1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* handling of writes to regular files and writing back to the server 3 * 4 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/backing-dev.h> 9 #include <linux/slab.h> 10 #include <linux/fs.h> 11 #include <linux/pagemap.h> 12 #include <linux/writeback.h> 13 #include <linux/pagevec.h> 14 #include <linux/netfs.h> 15 #include <trace/events/netfs.h> 16 #include "internal.h" 17 18 /* 19 * completion of write to server 20 */ 21 static void afs_pages_written_back(struct afs_vnode *vnode, loff_t start, unsigned int len) 22 { 23 _enter("{%llx:%llu},{%x @%llx}", 24 vnode->fid.vid, vnode->fid.vnode, len, start); 25 26 afs_prune_wb_keys(vnode); 27 _leave(""); 28 } 29 30 /* 31 * Find a key to use for the writeback. We cached the keys used to author the 32 * writes on the vnode. *_wbk will contain the last writeback key used or NULL 33 * and we need to start from there if it's set. 34 */ 35 static int afs_get_writeback_key(struct afs_vnode *vnode, 36 struct afs_wb_key **_wbk) 37 { 38 struct afs_wb_key *wbk = NULL; 39 struct list_head *p; 40 int ret = -ENOKEY, ret2; 41 42 spin_lock(&vnode->wb_lock); 43 if (*_wbk) 44 p = (*_wbk)->vnode_link.next; 45 else 46 p = vnode->wb_keys.next; 47 48 while (p != &vnode->wb_keys) { 49 wbk = list_entry(p, struct afs_wb_key, vnode_link); 50 _debug("wbk %u", key_serial(wbk->key)); 51 ret2 = key_validate(wbk->key); 52 if (ret2 == 0) { 53 refcount_inc(&wbk->usage); 54 _debug("USE WB KEY %u", key_serial(wbk->key)); 55 break; 56 } 57 58 wbk = NULL; 59 if (ret == -ENOKEY) 60 ret = ret2; 61 p = p->next; 62 } 63 64 spin_unlock(&vnode->wb_lock); 65 if (*_wbk) 66 afs_put_wb_key(*_wbk); 67 *_wbk = wbk; 68 return 0; 69 } 70 71 static void afs_store_data_success(struct afs_operation *op) 72 { 73 struct afs_vnode *vnode = op->file[0].vnode; 74 75 op->ctime = op->file[0].scb.status.mtime_client; 76 afs_vnode_commit_status(op, &op->file[0]); 77 if (!afs_op_error(op)) { 78 afs_pages_written_back(vnode, op->store.pos, op->store.size); 79 afs_stat_v(vnode, n_stores); 80 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes); 81 } 82 } 83 84 static const struct afs_operation_ops afs_store_data_operation = { 85 .issue_afs_rpc = afs_fs_store_data, 86 .issue_yfs_rpc = yfs_fs_store_data, 87 .success = afs_store_data_success, 88 }; 89 90 /* 91 * write to a file 92 */ 93 static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t pos) 94 { 95 struct afs_operation *op; 96 struct afs_wb_key *wbk = NULL; 97 loff_t size = iov_iter_count(iter); 98 int ret = -ENOKEY; 99 100 _enter("%s{%llx:%llu.%u},%llx,%llx", 101 vnode->volume->name, 102 vnode->fid.vid, 103 vnode->fid.vnode, 104 vnode->fid.unique, 105 size, pos); 106 107 ret = afs_get_writeback_key(vnode, &wbk); 108 if (ret) { 109 _leave(" = %d [no keys]", ret); 110 return ret; 111 } 112 113 op = afs_alloc_operation(wbk->key, vnode->volume); 114 if (IS_ERR(op)) { 115 afs_put_wb_key(wbk); 116 return -ENOMEM; 117 } 118 119 afs_op_set_vnode(op, 0, vnode); 120 op->file[0].dv_delta = 1; 121 op->file[0].modification = true; 122 op->store.pos = pos; 123 op->store.size = size; 124 op->flags |= AFS_OPERATION_UNINTR; 125 op->ops = &afs_store_data_operation; 126 127 try_next_key: 128 afs_begin_vnode_operation(op); 129 130 op->store.write_iter = iter; 131 op->store.i_size = max(pos + size, vnode->netfs.remote_i_size); 132 op->mtime = inode_get_mtime(&vnode->netfs.inode); 133 134 afs_wait_for_operation(op); 135 136 switch (afs_op_error(op)) { 137 case -EACCES: 138 case -EPERM: 139 case -ENOKEY: 140 case -EKEYEXPIRED: 141 case -EKEYREJECTED: 142 case -EKEYREVOKED: 143 _debug("next"); 144 145 ret = afs_get_writeback_key(vnode, &wbk); 146 if (ret == 0) { 147 key_put(op->key); 148 op->key = key_get(wbk->key); 149 goto try_next_key; 150 } 151 break; 152 } 153 154 afs_put_wb_key(wbk); 155 _leave(" = %d", afs_op_error(op)); 156 return afs_put_operation(op); 157 } 158 159 static void afs_upload_to_server(struct netfs_io_subrequest *subreq) 160 { 161 struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode); 162 ssize_t ret; 163 164 _enter("%x[%x],%zx", 165 subreq->rreq->debug_id, subreq->debug_index, subreq->io_iter.count); 166 167 trace_netfs_sreq(subreq, netfs_sreq_trace_submit); 168 ret = afs_store_data(vnode, &subreq->io_iter, subreq->start); 169 netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, 170 false); 171 } 172 173 static void afs_upload_to_server_worker(struct work_struct *work) 174 { 175 struct netfs_io_subrequest *subreq = 176 container_of(work, struct netfs_io_subrequest, work); 177 178 afs_upload_to_server(subreq); 179 } 180 181 /* 182 * Set up write requests for a writeback slice. We need to add a write