1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Unbuffered and direct write support. 3 * 4 * Copyright (C) 2023 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/export.h> 9 #include <linux/uio.h> 10 #include "internal.h" 11 12 /* 13 * Perform the cleanup rituals after an unbuffered write is complete. 14 */ 15 static void netfs_unbuffered_write_done(struct netfs_io_request *wreq) 16 { 17 struct netfs_inode *ictx = netfs_inode(wreq->inode); 18 19 _enter("R=%x", wreq->debug_id); 20 21 /* Okay, declare that all I/O is complete. */ 22 trace_netfs_rreq(wreq, netfs_rreq_trace_write_done); 23 24 if (!wreq->error) 25 netfs_update_i_size(ictx, &ictx->inode, wreq->start, wreq->transferred); 26 27 if (wreq->origin == NETFS_DIO_WRITE && 28 wreq->mapping->nrpages) { 29 /* mmap may have got underfoot and we may now have folios 30 * locally covering the region we just wrote. Attempt to 31 * discard the folios, but leave in place any modified locally. 32 * ->write_iter() is prevented from interfering by the DIO 33 * counter. 34 */ 35 pgoff_t first = wreq->start >> PAGE_SHIFT; 36 pgoff_t last = (wreq->start + wreq->transferred - 1) >> PAGE_SHIFT; 37 38 invalidate_inode_pages2_range(wreq->mapping, first, last); 39 } 40 41 if (wreq->origin == NETFS_DIO_WRITE) 42 inode_dio_end(wreq->inode); 43 44 _debug("finished"); 45 netfs_wake_rreq_flag(wreq, NETFS_RREQ_IN_PROGRESS, netfs_rreq_trace_wake_ip); 46 /* As we cleared NETFS_RREQ_IN_PROGRESS, we acquired its ref. */ 47 48 if (wreq->iocb) { 49 size_t written = umin(wreq->transferred, wreq->len); 50 51 wreq->iocb->ki_pos += written; 52 if (wreq->iocb->ki_complete) { 53 trace_netfs_rreq(wreq, netfs_rreq_trace_ki_complete); 54 wreq->iocb->ki_complete(wreq->iocb, wreq->error ?: written); 55 } 56 wreq->iocb = VFS_PTR_POISON; 57 } 58 59 netfs_clear_subrequests(wreq); 60 } 61 62 /* 63 * Collect the subrequest results of unbuffered write subrequests. 64 */ 65 static void netfs_unbuffered_write_collect(struct netfs_io_request *wreq, 66 struct netfs_io_stream *stream, 67 struct netfs_io_subrequest *subreq) 68 { 69 trace_netfs_collect_sreq(wreq, subreq); 70 71 spin_lock(&wreq->lock); 72 list_del_init(&subreq->rreq_link); 73 spin_unlock(&wreq->lock); 74 75 wreq->transferred += subreq->transferred; 76 iov_iter_advance(&wreq->buffer.iter, subreq->transferred); 77 78 stream->collected_to = subreq->start + subreq->transferred; 79 wreq->collected_to = stream->collected_to; 80 netfs_put_subrequest(subreq, netfs_sreq_trace_put_done); 81 82 trace_netfs_collect_stream(wreq, stream); 83 trace_netfs_collect_state(wreq, wreq->collected_to, 0); 84 } 85 86 /* 87 * Write data to the server without going through the pagecache and without 88 * writing it to the local cache. We dispatch the subrequests serially and 89 * wait for each to complete before dispatching the next, lest we leave a gap 90 * in the data written due to a failure such as ENOSPC. We could, however 91 * attempt to do preparation such as content encryption for the next subreq 92 * whilst the current is in progress. 93 */ 94 static int netfs_unbuffered_write(struct netfs_io_request *wreq) 95 { 96 struct netfs_io_subrequest *subreq = NULL; 97 struct netfs_io_stream *stream = &wreq->io_streams[0]; 98 int ret; 99 100 _enter("%llx", wreq->len); 101 102 if (wreq->origin == NETFS_DIO_WRITE) 103 inode_dio_begin(wreq->inode); 104 105 stream->collected_to = wreq->start; 106 107 for (;;) { 108 bool retry = false; 109 110 if (!subreq) { 111 netfs_prepare_write(wreq, stream, wreq->start + wreq->transferred); 112 subreq = stream->construct; 113 stream->construct = NULL; 114 } 115 116 /* Check if (re-)preparation failed. */ 117 if (unlikely(test_bit(NETFS_SREQ_FAILED, &subreq->flags))) { 118 netfs_write_subrequest_terminated(subreq, subreq->error); 119 wreq->error = subreq->error; 120 break; 121 } 122 123 iov_iter_truncate(&subreq->io_iter, wreq->len - wreq->transferred); 124 if (!iov_iter_count(&subreq->io_iter)) 125 break; 126 127 subreq->len = netfs_limit_iter(&subreq->io_iter, 0, 128 stream->sreq_max_len, 129 stream->sreq_max_segs); 130 iov_iter_truncate(&subreq->io_iter, subreq->len); 