fs/netfs/read_pgpriv2.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Read with PG_private_2 [DEPRECATED].
   3  *
   4  * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/export.h>
   9 #include <linux/fs.h>
  10 #include <linux/mm.h>
  11 #include <linux/pagemap.h>
  12 #include <linux/slab.h>
  13 #include <linux/task_io_accounting_ops.h>
  14 #include "internal.h"
  15
  16 /*
  17  * [DEPRECATED] Mark page as requiring copy-to-cache using PG_private_2.  The
  18  * third mark in the folio queue is used to indicate that this folio needs
  19  * writing.
  20  */
  21 void netfs_pgpriv2_mark_copy_to_cache(struct netfs_io_subrequest *subreq,
  22                                       struct netfs_io_request *rreq,
  23                                       struct folio_queue *folioq,
  24                                       int slot)
  25 {
  26         struct folio *folio = folioq_folio(folioq, slot);
  27
  28         trace_netfs_folio(folio, netfs_folio_trace_copy_to_cache);
  29         folio_start_private_2(folio);
  30         folioq_mark3(folioq, slot);
  31 }
  32
  33 /*
  34  * [DEPRECATED] Cancel PG_private_2 on all marked folios in the event of an
  35  * unrecoverable error.
  36  */
  37 static void netfs_pgpriv2_cancel(struct folio_queue *folioq)
  38 {
  39         struct folio *folio;
  40         int slot;
  41
  42         while (folioq) {
  43                 if (!folioq->marks3) {
  44                         folioq = folioq->next;
  45                         continue;
  46                 }
  47
  48                 slot = __ffs(folioq->marks3);
  49                 folio = folioq_folio(folioq, slot);
  50
  51                 trace_netfs_folio(folio, netfs_folio_trace_cancel_copy);
  52                 folio_end_private_2(folio);
  53                 folioq_unmark3(folioq, slot);
  54         }
  55 }
  56
  57 /*
  58  * [DEPRECATED] Copy a folio to the cache with PG_private_2 set.
  59  */
  60 static int netfs_pgpriv2_copy_folio(struct netfs_io_request *wreq, struct folio *folio)
  61 {
  62         struct netfs_io_stream *cache  = &wreq->io_streams[1];
  63         size_t fsize = folio_size(folio), flen = fsize;
  64         loff_t fpos = folio_pos(folio), i_size;
  65         bool to_eof = false;
  66
  67         _enter("");
  68
  69         /* netfs_perform_write() may shift i_size around the page or from out
  70          * of the page to beyond it, but cannot move i_size into or through the
  71          * page since we have it locked.
  72          */
  73         i_size = i_size_read(wreq->inode);
  74
  75         if (fpos >= i_size) {
  76                 /* mmap beyond eof. */
  77                 _debug("beyond eof");
  78                 folio_end_private_2(folio);
  79                 return 0;
  80         }
  81
  82         if (fpos + fsize > wreq->i_size)
  83                 wreq->i_size = i_size;
  84
  85         if (flen > i_size - fpos) {
  86                 flen = i_size - fpos;
  87                 to_eof = true;
  88         } else if (flen == i_size - fpos) {
  89                 to_eof = true;
  90         }
  91
  92         _debug("folio %zx %zx", flen, fsize);
  93
  94         trace_netfs_folio(folio, netfs_folio_trace_store_copy);
  95
  96         /* Attach the folio to the rolling buffer. */
  97         if (netfs_buffer_append_folio(wreq, folio, false) < 0)
  98                 return -ENOMEM;
  99
 100         cache->submit_extendable_to = fsize;
 101         cache->submit_off = 0;
 102         cache->submit_len = flen;
 103
 104         /* Attach the folio to one or more subrequests.  For a big folio, we
 105          * could end up with thousands of subrequests if the wsize is small -
 106          * but we might need to wait during the creation of subrequests for
 107          * network resources (eg. SMB credits).
 108          */
 109         do {
 110                 ssize_t part;
 111
 112                 wreq->io_iter.iov_offset = cache->submit_off;
 113
 114                 atomic64_set(&wreq->issued_to, fpos + cache->submit_off);
 115                 cache->submit_extendable_to = fsize - cache->submit_off;
 116                 part = netfs_advance_write(wreq, cache, fpos + cache->submit_off,
 117                                            cache->submit_len, to_eof);
 118                 cache->submit_off += part;
 119                 if (part > cache->submit_len)
 120                         cache->submit_len = 0;
 121                 else
 122                         cache->submit_len -= part;
 123         } while (cache->submit_len > 0);
 124
 125         wreq->io_iter.iov_offset = 0;
 126         iov_iter_advance(&wreq->io_iter, fsize);
 127         atomic64_set(&wreq->issued_to, fpos + fsize);
 128
 129         if (flen < fsize)
 130                 netfs_issue_write(wreq, cache);
 131
 132         _leave(" = 0");
 133         return 0;
 134 }
 135
 136 /*
 137  * [DEPRECATED] Go through the buffer and write any folios that are marked with
 138  * the third mark to the cache.
