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 struct nfs_pgio_header *p = kmem_cache_zalloc(nfs_rdata_cachep, GFP_KERNEL); 39 40 if (p) 41 p->rw_mode = FMODE_READ; 42 return p; 43 } 44 45 static void nfs_readhdr_free(struct nfs_pgio_header *rhdr) 46 { 47 kmem_cache_free(nfs_rdata_cachep, rhdr); 48 } 49 50 static 51 int nfs_return_empty_page(struct page *page) 52 { 53 zero_user(page, 0, PAGE_SIZE); 54 SetPageUptodate(page); 55 unlock_page(page); 56 return 0; 57 } 58 59 void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, 60 struct inode *inode, bool force_mds, 61 const struct nfs_pgio_completion_ops *compl_ops) 62 { 63 struct nfs_server *server = NFS_SERVER(inode); 64 const struct nfs_pageio_ops *pg_ops = &nfs_pgio_rw_ops; 65 66 #ifdef CONFIG_NFS_V4_1 67 if (server->pnfs_curr_ld && !force_mds) 68 pg_ops = server->pnfs_curr_ld->pg_read_ops; 69 #endif 70 nfs_pageio_init(pgio, inode, pg_ops, compl_ops, &nfs_rw_read_ops, 71 server->rsize, 0, GFP_KERNEL); 72 } 73 EXPORT_SYMBOL_GPL(nfs_pageio_init_read); 74 75 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio) 76 { 77 struct nfs_pgio_mirror *mirror; 78 79 if (pgio->pg_ops && pgio->pg_ops->pg_cleanup) 80 pgio->pg_ops->pg_cleanup(pgio); 81 82 pgio->pg_ops = &nfs_pgio_rw_ops; 83 84 /* read path should never have more than one mirror */ 85 WARN_ON_ONCE(pgio->pg_mirror_count != 1); 86 87 mirror = &pgio->pg_mirrors[0]; 88 mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize; 89 } 90 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); 91 92 static void nfs_readpage_release(struct nfs_page *req) 93 { 94 struct inode *inode = d_inode(req->wb_context->dentry); 95 96 dprintk("NFS: read done (%s/%llu %d@%lld)\n", inode->i_sb->s_id, 97 (unsigned long long)NFS_FILEID(inode), req->wb_bytes, 98 (long long)req_offset(req)); 99 100 if (nfs_page_group_sync_on_bit(req, PG_UNLOCKPAGE)) { 101 if (PageUptodate(req->wb_page)) 102 nfs_readpage_to_fscache(inode, req->wb_page, 0); 103 104 unlock_page(req->wb_page); 105 } 106 nfs_release_request(req); 107 } 108 109 int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode, 110 struct page *page) 111 { 112 struct nfs_page *new; 113 unsigned int len; 114 struct nfs_pageio_descriptor pgio; 115 struct nfs_pgio_mirror *pgm; 116 117 len = nfs_page_length(page); 118 if (len == 0) 119 return nfs_return_empty_page(page); 120 new = nfs_create_request(ctx, page, NULL, 0, len); 121 if (IS_ERR(new)) { 122 unlock_page(page); 123 return PTR_ERR(new); 124 } 125 if (len < PAGE_SIZE) 126 zero_user_segment(page, len, PAGE_SIZE); 127 128 nfs_pageio_init_read(&pgio, inode, false, 129 &nfs_async_read_completion_ops); 130 if (!nfs_pageio_add_request(&pgio, new)) { 131 nfs_list_remove_request(new); 132 nfs_readpage_release(new); 133 } 134 nfs_pageio_complete(&pgio); 135 136 /* It doesn't make sense to do mirrored reads! */ 137 WARN_ON_ONCE(pgio.pg_mirror_count != 1); 138 139 pgm = &pgio.pg_mirrors[0]; 140 NFS_I(inode)->read_io += pgm->pg_bytes_written; 141 142 return pgio.pg_error < 0 ? pgio.pg_error : 0; 143 } 144 145 static void nfs_page_group_set_uptodate(struct nfs_page *req) 146 { 147 if (nfs_page_group_sync_on_bit(req, PG_UPTODATE)) 148 SetPageUptodate(req->wb_page); 149 } 150 151 static void nfs_read_completion(struct nfs_pgio_header *hdr) 152 { 153 unsigned long bytes = 0; 154 155 if (test_bit(NFS_IOHDR_REDO, &hdr->flags)) 156 goto out; 157 while (!list_empty(&hdr->pages)) { 158 struct nfs_page *req = nfs_list_entry(hdr->pages.next); 159 struct page *page = req->wb_page; 160 unsigned long start = req->wb_pgbase; 161 unsigned long end = req->wb_pgbase + req->wb_bytes; 162 163 if (test_bit(NFS_IOHDR_EOF, &hdr->flags)) { 164 /* note: regions of the page not covered by a 165 * request are zeroed in nfs_readpage_async / 166 * readpage_async_filler */ 167 if (bytes > hdr->good_bytes) { 168 /* nothing in this request was good, so zero 169 * the full extent of the request */ 170 zero_user_segment(page, start, end); 171 172 } else if (hdr->good_bytes - bytes < req->wb_bytes) { 173 /* part of this request has good bytes, but 174 * not all. zero the bad bytes */ 175 start += hdr->good_bytes - bytes; 176 WARN_ON(start < req->wb_pgbase); 177 zero_user_segment(page, start, end); 178 } 179 } 180 bytes += req->wb_bytes; 181 if (test_bit(NFS_IOHDR_ERROR, &hdr->flags)) { 182 if (bytes <= hdr->good_bytes) 183 nfs_page_group_set_uptodate(req); 184 } else 185 nfs_page_group_set_uptodate(req); 186 nfs_list_remove_request(req); 187 nfs_readpage_release(req); 188 } 189 out: 190 hdr->release(hdr); 191 } 192 193 static void nfs_initiate_read(struct nfs_pgio_header *hdr, 194 struct rpc_message *msg, 195 const struct nfs_rpc_ops *rpc_ops, 196 struct rpc_task_setup *task_setup_data, int how) 197 { 198 struct inode *inode = hdr->inode; 199 int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0; 200 201 task_setup_data->flags |= swap_flags; 202 rpc_ops->read_setup(hdr, msg); 203 } 204 205 static void 206 nfs_async_read_error(struct list_head *head) 207 { 208 struct nfs_page *req; 209 210 while (!list_empty(head)) { 211 req = nfs_list_entry(head->next); 212 nfs_list_remove_request(req); 213 nfs_readpage_release(req); 214 } 215 } 216 217 static const struct nfs_pgio_completion_ops nfs_async_read_completion_ops = { 218 .error_cleanup = nfs_async_read_error, 219 .completion = nfs_read_completion, 220 }; 221 222 /* 223 * This is the callback from RPC telling us whether a reply was 224 * received or some error occurred (timeout or socket shutdown). 225 */ 226 static int nfs_readpage_done(struct rpc_task *task, 227 struct nfs_pgio_header *hdr, 228 struct inode *inode) 229 { 230 int status = NFS_PROTO(inode)->read_done(task, hdr); 231 if (status != 0) 232 return status; 233 234 nfs_add_stats(inode, NFSIOS_SERVERREADBYTES, hdr->res.count); 235 236 if (task->tk_status == -ESTALE) { 237 set_bit(NFS_INO_STALE, &NFS_I(inode)->flags); 238 nfs_mark_for_revalidate(inode); 239 } 240 return 0; 241 } 242 243 static void nfs_readpage_retry(struct rpc_task *task, 244 struct nfs_pgio_header *hdr) 245 { 246 struct nfs_pgio_args *argp = &hdr->args; 247 struct nfs_pgio_res *resp = &hdr->res; 248 249 /* This is a short read! */ 250 nfs_inc_stats(hdr->inode, NFSIOS_SHORTREAD); 251 /* Has the server at least made some progress? */ 252 if (resp->count == 0) { 253 nfs_set_pgio_error(hdr, -EIO, argp->offset); 254 return; 255 } 256 257 /* For non rpc-based layout drivers, retry-through-MDS */ 258 if (!task->tk_ops) { 259 hdr->pnfs_error = -EAGAIN; 260 return; 261 } 262 263 /* Yes, so retry the read at the end of the hdr */ 264 hdr->mds_offset += resp->count; 265 argp->offset += resp->count; 266 argp->pgbase += resp->count; 267 argp->count -= resp->count; 268 rpc_restart_call_prepare(task); 269 } 270 271 static void nfs_readpage_result(struct rpc_task *task, 272 struct nfs_pgio_header *hdr) 273 { 274 if (hdr->res.eof) { 275 loff_t bound; 276 277 bound = hdr->args.offset + hdr->res.count; 278 spin_lock(&hdr->lock); 279 if (bound < hdr->io_start + hdr->good_bytes) { 280 set_bit(NFS_IOHDR_EOF, &hdr->flags); 281 clear_bit(NFS_IOHDR_ERROR, &hdr->flags); 282 hdr->good_bytes = bound - hdr->io_start; 283 } 284 spin_unlock(&hdr->lock); 285 } else if (hdr->res.count < hdr->args.count) 286 nfs_readpage_retry(task, hdr); 287 } 288 289 /* 290 * Read a page over NFS. 291 * We read the page synchronously in the following case: 292 * - The error flag is set for this page. This happens only when a 293 * previous async read operation failed. 294 */ 295 int nfs_readpage(struct file *file, struct page *page) 296 { 297 struct nfs_open_context *ctx; 298 struct inode *inode = page_file_mapping(page)->host; 299 int error; 300 301 dprintk("NFS: nfs_readpage (%p %ld@%lu)\n", 302 page, PAGE_SIZE, page_index(page)); 303 nfs_inc_stats(inode, NFSIOS_VFSREADPAGE); 304 nfs_add_stats(inode, NFSIOS_READPAGES, 1); 305 306 /* 307 * Try to flush any pending writes to the file.. 308 * 309 * NOTE! Because we own the page lock, there cannot 310 * be any new pending writes generated at this point 311 * for this page (other pages can be written to). 