131 stream->submit_extendable_to = subreq->len; 132 133 trace_netfs_sreq(subreq, netfs_sreq_trace_submit); 134 stream->issue_write(subreq); 135 136 /* Async, need to wait. */ 137 netfs_wait_for_in_progress_stream(wreq, stream); 138 139 if (test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) { 140 retry = true; 141 } else if (test_bit(NETFS_SREQ_FAILED, &subreq->flags)) { 142 ret = subreq->error; 143 wreq->error = ret; 144 netfs_see_subrequest(subreq, netfs_sreq_trace_see_failed); 145 subreq = NULL; 146 break; 147 } 148 ret = 0; 149 150 if (!retry) { 151 netfs_unbuffered_write_collect(wreq, stream, subreq); 152 subreq = NULL; 153 if (wreq->transferred >= wreq->len) 154 break; 155 if (!wreq->iocb && signal_pending(current)) { 156 ret = wreq->transferred ? -EINTR : -ERESTARTSYS; 157 trace_netfs_rreq(wreq, netfs_rreq_trace_intr); 158 break; 159 } 160 continue; 161 } 162 163 /* We need to retry the last subrequest, so first reset the 164 * iterator, taking into account what, if anything, we managed 165 * to transfer. 166 */ 167 subreq->error = -EAGAIN; 168 trace_netfs_sreq(subreq, netfs_sreq_trace_retry); 169 if (subreq->transferred > 0) 170 iov_iter_advance(&wreq->buffer.iter, subreq->transferred); 171 172 if (stream->source == NETFS_UPLOAD_TO_SERVER && 173 wreq->netfs_ops->retry_request) 174 wreq->netfs_ops->retry_request(wreq, stream); 175 176 __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags); 177 __clear_bit(NETFS_SREQ_BOUNDARY, &subreq->flags); 178 __clear_bit(NETFS_SREQ_FAILED, &subreq->flags); 179 subreq->io_iter = wreq->buffer.iter; 180 subreq->start = wreq->start + wreq->transferred; 181 subreq->len = wreq->len - wreq->transferred; 182 subreq->transferred = 0; 183 subreq->retry_count += 1; 184 stream->sreq_max_len = UINT_MAX; 185 stream->sreq_max_segs = INT_MAX; 186 187 netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit); 188 189 if (stream->prepare_write) { 190 stream->prepare_write(subreq); 191 __set_bit(NETFS_SREQ_IN_PROGRESS, &subreq->flags); 192 netfs_stat(&netfs_n_wh_retry_write_subreq); 193 } else { 194 struct iov_iter source; 195 196 netfs_reset_iter(subreq); 197 source = subreq->io_iter; 198 netfs_reissue_write(stream, subreq, &source); 199 } 200 } 201 202 netfs_unbuffered_write_done(wreq); 203 _leave(" = %d", ret); 204 return ret; 205 } 206 207 static void netfs_unbuffered_write_async(struct work_struct *work) 208 { 209 struct netfs_io_request *wreq = container_of(work, struct netfs_io_request, work); 210 211 netfs_unbuffered_write(wreq); 212 netfs_put_request(wreq, netfs_rreq_trace_put_complete); 213 } 214 215 /* 216 * Perform an unbuffered write where we may have to do an RMW operation on an 217 * encrypted file. This can also be used for direct I/O writes. 218 */ 219 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter, 220 struct netfs_group *netfs_group) 221 { 222 struct netfs_io_request *wreq; 223 unsigned long long start = iocb->ki_pos; 224 unsigned long long end = start + iov_iter_count(iter); 225 ssize_t ret, n; 226 size_t len = iov_iter_count(iter); 227 bool async = !is_sync_kiocb(iocb); 228 229 _enter(""); 230 231 /* We're going to need a bounce buffer if what we transmit is going to 232 * be different in some way to the source buffer, e.g. because it gets 233 * encrypted/compressed or because it needs expanding to a block size. 234 */ 235 // TODO 236 237 _debug("uw %llx-%llx", start, end); 238 239 wreq = netfs_create_write_req(iocb->ki_filp->f_mapping, iocb->ki_filp, start, 240 iocb->ki_flags & IOCB_DIRECT ? 241 NETFS_DIO_WRITE : NETFS_UNBUFFERED_WRITE); 242 if (IS_ERR(wreq)) 243 return PTR_ERR(wreq); 244 245 wreq->io_streams[0].avail = true; 246 trace_netfs_write(wreq, (iocb->ki_flags & IOCB_DIRECT ? 247 netfs_write_trace_dio_write : 248 netfs_write_trace_unbuffered_write)); 249 250 { 251 /* If this is an async op and we're not using a bounce buffer, 252 * we have to save the source buffer as the iterator is only 253 * good until we return. In such a case, extract an iterator 254 * to represent as much of the the output buffer as we can 255 * manage. Note that the extraction might not be able to 256 * allocate a sufficiently large bvec array and may shorten the 257 * request. 