 139  */
 140 void netfs_pgpriv2_write_to_the_cache(struct netfs_io_request *rreq)
 141 {
 142         struct netfs_io_request *wreq;
 143         struct folio_queue *folioq;
 144         struct folio *folio;
 145         int error = 0;
 146         int slot = 0;
 147
 148         _enter("");
 149
 150         if (!fscache_resources_valid(&rreq->cache_resources))
 151                 goto couldnt_start;
 152
 153         /* Need the first folio to be able to set up the op. */
 154         for (folioq = rreq->buffer; folioq; folioq = folioq->next) {
 155                 if (folioq->marks3) {
 156                         slot = __ffs(folioq->marks3);
 157                         break;
 158                 }
 159         }
 160         if (!folioq)
 161                 return;
 162         folio = folioq_folio(folioq, slot);
 163
 164         wreq = netfs_create_write_req(rreq->mapping, NULL, folio_pos(folio),
 165                                       NETFS_PGPRIV2_COPY_TO_CACHE);
 166         if (IS_ERR(wreq)) {
 167                 kleave(" [create %ld]", PTR_ERR(wreq));
 168                 goto couldnt_start;
 169         }
 170
 171         trace_netfs_write(wreq, netfs_write_trace_copy_to_cache);
 172         netfs_stat(&netfs_n_wh_copy_to_cache);
 173
 174         for (;;) {
 175                 error = netfs_pgpriv2_copy_folio(wreq, folio);
 176                 if (error < 0)
 177                         break;
 178
 179                 folioq_unmark3(folioq, slot);
 180                 if (!folioq->marks3) {
 181                         folioq = folioq->next;
 182                         if (!folioq)
 183                                 break;
 184                 }
 185
 186                 slot = __ffs(folioq->marks3);
 187                 folio = folioq_folio(folioq, slot);
 188         }
 189
 190         netfs_issue_write(wreq, &wreq->io_streams[1]);
 191         smp_wmb(); /* Write lists before ALL_QUEUED. */
 192         set_bit(NETFS_RREQ_ALL_QUEUED, &wreq->flags);
 193
 194         netfs_put_request(wreq, false, netfs_rreq_trace_put_return);
 195         _leave(" = %d", error);
 196 couldnt_start:
 197         netfs_pgpriv2_cancel(rreq->buffer);
 198 }
 199
 200 /*
 201  * [DEPRECATED] Remove the PG_private_2 mark from any folios we've finished
 202  * copying.
 203  */
 204 bool netfs_pgpriv2_unlock_copied_folios(struct netfs_io_request *wreq)
 205 {
 206         struct folio_queue *folioq = wreq->buffer;
 207         unsigned long long collected_to = wreq->collected_to;
 208         unsigned int slot = wreq->buffer_head_slot;
 209         bool made_progress = false;
 210
 211         if (slot >= folioq_nr_slots(folioq)) {
 212                 folioq = netfs_delete_buffer_head(wreq);
 213                 slot = 0;
 214         }
 215
 216         for (;;) {
 217                 struct folio *folio;
 218                 unsigned long long fpos, fend;
 219                 size_t fsize, flen;
 220
 221                 folio = folioq_folio(folioq, slot);
 222                 if (WARN_ONCE(!folio_test_private_2(folio),
 223                               "R=%08x: folio %lx is not marked private_2\n",
 224                               wreq->debug_id, folio->index))
 225                         trace_netfs_folio(folio, netfs_folio_trace_not_under_wback);
 226
 227                 fpos = folio_pos(folio);
 228                 fsize = folio_size(folio);
 229                 flen = fsize;
 230
 231                 fend = min_t(unsigned long long, fpos + flen, wreq->i_size);
 232
 233                 trace_netfs_collect_folio(wreq, folio, fend, collected_to);
 234
 235                 /* Unlock any folio we've transferred all of. */
 236                 if (collected_to < fend)
 237                         break;
 238
 239                 trace_netfs_folio(folio, netfs_folio_trace_end_copy);
 240                 folio_end_private_2(folio);
 241                 wreq->cleaned_to = fpos + fsize;
 242                 made_progress = true;
 243
 244                 /* Clean up the head folioq.  If we clear an entire folioq, then
 245                  * we can get rid of it provided it's not also the tail folioq
 246                  * being filled by the issuer.
 247                  */
 248                 folioq_clear(folioq, slot);
 249                 slot++;
 250                 if (slot >= folioq_nr_slots(folioq)) {
 251                         if (READ_ONCE(wreq->buffer_tail) == folioq)
 252                                 break;
 253                         folioq = netfs_delete_buffer_head(wreq);
 254                         slot = 0;
 255                 }
 256
 257                 if (fpos + fsize >= collected_to)
 258                         break;
 259         }
 260
 261         wreq->buffer = folioq;
 262         wreq->buffer_head_slot = slot;
 263         return made_progress;
 264 }