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_ag.h" 24 #include "xfs_sb.h" 25 #include "xfs_mount.h" 26 #include "xfs_inum.h" 27 #include "xfs_inode.h" 28 #include "xfs_bmap.h" 29 #include "xfs_bmap_util.h" 30 #include "xfs_alloc.h" 31 #include "xfs_mru_cache.h" 32 #include "xfs_dinode.h" 33 #include "xfs_filestream.h" 34 #include "xfs_trace.h" 35 36 struct xfs_fstrm_item { 37 struct xfs_mru_cache_elem mru; 38 struct xfs_inode *ip; 39 xfs_agnumber_t ag; /* AG in use for this directory */ 40 }; 41 42 enum xfs_fstrm_alloc { 43 XFS_PICK_USERDATA = 1, 44 XFS_PICK_LOWSPACE = 2, 45 }; 46 47 /* 48 * Allocation group filestream associations are tracked with per-ag atomic 49 * counters. These counters allow xfs_filestream_pick_ag() to tell whether a 50 * particular AG already has active filestreams associated with it. The mount 51 * point's m_peraglock is used to protect these counters from per-ag array 52 * re-allocation during a growfs operation. When xfs_growfs_data_private() is 53 * about to reallocate the array, it calls xfs_filestream_flush() with the 54 * m_peraglock held in write mode. 55 * 56 * Since xfs_mru_cache_flush() guarantees that all the free functions for all 57 * the cache elements have finished executing before it returns, it's safe for 58 * the free functions to use the atomic counters without m_peraglock protection. 59 * This allows the implementation of xfs_fstrm_free_func() to be agnostic about 60 * whether it was called with the m_peraglock held in read mode, write mode or 61 * not held at all. The race condition this addresses is the following: 62 * 63 * - The work queue scheduler fires and pulls a filestream directory cache 64 * element off the LRU end of the cache for deletion, then gets pre-empted. 65 * - A growfs operation grabs the m_peraglock in write mode, flushes all the 66 * remaining items from the cache and reallocates the mount point's per-ag 67 * array, resetting all the counters to zero. 68 * - The work queue thread resumes and calls the free function for the element 69 * it started cleaning up earlier. In the process it decrements the 70 * filestreams counter for an AG that now has no references. 71 * 72 * With a shrinkfs feature, the above scenario could panic the system. 73 * 74 * All other uses of the following macros should be protected by either the 75 * m_peraglock held in read mode, or the cache's internal locking exposed by the 76 * interval between a call to xfs_mru_cache_lookup() and a call to 77 * xfs_mru_cache_done(). In addition, the m_peraglock must be held in read mode 78 * when new elements are added to the cache. 79 * 80 * Combined, these locking rules ensure that no associations will ever exist in 81 * the cache that reference per-ag array elements that have since been 82 * reallocated. 83 */ 84 int 85 xfs_filestream_peek_ag( 86 xfs_mount_t *mp, 87 xfs_agnumber_t agno) 88 { 89 struct xfs_perag *pag; 90 int ret; 91 92 pag = xfs_perag_get(mp, agno); 93 ret = atomic_read(&pag->pagf_fstrms); 94 xfs_perag_put(pag); 95 return ret; 96 } 97 98 static int 99 xfs_filestream_get_ag( 100 xfs_mount_t *mp, 101 xfs_agnumber_t agno) 102 { 103 struct xfs_perag *pag; 104 int ret; 105 106 pag = xfs_perag_get(mp, agno); 107 ret = atomic_inc_return(&pag->pagf_fstrms); 108 xfs_perag_put(pag); 109 return ret; 110 } 111 112 static void 113 xfs_filestream_put_ag( 114 xfs_mount_t *mp, 115 xfs_agnumber_t agno) 116 { 117 struct xfs_perag *pag; 118 119 pag = xfs_perag_get(mp, agno); 120 atomic_dec(&pag->pagf_fstrms); 121 xfs_perag_put(pag); 122 } 123 124 static void 125 xfs_fstrm_free_func( 126 struct xfs_mru_cache_elem *mru) 127 { 128 struct xfs_fstrm_item *item = 129 container_of(mru, struct xfs_fstrm_item, mru); 130 131 xfs_filestream_put_ag(item->ip->i_mount, item->ag); 132 133 trace_xfs_filestream_free(item->ip, item->ag); 134 135 kmem_free(item); 136 } 137 138 /* 139 * Scan the AGs starting at startag looking for an AG that isn't in use and has 140 * at least minlen blocks free. 141 */ 142 static int 143 xfs_filestream_pick_ag( 144 struct xfs_inode *ip, 145 xfs_agnumber_t startag, 146 xfs_agnumber_t *agp, 147 int flags, 148 xfs_extlen_t minlen) 149 { 150 struct xfs_mount *mp = ip->i_mount; 151 struct xfs_fstrm_item *item; 152 struct xfs_perag *pag; 153 xfs_extlen_t longest, free = 0, minfree, maxfree = 0; 154 xfs_agnumber_t ag, max_ag = NULLAGNUMBER; 155 int err, trylock, nscan; 156 157 ASSERT(S_ISDIR(ip->i_d.di_mode)); 158 159 /* 2% of an AG's blocks must be free for it to be chosen. */ 160 minfree = mp->m_sb.sb_agblocks / 50; 161 162 ag = startag; 163 *agp = NULLAGNUMBER; 