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