1 // SPDX-License-Identifier: GPL-2.0-only 2 /* Network filesystem write retrying. 3 * 4 * Copyright (C) 2024 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/fs.h> 9 #include <linux/mm.h> 10 #include <linux/pagemap.h> 11 #include <linux/slab.h> 12 #include "internal.h" 13 14 /* 15 * Perform retries on the streams that need it. 16 */ 17 static void netfs_retry_write_stream(struct netfs_io_request *wreq, 18 struct netfs_io_stream *stream) 19 { 20 struct list_head *next; 21 22 _enter("R=%x[%x:]", wreq->debug_id, stream->stream_nr); 23 24 if (list_empty(&stream->subrequests)) 25 return; 26 27 if (stream->source == NETFS_UPLOAD_TO_SERVER && 28 wreq->netfs_ops->retry_request) 29 wreq->netfs_ops->retry_request(wreq, stream); 30 31 if (unlikely(stream->failed)) 32 return; 33 34 /* If there's no renegotiation to do, just resend each failed subreq. */ 35 if (!stream->prepare_write) { 36 struct netfs_io_subrequest *subreq; 37 38 list_for_each_entry(subreq, &stream->subrequests, rreq_link) { 39 if (test_bit(NETFS_SREQ_FAILED, &subreq->flags)) 40 break; 41 if (__test_and_clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) { 42 struct iov_iter source; 43 44 netfs_reset_iter(subreq); 45 source = subreq->io_iter; 46 netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit); 47 netfs_reissue_write(stream, subreq, &source); 48 } 49 } 50 return; 51 } 52 53 next = stream->subrequests.next; 54 55 do { 56 struct netfs_io_subrequest *subreq = NULL, *from, *to, *tmp; 57 struct iov_iter source; 58 unsigned long long start, len; 59 size_t part; 60 bool boundary = false; 61 62 /* Go through the stream and find the next span of contiguous 63 * data that we then rejig (cifs, for example, needs the wsize 64 * renegotiating) and reissue. 65 */ 66 from = list_entry(next, struct netfs_io_subrequest, rreq_link); 67 to = from; 68 start = from->start + from->transferred; 69 len = from->len - from->transferred; 70 71 if (test_bit(NETFS_SREQ_FAILED, &from->flags) || 72 !test_bit(NETFS_SREQ_NEED_RETRY, &from->flags)) 73 return; 74 75 list_for_each_continue(next, &stream->subrequests) { 76 subreq = list_entry(next, struct netfs_io_subrequest, rreq_link); 77 if (subreq->start + subreq->transferred != start + len || 78 test_bit(NETFS_SREQ_BOUNDARY, &subreq->flags) || 79 !test_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags)) 80 break; 81 to = subreq; 82 len += to->len; 83 } 84 85 /* Determine the set of buffers we're going to use. Each 86 * subreq gets a subset of a single overall contiguous buffer. 87 */ 88 netfs_reset_iter(from); 89 source = from->io_iter; 90 source.count = len; 91 92 /* Work through the sublist. */ 93 subreq = from; 94 list_for_each_entry_from(subreq, &stream->subrequests, rreq_link) { 95 if (!len) 96 break; 97 98 subreq->start = start; 99 subreq->len = len; 100 __clear_bit(NETFS_SREQ_NEED_RETRY, &subreq->flags); 101 subreq->retry_count++; 102 trace_netfs_sreq(subreq, netfs_sreq_trace_retry); 103 104 /* Renegotiate max_len (wsize) */ 105 stream->sreq_max_len = len; 106 stream->prepare_write(subreq); 107 108 part = umin(len, stream->sreq_max_len); 109 if (unlikely(stream->sreq_max_segs)) 110 part = netfs_limit_iter(&source, 0, part, stream->sreq_max_segs); 111 subreq->len = part; 112 subreq->transferred = 0; 113 len -= part; 114 start += part; 115 if (len && subreq == to && 116 __test_and_clear_bit(NETFS_SREQ_BOUNDARY, &to->flags)) 117 boundary = true; 118 119 netfs_get_subrequest(subreq, netfs_sreq_trace_get_resubmit); 120 netfs_reissue_write(stream, subreq, &source); 121 if (subreq == to) 122 break; 123 } 124 125 /* If we managed to use fewer subreqs, we can discard the 126 * excess; if we used the same number, then we're done. 127 */ 128 if (!len) { 129 if (subreq == to) 130 continue; 131 list_for_each_entry_safe_from(subreq, tmp, 132 &stream->subrequests, rreq_link) { 133 trace_netfs_sreq(subreq, netfs_sreq_trace_discard); 134 list_del(&subreq->rreq_link); 135 netfs_put_subrequest(subreq, netfs_sreq_trace_put_done); 136 if (subreq == to) 137 break; 138 } 139 continue; 140 } 141 142 /* We ran out of subrequests, so we need to allocate some more 143 * and insert them after. 144 */ 145 do { 146 subreq = netfs_alloc_subrequest(wreq); 147 subreq->source = to->source; 148 subreq->start = start; 149 subreq->stream_nr = to->stream_nr; 150 subreq->retry_count = 1; 151 152 trace_netfs_sreq_ref(wreq->debug_id, subreq->debug_index, 153 refcount_read(&subreq->ref), 154 netfs_sreq_trace_new); 155 trace_netfs_sreq(subreq, netfs_sreq_trace_split); 156 157 list_add(&subreq->rreq_link, &to->rreq_link); 158 to = list_next_entry(to, rreq_link); 159 trace_netfs_sreq(subreq, netfs_sreq_trace_retry); 160 161 stream->sreq_max_len = len; 162 stream->sreq_max_segs = INT_MAX; 163 switch (stream->source) { 164 case NETFS_UPLOAD_TO_SERVER: 165 netfs_stat(&netfs_n_wh_upload); 166 stream->sreq_max_len = umin(len, wreq->wsize); 167 break; 168 case NETFS_WRITE_TO_CACHE: 169 netfs_stat(&netfs_n_wh_write); 170 break; 171 default: 172 WARN_ON_ONCE(1); 173 } 174 175 stream->prepare_write(subreq); 176 177 part = umin(len, stream->sreq_max_len); 178 subreq->len = subreq->transferred + part; 179 len -= part; 180 start += part; 181 if (!len && boundary) { 182 __set_bit(NETFS_SREQ_BOUNDARY, &to->flags); 183 boundary = false; 184 } 185 186 netfs_reissue_write(stream, subreq, &source); 187 if (!len) 188 break; 189 190 } while (len); 191 192 } while (!list_is_head(next, &stream->subrequests)); 193 } 194 195 /* 196 * Perform retries on the streams that need it. If we're doing content 197 * encryption and the server copy changed due to a third-party write, we may 198 * need to do an RMW cycle and also rewrite the data to the cache. 199 */ 200 void netfs_retry_writes(struct netfs_io_request *wreq) 201 { 202 struct netfs_io_stream *stream; 203 int s; 204 205 netfs_stat(&netfs_n_wh_retry_write_req); 206 207 /* Wait for all outstanding I/O to quiesce before performing retries as 208 * we may need to renegotiate the I/O sizes. 209 */ 210 set_bit(NETFS_RREQ_RETRYING, &wreq->flags); 211 for (s = 0; s < NR_IO_STREAMS; s++) { 212 stream = &wreq->io_streams[s]; 213 if (stream->active) 214 netfs_wait_for_in_progress_stream(wreq, stream); 215 } 216 clear_bit(NETFS_RREQ_RETRYING, &wreq->flags); 217 218 // TODO: Enc: Fetch changed partial pages 219 // TODO: Enc: Reencrypt content if needed. 220 // TODO: Enc: Wind back transferred point. 221 // TODO: Enc: Mark cache pages for retry. 222 223 for (s = 0; s < NR_IO_STREAMS; s++) { 224 stream = &wreq->io_streams[s]; 225 if (stream->need_retry) { 226 stream->need_retry = false; 227 netfs_retry_write_stream(wreq, stream); 228 } 229 } 230 } 231