1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (c) 2006-2007 Silicon Graphics, Inc. 4 * Copyright (c) 2014 Christoph Hellwig. 5 * All Rights Reserved. 6 */ 7 #include "xfs.h" 8 #include "xfs_shared.h" 9 #include "xfs_format.h" 10 #include "xfs_log_format.h" 11 #include "xfs_trans_resv.h" 12 #include "xfs_sb.h" 13 #include "xfs_mount.h" 14 #include "xfs_inode.h" 15 #include "xfs_bmap.h" 16 #include "xfs_alloc.h" 17 #include "xfs_mru_cache.h" 18 #include "xfs_trace.h" 19 #include "xfs_ag_resv.h" 20 #include "xfs_trans.h" 21 22 struct xfs_fstrm_item { 23 struct xfs_mru_cache_elem mru; 24 xfs_agnumber_t ag; /* AG in use for this directory */ 25 }; 26 27 enum xfs_fstrm_alloc { 28 XFS_PICK_USERDATA = 1, 29 XFS_PICK_LOWSPACE = 2, 30 }; 31 32 /* 33 * Allocation group filestream associations are tracked with per-ag atomic 34 * counters. These counters allow xfs_filestream_pick_ag() to tell whether a 35 * particular AG already has active filestreams associated with it. The mount 36 * point's m_peraglock is used to protect these counters from per-ag array 37 * re-allocation during a growfs operation. When xfs_growfs_data_private() is 38 * about to reallocate the array, it calls xfs_filestream_flush() with the 39 * m_peraglock held in write mode. 40 * 41 * Since xfs_mru_cache_flush() guarantees that all the free functions for all 42 * the cache elements have finished executing before it returns, it's safe for 43 * the free functions to use the atomic counters without m_peraglock protection. 44 * This allows the implementation of xfs_fstrm_free_func() to be agnostic about 45 * whether it was called with the m_peraglock held in read mode, write mode or 46 * not held at all. The race condition this addresses is the following: 47 * 48 * - The work queue scheduler fires and pulls a filestream directory cache 49 * element off the LRU end of the cache for deletion, then gets pre-empted. 50 * - A growfs operation grabs the m_peraglock in write mode, flushes all the 51 * remaining items from the cache and reallocates the mount point's per-ag 52 * array, resetting all the counters to zero. 53 * - The work queue thread resumes and calls the free function for the element 54 * it started cleaning up earlier. In the process it decrements the 55 * filestreams counter for an AG that now has no references. 56 * 57 * With a shrinkfs feature, the above scenario could panic the system. 58 * 59 * All other uses of the following macros should be protected by either the 60 * m_peraglock held in read mode, or the cache's internal locking exposed by the 61 * interval between a call to xfs_mru_cache_lookup() and a call to 62 * xfs_mru_cache_done(). In addition, the m_peraglock must be held in read mode 63 * when new elements are added to the cache. 64 * 65 * Combined, these locking rules ensure that no associations will ever exist in 66 * the cache that reference per-ag array elements that have since been 67 * reallocated. 68 */ 69 int 70 xfs_filestream_peek_ag( 71 xfs_mount_t *mp, 72 xfs_agnumber_t agno) 73 { 74 struct xfs_perag *pag; 75 int ret; 76 77 pag = xfs_perag_get(mp, agno); 78 ret = atomic_read(&pag->pagf_fstrms); 79 xfs_perag_put(pag); 80 return ret; 81 } 82 83 static int 84 xfs_filestream_get_ag( 85 xfs_mount_t *mp, 86 xfs_agnumber_t agno) 87 { 88 struct xfs_perag *pag; 89 int ret; 90 91 pag = xfs_perag_get(mp, agno); 92 ret = atomic_inc_return(&pag->pagf_fstrms); 93 xfs_perag_put(pag); 94 return ret; 95 } 96 97 static void 98 xfs_filestream_put_ag( 99 xfs_mount_t *mp, 100 xfs_agnumber_t agno) 101 { 102 struct xfs_perag *pag; 103 104 pag = xfs_perag_get(mp, agno); 105 atomic_dec(&pag->pagf_fstrms); 106 xfs_perag_put(pag); 107 } 108 109 static void 110 xfs_fstrm_free_func( 111 void *data, 112 struct xfs_mru_cache_elem *mru) 113 { 114 struct xfs_mount *mp = data; 115 struct xfs_fstrm_item *item = 116 container_of(mru, struct xfs_fstrm_item, mru); 117 118 xfs_filestream_put_ag(mp, item->ag); 119 