258 */ 259 if (user_backed_iter(iter)) { 260 n = netfs_extract_user_iter(iter, len, &wreq->buffer.iter, 0); 261 if (n < 0) { 262 ret = n; 263 goto error_put; 264 } 265 wreq->direct_bv = (struct bio_vec *)wreq->buffer.iter.bvec; 266 wreq->direct_bv_count = n; 267 wreq->direct_bv_unpin = iov_iter_extract_will_pin(iter); 268 } else { 269 /* If this is a kernel-generated async DIO request, 270 * assume that any resources the iterator points to 271 * (eg. a bio_vec array) will persist till the end of 272 * the op. 273 */ 274 wreq->buffer.iter = *iter; 275 } 276 277 wreq->len = iov_iter_count(&wreq->buffer.iter); 278 } 279 280 __set_bit(NETFS_RREQ_USE_IO_ITER, &wreq->flags); 281 282 /* Copy the data into the bounce buffer and encrypt it. */ 283 // TODO 284 285 /* Dispatch the write. */ 286 __set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags); 287 288 if (async) { 289 INIT_WORK(&wreq->work, netfs_unbuffered_write_async); 290 wreq->iocb = iocb; 291 queue_work(system_dfl_wq, &wreq->work); 292 ret = -EIOCBQUEUED; 293 } else { 294 ret = netfs_unbuffered_write(wreq); 295 if (ret < 0) { 296 _debug("begin = %zd", ret); 297 } else { 298 iocb->ki_pos += wreq->transferred; 299 ret = wreq->transferred ?: wreq->error; 300 } 301 302 netfs_put_request(wreq, netfs_rreq_trace_put_complete); 303 } 304 305 netfs_put_request(wreq, netfs_rreq_trace_put_return); 306 return ret; 307 308 error_put: 309 netfs_put_failed_request(wreq); 310 return ret; 311 } 312 EXPORT_SYMBOL(netfs_unbuffered_write_iter_locked); 313 314 /** 315 * netfs_unbuffered_write_iter - Unbuffered write to a file 316 * @iocb: IO state structure 317 * @from: iov_iter with data to write 318 * 319 * Do an unbuffered write to a file, writing the data directly to the server 320 * and not lodging the data in the pagecache. 321 * 322 * Return: 323 * * Negative error code if no data has been written at all of 324 * vfs_fsync_range() failed for a synchronous write 325 * * Number of bytes written, even for truncated writes 326 */ 327 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from) 328 { 329 struct file *file = iocb->ki_filp; 330 struct address_space *mapping = file->f_mapping; 331 struct inode *inode = mapping->host; 332 struct netfs_inode *ictx = netfs_inode(inode); 333 ssize_t ret; 334 loff_t pos = iocb->ki_pos; 335 unsigned long long end = pos + iov_iter_count(from) - 1; 336 337 _enter("%llx,%zx,%llx", pos, iov_iter_count(from), i_size_read(inode)); 338 339 if (!iov_iter_count(from)) 340 return 0; 341 342 trace_netfs_write_iter(iocb, from); 343 netfs_stat(&netfs_n_wh_dio_write); 344 345 ret = netfs_start_io_direct(inode); 346 if (ret < 0) 347 return ret; 348 ret = generic_write_checks(iocb, from); 349 if (ret <= 0) 350 goto out; 351 ret = file_remove_privs(file); 352 if (ret < 0) 353 goto out; 354 ret = file_update_time(file); 355 if (ret < 0) 356 goto out; 357 if (iocb->ki_flags & IOCB_NOWAIT) { 358 /* We could block if there are any pages in the range. */ 359 ret = -EAGAIN; 360 if (filemap_range_has_page(mapping, pos, end)) 361 if (filemap_invalidate_inode(inode, true, pos, end)) 362 goto out; 363 } else { 364 ret = filemap_write_and_wait_range(mapping, pos, end); 365 if (ret < 0) 366 goto out; 367 } 368 369 /* 370 * After a write we want buffered reads to be sure to go to disk to get 371 * the new data. We invalidate clean cached page from the region we're 372 * about to write. We do this *before* the write so that we can return 373 * without clobbering -EIOCBQUEUED from ->direct_IO(). 374 */ 375 ret = filemap_invalidate_inode(inode, true, pos, end); 376 if (ret < 0) 377 goto out; 378 end = iocb->ki_pos + iov_iter_count(from); 379 if (end > ictx->zero_point) 380 ictx->zero_point = end; 381 382 fscache_invalidate(netfs_i_cookie(ictx), NULL, i_size_read(inode), 383 FSCACHE_INVAL_DIO_WRITE); 384 ret = netfs_unbuffered_write_iter_locked(iocb, from, NULL); 385 out: 386 netfs_end_io_direct(inode); 387 return ret; 388 } 389 EXPORT_SYMBOL(netfs_unbuffered_write_iter); 390