request 183 * for each write we want to make. 184 */ 185 void afs_create_write_requests(struct netfs_io_request *wreq, loff_t start, size_t len) 186 { 187 struct netfs_io_subrequest *subreq; 188 189 _enter("%x,%llx-%llx", wreq->debug_id, start, start + len); 190 191 subreq = netfs_create_write_request(wreq, NETFS_UPLOAD_TO_SERVER, 192 start, len, afs_upload_to_server_worker); 193 if (subreq) 194 netfs_queue_write_request(subreq); 195 } 196 197 /* 198 * Writeback calls this when it finds a folio that needs uploading. This isn't 199 * called if writeback only has copy-to-cache to deal with. 200 */ 201 void afs_begin_writeback(struct netfs_io_request *wreq) 202 { 203 wreq->io_streams[0].avail = true; 204 } 205 206 /* 207 * Prepare a subrequest to write to the server. This sets the max_len 208 * parameter. 209 */ 210 void afs_prepare_write(struct netfs_io_subrequest *subreq) 211 { 212 //if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags)) 213 // subreq->max_len = 512 * 1024; 214 //else 215 subreq->max_len = 256 * 1024 * 1024; 216 } 217 218 /* 219 * Issue a subrequest to write to the server. 220 */ 221 static void afs_issue_write_worker(struct work_struct *work) 222 { 223 struct netfs_io_subrequest *subreq = container_of(work, struct netfs_io_subrequest, work); 224 struct afs_vnode *vnode = AFS_FS_I(subreq->rreq->inode); 225 ssize_t ret; 226 227 _enter("%x[%x],%zx", 228 subreq->rreq->debug_id, subreq->debug_index, subreq->io_iter.count); 229 230 #if 0 // Error injection 231 if (subreq->debug_index == 3) 232 return netfs_write_subrequest_terminated(subreq, -ENOANO, false); 233 234 if (!test_bit(NETFS_SREQ_RETRYING, &subreq->flags)) { 235 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags); 236 return netfs_write_subrequest_terminated(subreq, -EAGAIN, false); 237 } 238 #endif 239 240 ret = afs_store_data(vnode, &subreq->io_iter, subreq->start); 241 netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, false); 242 } 243 244 void afs_issue_write(struct netfs_io_subrequest *subreq) 245 { 246 subreq->work.func = afs_issue_write_worker; 247 if (!queue_work(system_unbound_wq, &subreq->work)) 248 WARN_ON_ONCE(1); 249 } 250 251 /* 252 * write some of the pending data back to the server 253 */ 254 int afs_writepages(struct address_space *mapping, struct writeback_control *wbc) 255 { 256 struct afs_vnode *vnode = AFS_FS_I(mapping->host); 257 int ret; 258 259 /* We have to be careful as we can end up racing with setattr() 260 * truncating the pagecache since the caller doesn't take a lock here 261 * to prevent it. 262 */ 263 if (wbc->sync_mode == WB_SYNC_ALL) 264 down_read(&vnode->validate_lock); 265 else if (!down_read_trylock(&vnode->validate_lock)) 266 return 0; 267 268 ret = netfs_writepages(mapping, wbc); 269 up_read(&vnode->validate_lock); 270 return ret; 271 } 272 273 /* 274 * flush any dirty pages for this process, and check for write errors. 275 * - the return status from this call provides a reliable indication of 276 * whether any write errors occurred for this process. 277 */ 278 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 279 { 280 struct afs_vnode *vnode = AFS_FS_I(file_inode(file)); 281 struct afs_file *af = file->private_data; 282 int ret; 283 284 _enter("{%llx:%llu},{n=%pD},%d", 285 vnode->fid.vid, vnode->fid.vnode, file, 286 datasync); 287 288 ret = afs_validate(vnode, af->key); 289 if (ret < 0) 290 return ret; 291 292 return file_write_and_wait_range(file, start, end); 293 } 294 295 /* 296 * notification that a previously read-only page is about to become writable 297 * - if it returns an error, the caller will deliver a bus error signal 298 */ 299 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf) 300 { 301 struct file *file = vmf->vma->vm_file; 302 303 if (afs_validate(AFS_FS_I(file_inode(file)), afs_file_key(file)) < 0) 304 return VM_FAULT_SIGBUS; 305 return netfs_page_mkwrite(vmf, NULL); 306 } 307 308 /* 309 * Prune the keys cached for writeback. The caller must hold vnode->wb_lock. 310 */ 311 void afs_prune_wb_keys(struct afs_vnode *vnode) 312 { 313 LIST_HEAD(graveyard); 314 struct afs_wb_key *wbk, *tmp; 315 316 /* Discard unused keys */ 317 spin_lock(&vnode->wb_lock); 318 319 if (!mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) && 320 !mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) { 321 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) { 322 if (refcount_read(&wbk->usage) == 1) 323 list_move(&wbk->vnode_link, &graveyard); 324 } 325 } 326 327 spin_unlock(&vnode->wb_lock); 328 329 while (!list_empty(&graveyard)) { 330 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link); 331 list_del(&wbk->vnode_link); 332 afs_put_wb_key(wbk); 333 } 334 } 335