1 /* 2 * linux/fs/nfs/read.c 3 * 4 * Block I/O for NFS 5 * 6 * Partial copy of Linus' read cache modifications to fs/nfs/file.c 7 * modified for async RPC by okir@monad.swb.de 8 */ 9 10 #include <linux/time.h> 11 #include <linux/kernel.h> 12 #include <linux/errno.h> 13 #include <linux/fcntl.h> 14 #include <linux/stat.h> 15 #include <linux/mm.h> 16 #include <linux/slab.h> 17 #include <linux/pagemap.h> 18 #include <linux/sunrpc/clnt.h> 19 #include <linux/nfs_fs.h> 20 #include <linux/nfs_page.h> 21 #include <linux/module.h> 22 23 #include "nfs4_fs.h" 24 #include "internal.h" 25 #include "iostat.h" 26 #include "fscache.h" 27 #include "pnfs.h" 28 29 #define NFSDBG_FACILITY NFSDBG_PAGECACHE 30 31 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops; 32 static const struct nfs_rw_ops nfs_rw_read_ops; 33 34 static struct kmem_cache *nfs_rdata_cachep; 35 36 static struct nfs_pgio_header *nfs_readhdr_alloc(void) 37 { 38 return kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL); 39 } 40 41 static void nfs_readhdr_free(struct nfs_pgio_header *rhdr) 42 { 43 kmem_cache_free(nfs_rdata_cachep, rhdr); 44 } 45 46 static 47 int nfs_return_empty_page(struct page *page) 48 { 49 zero_user(page, 0, PAGE_CACHE_SIZE); 50 SetPageUptodate(page); 51 unlock_page(page); 52 return 0; 53 } 54 55 void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, 56 struct inode *inode, bool force_mds, 57 const struct nfs_pgio_completion_ops *compl_ops) 58 { 59 struct nfs_server *server = NFS_SERVER(inode); 60 const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops; 61 62 #ifdef CONFIG_NFS_V4_1 63 if (server->pnfs_curr_ld && !force_mds) 64 pg_ops = server->pnfs_curr_ld->pg_read_ops; 65 #endif 66 nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops, 67 server->rsize, 0); 68 } 69 EXPORT_SYMBOL_GPL(nfs_pageio_init_read); 70 71 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio) 72 { 73 struct nfs_pgio_mirror *mirror; 74 75 pgio->pg_ops = &nfs_pgio_rw_ops; 76 77 /* read path should never have more than one mirror */ 78 WARN_ON_ONCE(pgio->pg_mirror_count != 1); 79 80 mirror = &pgio->pg_mirrors[0]; 81 mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize; 82 } 83 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); 84 85 int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode, 86 struct page *page) 87 { 88 struct nfs_page *new; 89 unsigned int len; 90 struct nfs_pageio_descriptor pgio; 91 struct nfs_pgio_mirror *pgm; 92 93 len = nfs_page_length(page); 94 if (len == 0) 95 return nfs_return_empty_page(page); 96 new = nfs_create_request(ctx, page, NULL, 0, len); 97 if (IS_ERR(new)) { 98 unlock_page(page); 99 return PTR_ERR(new); 100 } 101 if (len < PAGE_CACHE_SIZE) 102 zero_user_segment(page, len, PAGE_CACHE_SIZE); 103 104 nfs_pageio_init_read(&pgio, inode, false, 105 &nfs_async_read_completion_ops); 106 nfs_pageio_add_request(&pgio, new); 107 nfs_pageio_complete(&pgio); 108 109 /* It doesn't make sense to do mirrored reads! */ 110 WARN_ON_ONCE(pgio.pg_mirror_count != 1); 111 112 pgm = &pgio.pg_mirrors[0]; 113 NFS_I(inode)->read_io += pgm->pg_bytes_written; 114 115 return 0; 116 } 117 118 static void nfs_readpage_release(struct nfs_page *req) 119 { 120 struct inode *inode = d_inode(req->wb_context->dentry); 121 122 dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id, 123 (unsigned long long)NFS_FILEID(inode), req->wb_bytes, 124 (long long)req_offset(req)); 125 126 if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) { 127 if (PageUptodate(req->wb_page)) 128 nfs_readpage_to_fscache(inode, req->wb_page, 0); 129 130 unlock_page(req->wb_page); 131 } 132 nfs_release_request(req); 133 } 134 135 static void nfs_page_group_set_uptodate(struct nfs_page *req) 136 { 137 if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) 138 SetPageUptodate(req->wb_page); 139 } 140 141 static void nfs_read_completion(struct nfs_pgio_header *hdr) 142 { 143 unsigned long bytes = 0; 144 145 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 146 goto out; 147 while (!list_empty(&hdr->pages)) { 148 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 149 struct page *page = req->wb_page; 150 unsigned long start = req->wb_pgbase; 151 unsigned long end = req->wb_pgbase + req->wb_bytes; 152 153 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { 154 /* note: regions of the page not covered by a 155 * request are zeroed in nfs_readpage_async / 156 * readpage_async_filler */ 157 if (bytes > hdr->good_bytes) { 158 /* nothing in this request was good, so zero 159 * the full extent of the request */ 160 zero_user_segment(page, start, end); 161 162 } else if (hdr->good_bytes - bytes < req->wb_bytes) { 163 /* part of this request has good bytes, but 164 * not all. zero the bad bytes */ 165 start += hdr->good_bytes - bytes; 166 WARN_ON(start < req->wb_pgbase); 167 zero_user_segment(page, start, end); 168 } 169 } 170 bytes += req->wb_bytes; 171 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 172 if (bytes <= hdr->good_bytes) 173 nfs_page_group_set_uptodate(req); 174 } else 175 nfs_page_group_set_uptodate(req); 176 nfs_list_remove_request(req); 177 nfs_readpage_release(req); 178 } 179 out: 180 hdr->release(hdr); 181 } 182 183 static void nfs_initiate_read(struct nfs_pgio_header *hdr, 184 struct rpc_message *msg, 185 const struct nfs_rpc_ops *rpc_ops, 186 struct rpc_task_setup *task_setup_data, int how) 187 { 188 struct inode *inode = hdr->inode; 189 int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0; 190 191 task_setup_data->flags |= swap_flags; 192 rpc_ops->read_setup(hdr, msg); 193 } 194 195 static void 196 nfs_async_read_error(struct list_head *head) 197 { 198 struct nfs_page *req; 199 200 while (!list_empty(head)) { 201 req = nfs_list_entry(head->next); 202 nfs_list_remove_request(req); 203 nfs_readpage_release(req); 204 } 205 } 206 207 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { 208 .error_cleanup = nfs_async_read_error, 209 .completion = nfs_read_completion, 210 }; 211 212 /* 213 * This is the callback from RPC telling us whether a reply was 214 * received or some error occurred (timeout or socket shutdown). 215 */ 216 static int nfs_readpage_done(struct rpc_task *task, 217 struct nfs_pgio_header *hdr, 218 struct inode *inode) 219 { 220 int status = NFS_PROTO(inode)->read_done(task, hdr); 221 if (status != 0) 222 return status; 223 224 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count); 225 226 if (task->tk_status == -ESTALE) { 227 set_bit(NFS_INO_STALE, &NFS_I(inode)->flags); 228 nfs_mark_for_revalidate(inode); 229 } 230 return 0; 231 } 232 233 static void nfs_readpage_retry(struct rpc_task *task, 234 struct nfs_pgio_header *hdr) 235 { 236 struct nfs_pgio_args *argp = &hdr->args; 237 struct nfs_pgio_res *resp = &hdr->res; 238 239 /* This is a short read! */ 240 nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD); 241 /* Has the server at least made some progress? */ 242 if (resp->count == 0) { 243 nfs_set_pgio_error(hdr, -EIO, argp->offset); 244 return; 245 } 246 /* Yes, so retry the read at the end of the hdr */ 247 hdr->mds_offset += resp->count; 248 argp->offset += resp->count; 249 argp->pgbase += resp->count; 250 argp->count -= resp->count; 251 rpc_restart_call_prepare(task); 252 } 253 254 static void nfs_readpage_result(struct rpc_task *task, 255 struct nfs_pgio_header *hdr) 256 { 257 if (hdr->res.eof) { 258 loff_t bound; 259 260 bound = hdr->args.offset + hdr->res.count; 261 spin_lock(&hdr->lock); 262 if (bound < hdr->io_start + hdr->good_bytes) { 263 set_bit(NFS_IOHDR_EOF, &hdr->flags); 264 clear_bit(NFS_IOHDR_ERROR, &hdr->flags); 265 hdr->good_bytes = bound - hdr->io_start; 266 } 267 spin_unlock(&hdr->lock); 268 } else if (hdr->res.count != hdr->args.count) 269 nfs_readpage_retry(task, hdr); 270 } 271 272 /* 273 * Read a page over NFS. 274 * We read the page synchronously in the following case: 275 * - The error flag is set for this page. This happens only when a 276 * previous async read operation failed. 277 */ 278 int nfs_readpage(struct file *file, struct page *page) 279 { 280 struct nfs_open_context *ctx; 281 struct inode *inode = page_file_mapping(page)->host; 282 int error; 283 284 dprintk("NFS: nfs_readpage (%p %ld@%lu)\n", 285 page, PAGE_CACHE_SIZE, page_file_index(page)); 286 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); 287 nfs_add_stats(inode, NFSIOS_READPAGES, 1); 288 289 /* 290 * Try to flush any pending writes to the file.. 291 * 292 * NOTE! Because we own the page lock, there cannot 293 * be any new pending writes generated at this point 294 * for this page (other pages can be written to). 