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cf8ce220 DW |
1 | /* |
2 | * Copyright (C) 2016 Oracle. All Rights Reserved. | |
3 | * | |
4 | * Author: Darrick J. Wong <darrick.wong@oracle.com> | |
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 | |
8 | * as published by the Free Software Foundation; either version 2 | |
9 | * of the License, or (at your option) any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it would be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program; if not, write the Free Software Foundation, | |
18 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. | |
19 | */ | |
20 | #include "libxfs_priv.h" | |
21 | #include "xfs_fs.h" | |
22 | #include "xfs_shared.h" | |
23 | #include "xfs_format.h" | |
24 | #include "xfs_log_format.h" | |
25 | #include "xfs_trans_resv.h" | |
26 | #include "xfs_sb.h" | |
27 | #include "xfs_mount.h" | |
28 | #include "xfs_defer.h" | |
29 | #include "xfs_alloc.h" | |
56d3fc2b | 30 | #include "xfs_errortag.h" |
cf8ce220 DW |
31 | #include "xfs_trace.h" |
32 | #include "xfs_cksum.h" | |
33 | #include "xfs_trans.h" | |
34 | #include "xfs_bit.h" | |
35 | #include "xfs_bmap.h" | |
36 | #include "xfs_bmap_btree.h" | |
37 | #include "xfs_ag_resv.h" | |
38 | #include "xfs_trans_space.h" | |
39 | #include "xfs_rmap_btree.h" | |
40 | #include "xfs_btree.h" | |
02cc8b2a | 41 | #include "xfs_refcount_btree.h" |
74e502ac | 42 | #include "xfs_ialloc_btree.h" |
cf8ce220 DW |
43 | |
44 | /* | |
45 | * Per-AG Block Reservations | |
46 | * | |
47 | * For some kinds of allocation group metadata structures, it is advantageous | |
48 | * to reserve a small number of blocks in each AG so that future expansions of | |
49 | * that data structure do not encounter ENOSPC because errors during a btree | |
50 | * split cause the filesystem to go offline. | |
51 | * | |
52 | * Prior to the introduction of reflink, this wasn't an issue because the free | |
53 | * space btrees maintain a reserve of space (the AGFL) to handle any expansion | |
54 | * that may be necessary; and allocations of other metadata (inodes, BMBT, | |
55 | * dir/attr) aren't restricted to a single AG. However, with reflink it is | |
56 | * possible to allocate all the space in an AG, have subsequent reflink/CoW | |
57 | * activity expand the refcount btree, and discover that there's no space left | |
58 | * to handle that expansion. Since we can calculate the maximum size of the | |
59 | * refcount btree, we can reserve space for it and avoid ENOSPC. | |
60 | * | |
61 | * Handling per-AG reservations consists of three changes to the allocator's | |
62 | * behavior: First, because these reservations are always needed, we decrease | |
63 | * the ag_max_usable counter to reflect the size of the AG after the reserved | |
64 | * blocks are taken. Second, the reservations must be reflected in the | |
65 | * fdblocks count to maintain proper accounting. Third, each AG must maintain | |
66 | * its own reserved block counter so that we can calculate the amount of space | |
67 | * that must remain free to maintain the reservations. Fourth, the "remaining | |
68 | * reserved blocks" count must be used when calculating the length of the | |
69 | * longest free extent in an AG and to clamp maxlen in the per-AG allocation | |
70 | * functions. In other words, we maintain a virtual allocation via in-core | |
71 | * accounting tricks so that we don't have to clean up after a crash. :) | |
72 | * | |
73 | * Reserved blocks can be managed by passing one of the enum xfs_ag_resv_type | |
74 | * values via struct xfs_alloc_arg or directly to the xfs_free_extent | |
75 | * function. It might seem a little funny to maintain a reservoir of blocks | |
76 | * to feed another reservoir, but the AGFL only holds enough blocks to get | |