312 */ 313 error = nfs_wb_page(inode, page); 314 if (error) 315 goto out_unlock; 316 if (PageUptodate(page)) 317 goto out_unlock; 318 319 error = -ESTALE; 320 if (NFS_STALE(inode)) 321 goto out_unlock; 322 323 if (file == NULL) { 324 error = -EBADF; 325 ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 326 if (ctx == NULL) 327 goto out_unlock; 328 } else 329 ctx = get_nfs_open_context(nfs_file_open_context(file)); 330 331 if (!IS_SYNC(inode)) { 332 error = nfs_readpage_from_fscache(ctx, inode, page); 333 if (error == 0) 334 goto out; 335 } 336 337 error = nfs_readpage_async(ctx, inode, page); 338 339 out: 340 put_nfs_open_context(ctx); 341 return error; 342 out_unlock: 343 unlock_page(page); 344 return error; 345 } 346 347 struct nfs_readdesc { 348 struct nfs_pageio_descriptor *pgio; 349 struct nfs_open_context *ctx; 350 }; 351 352 static int 353 readpage_async_filler(void *data, struct page *page) 354 { 355 struct nfs_readdesc *desc = (struct nfs_readdesc *)data; 356 struct nfs_page *new; 357 unsigned int len; 358 int error; 359 360 len = nfs_page_length(page); 361 if (len == 0) 362 return nfs_return_empty_page(page); 363 364 new = nfs_create_request(desc->ctx, page, NULL, 0, len); 365 if (IS_ERR(new)) 366 goto out_error; 367 368 if (len < PAGE_SIZE) 369 zero_user_segment(page, len, PAGE_SIZE); 370 if (!nfs_pageio_add_request(desc->pgio, new)) { 371 nfs_list_remove_request(new); 372 nfs_readpage_release(new); 373 error = desc->pgio->pg_error; 374 goto out; 375 } 376 return 0; 377 out_error: 378 error = PTR_ERR(new); 379 unlock_page(page); 380 out: 381 return error; 382 } 383 384 int nfs_readpages(struct file *filp, struct address_space *mapping, 385 struct list_head *pages, unsigned nr_pages) 386 { 387 struct nfs_pageio_descriptor pgio; 388 struct nfs_pgio_mirror *pgm; 389 struct nfs_readdesc desc = { 390 .pgio = &pgio, 391 }; 392 struct inode *inode = mapping->host; 393 unsigned long npages; 394 int ret = -ESTALE; 395 396 dprintk("NFS: nfs_readpages (%s/%Lu %d)\n", 397 inode->i_sb->s_id, 398 (unsigned long long)NFS_FILEID(inode), 399 nr_pages); 400 nfs_inc_stats(inode, NFSIOS_VFSREADPAGES); 401 402 if (NFS_STALE(inode)) 403 goto out; 404 405 if (filp == NULL) { 406 desc.ctx = nfs_find_open_context(inode, NULL, FMODE_READ); 407 if (desc.ctx == NULL) 408 return -EBADF; 409 } else 410 desc.ctx = get_nfs_open_context(nfs_file_open_context(filp)); 411 412 /* attempt to read as many of the pages as possible from the cache 413 * - this returns -ENOBUFS immediately if the cookie is negative 414 */ 415 ret = nfs_readpages_from_fscache(desc.ctx, inode, mapping, 416 pages, &nr_pages); 417 if (ret == 0) 418 goto read_complete; /* all pages were read */ 419 420 nfs_pageio_init_read(&pgio, inode, false, 421 &nfs_async_read_completion_ops); 422 423 ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc); 424 nfs_pageio_complete(&pgio); 425 426 /* It doesn't make sense to do mirrored reads! */ 427 WARN_ON_ONCE(pgio.pg_mirror_count != 1); 428 429 pgm = &pgio.pg_mirrors[0]; 430 NFS_I(inode)->read_io += pgm->pg_bytes_written; 431 npages = (pgm->pg_bytes_written + PAGE_SIZE - 1) >> 432 PAGE_SHIFT; 433 nfs_add_stats(inode, NFSIOS_READPAGES, npages); 434 read_complete: 435 put_nfs_open_context(desc.ctx); 436 out: 437 return ret; 438 } 439 440 int __init nfs_init_readpagecache(void) 441 { 442 nfs_rdata_cachep = kmem_cache_create("nfs_read_data", 443 sizeof(struct nfs_pgio_header), 444 0, SLAB_HWCACHE_ALIGN, 445 NULL); 446 if (nfs_rdata_cachep == NULL) 447 return -ENOMEM; 448 449 return 0; 450 } 451 452 void nfs_destroy_readpagecache(void) 453 { 454 kmem_cache_destroy(nfs_rdata_cachep); 455 } 456 457 static const struct nfs_rw_ops nfs_rw_read_ops = { 458 .rw_alloc_header = nfs_readhdr_alloc, 459 .rw_free_header = nfs_readhdr_free, 460 .rw_done = nfs_readpage_done, 461 .rw_result = nfs_readpage_result, 462 .rw_initiate = nfs_initiate_read, 463 }; 464