2 * Copyright (c) 2006-2007 Silicon Graphics, Inc.
3 * Copyright (c) 2014 Christoph Hellwig.
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.
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.
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
20 #include "xfs_format.h"
21 #include "xfs_log_format.h"
22 #include "xfs_trans_resv.h"
24 #include "xfs_mount.h"
25 #include "xfs_inode.h"
27 #include "xfs_bmap_util.h"
28 #include "xfs_alloc.h"
29 #include "xfs_mru_cache.h"
30 #include "xfs_filestream.h"
31 #include "xfs_trace.h"
33 struct xfs_fstrm_item {
34 struct xfs_mru_cache_elem mru;
36 xfs_agnumber_t ag; /* AG in use for this directory */
39 enum xfs_fstrm_alloc {
40 XFS_PICK_USERDATA = 1,
41 XFS_PICK_LOWSPACE = 2,
45 * Allocation group filestream associations are tracked with per-ag atomic
46 * counters. These counters allow xfs_filestream_pick_ag() to tell whether a
47 * particular AG already has active filestreams associated with it. The mount
48 * point's m_peraglock is used to protect these counters from per-ag array
49 * re-allocation during a growfs operation. When xfs_growfs_data_private() is
50 * about to reallocate the array, it calls xfs_filestream_flush() with the
51 * m_peraglock held in write mode.
53 * Since xfs_mru_cache_flush() guarantees that all the free functions for all
54 * the cache elements have finished executing before it returns, it's safe for
55 * the free functions to use the atomic counters without m_peraglock protection.
56 * This allows the implementation of xfs_fstrm_free_func() to be agnostic about
57 * whether it was called with the m_peraglock held in read mode, write mode or
58 * not held at all. The race condition this addresses is the following:
60 * - The work queue scheduler fires and pulls a filestream directory cache
61 * element off the LRU end of the cache for deletion, then gets pre-empted.
62 * - A growfs operation grabs the m_peraglock in write mode, flushes all the
63 * remaining items from the cache and reallocates the mount point's per-ag
64 * array, resetting all the counters to zero.
65 * - The work queue thread resumes and calls the free function for the element
66 * it started cleaning up earlier. In the process it decrements the
67 * filestreams counter for an AG that now has no references.
69 * With a shrinkfs feature, the above scenario could panic the system.
71 * All other uses of the following macros should be protected by either the
72 * m_peraglock held in read mode, or the cache's internal locking exposed by the
73 * interval between a call to xfs_mru_cache_lookup() and a call to
74 * xfs_mru_cache_done(). In addition, the m_peraglock must be held in read mode
75 * when new elements are added to the cache.
77 * Combined, these locking rules ensure that no associations will ever exist in
78 * the cache that reference per-ag array elements that have since been
82 xfs_filestream_peek_ag(
86 struct xfs_perag *pag;
89 pag = xfs_perag_get(mp, agno);
90 ret = atomic_read(&pag->pagf_fstrms);
96 xfs_filestream_get_ag(
100 struct xfs_perag *pag;
103 pag = xfs_perag_get(mp, agno);
104 ret = atomic_inc_return(&pag->pagf_fstrms);
110 xfs_filestream_put_ag(
114 struct xfs_perag *pag;
116 pag = xfs_perag_get(mp, agno);
117 atomic_dec(&pag->pagf_fstrms);
123 struct xfs_mru_cache_elem *mru)
125 struct xfs_fstrm_item *item =
126 container_of(mru, struct xfs_fstrm_item, mru);
128 xfs_filestream_put_ag(item->ip->i_mount, item->ag);
130 trace_xfs_filestream_free(item->ip, item->ag);
136 * Scan the AGs starting at startag looking for an AG that isn't in use and has
137 * at least minlen blocks free.
140 xfs_filestream_pick_ag(
141 struct xfs_inode *ip,
142 xfs_agnumber_t startag,
147 struct xfs_mount *mp = ip->i_mount;
148 struct xfs_fstrm_item *item;
149 struct xfs_perag *pag;
150 xfs_extlen_t longest, free = 0, minfree, maxfree = 0;
151 xfs_agnumber_t ag, max_ag = NULLAGNUMBER;
152 int err, trylock, nscan;
154 ASSERT(S_ISDIR(VFS_I(ip)->i_mode));
156 /* 2% of an AG's blocks must be free for it to be chosen. */
157 minfree = mp->m_sb.sb_agblocks / 50;
162 /* For the first pass, don't sleep trying to init the per-AG. */
163 trylock = XFS_ALLOC_FLAG_TRYLOCK;
165 for (nscan = 0; 1; nscan++) {
166 trace_xfs_filestream_scan(ip, ag);
168 pag = xfs_perag_get(mp, ag);
170 if (!pag->pagf_init) {
171 err = xfs_alloc_pagf_init(mp, NULL, ag, trylock);
172 if (err && !trylock) {
178 /* Might fail sometimes during the 1st pass with trylock set. */
182 /* Keep track of the AG with the most free blocks. */
183 if (pag->pagf_freeblks > maxfree) {
184 maxfree = pag->pagf_freeblks;
189 * The AG reference count does two things: it enforces mutual
190 * exclusion when examining the suitability of an AG in this
191 * loop, and it guards against two filestreams being established
192 * in the same AG as each other.
