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>
24 static struct kmem_cache
*nfs_page_cachep
;
26 static inline struct nfs_page
*
30 p
= kmem_cache_alloc(nfs_page_cachep
, GFP_KERNEL
);
32 memset(p
, 0, sizeof(*p
));
33 INIT_LIST_HEAD(&p
->wb_list
);
39 nfs_page_free(struct nfs_page
*p
)
41 kmem_cache_free(nfs_page_cachep
, p
);
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
52 * The page must be locked by the caller. This makes sure we never
53 * create two different requests for the same page.
54 * User should ensure it is safe to sleep in this function.
57 nfs_create_request(struct nfs_open_context
*ctx
, struct inode
*inode
,
59 unsigned int offset
, unsigned int count
)
61 struct nfs_server
*server
= NFS_SERVER(inode
);
65 /* try to allocate the request struct */
66 req
= nfs_page_alloc();
70 if (signalled() && (server
->flags
& NFS_MOUNT_INTR
))
71 return ERR_PTR(-ERESTARTSYS
);
75 /* Initialize the request struct. Initially, we assume a
76 * long write-back delay. This will be adjusted in
77 * update_nfs_request below if the region is not locked. */
79 atomic_set(&req
->wb_complete
, 0);
80 req
->wb_index
= page
->index
;
82 BUG_ON(PagePrivate(page
));
83 BUG_ON(!PageLocked(page
));
84 BUG_ON(page
->mapping
->host
!= inode
);
85 req
->wb_offset
= offset
;
86 req
->wb_pgbase
= offset
;
87 req
->wb_bytes
= count
;
88 atomic_set(&req
->wb_count
, 1);
89 req
->wb_context
= get_nfs_open_context(ctx
);
95 * nfs_unlock_request - Unlock request and wake up sleepers.
98 void nfs_unlock_request(struct nfs_page
*req
)
100 if (!NFS_WBACK_BUSY(req
)) {
101 printk(KERN_ERR
"NFS: Invalid unlock attempted\n");
104 smp_mb__before_clear_bit();
105 clear_bit(PG_BUSY
, &req
->wb_flags
);
106 smp_mb__after_clear_bit();
107 wake_up_bit(&req
->wb_flags
, PG_BUSY
);
108 nfs_release_request(req
);
112 * nfs_set_page_writeback_locked - Lock a request for writeback
115 int nfs_set_page_writeback_locked(struct nfs_page
*req
)
117 struct nfs_inode
*nfsi
= NFS_I(req
->wb_context
->dentry
->d_inode
);
119 if (!nfs_lock_request(req
))
121 radix_tree_tag_set(&nfsi
->nfs_page_tree
, req
->wb_index
, NFS_PAGE_TAG_WRITEBACK
);
126 * nfs_clear_page_writeback - Unlock request and wake up sleepers
128 void nfs_clear_page_writeback(struct nfs_page
*req
)
130 struct nfs_inode
*nfsi
= NFS_I(req
->wb_context
->dentry
->d_inode
);
132 if (req
->wb_page
!= NULL
) {
133 spin_lock(&nfsi
->req_lock
);
134 radix_tree_tag_clear(&nfsi
->nfs_page_tree
, req
->wb_index
, NFS_PAGE_TAG_WRITEBACK
);
135 spin_unlock(&nfsi
->req_lock
);
137 nfs_unlock_request(req
);
141 * nfs_clear_request - Free up all resources allocated to the request
144 * Release page resources associated with a write request after it
147 void nfs_clear_request(struct nfs_page
*req
)
149 struct page
*page
= req
->wb_page
;
151 page_cache_release(page
);
158 * nfs_release_request - Release the count on an NFS read/write request
159 * @req: request to release
161 * Note: Should never be called with the spinlock held!
164 nfs_release_request(struct nfs_page
*req
)
166 if (!atomic_dec_and_test(&req
->wb_count
))
169 /* Release struct file or cached credential */
170 nfs_clear_request(req
);
171 put_nfs_open_context(req
->wb_context
);
175 static int nfs_wait_bit_interruptible(void *word
)
179 if (signal_pending(current
))
187 * nfs_wait_on_request - Wait for a request to complete.
188 * @req: request to wait upon.
190 * Interruptible by signals only if mounted with intr flag.
191 * The user is responsible for holding a count on the request.
194 nfs_wait_on_request(struct nfs_page
*req
)
196 struct rpc_clnt
*clnt
= NFS_CLIENT(req
->wb_context
->dentry
->d_inode
);
200 if (!test_bit(PG_BUSY
, &req
->wb_flags
))
203 * Note: the call to rpc_clnt_sigmask() suffices to ensure that we
204 * are not interrupted if intr flag is not set
206 rpc_clnt_sigmask(clnt
, &oldmask
);
207 ret
= out_of_line_wait_on_bit(&req
->wb_flags
, PG_BUSY
,
208 nfs_wait_bit_interruptible
, TASK_INTERRUPTIBLE
);
209 rpc_clnt_sigunmask(clnt
, &oldmask
);
215 * nfs_pageio_init - initialise a page io descriptor
216 * @desc: pointer to descriptor
217 * @inode: pointer to inode
218 * @doio: pointer to io function
219 * @bsize: io block size
220 * @io_flags: extra parameters for the io function
222 void nfs_pageio_init(struct nfs_pageio_descriptor
*desc
,
224 int (*doio
)(struct inode
*, struct list_head
*, unsigned int, size_t, int),
228 INIT_LIST_HEAD(&desc
->pg_list
);
229 desc
->pg_bytes_written
= 0;
231 desc
->pg_bsize
= bsize
;
233 desc
->pg_inode
= inode
;
234 desc
->pg_doio
= doio
;
235 desc
->pg_ioflags
= io_flags
;
240 * nfs_can_coalesce_requests - test two requests for compatibility
241 * @prev: pointer to nfs_page
242 * @req: pointer to nfs_page
244 * The nfs_page structures 'prev' and 'req' are compared to ensure that the
245 * page data area they describe is contiguous, and that their RPC
246 * credentials, NFSv4 open state, and lockowners are the same.
