2 * linux/fs/nfs/pagelist.c
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.
8 * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
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>
25 static struct kmem_cache
*nfs_page_cachep
;
27 static inline struct nfs_page
*
30 struct nfs_page
*p
= kmem_cache_zalloc(nfs_page_cachep
, GFP_KERNEL
);
32 INIT_LIST_HEAD(&p
->wb_list
);
37 nfs_page_free(struct nfs_page
*p
)
39 kmem_cache_free(nfs_page_cachep
, p
);
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
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.
55 nfs_create_request(struct nfs_open_context
*ctx
, struct inode
*inode
,
57 unsigned int offset
, unsigned int count
)
61 /* try to allocate the request struct */
62 req
= nfs_page_alloc();
64 return ERR_PTR(-ENOMEM
);
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
) {
70 return ERR_PTR(-ENOMEM
);
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. */
77 atomic_set(&req
->wb_complete
, 0);
78 req
->wb_index
= page
->index
;
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
);
92 * nfs_unlock_request - Unlock request and wake up sleepers.
95 void nfs_unlock_request(struct nfs_page
*req
)
97 if (!NFS_WBACK_BUSY(req
)) {
98 printk(KERN_ERR
"NFS: Invalid unlock attempted\n");
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
);
109 * nfs_set_page_tag_locked - Tag a request as locked
112 int nfs_set_page_tag_locked(struct nfs_page
*req
)
114 if (!nfs_lock_request_dontget(req
))
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
);
122 * nfs_clear_page_tag_locked - Clear request tag and wake up sleepers
124 void nfs_clear_page_tag_locked(struct nfs_page
*req
)
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
);
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
);
135 nfs_unlock_request(req
);
139 * nfs_clear_request - Free up all resources allocated to the request
142 * Release page and open context resources associated with a read/write
143 * request after it has completed.
145 static void nfs_clear_request(struct nfs_page
*req
)
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
;
152 page_cache_release(page
);
156 nfs_put_lock_context(l_ctx
);
157 req
->wb_lock_context
= NULL
;
160 put_nfs_open_context(ctx
);
161 req
->wb_context
= NULL
;
167 * nfs_release_request - Release the count on an NFS read/write request
168 * @req: request to release
170 * Note: Should never be called with the spinlock held!
172 static void nfs_free_request(struct kref
*kref
)
174 struct nfs_page
*req
= container_of(kref
, struct nfs_page
, wb_kref
);
176 /* Release struct file and open context */
177 nfs_clear_request(req
);
181 void nfs_release_request(struct nfs_page
*req
)
183 kref_put(&req
->wb_kref
, nfs_free_request
);
186 static int nfs_wait_bit_uninterruptible(void *word
)
193 * nfs_wait_on_request - Wait for a request to complete.
194 * @req: request to wait upon.
196 * Interruptible by fatal signals only.
197 * The user is responsible for holding a count on the request.
200 nfs_wait_on_request(struct nfs_page
*req
)
202 return wait_on_bit(&req
->wb_flags
, PG_BUSY
,
203 nfs_wait_bit_uninterruptible
,
204 TASK_UNINTERRUPTIBLE
);
207 static bool nfs_generic_pg_test(struct nfs_pageio_descriptor
*desc
, struct nfs_page
*prev
, struct nfs_page
*req
)
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.
216 if (desc
->pg_bsize
< PAGE_SIZE
)
219 return desc
->pg_count
+ req
->wb_bytes
<= desc
->pg_bsize
;
223 * nfs_pageio_init - initialise a page io descriptor
224 * @desc: pointer to descriptor
225 * @inode: pointer to inode
226 * @doio: pointer to io function
227 * @bsize: io block size
228 * @io_flags: extra parameters for the io function
230 void nfs_pageio_init(struct nfs_pageio_descriptor
*desc
,
232 int (*doio
)(struct nfs_pageio_descriptor
*),
236 INIT_LIST_HEAD(&desc
->pg_list
);
237 desc
->pg_bytes_written
= 0;
239 desc
->pg_bsize
= bsize
;
242 desc
->pg_inode
= inode
;
243 desc
->pg_doio
= doio
;
244 desc
->pg_ioflags
= io_flags
;
246 desc
->pg_lseg
= NULL
;
247 desc
->pg_test
= nfs_generic_pg_test
;
248 pnfs_pageio_init(desc
, inode
);
252 * nfs_can_coalesce_requests - test two requests for compatibility
253 * @prev: pointer to nfs_page
254 * @req: pointer to nfs_page
256 * The nfs_page structures 'prev' and 'req' are compared to ensure that the
257 * page data area they describe is contiguous, and that their RPC
258 * credentials, NFSv4 open state, and lockowners are the same.
260 * Return 'true' if this is the case, else return 'false'.