trace_xfs_filestream_free(mp, mru->key, item->ag); 120 121 kmem_free(item); 122 } 123 124 /* 125 * Scan the AGs starting at startag looking for an AG that isn't in use and has 126 * at least minlen blocks free. 127 */ 128 static int 129 xfs_filestream_pick_ag( 130 struct xfs_inode *ip, 131 xfs_agnumber_t startag, 132 xfs_agnumber_t *agp, 133 int flags, 134 xfs_extlen_t minlen) 135 { 136 struct xfs_mount *mp = ip->i_mount; 137 struct xfs_fstrm_item *item; 138 struct xfs_perag *pag; 139 xfs_extlen_t longest, free = 0, minfree, maxfree = 0; 140 xfs_agnumber_t ag, max_ag = NULLAGNUMBER; 141 int err, trylock, nscan; 142 143 ASSERT(S_ISDIR(VFS_I(ip)->i_mode)); 144 145 /* 2% of an AG's blocks must be free for it to be chosen. */ 146 minfree = mp->m_sb.sb_agblocks / 50; 147 148 ag = startag; 149 *agp = NULLAGNUMBER; 150 151 /* For the first pass, don't sleep trying to init the per-AG. */ 152 trylock = XFS_ALLOC_FLAG_TRYLOCK; 153 154 for (nscan = 0; 1; nscan++) { 155 trace_xfs_filestream_scan(mp, ip->i_ino, ag); 156 157 pag = xfs_perag_get(mp, ag); 158 159 if (!pag->pagf_init) { 160 err = xfs_alloc_pagf_init(mp, NULL, ag, trylock); 161 if (err && !trylock) { 162 xfs_perag_put(pag); 163 return err; 164 } 165 } 166 167 /* Might fail sometimes during the 1st pass with trylock set. */ 168 if (!pag->pagf_init) 169 goto next_ag; 170 171 /* Keep track of the AG with the most free blocks. */ 172 if (pag->pagf_freeblks > maxfree) { 173 maxfree = pag->pagf_freeblks; 174 max_ag = ag; 175 } 176 177 /* 178 * The AG reference count does two things: it enforces mutual 179 * exclusion when examining the suitability of an AG in this 180 * loop, and it guards against two filestreams being established 181 * in the same AG as each other. 182 */ 183 if (xfs_filestream_get_ag(mp, ag) > 1) { 184 xfs_filestream_put_ag(mp, ag); 185 goto next_ag; 186 } 187 188 longest = xfs_alloc_longest_free_extent(pag, 189 xfs_alloc_min_freelist(mp, pag), 190 xfs_ag_resv_needed(pag, XFS_AG_RESV_NONE)); 191 if (((minlen && longest >= minlen) || 192 (!minlen && pag->pagf_freeblks >= minfree)) && 193 (!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) || 194 (flags & XFS_PICK_LOWSPACE))) { 195 196 /* Break out, retaining the reference on the AG. */ 197 free = pag->pagf_freeblks; 198 xfs_perag_put(pag); 199 *agp = ag; 200 break; 201 } 202 203 /* Drop the reference on this AG, it's not usable. */ 204 xfs_filestream_put_ag(mp, ag); 205 next_ag: 206 xfs_perag_put(pag); 207 /* Move to the next AG, wrapping to AG 0 if necessary. */ 208 if (++ag >= mp->m_sb.sb_agcount) 209 ag = 0; 210 211 /* If a full pass of the AGs hasn't been done yet, continue. */ 212 if (ag != startag) 213 continue; 214 215 /* Allow sleeping in xfs_alloc_pagf_init() on the 2nd pass. */ 216 if (trylock != 0) { 217 trylock = 0; 218 continue; 219 } 220 221 /* Finally, if lowspace wasn't set, set it for the 3rd pass. */ 222 if (!(flags & XFS_PICK_LOWSPACE)) { 223 flags |= XFS_PICK_LOWSPACE; 224 continue; 225 } 226 227 /* 228 * Take the AG with the most free space, regardless of whether 229 * it's already in use by another filestream. 230 */ 231 if (max_ag != NULLAGNUMBER) { 232 xfs_filestream_get_ag(mp, max_ag); 233 free = maxfree; 234 *agp = max_ag; 235 break; 236 } 237 238 /* take AG 0 if none matched */ 239 trace_xfs_filestream_pick(ip, *agp, free, nscan); 240 *agp = 0; 241 return 0; 242 } 243 244 trace_xfs_filestream_pick(ip, *agp, free, nscan); 245 246 if (*agp == NULLAGNUMBER) 247 return 0; 248 249 err = -ENOMEM; 250 item = kmem_alloc(sizeof(*item), KM_MAYFAIL); 251 if (!item) 252 goto out_put_ag; 253 254 item->ag = *agp; 255 256 err = xfs_mru_cache_insert(mp->m_filestream, ip->i_ino, &item->mru); 257 if (err) { 258 if (err == -EEXIST) 259 err = 0; 260 goto out_free_item; 261 } 262 263 return 0; 264 265 out_free_item: 266 kmem_free(item); 267 out_put_ag: 268 xfs_filestream_put_ag(mp, *agp); 269 return err; 270 } 271 272 static struct xfs_inode * 273 