1 /* 2 * Copyright (c) 2006-2007 Silicon Graphics, Inc. 3 * Copyright (c) 2014 Christoph Hellwig. 4 * All Rights Reserved. 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. 9 * 10 * This program is distributed in the hope that it would be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program; if not, write the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 18 */ 19 #include "xfs.h" 20 #include "xfs_format.h" 21 #include "xfs_log_format.h" 22 #include "xfs_trans_resv.h" 23 #include "xfs_sb.h" 24 #include "xfs_mount.h" 25 #include "xfs_defer.h" 26 #include "xfs_inode.h" 27 #include "xfs_bmap.h" 28 #include "xfs_bmap_util.h" 29 #include "xfs_alloc.h" 30 #include "xfs_mru_cache.h" 31 #include "xfs_filestream.h" 32 #include "xfs_trace.h" 33 #include "xfs_ag_resv.h" 34 35 struct xfs_fstrm_item { 36 struct xfs_mru_cache_elem mru; 37 xfs_agnumber_t ag; /* AG in use for this directory */ 38 }; 39 40 enum xfs_fstrm_alloc { 41 XFS_PICK_USERDATA = 1, 42 XFS_PICK_LOWSPACE = 2, 43 }; 44 45 /* 46 * Allocation group filestream associations are tracked with per-ag atomic 47 * counters. These counters allow xfs_filestream_pick_ag() to tell whether a 48 * particular AG already has active filestreams associated with it. The mount 49 * point's m_peraglock is used to protect these counters from per-ag array 50 * re-allocation during a growfs operation. When xfs_growfs_data_private() is 51 * about to reallocate the array, it calls xfs_filestream_flush() with the 52 * m_peraglock held in write mode. 53 * 54 * Since xfs_mru_cache_flush() guarantees that all the free functions for all 55 * the cache elements have finished executing before it returns, it's safe for 56 * the free functions to use the atomic counters without m_peraglock protection. 57 * This allows the implementation of xfs_fstrm_free_func() to be agnostic about 58 * whether it was called with the m_peraglock held in read mode, write mode or 59 * not held at all. The race condition this addresses is the following: 60 * 61 * - The work queue scheduler fires and pulls a filestream directory cache 62 * element off the LRU end of the cache for deletion, then gets pre-empted. 63 * - A growfs operation grabs the m_peraglock in write mode, flushes all the 64 * remaining items from the cache and reallocates the mount point's per-ag 65 * array, resetting all the counters to zero. 66 * - The work queue thread resumes and calls the free function for the element 67 * it started cleaning up earlier. In the process it decrements the 68 * filestreams counter for an AG that now has no references. 69 * 70 * With a shrinkfs feature, the above scenario could panic the system. 71 * 72 * All other uses of the following macros should be protected by either the 73 * m_peraglock held in read mode, or the cache's internal locking exposed by the 74 * interval between a call to xfs_mru_cache_lookup() and a call to 75 * xfs_mru_cache_done(). In addition, the m_peraglock must be held in read mode 76 * when new elements are added to the cache. 77 * 78 * Combined, these locking rules ensure that no associations will ever exist in 79 * the cache that reference per-ag array elements that have since been 80 * reallocated. 81 */ 82 int 83 xfs_filestream_peek_ag( 84 xfs_mount_t *mp, 85 xfs_agnumber_t agno) 86 { 87 struct xfs_perag *pag; 88 int ret; 89 90 pag = xfs_perag_get(mp, agno); 91 ret = atomic_read(&pag->pagf_fstrms); 92 xfs_perag_put(pag); 93 return ret; 94 } 95 96 static int 97 xfs_filestream_get_ag( 98 xfs_mount_t *mp, 99 xfs_agnumber_t agno) 100 { 101 struct xfs_perag *pag; 102 int ret; 103 104 pag = xfs_perag_get(mp, agno); 105 ret = atomic_inc_return(&pag->pagf_fstrms); 106 xfs_perag_put(pag); 107 return ret; 108 } 109 110 static void 111 xfs_filestream_put_ag( 112 xfs_mount_t *mp, 113 xfs_agnumber_t agno) 114 { 115 struct xfs_perag *pag; 116 117 pag = xfs_perag_get(mp, agno); 118 atomic_dec(&pag->pagf_fstrms); 119 xfs_perag_put(pag); 120 } 121 122 static void 123 xfs_fstrm_free_func( 124 void *data, 125 struct xfs_mru_cache_elem *mru) 126 { 127 struct xfs_mount *mp = data; 128 struct xfs_fstrm_item *item = 129 container_of(mru, struct xfs_fstrm_item, mru); 130 131 xfs_filestream_put_ag(mp, item->ag); 132 trace_xfs_filestream_free(mp, mru->key, item->ag); 133 134 kmem_free(item); 135 } 136 137 /* 138 * Scan the AGs starting at startag looking for an AG that isn't in use and has 139 * at least minlen blocks free. 140 */ 141 static int 142 xfs_filestream_pick_ag( 143 struct xfs_inode *ip, 144 xfs_agnumber_t startag, 145 xfs_agnumber_t *agp, 146 int flags, 147 xfs_extlen_t minlen) 148 { 149 struct xfs_mount *mp = ip->i_mount; 150 struct xfs_fstrm_item *item; 151 struct xfs_perag *pag; 152 xfs_extlen_t longest, free = 0, minfree, maxfree = 0; 153 xfs_agnumber_t ag, max_ag = NULLAGNUMBER; 154 int err, trylock, nscan; 155 156 ASSERT(S_ISDIR(VFS_I(ip)->i_mode)); 157 158 /* 2% of an AG's blocks must be free for it to be chosen. */ 159 minfree = mp->m_sb.sb_agblocks / 50; 160 161 ag = startag; 162 *agp = NULLAGNUMBER; 163 164 /* For the first pass, don't sleep trying to init the per-AG. */ 165 trylock = XFS_ALLOC_FLAG_TRYLOCK; 166 167 for (nscan = 0; 1; nscan++) { 168 trace_xfs_filestream_scan(mp, ip->i_ino, ag); 169 170 pag = xfs_perag_get(mp, ag); 171 172 if (!pag->pagf_init) { 173 err = xfs_alloc_pagf_init(mp, NULL, ag, trylock); 174 if (err && !trylock) { 175 xfs_perag_put(pag); 176 return err; 177 } 178 } 179 180 /* Might fail sometimes during the 1st pass with trylock set. */ 181 if (!pag->pagf_init) 182 goto next_ag; 183 184 /* Keep track of the AG with the most free blocks. */ 185 if (pag->pagf_freeblks > maxfree) { 186 maxfree = pag->pagf_freeblks; 187 max_ag = ag; 188 } 189 190 /* 191 * The AG reference count does two things: it enforces mutual 192 * exclusion when examining the suitability of an AG in this 193 * loop, and it guards against two filestreams being established 194 * in the same AG as each other. 195 */ 196 if (xfs_filestream_get_ag(mp, ag) > 1) { 197 xfs_filestream_put_ag(mp, ag); 198 goto next_ag; 199 } 200 201 longest = xfs_alloc_longest_free_extent(pag, 202 xfs_alloc_min_freelist(mp, pag), 203 xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE)); 204 if (((minlen && longest >= minlen) || 205 (!minlen && pag->pagf_freeblks >= minfree)) && 206 (!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) || 207 (flags & XFS_PICK_LOWSPACE))) { 208 209 /* Break out, retaining the reference on the AG. */ 210 free = pag->pagf_freeblks; 211 xfs_perag_put(pag); 212 *agp = ag; 213 break; 214 } 215 216 /* Drop the reference on this AG, it's not usable. */ 217 xfs_filestream_put_ag(mp, ag); 218 next_ag: 219 xfs_perag_put(pag); 220 /* Move to the next AG, wrapping to AG 0 if necessary. */ 221 if (++ag >= mp->m_sb.sb_agcount) 222 ag = 0; 223 224 /* If a full pass of the AGs hasn't been done yet, continue. */ 225 if (ag != startag) 226 continue; 227 228 /* Allow sleeping in xfs_alloc_pagf_init() on the 2nd pass. */ 229 if (trylock != 0) { 230 trylock = 0; 231 continue; 232 } 233 234 /* Finally, if lowspace wasn't set, set it for the 3rd pass. */ 235 if (!(flags & XFS_PICK_LOWSPACE)) { 236 flags |= XFS_PICK_LOWSPACE; 237 continue; 238 } 239 240 /* 241 * Take the AG with the most free space, regardless of whether 242 * it's already in use by another filestream. 243 */ 244 if (max_ag != NULLAGNUMBER) { 245 xfs_filestream_get_ag(mp, max_ag); 246 free = maxfree; 247 *agp = max_ag; 248 break; 249 } 250 251 /* take AG 0 if none matched */ 252 trace_xfs_filestream_pick(ip, *agp, free, nscan); 253 *agp = 0; 254 return 0; 255 } 256 257 trace_xfs_filestream_pick(ip, *agp, free, nscan); 258 259 if (*agp == NULLAGNUMBER) 260 return 0; 261 262 err = -ENOMEM; 263 item = kmem_alloc(sizeof(*item), KM_MAYFAIL); 264 if (!item) 265 goto out_put_ag; 266 267 item->ag = *agp; 268 269 err = xfs_mru_cache_insert(mp->m_filestream, ip->i_ino, &item->mru); 270 if (err) { 271 if (err == -EEXIST) 272 err = 0; 273 goto out_free_item; 274 } 275 276 return 0; 277 278 out_free_item: 279 kmem_free(item); 280 