fs/afs/write.c

   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.  wreq->netfs_priv2 will contain the last writeback key
  33  * record used or NULL and we need to start from there if it's set.
  34  * wreq->netfs_priv will be set to the key itself or NULL.
  35  */
  36 static void afs_get_writeback_key(struct netfs_io_request *wreq)
  37 {
  38         struct afs_wb_key *wbk, *old = wreq->netfs_priv2;
  39         struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
  40
  41         key_put(wreq->netfs_priv);
  42         wreq->netfs_priv = NULL;
  43         wreq->netfs_priv2 = NULL;
  44
  45         spin_lock(&vnode->wb_lock);
  46         if (old)
  47                 wbk = list_next_entry(old, vnode_link);
  48         else
  49                 wbk = list_first_entry(&vnode->wb_keys, struct afs_wb_key, vnode_link);
  50
  51         list_for_each_entry_from(wbk, &vnode->wb_keys, vnode_link) {
  52                 _debug("wbk %u", key_serial(wbk->key));
  53                 if (key_validate(wbk->key) == 0) {
  54                         refcount_inc(&wbk->usage);
  55                         wreq->netfs_priv = key_get(wbk->key);
  56                         wreq->netfs_priv2 = wbk;
  57                         _debug("USE WB KEY %u", key_serial(wbk->key));
  58                         break;
  59                 }
  60         }
  61
  62         spin_unlock(&vnode->wb_lock);
  63
  64         afs_put_wb_key(old);
  65 }
  66
  67 static void afs_store_data_success(struct afs_operation *op)
  68 {
  69         struct afs_vnode *vnode = op->file[0].vnode;
  70
  71         op->ctime = op->file[0].scb.status.mtime_client;
  72         afs_vnode_commit_status(op, &op->file[0]);
  73         if (!afs_op_error(op)) {
  74                 afs_pages_written_back(vnode, op->store.pos, op->store.size);
  75                 afs_stat_v(vnode, n_stores);
  76                 atomic_long_add(op->store.size, &afs_v2net(vnode)->n_store_bytes);
  77         }
  78 }
  79
  80 static const struct afs_operation_ops afs_store_data_operation = {
  81         .issue_afs_rpc  = afs_fs_store_data,
  82         .issue_yfs_rpc  = yfs_fs_store_data,
  83         .success        = afs_store_data_success,
  84 };
  85
  86 /*
  87  * Prepare a subrequest to write to the server.  This sets the max_len
  88  * parameter.
  89  */
  90 void afs_prepare_write(struct netfs_io_subrequest *subreq)
  91 {
  92         struct netfs_io_stream *stream = &subreq->rreq->io_streams[subreq->stream_nr];
  93
  94         //if (test_bit(NETFS_SREQ_RETRYING, &subreq->flags))
  95         //      subreq->max_len = 512 * 1024;
  96         //else
  97         stream->sreq_max_len = 256 * 1024 * 1024;
  98 }
  99
 100 /*
 101  * Issue a subrequest to write to the server.
 102  */
 103 static void afs_issue_write_worker(struct work_struct *work)
 104 {
 105         struct netfs_io_subrequest *subreq = container_of(work, struct netfs_io_subrequest, work);
 106         struct netfs_io_request *wreq = subreq->rreq;
 107         struct afs_operation *op;
 108         struct afs_vnode *vnode = AFS_FS_I(wreq->inode);
 109         unsigned long long pos = subreq->start + subreq->transferred;
 110         size_t len = subreq->len - subreq->transferred;
 111         int ret = -ENOKEY;
 112
 113         _enter("R=%x[%x],%s{%llx:%llu.%u},%llx,%zx",
 114                wreq->debug_id, subreq->debug_index,
 115                vnode->volume->name,
 116                vnode->fid.vid,
 117                vnode->fid.vnode,
 118                vnode->fid.unique,
 119                pos, len);
 120
 121 #if 0 // Error injection
 122         if (subreq->debug_index == 3)
 123                 return netfs_write_subrequest_terminated(subreq, -ENOANO, false);
 124
 125         if (!subreq->retry_count) {
 126                 set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 127                 return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
 128         }
 129 #endif
 130
 131         op = afs_alloc_operation(wreq->netfs_priv, vnode->volume);
 132         if (IS_ERR(op))
 133                 return netfs_write_subrequest_terminated(subreq, -EAGAIN, false);
 134
 135         afs_op_set_vnode(op, 0, vnode);
 136         op->file[0].dv_delta    = 1;
 137         op->file[0].modification = true;
 138         op->store.pos           = pos;
 139         op->store.size          = len;
 140         op->flags               |= AFS_OPERATION_UNINTR;
 141         op->ops                 = &afs_store_data_operation;
 142
 143         afs_begin_vnode_operation(op);
 144
 145         op->store.write_iter    = &subreq->io_iter;
 146         op->store.i_size        = umax(pos + len, vnode->netfs.remote_i_size);
 147         op->mtime               = inode_get_mtime(&vnode->netfs.inode);
 148
 149         afs_wait_for_operation(op);
 150         ret = afs_put_operation(op);
 151         switch (ret) {
 152         case 0:
 153                 __set_bit(NETFS_SREQ_MADE_PROGRESS, &subreq->flags);
 154                 break;
 155         case -EACCES:
 156         case -EPERM:
 157         case -ENOKEY:
 158         case -EKEYEXPIRED:
 159         case -EKEYREJECTED:
 160         case -EKEYREVOKED:
 161                 /* If there are more keys we can try, use the retry algorithm
 162                  * to rotate the keys.
