aboutsummaryrefslogtreecommitdiffstats
path: root/fs/nfs/pagelist.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /fs/nfs/pagelist.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'fs/nfs/pagelist.c')
-rw-r--r--fs/nfs/pagelist.c309
1 files changed, 309 insertions, 0 deletions
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
new file mode 100644
index 000000000000..4f1ba723848d
--- /dev/null
+++ b/fs/nfs/pagelist.c
@@ -0,0 +1,309 @@
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/config.h>
13#include <linux/slab.h>
14#include <linux/file.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#define NFS_PARANOIA 1
23
24static kmem_cache_t *nfs_page_cachep;
25
26static inline struct nfs_page *
27nfs_page_alloc(void)
28{
29 struct nfs_page *p;
30 p = kmem_cache_alloc(nfs_page_cachep, SLAB_KERNEL);
31 if (p) {
32 memset(p, 0, sizeof(*p));
33 INIT_LIST_HEAD(&p->wb_list);
34 }
35 return p;
36}
37
38static inline void
39nfs_page_free(struct nfs_page *p)
40{
41 kmem_cache_free(nfs_page_cachep, p);
42}
43
44/**
45 * nfs_create_request - Create an NFS read/write request.
46 * @file: file descriptor to use
47 * @inode: inode to which the request is attached
48 * @page: page to write
49 * @offset: starting offset within the page for the write
50 * @count: number of bytes to read/write
51 *
52 * The page must be locked by the caller. This makes sure we never
53 * create two different requests for the same page, and avoids
54 * a possible deadlock when we reach the hard limit on the number
55 * of dirty pages.
56 * User should ensure it is safe to sleep in this function.
57 */
58struct nfs_page *
59nfs_create_request(struct nfs_open_context *ctx, struct inode *inode,
60 struct page *page,
61 unsigned int offset, unsigned int count)
62{
63 struct nfs_server *server = NFS_SERVER(inode);
64 struct nfs_page *req;
65
66 /* Deal with hard limits. */
67 for (;;) {
68 /* try to allocate the request struct */
69 req = nfs_page_alloc();
70 if (req != NULL)
71 break;
72
73 /* Try to free up at least one request in order to stay
74 * below the hard limit
75 */
76 if (signalled() && (server->flags & NFS_MOUNT_INTR))
77 return ERR_PTR(-ERESTARTSYS);
78 yield();
79 }
80
81 /* Initialize the request struct. Initially, we assume a
82 * long write-back delay. This will be adjusted in
83 * update_nfs_request below if the region is not locked. */
84 req->wb_page = page;
85 atomic_set(&req->wb_complete, 0);
86 req->wb_index = page->index;
87 page_cache_get(page);
88 req->wb_offset = offset;
89 req->wb_pgbase = offset;
90 req->wb_bytes = count;
91 atomic_set(&req->wb_count, 1);
92 req->wb_context = get_nfs_open_context(ctx);
93
94 return req;
95}
96
97/**
98 * nfs_unlock_request - Unlock request and wake up sleepers.
99 * @req:
100 */
101void nfs_unlock_request(struct nfs_page *req)
102{
103 if (!NFS_WBACK_BUSY(req)) {
104 printk(KERN_ERR "NFS: Invalid unlock attempted\n");
105 BUG();
106 }
107 smp_mb__before_clear_bit();
108 clear_bit(PG_BUSY, &req->wb_flags);
109 smp_mb__after_clear_bit();
110 wake_up_all(&req->wb_context->waitq);
111 nfs_release_request(req);
112}
113
114/**
115 * nfs_clear_request - Free up all resources allocated to the request
116 * @req:
117 *
118 * Release page resources associated with a write request after it
119 * has completed.
120 */
121void nfs_clear_request(struct nfs_page *req)
122{
123 if (req->wb_page) {
124 page_cache_release(req->wb_page);
125 req->wb_page = NULL;
126 }
127}
128
129
130/**
131 * nfs_release_request - Release the count on an NFS read/write request
132 * @req: request to release
133 *
134 * Note: Should never be called with the spinlock held!
135 */
136void
137nfs_release_request(struct nfs_page *req)
138{
139 if (!atomic_dec_and_test(&req->wb_count))
140 return;
141
142#ifdef NFS_PARANOIA
143 BUG_ON (!list_empty(&req->wb_list));
144 BUG_ON (NFS_WBACK_BUSY(req));
145#endif
146
147 /* Release struct file or cached credential */
148 nfs_clear_request(req);
149 put_nfs_open_context(req->wb_context);
150 nfs_page_free(req);
151}
152
153/**
154 * nfs_list_add_request - Insert a request into a sorted list
155 * @req: request
156 * @head: head of list into which to insert the request.
157 *
158 * Note that the wb_list is sorted by page index in order to facilitate
159 * coalescing of requests.
