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