295 */ 296 error = nfs_wb_page(inode, page); 297 if (error) 298 goto out_unlock; 299 if (PageUptodate(page)) 300 goto out_unlock; 301 302 error = -ESTALE; 303 if (NFS_STALE(inode)) 304 goto out_unlock; 305 306 if (file == NULL) { 307 error = -EBADF; 308 ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 309 if (ctx == NULL) 310 goto out_unlock; 311 } else 312 ctx = get_nfs_open_context(nfs_file_open_context(file)); 313 314 if (!IS_SYNC(inode)) { 315 error = nfs_readpage_from_fscache(ctx, inode, page); 316 if (error == 0) 317 goto out; 318 } 319 320 error = nfs_readpage_async(ctx, inode, page); 321 322 out: 323 put_nfs_open_context(ctx); 324 return error; 325 out_unlock: 326 unlock_page(page); 327 return error; 328 } 329 330 struct nfs_readdesc { 331 struct nfs_pageio_descriptor *pgio; 332 struct nfs_open_context *ctx; 333 }; 334 335 static int 336 readpage_async_filler(void *data, struct page *page) 337 { 338 struct nfs_readdesc *desc = (struct nfs_readdesc *)data; 339 struct nfs_page *new; 340 unsigned int len; 341 int error; 342 343 len = nfs_page_length(page); 344 if (len == 0) 345 return nfs_return_empty_page(page); 346 347 new = nfs_create_request(desc->ctx, page, NULL, 0, len); 348 if (IS_ERR(new)) 349 goto out_error; 350 351 if (len < PAGE_CACHE_SIZE) 352 zero_user_segment(page, len, PAGE_CACHE_SIZE); 353 if (!nfs_pageio_add_request(desc->pgio, new)) { 354 error = desc->pgio->pg_error; 355 goto out_unlock; 356 } 357 return 0; 358 out_error: 359 error = PTR_ERR(new); 360 out_unlock: 361 unlock_page(page); 362 return error; 363 } 364 365 int nfs_readpages(struct file *filp, struct address_space *mapping, 366 struct list_head *pages, unsigned nr_pages) 367 { 368 struct nfs_pageio_descriptor pgio; 369 struct nfs_pgio_mirror *pgm; 370 struct nfs_readdesc desc = { 371 .pgio = &pgio, 372 }; 373 struct inode *inode = mapping->host; 374 unsigned long npages; 375 int ret = -ESTALE; 376 377 dprintk("NFS: nfs_readpages (%s/%Lu %d)\n", 378 inode->i_sb->s_id, 379 (unsigned long long)NFS_FILEID(inode), 380 nr_pages); 381 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); 382 383 if (NFS_STALE(inode)) 384 goto out; 385 386 if (filp == NULL) { 387 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 388 if (desc.ctx == NULL) 389 return -EBADF; 390 } else 391 desc.ctx = get_nfs_open_context(nfs_file_open_context(filp)); 392 393 /* attempt to read as many of the pages as possible from the cache 394 * - this returns -ENOBUFS immediately if the cookie is negative 395 */ 396 ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping, 397 pages, &nr_pages); 398 if (ret == 0) 399 goto read_complete; /* all pages were read */ 400 401 nfs_pageio_init_read(&pgio, inode, false, 402 &nfs_async_read_completion_ops); 403 404 ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc); 405 nfs_pageio_complete(&pgio); 406 407 /* It doesn't make sense to do mirrored reads! */ 408 WARN_ON_ONCE(pgio.pg_mirror_count != 1); 409 410 pgm = &pgio.pg_mirrors[0]; 411 NFS_I(inode)->read_io += pgm->pg_bytes_written; 412 npages = (pgm->pg_bytes_written + PAGE_CACHE_SIZE - 1) >> 413 PAGE_CACHE_SHIFT; 414 nfs_add_stats(inode, NFSIOS_READPAGES, npages); 415 read_complete: 416 put_nfs_open_context(desc.ctx); 417 out: 418 return ret; 419 } 420 421 int __init nfs_init_readpagecache(void) 422 { 423 nfs_rdata_cachep = kmem_cache_create("nfs_read_data", 424 sizeof(struct nfs_pgio_header), 425 0, SLAB_HWCACHE_ALIGN, 426 NULL); 427 if (nfs_rdata_cachep == NULL) 428 return -ENOMEM; 429 430 return 0; 431 } 432 433 void nfs_destroy_readpagecache(void) 434 { 435 kmem_cache_destroy(nfs_rdata_cachep); 436 } 437 438 static const struct nfs_rw_ops nfs_rw_read_ops = { 439 .rw_mode = FMODE_READ, 440 .rw_alloc_header = nfs_readhdr_alloc, 441 .rw_free_header = nfs_readhdr_free, 442 .rw_done = nfs_readpage_done, 443 .rw_result = nfs_readpage_result, 444 .rw_initiate = nfs_initiate_read, 445 }; 446