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 cres->cache_priv = NULL; 88 return -ENOBUFS; 89 } 90 91 again: 92 spin_lock(&cookie->lock); 93 94 state = fscache_cookie_state(cookie); 95 _enter("c=%08x{%u},%x", cookie->debug_id, state, want_state); 96 97 switch (state) { 98 case FSCACHE_COOKIE_STATE_LOOKING_UP: 99 case FSCACHE_COOKIE_STATE_LRU_DISCARDING: 100 case FSCACHE_COOKIE_STATE_INVALIDATING: 101 goto wait_for_file_wrangling; 102 case FSCACHE_COOKIE_STATE_CREATING: 103 if (want_state == FSCACHE_WANT_PARAMS) 104 goto ready; /* There can be no content */ 105 goto wait_for_file_wrangling; 106 case FSCACHE_COOKIE_STATE_ACTIVE: 107 goto ready; 108 case FSCACHE_COOKIE_STATE_DROPPED: 109 case FSCACHE_COOKIE_STATE_RELINQUISHING: 110 WARN(1, "Can't use cookie in state %u\n", cookie->state); 111 goto not_live; 112 default: 113 goto not_live; 114 } 115 116 ready: 117 spin_unlock(&cookie->lock); 118 if (!cookie->volume->cache->ops->begin_operation(cres, want_state)) 119 goto failed; 120 return 0; 121 122 wait_for_file_wrangling: 123 spin_unlock(&cookie->lock); 124 trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref), 125 atomic_read(&cookie->n_accesses), 126 fscache_access_io_wait); 127 timeo = wait_var_event_timeout(&cookie->state, 128 fscache_cookie_state(cookie) != state, 20 * HZ); 129 if (timeo <= 1 && !once_only) { 130 pr_warn("%s: cookie state change wait timed out: cookie->state=%u state=%u", 131 __func__, fscache_cookie_state(cookie), state); 132 fscache_print_cookie(cookie, 'O'); 133 once_only = true; 134 } 135 goto again; 136 137 not_live: 138 spin_unlock(&cookie->lock); 139 failed: 140 cres->cache_priv = NULL; 141 cres->ops = NULL; 142 fscache_end_cookie_access(cookie, fscache_access_io_not_live); 143 _leave(" = -ENOBUFS"); 144 return -ENOBUFS; 145 } 146 147 int __fscache_begin_read_operation(struct netfs_cache_resources *cres, 148 struct fscache_cookie *cookie) 149 { 150 return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS, 151 fscache_access_io_read); 152 } 153 EXPORT_SYMBOL(__fscache_begin_read_operation); 154 155 int __fscache_begin_write_operation(struct netfs_cache_resources *cres, 156 struct fscache_cookie *cookie) 157 { 158 return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS, 159 fscache_access_io_write); 160 } 161 EXPORT_SYMBOL(__fscache_begin_write_operation); 162 163 struct fscache_write_request { 164 struct netfs_cache_resources cache_resources; 165 struct address_space *mapping; 166 loff_t start; 167 size_t len; 168 bool set_bits; 169 netfs_io_terminated_t term_func; 170 void *term_func_priv; 171 }; 172 173 void __fscache_clear_page_bits(struct address_space *mapping, 174 loff_t start, size_t len) 175 { 176 pgoff_t first = start / PAGE_SIZE; 177 pgoff_t last = (start + len - 1) / PAGE_SIZE; 178 struct page *page; 179 180 if (len) { 181 XA_STATE(xas, &mapping->i_pages, first); 182 183 rcu_read_lock(); 184 xas_for_each(&xas, page, last) { 185 end_page_fscache(page); 186 } 187 rcu_read_unlock(); 188 } 189 } 190 EXPORT_SYMBOL(__fscache_clear_page_bits); 191 192 /* 193 * Deal with the completion of writing the data to the cache. 194 */ 195 static void fscache_wreq_done(void *priv, ssize_t transferred_or_error, 196 bool was_async) 197 { 198 struct fscache_write_request *wreq = priv; 199 200 fscache_clear_page_bits(wreq->mapping, wreq->start, wreq->len, 201 wreq->set_bits); 202 203 if (wreq->term_func) 204 wreq->term_func(wreq->term_func_priv, transferred_or_error, 205 was_async); 206 fscache_end_operation(&wreq->cache_resources); 207 kfree(wreq); 208 } 209 210 void __fscache_write_to_cache(struct fscache_cookie *cookie, 211 struct address_space *mapping, 212 loff_t start, size_t len, loff_t i_size, 213 netfs_io_terminated_t term_func, 214 void *term_func_priv, 215 bool cond) 216 { 217 struct fscache_write_request *wreq; 218 struct netfs_cache_resources *cres; 219 struct iov_iter iter; 220 int ret = -ENOBUFS; 221 222 if (len == 0) 223 goto abandon; 224 225 _enter("%llx,%zx", start, len); 226 227 wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS); 228 if (!wreq) 229 goto abandon; 230 wreq->mapping = mapping; 231 wreq->start = start; 232 wreq->len = len; 233 wreq->set_bits = cond; 234 wreq->term_func = term_func; 235 wreq->term_func_priv = term_func_priv; 236 237 cres = &wreq->cache_resources; 238 if (fscache_begin_operation(cres, cookie, FSCACHE_WANT_WRITE, 239 fscache_access_io_write) < 0) 240 goto abandon_free; 241 242 ret = cres->ops->prepare_write(cres, &start, &len, len, i_size, false); 243 if (ret < 0) 244 goto abandon_end; 245 246 /* TODO: Consider clearing page bits now for space the write isn't 247 * covering. This is more complicated than it appears when THPs are 248 * taken into account. 249 */ 250 251 iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len); 252 fscache_write(cres, start, &iter, fscache_wreq_done, wreq); 253 return; 254 255 abandon_end: 256 return fscache_wreq_done(wreq, ret, false); 257 abandon_free: 258 kfree(wreq); 259 abandon: 260 fscache_clear_page_bits(mapping, start, len, cond); 261 if (term_func) 262 term_func(term_func_priv, ret, false); 263 } 264 EXPORT_SYMBOL(__fscache_write_to_cache); 265 266 /* 267 * Change the size of a backing object. 268 */ 269 void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size) 270 { 271 struct netfs_cache_resources cres; 272 273 trace_fscache_resize(cookie, new_size); 274 if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE, 275 fscache_access_io_resize) == 0) { 276 fscache_stat(&fscache_n_resizes); 277 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags); 278 279 /* We cannot defer a resize as we need to do it inside the 280 * netfs's inode lock so that we're serialised with respect to 281 * writes. 282 */ 283 cookie->volume->cache->ops->resize_cookie(&cres, new_size); 284 fscache_end_operation(&cres); 285 } else { 286 fscache_stat(&fscache_n_resizes_null); 287 } 288 } 289 EXPORT_SYMBOL(__fscache_resize_cookie); 290