164 165 /* For the first pass, don't sleep trying to init the per-AG. */ 166 trylock = XFS_ALLOC_FLAG_TRYLOCK; 167 168 for (nscan = 0; 1; nscan++) { 169 trace_xfs_filestream_scan(ip, ag); 170 171 pag = xfs_perag_get(mp, ag); 172 173 if (!pag->pagf_init) { 174 err = xfs_alloc_pagf_init(mp, NULL, ag, trylock); 175 if (err && !trylock) { 176 xfs_perag_put(pag); 177 return err; 178 } 179 } 180 181 /* Might fail sometimes during the 1st pass with trylock set. */ 182 if (!pag->pagf_init) 183 goto next_ag; 184 185 /* Keep track of the AG with the most free blocks. */ 186 if (pag->pagf_freeblks > maxfree) { 187 maxfree = pag->pagf_freeblks; 188 max_ag = ag; 189 } 190 191 /* 192 * The AG reference count does two things: it enforces mutual 193 * exclusion when examining the suitability of an AG in this 194 * loop, and it guards against two filestreams being established 195 * in the same AG as each other. 196 */ 197 if (xfs_filestream_get_ag(mp, ag) > 1) { 198 xfs_filestream_put_ag(mp, ag); 199 goto next_ag; 200 } 201 202 longest = xfs_alloc_longest_free_extent(mp, pag); 203 if (((minlen && longest >= minlen) || 204 (!minlen && pag->pagf_freeblks >= minfree)) && 205 (!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) || 206 (flags & XFS_PICK_LOWSPACE))) { 207 208 /* Break out, retaining the reference on the AG. */ 209 free = pag->pagf_freeblks; 210 xfs_perag_put(pag); 211 *agp = ag; 212 break; 213 } 214 215 /* Drop the reference on this AG, it's not usable. */ 216 xfs_filestream_put_ag(mp, ag); 217 next_ag: 218 xfs_perag_put(pag); 219 /* Move to the next AG, wrapping to AG 0 if necessary. */ 220 if (++ag >= mp->m_sb.sb_agcount) 221 ag = 0; 222 223 /* If a full pass of the AGs hasn't been done yet, continue. */ 224 if (ag != startag) 225 continue; 226 227 /* Allow sleeping in xfs_alloc_pagf_init() on the 2nd pass. */ 228 if (trylock != 0) { 229 trylock = 0; 230 continue; 231 } 232 233 /* Finally, if lowspace wasn't set, set it for the 3rd pass. */ 234 if (!(flags & XFS_PICK_LOWSPACE)) { 235 flags |= XFS_PICK_LOWSPACE; 236 continue; 237 } 238 239 /* 240 * Take the AG with the most free space, regardless of whether 241 * it's already in use by another filestream. 242 */ 243 if (max_ag != NULLAGNUMBER) { 244 xfs_filestream_get_ag(mp, max_ag); 245 free = maxfree; 246 *agp = max_ag; 247 break; 248 } 249 250 /* take AG 0 if none matched */ 251 trace_xfs_filestream_pick(ip, *agp, free, nscan); 252 *agp = 0; 253 return 0; 254 } 255 256 trace_xfs_filestream_pick(ip, *agp, free, nscan); 257 258 if (*agp == NULLAGNUMBER) 259 return 0; 260 261 err = ENOMEM; 262 item = kmem_alloc(sizeof(*item), KM_MAYFAIL); 263 if (!item) 264 goto out_put_ag; 265 266 item->ag = *agp; 267 item->ip = ip; 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(parent->d_inode); 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(ip->i_d.di_mode)); 325 326 pip = xfs_filestream_get_parent(ip); 327 if (!pip) 328 goto out; 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(ip, 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, err = 0; 374 struct xfs_mru_cache_elem *mru; 375 376 *agp = NULLAGNUMBER; 377 378 pip = xfs_filestream_get_parent(ip); 379 if (!pip) 380 goto exit; 381 382 mru = xfs_mru_cache_remove(mp->m_filestream, pip->i_ino); 383 if (mru) { 384 struct xfs_fstrm_item *item = 385 container_of(mru, struct xfs_fstrm_item, mru); 386 startag = (item->ag + 1) % mp->m_sb.sb_agcount; 387 } 388 389 flags = (ap->userdata ? XFS_PICK_USERDATA : 0) | 390 (ap->flist->xbf_low ? XFS_PICK_LOWSPACE : 0); 391 392 err = xfs_filestream_pick_ag(pip, startag, agp, flags, minlen); 393 394 /* 395 * Only free the item here so we skip over the old AG earlier. 396 */ 397 if (mru) 398 xfs_fstrm_free_func(mru); 399 400 IRELE(pip); 401 exit: 402 if (*agp == NULLAGNUMBER) 403 *agp = 0; 404 return err; 405 } 406 407 void 408 xfs_filestream_deassociate( 409 struct xfs_inode *ip) 410 { 411 xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino); 412 } 413 414 int 415 xfs_filestream_mount( 416 xfs_mount_t *mp) 417 { 418 /* 419 * The filestream timer tunable is currently fixed within the range of 420 * one second to four minutes, with five seconds being the default. The 421 * group count is somewhat arbitrary, but it'd be nice to adhere to the 422 * timer tunable to within about 10 percent. This requires at least 10 423 * groups. 424 */ 425 return xfs_mru_cache_create(&mp->m_filestream, xfs_fstrm_centisecs * 10, 426 10, xfs_fstrm_free_func); 427 } 428 429 void 430 xfs_filestream_unmount( 431 xfs_mount_t *mp) 432 { 433 xfs_mru_cache_destroy(mp->m_filestream); 434 } 435