 163                  */
 164                 if (wreq->netfs_priv2)
 165                         set_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags);
 166                 break;
 167         }
 168
 169         netfs_write_subrequest_terminated(subreq, ret < 0 ? ret : subreq->len, false);
 170 }
 171
 172 void afs_issue_write(struct netfs_io_subrequest *subreq)
 173 {
 174         subreq->work.func = afs_issue_write_worker;
 175         if (!queue_work(system_unbound_wq, &subreq->work))
 176                 WARN_ON_ONCE(1);
 177 }
 178
 179 /*
 180  * Writeback calls this when it finds a folio that needs uploading.  This isn't
 181  * called if writeback only has copy-to-cache to deal with.
 182  */
 183 void afs_begin_writeback(struct netfs_io_request *wreq)
 184 {
 185         if (S_ISREG(wreq->inode->i_mode))
 186                 afs_get_writeback_key(wreq);
 187 }
 188
 189 /*
 190  * Prepare to retry the writes in request.  Use this to try rotating the
 191  * available writeback keys.
 192  */
 193 void afs_retry_request(struct netfs_io_request *wreq, struct netfs_io_stream *stream)
 194 {
 195         struct netfs_io_subrequest *subreq =
 196                 list_first_entry(&stream->subrequests,
 197                                  struct netfs_io_subrequest, rreq_link);
 198
 199         switch (wreq->origin) {
 200         case NETFS_READAHEAD:
 201         case NETFS_READPAGE:
 202         case NETFS_READ_GAPS:
 203         case NETFS_READ_SINGLE:
 204         case NETFS_READ_FOR_WRITE:
 205         case NETFS_DIO_READ:
 206                 return;
 207         default:
 208                 break;
 209         }
 210
 211         switch (subreq->error) {
 212         case -EACCES:
 213         case -EPERM:
 214         case -ENOKEY:
 215         case -EKEYEXPIRED:
 216         case -EKEYREJECTED:
 217         case -EKEYREVOKED:
 218                 afs_get_writeback_key(wreq);
 219                 if (!wreq->netfs_priv)
 220                         stream->failed = true;
 221                 break;
 222         }
 223 }
 224
 225 /*
 226  * write some of the pending data back to the server
 227  */
 228 int afs_writepages(struct address_space *mapping, struct writeback_control *wbc)
 229 {
 230         struct afs_vnode *vnode = AFS_FS_I(mapping->host);
 231         int ret;
 232
 233         /* We have to be careful as we can end up racing with setattr()
 234          * truncating the pagecache since the caller doesn't take a lock here
 235          * to prevent it.
 236          */
 237         if (wbc->sync_mode == WB_SYNC_ALL)
 238                 down_read(&vnode->validate_lock);
 239         else if (!down_read_trylock(&vnode->validate_lock))
 240                 return 0;
 241
 242         ret = netfs_writepages(mapping, wbc);
 243         up_read(&vnode->validate_lock);
 244         return ret;
 245 }
 246
 247 /*
 248  * flush any dirty pages for this process, and check for write errors.
 249  * - the return status from this call provides a reliable indication of
 250  *   whether any write errors occurred for this process.
 251  */
 252 int afs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
 253 {
 254         struct afs_vnode *vnode = AFS_FS_I(file_inode(file));
 255         struct afs_file *af = file->private_data;
 256         int ret;
 257
 258         _enter("{%llx:%llu},{n=%pD},%d",
 259                vnode->fid.vid, vnode->fid.vnode, file,
 260                datasync);
 261
 262         ret = afs_validate(vnode, af->key);
 263         if (ret < 0)
 264                 return ret;
 265
 266         return file_write_and_wait_range(file, start, end);
 267 }
 268
 269 /*
 270  * notification that a previously read-only page is about to become writable
 271  * - if it returns an error, the caller will deliver a bus error signal
 272  */
 273 vm_fault_t afs_page_mkwrite(struct vm_fault *vmf)
 274 {
 275         struct file *file = vmf->vma->vm_file;
 276
 277         if (afs_validate(AFS_FS_I(file_inode(file)), afs_file_key(file)) < 0)
 278                 return VM_FAULT_SIGBUS;
 279         return netfs_page_mkwrite(vmf, NULL);
 280 }
 281
 282 /*
 283  * Prune the keys cached for writeback.  The caller must hold vnode->wb_lock.
 284  */
 285 void afs_prune_wb_keys(struct afs_vnode *vnode)
 286 {
 287         LIST_HEAD(graveyard);
 288         struct afs_wb_key *wbk, *tmp;
 289
 290         /* Discard unused keys */
 291         spin_lock(&vnode->wb_lock);
 292
 293         if (!mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_WRITEBACK) &&
 294             !mapping_tagged(&vnode->netfs.inode.i_data, PAGECACHE_TAG_DIRTY)) {
 295                 list_for_each_entry_safe(wbk, tmp, &vnode->wb_keys, vnode_link) {
 296                         if (refcount_read(&wbk->usage) == 1)
 297                                 list_move(&wbk->vnode_link, &graveyard);
 298                 }
 299         }
 300
 301         spin_unlock(&vnode->wb_lock);
 302
 303         while (!list_empty(&graveyard)) {
 304                 wbk = list_entry(graveyard.next, struct afs_wb_key, vnode_link);
 305                 list_del(&wbk->vnode_link);
 306                 afs_put_wb_key(wbk);
 307         }
 308 }