1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
|
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2013 Jie Liu.
* All Rights Reserved.
*/
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_da_format.h"
#include "xfs_trans_space.h"
#include "xfs_da_btree.h"
#include "xfs_bmap_btree.h"
#include "xfs_trace.h"
/*
* Shortly after enabling the large extents count feature in 2023, longstanding
* bugs were found in the code that computes the minimum log size. Luckily,
* the bugs resulted in over-estimates of that size, so there's no impact to
* existing users. However, we don't want to reduce the minimum log size
* because that can create the situation where a newer mkfs writes a new
* filesystem that an older kernel won't mount.
*
* Several years prior, we also discovered that the transaction reservations
* for rmap and reflink operations were unnecessarily large. That was fixed,
* but the minimum log size computation was left alone to avoid the
* compatibility problems noted above. Fix that too.
*
* Therefore, we only may correct the computation starting with filesystem
* features that didn't exist in 2023. In other words, only turn this on if
* the filesystem has parent pointers.
*
* This function can be called before the XFS_HAS_* flags have been set up,
* (e.g. mkfs) so we must check the ondisk superblock.
*/
static inline bool
xfs_want_minlogsize_fixes(
struct xfs_sb *sb)
{
return xfs_sb_is_v5(sb) &&
xfs_sb_has_incompat_feature(sb, XFS_SB_FEAT_INCOMPAT_PARENT);
}
/*
* Calculate the maximum length in bytes that would be required for a local
* attribute value as large attributes out of line are not logged.
*/
STATIC int
xfs_log_calc_max_attrsetm_res(
struct xfs_mount *mp)
{
int size;
int nblks;
size = xfs_attr_leaf_entsize_local_max(mp->m_attr_geo->blksize) -
MAXNAMELEN - 1;
nblks = XFS_DAENTER_SPACE_RES(mp, XFS_ATTR_FORK);
nblks += XFS_B_TO_FSB(mp, size);
/*
* If the feature set is new enough, correct a unit conversion error in
* the xattr transaction reservation code that resulted in oversized
* minimum log size computations.
*/
if (xfs_want_minlogsize_fixes(&mp->m_sb))
size = XFS_B_TO_FSB(mp, size);
nblks += XFS_NEXTENTADD_SPACE_RES(mp, size, XFS_ATTR_FORK);
return M_RES(mp)->tr_attrsetm.tr_logres +
M_RES(mp)->tr_attrsetrt.tr_logres * nblks;
}
/*
* Compute an alternate set of log reservation sizes for use exclusively with
* minimum log size calculations.
*/
static void
xfs_log_calc_trans_resv_for_minlogblocks(
struct xfs_mount *mp,
struct xfs_trans_resv *resv)
{
unsigned int rmap_maxlevels = mp->m_rmap_maxlevels;
/*
* If the feature set is new enough, drop the oversized minimum log
* size computation introduced by the original reflink code.
*/
if (xfs_want_minlogsize_fixes(&mp->m_sb)) {
xfs_trans_resv_calc(mp, resv);
return;
}
/*
* In the early days of rmap+reflink, we always set the rmap maxlevels
* to 9 even if the AG was small enough that it would never grow to
* that height. Transaction reservation sizes influence the minimum
* log size calculation, which influences the size of the log that mkfs
* creates. Use the old value here to ensure that newly formatted
* small filesystems will mount on older kernels.
*/
if (xfs_has_rmapbt(mp) && xfs_has_reflink(mp))
mp->m_rmap_maxlevels = XFS_OLD_REFLINK_RMAP_MAXLEVELS;
xfs_trans_resv_calc(mp, resv);
if (xfs_has_reflink(mp)) {
/*
* In the early days of reflink, typical log operation counts
* were greatly overestimated.
*/
resv->tr_write.tr_logcount = XFS_WRITE_LOG_COUNT_REFLINK;
resv->tr_itruncate.tr_logcount =
XFS_ITRUNCATE_LOG_COUNT_REFLINK;
resv->tr_qm_dqalloc.tr_logcount = XFS_WRITE_LOG_COUNT_REFLINK;
} else if (xfs_has_rmapbt(mp)) {
/*
* In the early days of non-reflink rmap, the impact of rmapbt
* updates on log counts were not taken into account at all.