194 if (xfs_filestream_get_ag(mp, ag) > 1) {
195 xfs_filestream_put_ag(mp, ag);
199 longest = xfs_alloc_longest_free_extent(mp, pag,
200 xfs_alloc_min_freelist(mp, pag));
201 if (((minlen && longest >= minlen) ||
202 (!minlen && pag->pagf_freeblks >= minfree)) &&
203 (!pag->pagf_metadata || !(flags & XFS_PICK_USERDATA) ||
204 (flags & XFS_PICK_LOWSPACE))) {
206 /* Break out, retaining the reference on the AG. */
207 free = pag->pagf_freeblks;
213 /* Drop the reference on this AG, it's not usable. */
214 xfs_filestream_put_ag(mp, ag);
217 /* Move to the next AG, wrapping to AG 0 if necessary. */
218 if (++ag >= mp->m_sb.sb_agcount)
221 /* If a full pass of the AGs hasn't been done yet, continue. */
225 /* Allow sleeping in xfs_alloc_pagf_init() on the 2nd pass. */
231 /* Finally, if lowspace wasn't set, set it for the 3rd pass. */
232 if (!(flags & XFS_PICK_LOWSPACE)) {
233 flags |= XFS_PICK_LOWSPACE;
238 * Take the AG with the most free space, regardless of whether
239 * it's already in use by another filestream.
241 if (max_ag != NULLAGNUMBER) {
242 xfs_filestream_get_ag(mp, max_ag);
248 /* take AG 0 if none matched */
249 trace_xfs_filestream_pick(ip, *agp, free, nscan);
254 trace_xfs_filestream_pick(ip, *agp, free, nscan);
256 if (*agp == NULLAGNUMBER)
260 item = kmem_alloc(sizeof(*item), KM_MAYFAIL);
267 err = xfs_mru_cache_insert(mp->m_filestream, ip->i_ino, &item->mru);
279 xfs_filestream_put_ag(mp, *agp);
283 static struct xfs_inode *
284 xfs_filestream_get_parent(
285 struct xfs_inode *ip)
287 struct inode *inode = VFS_I(ip), *dir = NULL;
288 struct dentry *dentry, *parent;
290 dentry = d_find_alias(inode);
294 parent = dget_parent(dentry);
298 dir = igrab(d_inode(parent));
304 return dir ? XFS_I(dir) : NULL;
308 * Find the right allocation group for a file, either by finding an
309 * existing file stream or creating a new one.
311 * Returns NULLAGNUMBER in case of an error.
314 xfs_filestream_lookup_ag(
315 struct xfs_inode *ip)
317 struct xfs_mount *mp = ip->i_mount;
318 struct xfs_inode *pip = NULL;
319 xfs_agnumber_t startag, ag = NULLAGNUMBER;
320 struct xfs_mru_cache_elem *mru;
322 ASSERT(S_ISREG(VFS_I(ip)->i_mode));
324 pip = xfs_filestream_get_parent(ip);
328 mru = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino);
330 ag = container_of(mru, struct xfs_fstrm_item, mru)->ag;
331 xfs_mru_cache_done(mp->m_filestream);
333 trace_xfs_filestream_lookup(ip, ag);
338 * Set the starting AG using the rotor for inode32, otherwise
339 * use the directory inode's AG.
341 if (mp->m_flags & XFS_MOUNT_32BITINODES) {
342 xfs_agnumber_t rotorstep = xfs_rotorstep;
343 startag = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount;
344 mp->m_agfrotor = (mp->m_agfrotor + 1) %
345 (mp->m_sb.sb_agcount * rotorstep);
347 startag = XFS_INO_TO_AGNO(mp, pip->i_ino);
349 if (xfs_filestream_pick_ag(pip, startag, &ag, 0, 0))
357 * Pick a new allocation group for the current file and its file stream.
359 * This is called when the allocator can't find a suitable extent in the
360 * current AG, and we have to move the stream into a new AG with more space.
363 xfs_filestream_new_ag(
364 struct xfs_bmalloca *ap,
367 struct xfs_inode *ip = ap->ip, *pip;
368 struct xfs_mount *mp = ip->i_mount;
369 xfs_extlen_t minlen = ap->length;
370 xfs_agnumber_t startag = 0;
372 struct xfs_mru_cache_elem *mru;
376 pip = xfs_filestream_get_parent(ip);
380 mru = xfs_mru_cache_remove(mp->m_filestream, pip->i_ino);
382 struct xfs_fstrm_item *item =
383 container_of(mru, struct xfs_fstrm_item, mru);
384 startag = (item->ag + 1) % mp->m_sb.sb_agcount;
387 flags = (ap->userdata ? XFS_PICK_USERDATA : 0) |
388 (ap->flist->xbf_low ? XFS_PICK_LOWSPACE : 0);
390 err = xfs_filestream_pick_ag(pip, startag, agp, flags, minlen);
393 * Only free the item here so we skip over the old AG earlier.
396 xfs_fstrm_free_func(mru);
400 if (*agp == NULLAGNUMBER)
406 xfs_filestream_deassociate(
407 struct xfs_inode *ip)
409 xfs_mru_cache_delete(ip->i_mount->m_filestream, ip->i_ino);
413 xfs_filestream_mount(
417 * The filestream timer tunable is currently fixed within the range of
418 * one second to four minutes, with five seconds being the default. The
419 * group count is somewhat arbitrary, but it'd be nice to adhere to the
420 * timer tunable to within about 10 percent. This requires at least 10
423 return xfs_mru_cache_create(&mp->m_filestream, xfs_fstrm_centisecs * 10,
424 10, xfs_fstrm_free_func);
428 xfs_filestream_unmount(
431 xfs_mru_cache_destroy(mp->m_filestream);