262 static bool nfs_can_coalesce_requests(struct nfs_page
*prev
,
263 struct nfs_page
*req
,
264 struct nfs_pageio_descriptor
*pgio
)
266 if (req
->wb_context
->cred
!= prev
->wb_context
->cred
)
268 if (req
->wb_lock_context
->lockowner
!= prev
->wb_lock_context
->lockowner
)
270 if (req
->wb_context
->state
!= prev
->wb_context
->state
)
272 if (req
->wb_index
!= (prev
->wb_index
+ 1))
274 if (req
->wb_pgbase
!= 0)
276 if (prev
->wb_pgbase
+ prev
->wb_bytes
!= PAGE_CACHE_SIZE
)
278 return pgio
->pg_test(pgio
, prev
, req
);
282 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
283 * @desc: destination io descriptor
286 * Returns true if the request 'req' was successfully coalesced into the
287 * existing list of pages 'desc'.
289 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor
*desc
,
290 struct nfs_page
*req
)
292 if (desc
->pg_count
!= 0) {
293 struct nfs_page
*prev
;
295 prev
= nfs_list_entry(desc
->pg_list
.prev
);
296 if (!nfs_can_coalesce_requests(prev
, req
, desc
))
299 desc
->pg_base
= req
->wb_pgbase
;
301 nfs_list_remove_request(req
);
302 nfs_list_add_request(req
, &desc
->pg_list
);
303 desc
->pg_count
+= req
->wb_bytes
;
308 * Helper for nfs_pageio_add_request and nfs_pageio_complete
310 static void nfs_pageio_doio(struct nfs_pageio_descriptor
*desc
)
312 if (!list_empty(&desc
->pg_list
)) {
313 int error
= desc
->pg_doio(desc
);
315 desc
->pg_error
= error
;
317 desc
->pg_bytes_written
+= desc
->pg_count
;
319 if (list_empty(&desc
->pg_list
)) {
326 * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
327 * @desc: destination io descriptor
330 * Returns true if the request 'req' was successfully coalesced into the
331 * existing list of pages 'desc'.
333 int nfs_pageio_add_request(struct nfs_pageio_descriptor
*desc
,
334 struct nfs_page
*req
)
336 while (!nfs_pageio_do_add_request(desc
, req
)) {
338 nfs_pageio_doio(desc
);
339 if (desc
->pg_error
< 0)
347 * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
348 * @desc: pointer to io descriptor
350 void nfs_pageio_complete(struct nfs_pageio_descriptor
*desc
)
352 nfs_pageio_doio(desc
);
356 * nfs_pageio_cond_complete - Conditional I/O completion
357 * @desc: pointer to io descriptor
360 * It is important to ensure that processes don't try to take locks
361 * on non-contiguous ranges of pages as that might deadlock. This
362 * function should be called before attempting to wait on a locked
363 * nfs_page. It will complete the I/O if the page index 'index'
364 * is not contiguous with the existing list of pages in 'desc'.
366 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor
*desc
, pgoff_t index
)
368 if (!list_empty(&desc
->pg_list
)) {
369 struct nfs_page
*prev
= nfs_list_entry(desc
->pg_list
.prev
);
370 if (index
!= prev
->wb_index
+ 1)
371 nfs_pageio_doio(desc
);
375 #define NFS_SCAN_MAXENTRIES 16
377 * nfs_scan_list - Scan a list for matching requests
379 * @dst: Destination list
380 * @idx_start: lower bound of page->index to scan
381 * @npages: idx_start + npages sets the upper bound to scan.
382 * @tag: tag to scan for
384 * Moves elements from one of the inode request lists.
385 * If the number of requests is set to 0, the entire address_space
386 * starting at index idx_start, is scanned.
387 * The requests are *not* checked to ensure that they form a contiguous set.
388 * You must be holding the inode's i_lock when calling this function
390 int nfs_scan_list(struct nfs_inode
*nfsi
,
391 struct list_head
*dst
, pgoff_t idx_start
,
392 unsigned int npages
, int tag
)
394 struct nfs_page
*pgvec
[NFS_SCAN_MAXENTRIES
];
395 struct nfs_page
*req
;
399 struct list_head
*list
;
405 idx_end
= idx_start
+ npages
- 1;
408 found
= radix_tree_gang_lookup_tag(&nfsi
->nfs_page_tree
,
409 (void **)&pgvec
[0], idx_start
,
410 NFS_SCAN_MAXENTRIES
, tag
);
413 for (i
= 0; i
< found
; i
++) {
415 if (req
->wb_index
> idx_end
)
417 idx_start
= req
->wb_index
+ 1;
418 if (nfs_set_page_tag_locked(req
)) {
419 kref_get(&req
->wb_kref
);
420 radix_tree_tag_clear(&nfsi
->nfs_page_tree
,
422 list
= pnfs_choose_commit_list(req
, dst
);
423 nfs_list_add_request(req
, list
);
429 /* for latency reduction */
430 cond_resched_lock(&nfsi
->vfs_inode
.i_lock
);
436 int __init
nfs_init_nfspagecache(void)
438 nfs_page_cachep
= kmem_cache_create("nfs_page",
439 sizeof(struct nfs_page
),
440 0, SLAB_HWCACHE_ALIGN
,
442 if (nfs_page_cachep
== NULL
)
448 void nfs_destroy_nfspagecache(void)
450 kmem_cache_destroy(nfs_page_cachep
);