// 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);
}
Codebase Browser
linux