xfs_filestream_get_parent( 274 struct xfs_inode *ip) 275 { 276 struct inode *inode = VFS_I(ip), *dir = NULL; 277 struct dentry *dentry, *parent; 278 279 dentry = d_find_alias(inode); 280 if (!dentry) 281 goto out; 282 283 parent = dget_parent(dentry); 284 if (!parent) 285 goto out_dput; 286 287 dir = igrab(d_inode(parent)); 288 dput(parent); 289 290 out_dput: 291 dput(dentry); 292 out: 293 return dir ? XFS_I(dir) : NULL; 294 } 295 296 /* 297 * Find the right allocation group for a file, either by finding an 298 * existing file stream or creating a new one. 299 * 300 * Returns NULLAGNUMBER in case of an error. 301 */ 302 xfs_agnumber_t 303 xfs_filestream_lookup_ag( 304 struct xfs_inode *ip) 305 { 306 struct xfs_mount *mp = ip->i_mount; 307 struct xfs_inode *pip = NULL; 308 xfs_agnumber_t startag, ag = NULLAGNUMBER; 309 struct xfs_mru_cache_elem *mru; 310 311 ASSERT(S_ISREG(VFS_I(ip)->i_mode)); 312 313 pip = xfs_filestream_get_parent(ip); 314 if (!pip) 315 return NULLAGNUMBER; 316 317 mru = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino); 318 if (mru) { 319 ag = container_of(mru, struct xfs_fstrm_item, mru)->ag; 320 xfs_mru_cache_done(mp->m_filestream); 321 322 trace_xfs_filestream_lookup(mp, ip->i_ino, ag); 323 goto out; 324 } 325 326 /* 327 * Set the starting AG using the rotor for inode32, otherwise 328 * use the directory inode's AG. 329 */ 330 if (mp->m_flags & XFS_MOUNT_32BITINODES) { 331 xfs_agnumber_t rotorstep = xfs_rotorstep; 332 startag = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount; 333 mp->m_agfrotor = (mp->m_agfrotor + 1) % 334 (mp->m_sb.sb_agcount * rotorstep); 335 } else 336 startag = XFS_INO_TO_AGNO(mp, pip->i_ino); 337 338 if (xfs_filestream_pick_ag(pip, startag, &ag, 0, 0)) 339 ag = NULLAGNUMBER; 340 out: 341 xfs_irele(pip); 342 return ag; 343 } 344 345 /* 346 * Pick a new allocation group for the current file and its file stream. 347 * 348 * This is called when the allocator can't find a suitable extent in the 349 * current AG, and we have to move the stream into a new AG with more space. 350 */ 351 int 352 xfs_filestream_new_ag( 353 struct xfs_bmalloca *ap, 354 xfs_agnumber_t *agp) 355 { 356 struct xfs_inode *ip = ap->ip, *pip; 357 struct xfs_mount *mp = ip->i_mount; 358 xfs_extlen_t minlen = ap->length; 359 xfs_agnumber_t startag = 0; 360 int flags = 0; 361 int err = 0; 362 struct xfs_mru_cache_elem *mru; 363 364 *agp = NULLAGNUMBER; 365 366 pip = xfs_filestream_get_parent(ip); 367 if (!pip) 368 goto exit; 369 370 mru = xfs_mru_cache_remove(mp->m_filestream, pip->i_ino); 371 if (mru) { 372 struct xfs_fstrm_item *item = 373 container_of(mru, struct xfs_fstrm_item, mru); 374 startag = (item->ag + 1) % mp->m_sb.sb_agcount; 375 } 376 377 if (ap->datatype & XFS_ALLOC_USERDATA) 378 flags |= XFS_PICK_USERDATA; 379 if (ap->tp->t_flags & XFS_TRANS_LOWMODE) 380 flags |= XFS_PICK_LOWSPACE; 381 382 err = xfs_filestream_pick_ag(pip, startag, agp, flags, minlen); 383 384 /* 385 * Only free the item here so we skip over the old AG earlier. 386 */ 387 if (mru) 388 xfs_fstrm_free_func(mp, mru); 389 390 xfs_irele(pip); 391 exit: 392 if (*agp == NULLAGNUMBER) 393 *agp = 0; 394 return err; 395 } 396 397 void 398 xfs_filestream_deassociate( 399 struct xfs_inode *ip) 400 { 401 xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino); 402 } 403 404 int 405 xfs_filestream_mount( 406 xfs_mount_t *mp) 407 { 408 /* 409 * The filestream timer tunable is currently fixed within the range of 410 * one second to four minutes, with five seconds being the default. The 411 * group count is somewhat arbitrary, but it'd be nice to adhere to the 412 * timer tunable to within about 10 percent. This requires at least 10 413 * groups. 414 */ 415 return xfs_mru_cache_create(&mp->m_filestream, mp, 416 xfs_fstrm_centisecs * 10, 10, xfs_fstrm_free_func); 417 } 418 419 void 420 xfs_filestream_unmount( 421 xfs_mount_t *mp) 422 { 423 xfs_mru_cache_destroy(mp->m_filestream); 424 } 425