out_put_ag: 281 xfs_filestream_put_ag(mp, *agp); 282 return err; 283 } 284 285 static struct xfs_inode * 286 xfs_filestream_get_parent( 287 struct xfs_inode *ip) 288 { 289 struct inode *inode = VFS_I(ip), *dir = NULL; 290 struct dentry *dentry, *parent; 291 292 dentry = d_find_alias(inode); 293 if (!dentry) 294 goto out; 295 296 parent = dget_parent(dentry); 297 if (!parent) 298 goto out_dput; 299 300 dir = igrab(d_inode(parent)); 301 dput(parent); 302 303 out_dput: 304 dput(dentry); 305 out: 306 return dir ? XFS_I(dir) : NULL; 307 } 308 309 /* 310 * Find the right allocation group for a file, either by finding an 311 * existing file stream or creating a new one. 312 * 313 * Returns NULLAGNUMBER in case of an error. 314 */ 315 xfs_agnumber_t 316 xfs_filestream_lookup_ag( 317 struct xfs_inode *ip) 318 { 319 struct xfs_mount *mp = ip->i_mount; 320 struct xfs_inode *pip = NULL; 321 xfs_agnumber_t startag, ag = NULLAGNUMBER; 322 struct xfs_mru_cache_elem *mru; 323 324 ASSERT(S_ISREG(VFS_I(ip)->i_mode)); 325 326 pip = xfs_filestream_get_parent(ip); 327 if (!pip) 328 return NULLAGNUMBER; 329 330 mru = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino); 331 if (mru) { 332 ag = container_of(mru, struct xfs_fstrm_item, mru)->ag; 333 xfs_mru_cache_done(mp->m_filestream); 334 335 trace_xfs_filestream_lookup(mp, ip->i_ino, ag); 336 goto out; 337 } 338 339 /* 340 * Set the starting AG using the rotor for inode32, otherwise 341 * use the directory inode's AG. 342 */ 343 if (mp->m_flags & XFS_MOUNT_32BITINODES) { 344 xfs_agnumber_t rotorstep = xfs_rotorstep; 345 startag = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount; 346 mp->m_agfrotor = (mp->m_agfrotor + 1) % 347 (mp->m_sb.sb_agcount * rotorstep); 348 } else 349 startag = XFS_INO_TO_AGNO(mp, pip->i_ino); 350 351 if (xfs_filestream_pick_ag(pip, startag, &ag, 0, 0)) 352 ag = NULLAGNUMBER; 353 out: 354 IRELE(pip); 355 return ag; 356 } 357 358 /* 359 * Pick a new allocation group for the current file and its file stream. 360 * 361 * This is called when the allocator can't find a suitable extent in the 362 * current AG, and we have to move the stream into a new AG with more space. 363 */ 364 int 365 xfs_filestream_new_ag( 366 struct xfs_bmalloca *ap, 367 xfs_agnumber_t *agp) 368 { 369 struct xfs_inode *ip = ap->ip, *pip; 370 struct xfs_mount *mp = ip->i_mount; 371 xfs_extlen_t minlen = ap->length; 372 xfs_agnumber_t startag = 0; 373 int flags = 0; 374 int err = 0; 375 struct xfs_mru_cache_elem *mru; 376 377 *agp = NULLAGNUMBER; 378 379 pip = xfs_filestream_get_parent(ip); 380 if (!pip) 381 goto exit; 382 383 mru = xfs_mru_cache_remove(mp->m_filestream, pip->i_ino); 384 if (mru) { 385 struct xfs_fstrm_item *item = 386 container_of(mru, struct xfs_fstrm_item, mru); 387 startag = (item->ag + 1) % mp->m_sb.sb_agcount; 388 } 389 390 if (xfs_alloc_is_userdata(ap->datatype)) 391 flags |= XFS_PICK_USERDATA; 392 if (ap->dfops->dop_low) 393 flags |= XFS_PICK_LOWSPACE; 394 395 err = xfs_filestream_pick_ag(pip, startag, agp, flags, minlen); 396 397 /* 398 * Only free the item here so we skip over the old AG earlier. 399 */ 400 if (mru) 401 xfs_fstrm_free_func(mp, mru); 402 403 IRELE(pip); 404 exit: 405 if (*agp == NULLAGNUMBER) 406 *agp = 0; 407 return err; 408 } 409 410 void 411 xfs_filestream_deassociate( 412 struct xfs_inode *ip) 413 { 414 xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino); 415 } 416 417 int 418 xfs_filestream_mount( 419 xfs_mount_t *mp) 420 { 421 /* 422 * The filestream timer tunable is currently fixed within the range of 423 * one second to four minutes, with five seconds being the default. The 424 * group count is somewhat arbitrary, but it'd be nice to adhere to the 425 * timer tunable to within about 10 percent. This requires at least 10 426 * groups. 427 */ 428 return xfs_mru_cache_create(&mp->m_filestream, mp, 429 xfs_fstrm_centisecs * 10, 10, xfs_fstrm_free_func); 430 } 431 432 void 433 xfs_filestream_unmount( 434 xfs_mount_t *mp) 435 { 436 xfs_mru_cache_destroy(mp->m_filestream); 437 } 438