1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* Cache data I/O routines 3 * 4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 #define FSCACHE_DEBUG_LEVEL OPERATION 8 #include <linux/fscache-cache.h> 9 #include <linux/uio.h> 10 #include <linux/bvec.h> 11 #include <linux/slab.h> 12 #include <linux/uio.h> 13 #include "internal.h" 14 15 /** 16 * fscache_wait_for_operation - Wait for an object become accessible 17 * @cres: The cache resources for the operation being performed 18 * @want_state: The minimum state the object must be at 19 * 20 * See if the target cache object is at the specified minimum state of 21 * accessibility yet, and if not, wait for it. 22 */ 23 bool fscache_wait_for_operation(struct netfs_cache_resources *cres, 24 enum fscache_want_state want_state) 25 { 26 struct fscache_cookie *cookie = fscache_cres_cookie(cres); 27 enum fscache_cookie_state state; 28 29 again: 30 if (!fscache_cache_is_live(cookie->volume->cache)) { 31 _leave(" [broken]"); 32 return false; 33 } 34 35 state = fscache_cookie_state(cookie); 36 _enter("c=%08x{%u},%x", cookie->debug_id, state, want_state); 37 38 switch (state) { 39 case FSCACHE_COOKIE_STATE_CREATING: 40 case FSCACHE_COOKIE_STATE_INVALIDATING: 41 if (want_state == FSCACHE_WANT_PARAMS) 42 goto ready; /* There can be no content */ 43 fallthrough; 44 case FSCACHE_COOKIE_STATE_LOOKING_UP: 45 case FSCACHE_COOKIE_STATE_LRU_DISCARDING: 46 wait_var_event(&cookie->state, 47 fscache_cookie_state(cookie) != state); 48 goto again; 49 50 case FSCACHE_COOKIE_STATE_ACTIVE: 51 goto ready; 52 case FSCACHE_COOKIE_STATE_DROPPED: 53 case FSCACHE_COOKIE_STATE_RELINQUISHING: 54 default: 55 _leave(" [not live]"); 56 return false; 57 } 58 59 ready: 60 if (!cres->cache_priv2) 61 return cookie->volume->cache->ops->begin_operation(cres, want_state); 62 return true; 63 } 64 EXPORT_SYMBOL(fscache_wait_for_operation); 65 66 /* 67 * Begin an I/O operation on the cache, waiting till we reach the right state. 68 * 69 * Attaches the resources required to the operation resources record. 70 */ 71 static int fscache_begin_operation(struct netfs_cache_resources *cres, 72 struct fscache_cookie *cookie, 73 enum fscache_want_state want_state, 74 enum fscache_access_trace why) 75 { 76 enum fscache_cookie_state state; 77 long timeo; 78 bool once_only = false; 79 80 cres->ops = NULL; 81 cres->cache_priv = cookie; 82 cres->cache_priv2 = NULL; 83 cres->debug_id = cookie->debug_id; 84 cres->inval_counter = cookie->inval_counter; 85 86 if (!fscache_begin_cookie_access(cookie, why)) 87 return -ENOBUFS; 88 89 again: 90 spin_lock(&cookie->lock); 91 92 state = fscache_cookie_state(cookie); 93 _enter("c=%08x{%u},%x", cookie->debug_id, state, want_state); 94 95 switch (state) { 96 case FSCACHE_COOKIE_STATE_LOOKING_UP: 97 case FSCACHE_COOKIE_STATE_LRU_DISCARDING: 98 case FSCACHE_COOKIE_STATE_INVALIDATING: 99 goto wait_for_file_wrangling; 100 case FSCACHE_COOKIE_STATE_CREATING: 101 if (want_state == FSCACHE_WANT_PARAMS) 102 goto ready; /* There can be no content */ 103 goto wait_for_file_wrangling; 104 case FSCACHE_COOKIE_STATE_ACTIVE: 105 goto ready; 106 case FSCACHE_COOKIE_STATE_DROPPED: 107 case FSCACHE_COOKIE_STATE_RELINQUISHING: 108 WARN(1, "Can't use cookie in state %u\n", cookie->state); 109 goto not_live; 110 default: 111 goto not_live; 112 } 113 114 ready: 115 spin_unlock(&cookie->lock); 116 if (!cookie->volume->cache->ops->begin_operation(cres, want_state)) 117 goto failed; 118 return 0; 119 120 wait_for_file_wrangling: 121 spin_unlock(&cookie->lock); 122 trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref), 123 atomic_read(&cookie->n_accesses), 124 fscache_access_io_wait); 125 timeo = wait_var_event_timeout(&cookie->state, 126 fscache_cookie_state(cookie) != state, 20 * HZ); 127 if (timeo <= 1 && !once_only) { 128 pr_warn("%s: cookie state change wait timed out: cookie->state=%u state=%u", 129 __func__, fscache_cookie_state(cookie), state); 130 fscache_print_cookie(cookie, 'O'); 131 once_only = true; 132 } 133 goto again; 134 135 not_live: 136 spin_unlock(&cookie->lock); 137 failed: 138 cres->cache_priv = NULL; 139 cres->ops = NULL; 140 fscache_end_cookie_access(cookie, fscache_access_io_not_live); 141 _leave(" = -ENOBUFS"); 142 return -ENOBUFS; 143 } 144 145 int __fscache_begin_read_operation(struct netfs_cache_resources *cres, 146 struct fscache_cookie *cookie) 147 { 148 return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS, 149 fscache_access_io_read); 150 } 151 EXPORT_SYMBOL(__fscache_begin_read_operation); 152 153 int __fscache_begin_write_operation(struct netfs_cache_resources *cres, 154 struct fscache_cookie *cookie) 155 { 156 return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS, 157 fscache_access_io_write); 158 } 159 EXPORT_SYMBOL(__fscache_begin_write_operation); 160 161 /** 162 * fscache_dirty_folio - Mark folio dirty and pin a cache object for writeback 163 * @mapping: The mapping the folio belongs to. 164 * @folio: The folio being dirtied. 