160 * We use an insertion sort that is optimized for the case of appended
161 * writes.
162 */
163void
164nfs_list_add_request(struct nfs_page *req, struct list_head *head)
165{
166 struct list_head *pos;
167
168#ifdef NFS_PARANOIA
169 if (!list_empty(&req->wb_list)) {
170 printk(KERN_ERR "NFS: Add to list failed!\n");
171 BUG();
172 }
173#endif
174 list_for_each_prev(pos, head) {
175 struct nfs_page *p = nfs_list_entry(pos);
176 if (p->wb_index < req->wb_index)
177 break;
178 }
179 list_add(&req->wb_list, pos);
180 req->wb_list_head = head;
181}
182
183/**
184 * nfs_wait_on_request - Wait for a request to complete.
185 * @req: request to wait upon.
186 *
187 * Interruptible by signals only if mounted with intr flag.
188 * The user is responsible for holding a count on the request.
189 */
190int
191nfs_wait_on_request(struct nfs_page *req)
192{
193 struct inode *inode = req->wb_context->dentry->d_inode;
194 struct rpc_clnt *clnt = NFS_CLIENT(inode);
195
196 if (!NFS_WBACK_BUSY(req))
197 return 0;
198 return nfs_wait_event(clnt, req->wb_context->waitq, !NFS_WBACK_BUSY(req));
199}
200
201/**
202 * nfs_coalesce_requests - Split coalesced requests out from a list.
203 * @head: source list
204 * @dst: destination list
205 * @nmax: maximum number of requests to coalesce
206 *
207 * Moves a maximum of 'nmax' elements from one list to another.
208 * The elements are checked to ensure that they form a contiguous set
209 * of pages, and that the RPC credentials are the same.
210 */
211int
212nfs_coalesce_requests(struct list_head *head, struct list_head *dst,
213 unsigned int nmax)
214{
215 struct nfs_page *req = NULL;
216 unsigned int npages = 0;
217
218 while (!list_empty(head)) {
219 struct nfs_page *prev = req;
220
221 req = nfs_list_entry(head->next);
222 if (prev) {
223 if (req->wb_context->cred != prev->wb_context->cred)
224 break;
225 if (req->wb_context->lockowner != prev->wb_context->lockowner)
226 break;
227 if (req->wb_context->state != prev->wb_context->state)
228 break;
229 if (req->wb_index != (prev->wb_index + 1))
230 break;
231
232 if (req->wb_pgbase != 0)
233 break;
234 }
235 nfs_list_remove_request(req);
236 nfs_list_add_request(req, dst);
237 npages++;
238 if (req->wb_pgbase + req->wb_bytes != PAGE_CACHE_SIZE)
239 break;
240 if (npages >= nmax)
241 break;
242 }
243 return npages;
244}
245
246/**
247 * nfs_scan_list - Scan a list for matching requests
248 * @head: One of the NFS inode request lists
249 * @dst: Destination list
250 * @idx_start: lower bound of page->index to scan
251 * @npages: idx_start + npages sets the upper bound to scan.
252 *
253 * Moves elements from one of the inode request lists.
254 * If the number of requests is set to 0, the entire address_space
255 * starting at index idx_start, is scanned.
256 * The requests are *not* checked to ensure that they form a contiguous set.
257 * You must be holding the inode's req_lock when calling this function
258 */
259int
260nfs_scan_list(struct list_head *head, struct list_head *dst,
261 unsigned long idx_start, unsigned int npages)
262{
263 struct list_head *pos, *tmp;
264 struct nfs_page *req;
265 unsigned long idx_end;
266 int res;
267
268 res = 0;
269 if (npages == 0)
270 idx_end = ~0;
271 else
272 idx_end = idx_start + npages - 1;
273
274 list_for_each_safe(pos, tmp, head) {
275
276 req = nfs_list_entry(pos);
277
278 if (req->wb_index < idx_start)
279 continue;
280 if (req->wb_index > idx_end)
281 break;
282
283 if (!nfs_lock_request(req))
284 continue;
285 nfs_list_remove_request(req);
286 nfs_list_add_request(req, dst);
287 res++;
288 }
289 return res;
290}
291
292int nfs_init_nfspagecache(void)
293{
294 nfs_page_cachep = kmem_cache_create("nfs_page",
295 sizeof(struct nfs_page),
296 0, SLAB_HWCACHE_ALIGN,
297 NULL, NULL);
298 if (nfs_page_cachep == NULL)
299 return -ENOMEM;
300
301 return 0;
302}
303
304void nfs_destroy_nfspagecache(void)
305{
306 if (kmem_cache_destroy(nfs_page_cachep))
307 printk(KERN_INFO "nfs_page: not all structures were freed\n");
308}
309