*/
resv->tr_write.tr_logcount = XFS_WRITE_LOG_COUNT;
resv->tr_itruncate.tr_logcount = XFS_ITRUNCATE_LOG_COUNT;
resv->tr_qm_dqalloc.tr_logcount = XFS_WRITE_LOG_COUNT;
}
/*
* In the early days of reflink, we did not use deferred refcount
* update log items, so log reservations must be recomputed using the
* old calculations.
*/
resv->tr_write.tr_logres =
xfs_calc_write_reservation_minlogsize(mp);
resv->tr_itruncate.tr_logres =
xfs_calc_itruncate_reservation_minlogsize(mp);
resv->tr_qm_dqalloc.tr_logres =
xfs_calc_qm_dqalloc_reservation_minlogsize(mp);
/* Put everything back the way it was. This goes at the end. */
mp->m_rmap_maxlevels = rmap_maxlevels;
}
/*
* Iterate over the log space reservation table to figure out and return
* the maximum one in terms of the pre-calculated values which were done
* at mount time.
*/
void
xfs_log_get_max_trans_res(
struct xfs_mount *mp,
struct xfs_trans_res *max_resp)
{
struct xfs_trans_resv resv = {};
struct xfs_trans_res *resp;
struct xfs_trans_res *end_resp;
unsigned int i;
int log_space = 0;
int attr_space;
attr_space = xfs_log_calc_max_attrsetm_res(mp);
xfs_log_calc_trans_resv_for_minlogblocks(mp, &resv);
resp = (struct xfs_trans_res *)&resv;
end_resp = (struct xfs_trans_res *)(&resv + 1);
for (i = 0; resp < end_resp; i++, resp++) {
int tmp = resp->tr_logcount > 1 ?
resp->tr_logres * resp->tr_logcount :
resp->tr_logres;
trace_xfs_trans_resv_calc_minlogsize(mp, i, resp);
if (log_space < tmp) {
log_space = tmp;
*max_resp = *resp; /* struct copy */
}
}
if (attr_space > log_space) {
*max_resp = resv.tr_attrsetm; /* struct copy */
max_resp->tr_logres = attr_space;
}
trace_xfs_log_get_max_trans_res(mp, max_resp);
}
/*
* Calculate the minimum valid log size for the given superblock configuration.
* Used to calculate the minimum log size at mkfs time, and to determine if
* the log is large enough or not at mount time. Returns the minimum size in
* filesystem block size units.
*/
int
xfs_log_calc_minimum_size(
struct xfs_mount *mp)
{
struct xfs_trans_res tres = {0};
int max_logres;
int min_logblks = 0;
int lsunit = 0;
xfs_log_get_max_trans_res(mp, &tres);
max_logres = xfs_log_calc_unit_res(mp, tres.tr_logres);
if (tres.tr_logcount > 1)
max_logres *= tres.tr_logcount;
if (xfs_has_logv2(mp) && mp->m_sb.sb_logsunit > 1)
lsunit = BTOBB(mp->m_sb.sb_logsunit);
/*
* Two factors should be taken into account for calculating the minimum
* log space.
* 1) The fundamental limitation is that no single transaction can be
* larger than half size of the log.
*
* From mkfs.xfs, this is considered by the XFS_MIN_LOG_FACTOR
* define, which is set to 3. That means we can definitely fit
* maximally sized 2 transactions in the log. We'll use this same
* value here.
*
* 2) If the lsunit option is specified, a transaction requires 2 LSU
* for the reservation because there are two log writes that can
* require padding - the transaction data and the commit record which
* are written separately and both can require padding to the LSU.
* Consider that we can have an active CIL reservation holding 2*LSU,
* but the CIL is not over a push threshold, in this case, if we
* don't have enough log space for at one new transaction, which
* includes another 2*LSU in the reservation, we will run into dead
* loop situation in log space grant procedure. i.e.
* xlog_grant_head_wait().
*
* Hence the log size needs to be able to contain two maximally sized
* and padded transactions, which is (2 * (2 * LSU + maxlres)).
*
* Also, the log size should be a multiple of the log stripe unit, round
* it up to lsunit boundary if lsunit is specified.
*/
if (lsunit) {
min_logblks = roundup_64(BTOBB(max_logres), lsunit) +
2 * lsunit;
} else
min_logblks = BTOBB(max_logres) + 2 * BBSIZE;
min_logblks *= XFS_MIN_LOG_FACTOR;
return XFS_BB_TO_FSB(mp, min_logblks);
}
|
