) {
338 desc->pg_moreio = 1;
339 nfs_pageio_doio(desc);
340 if (desc->pg_error < 0)
341 return 0;
342 desc->pg_moreio = 0;
343 }
344 return 1;
345 }
346
347 /**
348 * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
349 * @desc: pointer to io descriptor
350 */
351 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
352 {
353 nfs_pageio_doio(desc);
354 }
355
356 /**
357 * nfs_pageio_cond_complete - Conditional I/O completion
358 * @desc: pointer to io descriptor
359 * @index: page index
360 *
361 * It is important to ensure that processes don't try to take locks
362 * on non-contiguous ranges of pages as that might deadlock. This
363 * function should be called before attempting to wait on a locked
364 * nfs_page. It will complete the I/O if the page index 'index'
365 * is not contiguous with the existing list of pages in 'desc'.
366 */
367 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
368 {
369 if (!list_empty(&desc->pg_list)) {
370 struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
371 if (index != prev->wb_index + 1)
372 nfs_pageio_doio(desc);
373 }
374 }
375
376 #define NFS_SCAN_MAXENTRIES 16
377 /**
378 * nfs_scan_list - Scan a list for matching requests
379 * @nfsi: NFS inode
380 * @dst: Destination list
381 * @idx_start: lower bound of page->index to scan
382 * @npages: idx_start + npages sets the upper bound to scan.
383 * @tag: tag to scan for
384 *
385 * Moves elements from one of the inode request lists.
386 * If the number of requests is set to 0, the entire address_space
387 * starting at index idx_start, is scanned.
388 * The requests are *not* checked to ensure that they form a contiguous set.
389 * You must be holding the inode's i_lock when calling this function
390 */
391 int nfs_scan_list(struct nfs_inode *nfsi,
392 struct list_head *dst, pgoff_t idx_start,
393 unsigned int npages, int tag)
394 {
395 struct nfs_page *pgvec[NFS_SCAN_MAXENTRIES];
396 struct nfs_page *req;
397 pgoff_t idx_end;
398 int found, i;
399 int res;
400 struct list_head *list;
401
402 res = 0;
403 if (npages == 0)
404 idx_end = ~0;
405 else
406 idx_end = idx_start + npages - 1;
407
408 for (;;) {
409 found = radix_tree_gang_lookup_tag(&nfsi->nfs_page_tree,
410 (void **)&pgvec[0], idx_start,
411 NFS_SCAN_MAXENTRIES, tag);
412 if (found <= 0)
413 break;
414 for (i = 0; i < found; i++) {
415 req = pgvec[i];
416 if (req->wb_index > idx_end)
417 goto out;
418 idx_start = req->wb_index + 1;
419 if (nfs_set_page_tag_locked(req)) {
420 kref_get(&req->wb_kref);
421 radix_tree_tag_clear(&nfsi->nfs_page_tree,
422 req->wb_index, tag);
423 list = pnfs_choose_commit_list(req, dst);
424 nfs_list_add_request(req, list);
425 res++;
426 if (res == INT_MAX)
427 goto out;
428 }
429 }
430 /* for latency reduction */
431 cond_resched_lock(&nfsi->vfs_inode.i_lock);
432 }
433 out:
434 return res;
435 }
436
437 int __init nfs_init_nfspagecache(void)
438 {
439 nfs_page_cachep = kmem_cache_create("nfs_page",
440 sizeof(struct nfs_page),
441 0, SLAB_HWCACHE_ALIGN,
442 NULL);
443 if (nfs_page_cachep == NULL)
444 return -ENOMEM;
445
446 return 0;
447 }
448
449 void nfs_destroy_nfspagecache(void)
450 {
451 kmem_cache_destroy(nfs_page_cachep);
452 }
453