77 | * through the next transaction. The per-AG reservation is to ensure (we | |
78 | * hope) that each AG never runs out of blocks. Each data structure wanting | |
79 | * to use the reservation system should update ask/used in xfs_ag_resv_init. | |
80 | */ | |
81 | ||
82 | /* | |
83 | * Are we critically low on blocks? For now we'll define that as the number | |
84 | * of blocks we can get our hands on being less than 10% of what we reserved | |
85 | * or less than some arbitrary number (maximum btree height). | |
86 | */ | |
87 | bool | |
88 | xfs_ag_resv_critical( | |
89 | struct xfs_perag *pag, | |
90 | enum xfs_ag_resv_type type) | |
91 | { | |
92 | xfs_extlen_t avail; | |
93 | xfs_extlen_t orig; | |
94 | ||
95 | switch (type) { | |
96 | case XFS_AG_RESV_METADATA: | |
65a15e06 | 97 | avail = pag->pagf_freeblks - pag->pag_rmapbt_resv.ar_reserved; |
cf8ce220 DW |
98 | orig = pag->pag_meta_resv.ar_asked; |
99 | break; | |
65a15e06 | 100 | case XFS_AG_RESV_RMAPBT: |
cf8ce220 DW |
101 | avail = pag->pagf_freeblks + pag->pagf_flcount - |
102 | pag->pag_meta_resv.ar_reserved; | |
65a15e06 | 103 | orig = pag->pag_rmapbt_resv.ar_asked; |
cf8ce220 DW |
104 | break; |
105 | default: | |
106 | ASSERT(0); | |
107 | return false; | |
108 | } | |
109 | ||
110 | trace_xfs_ag_resv_critical(pag, type, avail); | |
111 | ||
112 | /* Critically low if less than 10% or max btree height remains. */ | |
c7bf1398 | 113 | return XFS_TEST_ERROR(avail < orig / 10 || avail < XFS_BTREE_MAXLEVELS, |
e2a190dd | 114 | pag->pag_mount, XFS_ERRTAG_AG_RESV_CRITICAL); |
cf8ce220 DW |
115 | } |
116 | ||
117 | /* | |
118 | * How many blocks are reserved but not used, and therefore must not be | |
119 | * allocated away? | |
120 | */ | |
121 | xfs_extlen_t | |
122 | xfs_ag_resv_needed( | |
123 | struct xfs_perag *pag, | |
124 | enum xfs_ag_resv_type type) | |
125 | { | |
126 | xfs_extlen_t len; | |
127 | ||
65a15e06 | 128 | len = pag->pag_meta_resv.ar_reserved + pag->pag_rmapbt_resv.ar_reserved; |
cf8ce220 DW |
129 | switch (type) { |
130 | case XFS_AG_RESV_METADATA: | |
65a15e06 | 131 | case XFS_AG_RESV_RMAPBT: |
cf8ce220 DW |
132 | len -= xfs_perag_resv(pag, type)->ar_reserved; |
133 | break; | |
134 | case XFS_AG_RESV_NONE: | |
135 | /* empty */ | |
136 | break; | |
137 | default: | |
138 | ASSERT(0); | |
139 | } | |
140 | ||
141 | trace_xfs_ag_resv_needed(pag, type, len); | |
142 | ||
143 | return len; | |
144 | } | |
145 | ||
146 | /* Clean out a reservation */ | |
147 | static int | |
148 | __xfs_ag_resv_free( | |
149 | struct xfs_perag *pag, | |
150 | enum xfs_ag_resv_type type) | |
151 | { | |
152 | struct xfs_ag_resv *resv; | |
153 | xfs_extlen_t oldresv; | |
154 | int error; | |
155 | ||
156 | trace_xfs_ag_resv_free(pag, type, 0); | |
157 | ||
158 | resv = xfs_perag_resv(pag, type); | |
8b068926 DW |
159 | if (pag->pag_agno == 0) |
160 | pag->pag_mount->m_ag_max_usable += resv->ar_asked; | |
cf8ce220 | 161 | /* |
65a15e06 BF |
162 | * RMAPBT blocks come from the AGFL and AGFL blocks are always |
163 | * considered "free", so whatever was reserved at mount time must be | |
164 | * given back at umount. | |
cf8ce220 | 165 | */ |
65a15e06 | 166 | if (type == XFS_AG_RESV_RMAPBT) |
cf8ce220 DW |
167 | oldresv = resv->ar_orig_reserved; |
168 | else | |
169 | oldresv = resv->ar_reserved; | |
170 | error = xfs_mod_fdblocks(pag->pag_mount, oldresv, true); | |
171 | resv->ar_reserved = 0; | |
172 | resv->ar_asked = 0; | |
173 | ||
174 | if (error) | |
175 | trace_xfs_ag_resv_free_error(pag->pag_mount, pag->pag_agno, | |
176 | error, _RET_IP_); | |
177 | return error; | |
178 | } | |
179 | ||
180 | /* Free a per-AG reservation. */ | |
181 | int | |
182 | xfs_ag_resv_free( | |
