1 /* 2 * General functionality supporting file paging. 3 * 4 * Copyright (C) 2021 Paul Boddie <paul@boddie.org.uk> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License as 8 * published by the Free Software Foundation; either version 2 of 9 * the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 * Boston, MA 02110-1301, USA 20 */ 21 22 #include "file_pager.h" 23 #include "file_paging.h" 24 25 #include <systypes/fcntl.h> 26 27 28 29 FilePaging::FilePaging(Pages *pages, FileNotifierRegistry *notifiers) 30 : _pages(pages), _notifiers(notifiers) 31 { 32 } 33 34 35 36 /* Return any registered page mapper for the given 'fileid' or NULL if no such 37 mapper is registered. */ 38 39 PageMapper *FilePaging::get(fileid_t fileid) 40 { 41 FileMapping::iterator entry = _mappers.find(fileid); 42 PageMapper *mapper; 43 44 if (entry == _mappers.end()) 45 mapper = NULL; 46 else 47 mapper = entry->second; 48 49 return mapper; 50 } 51 52 /* Remove a page mapper and its resources for the given 'fileid'. */ 53 54 void FilePaging::remove(fileid_t fileid, PageMapper *mapper) 55 { 56 _mappers.erase(fileid); 57 delete mapper->accessor(); 58 delete mapper; 59 } 60 61 /* Register a page 'mapper' and a notification manager for the given 'fileid'. */ 62 63 void FilePaging::set(fileid_t fileid, PageMapper *mapper) 64 { 65 FileMapping::iterator entry = _mappers.find(fileid); 66 67 if (entry != _mappers.end()) 68 return; 69 70 _mappers[fileid] = mapper; 71 } 72 73 74 75 /* Convert opening flags to map-compatible paging flags. */ 76 77 map_flags_t FilePaging::get_flags(flags_t flags) 78 { 79 return flags & (O_WRONLY | O_RDWR) ? L4RE_DS_MAP_FLAG_RW : L4RE_DS_MAP_FLAG_RO; 80 } 81 82 83 84 /* Obtain a page mapper for the 'fileid' or register a new one in the 85 paging object. */ 86 87 long FilePaging::get_mapper(FileOpening *opening, const char *path, flags_t flags, fileid_t fileid, PageMapper **mapper) 88 { 89 /* Obtain any registered page mapper. */ 90 91 *mapper = get(fileid); 92 93 if (*mapper != NULL) 94 return L4_EOK; 95 96 /* Make an accessor and page mapper, registering the mapper. */ 97 98 Accessor *accessor; 99 long err = opening->make_accessor(path, flags, fileid, &accessor); 100 101 if (err) 102 return err; 103 104 *mapper = new PageMapper(accessor, _pages); 105 106 set(fileid, *mapper); 107 _notifiers->attach(fileid); 108 109 return L4_EOK; 110 } 111 112 113 114 /* Return a pager initialised with a page mapper. */ 115 116 long FilePaging::get_pager(FileOpening *opening, const char *path, flags_t flags, fileid_t fileid, Pager **pager) 117 { 118 std::lock_guard<std::mutex> guard(_lock); 119 120 /* Obtain any existing page mapper registered for the file, or make a new 121 page mapper. */ 122 123 PageMapper *mapper; 124 long err = get_mapper(opening, path, flags, fileid, &mapper); 125 126 if (err) 127 return err; 128 129 /* Initialise the pager with the mapper and a reference to this object for 130 closing the mapper and accessor. */ 131 132 *pager = new FilePager(fileid, mapper, get_flags(flags), this); 133 return L4_EOK; 134 } 135 136 /* Detach a pager, potentially removing its resources. */ 137 138 void FilePaging::detach_pager(fileid_t fileid, PageMapper *mapper) 139 { 140 std::lock_guard<std::mutex> guard(_lock); 141 142 if (!mapper->detach()) 143 remove(fileid, mapper); 144 145 _notifiers->detach(fileid); 146 } 147 148 /* Obtain a file-specific notification manager. */ 149 150 FileNotification *FilePaging::notifier(fileid_t fileid) 151 { 152 return _notifiers->get(fileid); 153 } 154 155 // vim: tabstop=4 expandtab shiftwidth=4