248 * Return 'true' if this is the case, else return 'false'.
250 static int nfs_can_coalesce_requests(struct nfs_page
*prev
,
251 struct nfs_page
*req
)
253 if (req
->wb_context
->cred
!= prev
->wb_context
->cred
)
255 if (req
->wb_context
->lockowner
!= prev
->wb_context
->lockowner
)
257 if (req
->wb_context
->state
!= prev
->wb_context
->state
)
259 if (req
->wb_index
!= (prev
->wb_index
+ 1))
261 if (req
->wb_pgbase
!= 0)
263 if (prev
->wb_pgbase
+ prev
->wb_bytes
!= PAGE_CACHE_SIZE
)
269 * nfs_pageio_do_add_request - Attempt to coalesce a request into a page list.
270 * @desc: destination io descriptor
273 * Returns true if the request 'req' was successfully coalesced into the
274 * existing list of pages 'desc'.
276 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor
*desc
,
277 struct nfs_page
*req
)
279 size_t newlen
= req
->wb_bytes
;
281 if (desc
->pg_count
!= 0) {
282 struct nfs_page
*prev
;
285 * FIXME: ideally we should be able to coalesce all requests
286 * that are not block boundary aligned, but currently this
287 * is problematic for the case of bsize < PAGE_CACHE_SIZE,
288 * since nfs_flush_multi and nfs_pagein_multi assume you
289 * can have only one struct nfs_page.
291 if (desc
->pg_bsize
< PAGE_SIZE
)
293 newlen
+= desc
->pg_count
;
294 if (newlen
> desc
->pg_bsize
)
296 prev
= nfs_list_entry(desc
->pg_list
.prev
);
297 if (!nfs_can_coalesce_requests(prev
, req
))
300 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
= newlen
;
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
->pg_inode
,
315 nfs_page_array_len(desc
->pg_base
,
320 desc
->pg_error
= error
;
322 desc
->pg_bytes_written
+= desc
->pg_count
;
324 if (list_empty(&desc
->pg_list
)) {
331 * nfs_pageio_add_request - Attempt to coalesce a request into a page list.
332 * @desc: destination io descriptor
335 * Returns true if the request 'req' was successfully coalesced into the
336 * existing list of pages 'desc'.
338 int nfs_pageio_add_request(struct nfs_pageio_descriptor
*desc
,
339 struct nfs_page
*req
)
341 while (!nfs_pageio_do_add_request(desc
, req
)) {
342 nfs_pageio_doio(desc
);
343 if (desc
->pg_error
< 0)
350 * nfs_pageio_complete - Complete I/O on an nfs_pageio_descriptor
351 * @desc: pointer to io descriptor
353 void nfs_pageio_complete(struct nfs_pageio_descriptor
*desc
)
355 nfs_pageio_doio(desc
);
359 * nfs_pageio_cond_complete - Conditional I/O completion
360 * @desc: pointer to io descriptor
363 * It is important to ensure that processes don't try to take locks
364 * on non-contiguous ranges of pages as that might deadlock. This
365 * function should be called before attempting to wait on a locked
366 * nfs_page. It will complete the I/O if the page index 'index'
367 * is not contiguous with the existing list of pages in 'desc'.
369 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor
*desc
, pgoff_t index
)
371 if (!list_empty(&desc
->pg_list
)) {
372 struct nfs_page
*prev
= nfs_list_entry(desc
->pg_list
.prev
);
373 if (index
!= prev
->wb_index
+ 1)
374 nfs_pageio_doio(desc
);
378 #define NFS_SCAN_MAXENTRIES 16
380 * nfs_scan_list - Scan a list for matching requests
382 * @head: One of the NFS inode request lists
383 * @dst: Destination list
384 * @idx_start: lower bound of page->index to scan
385 * @npages: idx_start + npages sets the upper bound to scan.
387 * Moves elements from one of the inode request lists.
388 * If the number of requests is set to 0, the entire address_space
389 * starting at index idx_start, is scanned.
390 * The requests are *not* checked to ensure that they form a contiguous set.
391 * You must be holding the inode's req_lock when calling this function
393 int nfs_scan_list(struct nfs_inode
*nfsi
, struct list_head
*head
,
394 struct list_head
*dst
, pgoff_t idx_start
,
397 struct nfs_page
*pgvec
[NFS_SCAN_MAXENTRIES
];
398 struct nfs_page
*req
;
407 idx_end
= idx_start
+ npages
- 1;
410 found
= radix_tree_gang_lookup(&nfsi
->nfs_page_tree
,
411 (void **)&pgvec
[0], idx_start
,
412 NFS_SCAN_MAXENTRIES
);
415 for (i
= 0; i
< found
; i
++) {
417 if (req
->wb_index
> idx_end
)
419 idx_start
= req
->wb_index
+ 1;
420 if (req
->wb_list_head
!= head
)
422 if (nfs_set_page_writeback_locked(req
)) {
423 nfs_list_remove_request(req
);
424 nfs_list_add_request(req
, dst
);
434 int __init
nfs_init_nfspagecache(void)
436 nfs_page_cachep
= kmem_cache_create("nfs_page",
437 sizeof(struct nfs_page
),
438 0, SLAB_HWCACHE_ALIGN
,
440 if (nfs_page_cachep
== NULL
)
446 void nfs_destroy_nfspagecache(void)
448 kmem_cache_destroy(nfs_page_cachep
);