183 | struct xfs_perag *pag) | |
184 | { | |
185 | int error; | |
186 | int err2; | |
187 | ||
65a15e06 | 188 | error = __xfs_ag_resv_free(pag, XFS_AG_RESV_RMAPBT); |
cf8ce220 DW |
189 | err2 = __xfs_ag_resv_free(pag, XFS_AG_RESV_METADATA); |
190 | if (err2 && !error) | |
191 | error = err2; | |
192 | return error; | |
193 | } | |
194 | ||
195 | static int | |
196 | __xfs_ag_resv_init( | |
197 | struct xfs_perag *pag, | |
198 | enum xfs_ag_resv_type type, | |
199 | xfs_extlen_t ask, | |
200 | xfs_extlen_t used) | |
201 | { | |
202 | struct xfs_mount *mp = pag->pag_mount; | |
203 | struct xfs_ag_resv *resv; | |
204 | int error; | |
2ffa676f | 205 | xfs_extlen_t reserved; |
cf8ce220 | 206 | |
cf8ce220 DW |
207 | if (used > ask) |
208 | ask = used; | |
2ffa676f | 209 | reserved = ask - used; |
cf8ce220 | 210 | |
2ffa676f CH |
211 | error = xfs_mod_fdblocks(mp, -(int64_t)reserved, true); |
212 | if (error) { | |
cf8ce220 DW |
213 | trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno, |
214 | error, _RET_IP_); | |
74e502ac CH |
215 | xfs_warn(mp, |
216 | "Per-AG reservation for AG %u failed. Filesystem may run out of space.", | |
217 | pag->pag_agno); | |
2ffa676f CH |
218 | return error; |
219 | } | |
cf8ce220 | 220 | |
8b068926 DW |
221 | /* |
222 | * Reduce the maximum per-AG allocation length by however much we're | |
223 | * trying to reserve for an AG. Since this is a filesystem-wide | |
224 | * counter, we only make the adjustment for AG 0. This assumes that | |
225 | * there aren't any AGs hungrier for per-AG reservation than AG 0. | |
226 | */ | |
227 | if (pag->pag_agno == 0) | |
228 | mp->m_ag_max_usable -= ask; | |
2ffa676f CH |
229 | |
230 | resv = xfs_perag_resv(pag, type); | |
231 | resv->ar_asked = ask; | |
232 | resv->ar_reserved = resv->ar_orig_reserved = reserved; | |
233 | ||
234 | trace_xfs_ag_resv_init(pag, type, ask); | |
235 | return 0; | |
cf8ce220 DW |
236 | } |
237 | ||
238 | /* Create a per-AG block reservation. */ | |
239 | int | |
240 | xfs_ag_resv_init( | |
241 | struct xfs_perag *pag) | |
242 | { | |
74e502ac CH |
243 | struct xfs_mount *mp = pag->pag_mount; |
244 | xfs_agnumber_t agno = pag->pag_agno; | |
cf8ce220 DW |
245 | xfs_extlen_t ask; |
246 | xfs_extlen_t used; | |
247 | int error = 0; | |
248 | ||
249 | /* Create the metadata reservation. */ | |
250 | if (pag->pag_meta_resv.ar_asked == 0) { | |
251 | ask = used = 0; | |
252 | ||
74e502ac | 253 | error = xfs_refcountbt_calc_reserves(mp, agno, &ask, &used); |
02cc8b2a DW |
254 | if (error) |
255 | goto out; | |
256 | ||
74e502ac | 257 | error = xfs_finobt_calc_reserves(mp, agno, &ask, &used); |
cf8ce220 DW |
258 | if (error) |
259 | goto out; | |
74e502ac CH |
260 | |
261 | error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA, | |
262 | ask, used); | |
263 | if (error) { | |
264 | /* | |
265 | * Because we didn't have per-AG reservations when the | |
266 | * finobt feature was added we might not be able to | |
267 | * reserve all needed blocks. Warn and fall back to the | |
268 | * old and potentially buggy code in that case, but | |
269 | * ensure we do have the reservation for the refcountbt. | |
270 | */ | |
271 | ask = used = 0; | |
272 | ||
273 | mp->m_inotbt_nores = true; | |
274 | ||
275 | error = xfs_refcountbt_calc_reserves(mp, agno, &ask, | |
276 | &used); | |
277 | if (error) | |
278 | goto out; | |
279 | ||
280 | error = __xfs_ag_resv_init(pag, XFS_AG_RESV_METADATA, | |
281 | ask, used); | |
282 | if (error) | |
283 | goto out; | |
284 | } | |
cf8ce220 DW |
285 | } |
286 | ||
65a15e06 BF |
287 | /* Create the RMAPBT metadata reservation */ |
288 | if (pag->pag_rmapbt_resv.ar_asked == 0) { | |
cf8ce220 DW |
289 | ask = used = 0; |
290 | ||
74e502ac | 291 | error = xfs_rmapbt_calc_reserves(mp, agno, &ask, &used); |
