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