165 * @cookie: The cookie referring to the cache object 166 * 167 * Set the dirty flag on a folio and pin an in-use cache object in memory 168 * so that writeback can later write to it. This is intended 169 * to be called from the filesystem's ->dirty_folio() method. 170 * 171 * Return: true if the dirty flag was set on the folio, false otherwise. 172 */ 173 bool fscache_dirty_folio(struct address_space *mapping, struct folio *folio, 174 struct fscache_cookie *cookie) 175 { 176 struct inode *inode = mapping->host; 177 bool need_use = false; 178 179 _enter(""); 180 181 if (!filemap_dirty_folio(mapping, folio)) 182 return false; 183 if (!fscache_cookie_valid(cookie)) 184 return true; 185 186 if (!(inode->i_state & I_PINNING_FSCACHE_WB)) { 187 spin_lock(&inode->i_lock); 188 if (!(inode->i_state & I_PINNING_FSCACHE_WB)) { 189 inode->i_state |= I_PINNING_FSCACHE_WB; 190 need_use = true; 191 } 192 spin_unlock(&inode->i_lock); 193 194 if (need_use) 195 fscache_use_cookie(cookie, true); 196 } 197 return true; 198 } 199 EXPORT_SYMBOL(fscache_dirty_folio); 200 201 struct fscache_write_request { 202 struct netfs_cache_resources cache_resources; 203 struct address_space *mapping; 204 loff_t start; 205 size_t len; 206 bool set_bits; 207 netfs_io_terminated_t term_func; 208 void *term_func_priv; 209 }; 210 211 void __fscache_clear_page_bits(struct address_space *mapping, 212 loff_t start, size_t len) 213 { 214 pgoff_t first = start / PAGE_SIZE; 215 pgoff_t last = (start + len - 1) / PAGE_SIZE; 216 struct page *page; 217 218 if (len) { 219 XA_STATE(xas, &mapping->i_pages, first); 220 221 rcu_read_lock(); 222 xas_for_each(&xas, page, last) { 223 end_page_fscache(page); 224 } 225 rcu_read_unlock(); 226 } 227 } 228 EXPORT_SYMBOL(__fscache_clear_page_bits); 229 230 /* 231 * Deal with the completion of writing the data to the cache. 232 */ 233 static void fscache_wreq_done(void *priv, ssize_t transferred_or_error, 234 bool was_async) 235 { 236 struct fscache_write_request *wreq = priv; 237 238 fscache_clear_page_bits(wreq->mapping, wreq->start, wreq->len, 239 wreq->set_bits); 240 241 if (wreq->term_func) 242 wreq->term_func(wreq->term_func_priv, transferred_or_error, 243 was_async); 244 fscache_end_operation(&wreq->cache_resources); 245 kfree(wreq); 246 } 247 248 void __fscache_write_to_cache(struct fscache_cookie *cookie, 249 struct address_space *mapping, 250 loff_t start, size_t len, loff_t i_size, 251 netfs_io_terminated_t term_func, 252 void *term_func_priv, 253 bool cond) 254 { 255 struct fscache_write_request *wreq; 256 struct netfs_cache_resources *cres; 257 struct iov_iter iter; 258 int ret = -ENOBUFS; 259 260 if (len == 0) 261 goto abandon; 262 263 _enter("%llx,%zx", start, len); 264 265 wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS); 266 if (!wreq) 267 goto abandon; 268 wreq->mapping = mapping; 269 wreq->start = start; 270 wreq->len = len; 271 wreq->set_bits = cond; 272 wreq->term_func = term_func; 273 wreq->term_func_priv = term_func_priv; 274 275 cres = &wreq->cache_resources; 276 if (fscache_begin_operation(cres, cookie, FSCACHE_WANT_WRITE, 277 fscache_access_io_write) < 0) 278 goto abandon_free; 279 280 ret = cres->ops->prepare_write(cres, &start, &len, i_size, false); 281 if (ret < 0) 282 goto abandon_end; 283 284 /* TODO: Consider clearing page bits now for space the write isn't 285 * covering. This is more complicated than it appears when THPs are 286 * taken into account. 287 */ 288 289 iov_iter_xarray(&iter, WRITE, &mapping->i_pages, start, len); 290 fscache_write(cres, start, &iter, fscache_wreq_done, wreq); 291 return; 292 293 abandon_end: 294 return fscache_wreq_done(wreq, ret, false); 295 abandon_free: 296 kfree(wreq); 297 abandon: 298 fscache_clear_page_bits(mapping, start, len, cond); 299 if (term_func) 300 term_func(term_func_priv, ret, false); 301 } 302 EXPORT_SYMBOL(__fscache_write_to_cache); 303 304 /* 305 * Change the size of a backing object. 306 */ 307 void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size) 308 { 309 struct netfs_cache_resources cres; 310 311 trace_fscache_resize(cookie, new_size); 312 if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE, 313 fscache_access_io_resize) == 0) { 314 fscache_stat(&fscache_n_resizes); 315 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags); 316 317 /* We cannot defer a resize as we need to do it inside the 318 * netfs's inode lock so that we're serialised with respect to 319 * writes. 320 */ 321 cookie->volume->cache->ops->resize_cookie(&cres, new_size); 322 fscache_end_operation(&cres); 323 } else { 324 fscache_stat(&fscache_n_resizes_null); 325 } 326 } 327 EXPORT_SYMBOL(__fscache_resize_cookie); 328