02cc8b2a DW |
292 | if (error) |
293 | goto out; | |
294 | ||
65a15e06 | 295 | error = __xfs_ag_resv_init(pag, XFS_AG_RESV_RMAPBT, ask, used); |
cf8ce220 DW |
296 | if (error) |
297 | goto out; | |
298 | } | |
299 | ||
74e502ac CH |
300 | #ifdef DEBUG |
301 | /* need to read in the AGF for the ASSERT below to work */ | |
302 | error = xfs_alloc_pagf_init(pag->pag_mount, NULL, pag->pag_agno, 0); | |
303 | if (error) | |
304 | return error; | |
305 | ||
f21c57ed | 306 | ASSERT(xfs_perag_resv(pag, XFS_AG_RESV_METADATA)->ar_reserved + |
65a15e06 | 307 | xfs_perag_resv(pag, XFS_AG_RESV_RMAPBT)->ar_reserved <= |
f21c57ed | 308 | pag->pagf_freeblks + pag->pagf_flcount); |
74e502ac | 309 | #endif |
cf8ce220 DW |
310 | out: |
311 | return error; | |
312 | } | |
313 | ||
314 | /* Allocate a block from the reservation. */ | |
315 | void | |
316 | xfs_ag_resv_alloc_extent( | |
317 | struct xfs_perag *pag, | |
318 | enum xfs_ag_resv_type type, | |
319 | struct xfs_alloc_arg *args) | |
320 | { | |
321 | struct xfs_ag_resv *resv; | |
322 | xfs_extlen_t len; | |
323 | uint field; | |
324 | ||
325 | trace_xfs_ag_resv_alloc_extent(pag, type, args->len); | |
326 | ||
327 | switch (type) { | |
9760cac2 BF |
328 | case XFS_AG_RESV_AGFL: |
329 | return; | |
cf8ce220 | 330 | case XFS_AG_RESV_METADATA: |
65a15e06 | 331 | case XFS_AG_RESV_RMAPBT: |
cf8ce220 DW |
332 | resv = xfs_perag_resv(pag, type); |
333 | break; | |
334 | default: | |
335 | ASSERT(0); | |
336 | /* fall through */ | |
337 | case XFS_AG_RESV_NONE: | |
338 | field = args->wasdel ? XFS_TRANS_SB_RES_FDBLOCKS : | |
339 | XFS_TRANS_SB_FDBLOCKS; | |
340 | xfs_trans_mod_sb(args->tp, field, -(int64_t)args->len); | |
341 | return; | |
342 | } | |
343 | ||
344 | len = min_t(xfs_extlen_t, args->len, resv->ar_reserved); | |
345 | resv->ar_reserved -= len; | |
65a15e06 | 346 | if (type == XFS_AG_RESV_RMAPBT) |
cf8ce220 DW |
347 | return; |
348 | /* Allocations of reserved blocks only need on-disk sb updates... */ | |
349 | xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_RES_FDBLOCKS, -(int64_t)len); | |
350 | /* ...but non-reserved blocks need in-core and on-disk updates. */ | |
351 | if (args->len > len) | |
352 | xfs_trans_mod_sb(args->tp, XFS_TRANS_SB_FDBLOCKS, | |
353 | -((int64_t)args->len - len)); | |
354 | } | |
355 | ||
356 | /* Free a block to the reservation. */ | |
357 | void | |
358 | xfs_ag_resv_free_extent( | |
359 | struct xfs_perag *pag, | |
360 | enum xfs_ag_resv_type type, | |
361 | struct xfs_trans *tp, | |
362 | xfs_extlen_t len) | |
363 | { | |
364 | xfs_extlen_t leftover; | |
365 | struct xfs_ag_resv *resv; | |
366 | ||
367 | trace_xfs_ag_resv_free_extent(pag, type, len); | |
368 | ||
369 | switch (type) { | |
9760cac2 BF |
370 | case XFS_AG_RESV_AGFL: |
371 | return; | |
cf8ce220 | 372 | case XFS_AG_RESV_METADATA: |
65a15e06 | 373 | case XFS_AG_RESV_RMAPBT: |
cf8ce220 DW |
374 | resv = xfs_perag_resv(pag, type); |
375 | break; | |
376 | default: | |
377 | ASSERT(0); | |
378 | /* fall through */ | |
379 | case XFS_AG_RESV_NONE: | |
380 | xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, (int64_t)len); | |
381 | return; | |
382 | } | |
383 | ||
384 | leftover = min_t(xfs_extlen_t, len, resv->ar_asked - resv->ar_reserved); | |
385 | resv->ar_reserved += leftover; | |
65a15e06 | 386 | if (type == XFS_AG_RESV_RMAPBT) |
cf8ce220 DW |
387 | return; |
388 | /* Freeing into the reserved pool only requires on-disk update... */ | |
389 | xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FDBLOCKS, len); | |
390 | /* ...but freeing beyond that requires in-core and on-disk update. */ | |
391 | if (len > leftover) | |
392 | xfs_trans_mod_sb(tp, XFS_TRANS_SB_FDBLOCKS, len - leftover); | |
393 | } |