1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Single, monolithic object support (e.g. AFS directory). 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/uio.h> 14 #include <linux/sched/mm.h> 15 #include <linux/task_io_accounting_ops.h> 16 #include <linux/netfs.h> 17 #include "internal.h" 18 19 /** 20 * netfs_single_mark_inode_dirty - Mark a single, monolithic object inode dirty 21 * @inode: The inode to mark 22 * 23 * Mark an inode that contains a single, monolithic object as dirty so that its 24 * writepages op will get called. If set, the SINGLE_NO_UPLOAD flag indicates 25 * that the object will only be written to the cache and not uploaded (e.g. AFS 26 * directory contents). 27 */ 28 void netfs_single_mark_inode_dirty(struct inode *inode) 29 { 30 struct netfs_inode *ictx = netfs_inode(inode); 31 bool cache_only = test_bit(NETFS_ICTX_SINGLE_NO_UPLOAD, &ictx->flags); 32 bool caching = fscache_cookie_enabled(netfs_i_cookie(netfs_inode(inode))); 33 34 if (cache_only && !caching) 35 return; 36 37 mark_inode_dirty(inode); 38 39 if (caching && !(inode_state_read_once(inode) & I_PINNING_NETFS_WB)) { 40 bool need_use = false; 41 42 spin_lock(&inode->i_lock); 43 if (!(inode_state_read(inode) & I_PINNING_NETFS_WB)) { 44 inode_state_set(inode, I_PINNING_NETFS_WB); 45 need_use = true; 46 } 47 spin_unlock(&inode->i_lock); 48 49 if (need_use) 50 fscache_use_cookie(netfs_i_cookie(ictx), true); 51 } 52 53 } 54 EXPORT_SYMBOL(netfs_single_mark_inode_dirty); 55 56 static int netfs_single_begin_cache_read(struct netfs_io_request *rreq, struct netfs_inode *ctx) 57 { 58 return fscache_begin_read_operation(&rreq->cache_resources, netfs_i_cookie(ctx)); 59 } 60 61 static void netfs_single_read_cache(struct netfs_io_request *rreq, 62 struct netfs_io_subrequest *subreq) 63 { 64 struct netfs_cache_resources *cres = &rreq->cache_resources; 65 66 _enter("R=%08x[%x]", rreq->debug_id, subreq->debug_index); 67 netfs_stat(&netfs_n_rh_read); 68 cres->ops->read(cres, subreq->start, &subreq->io_iter, NETFS_READ_HOLE_FAIL, 69 netfs_cache_read_terminated, subreq); 70 } 71 72 /* 73 * Perform a read to a buffer from the cache or the server. Only a single 74 * subreq is permitted as the object must be fetched in a single transaction. 75 */ 76 static int netfs_single_dispatch_read(struct netfs_io_request *rreq) 77 { 78 struct fscache_occupancy occ = { 79 .query_from = 0, 80 .query_to = rreq->len, 81 .cached_from[0] = ULLONG_MAX, 82 .cached_to[0] = ULLONG_MAX, 83 .cached_from[1] = ULLONG_MAX, 84 .cached_to[1] = ULLONG_MAX, 85 }; 86 struct netfs_io_subrequest *subreq; 87 enum netfs_io_source source = NETFS_DOWNLOAD_FROM_SERVER; 88 int ret = 0; 89 90 /* Try to use the cache if the cache content matches the size of the 91 * remote file. 92 */ 93 netfs_read_query_cache(rreq, &occ); 94 if (occ.cached_from[0] == 0 && 95 occ.cached_to[0] >= rreq->len) 96 source = NETFS_READ_FROM_CACHE; 97 98 subreq = netfs_alloc_subrequest(rreq, source); 99 if (!subreq) 100 return -ENOMEM; 101 102 subreq->start = 0; 103 subreq->len = rreq->len; 104 subreq->io_iter = rreq->buffer.iter; 105 106 netfs_queue_read(rreq, subreq); 107 108 switch (subreq->source) { 109 case NETFS_DOWNLOAD_FROM_SERVER: 110 netfs_stat(&netfs_n_rh_download); 111 if (rreq->netfs_ops->prepare_read) { 112 ret = rreq->netfs_ops->prepare_read(subreq); 113 if (ret < 0) 114 goto cancel; 115 } 116 117 netfs_all_subreqs_queued(rreq); 118 rreq->netfs_ops->issue_read(subreq); 119 rreq->submitted += subreq->len; 120 break; 121 case NETFS_READ_FROM_CACHE: 122 if (rreq->cache_resources.ops->prepare_read) { 123 ret = rreq->cache_resources.ops->prepare_read(subreq); 124 if (ret < 0) 125 goto cancel; 126 } 127 128 netfs_all_subreqs_queued(rreq); 129 trace_netfs_sreq(subreq, netfs_sreq_trace_submit); 130 netfs_single_read_cache(rreq, subreq); 131 rreq->submitted += subreq->len; 132 ret = 0; 133 break; 134 default: 135 pr_warn("Unexpected single-read source %u\n", subreq->source); 136 WARN_ON_ONCE(true); 137 ret = -EIO; 138 goto cancel; 139 } 140 141 return ret; 142 cancel: 143 netfs_cancel_read(subreq, ret); 144 netfs_all_subreqs_queued(rreq); 145 netfs_wake_collector(rreq); 146 return ret; 147 } 148 149 /** 150 * netfs_read_single - Synchronously read a single blob of pages. 151 * @inode: The inode to read from. 152 * @file: The file we're using to read or NULL. 153 * @iter: The buffer we're reading into. 154 * 155 * Fulfil a read request for a single monolithic object by drawing data from 156 * the cache if possible, or the netfs if not. The buffer may be larger than 157 * the file content; unused beyond the EOF will be zero-filled. The content 158 * will be read with a single I/O request (though this may be retried). 159 * 160 * The calling netfs must initialise a netfs context contiguous to the vfs 161 * inode before calling this. 162 * 163 * This is usable whether or not caching is enabled. If caching is enabled, 164 * the data will be stored as a single object into the cache. 165 */ 166 ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter) 167 { 168 struct netfs_io_request *rreq; 169 struct netfs_inode *ictx = netfs_inode(inode); 170 ssize_t ret; 171 172 rreq = netfs_alloc_request(inode->i_mapping, file, 0, iov_iter_count(iter), 173 NETFS_READ_SINGLE); 174 if (IS_ERR(rreq)) 175 return PTR_ERR(rreq); 176 177 rreq->progress_at = rreq->len; 178 179 ret = netfs_single_begin_cache_read(rreq, ictx); 180 if (ret == -ENOMEM || ret == -EINTR || ret == -ERESTARTSYS) 181 goto cleanup_free; 182 183 netfs_stat(&netfs_n_rh_read_single); 184 trace_netfs_read(rreq, 0, rreq->len, netfs_read_trace_read_single); 185 186 rreq->buffer.iter = *iter; 187 netfs_single_dispatch_read(rreq); 188 189 ret = netfs_wait_for_read(rreq); 190 netfs_put_request(rreq, netfs_rreq_trace_put_return); 191 return ret; 192 193 cleanup_free: 194 netfs_put_failed_request(rreq); 195 return ret; 196 } 197 EXPORT_SYMBOL(netfs_read_single); 198