// SPDX-License-Identifier: GPL-2.0 /* * Copyright (c) 2013 Jie Liu. * All Rights Reserved. */ #include "xfs_platform.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); resv->tr_atomic_ioend = M_RES(mp)->tr_atomic_ioend; 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); /* Copy the dynamic transaction reservation types from the running fs */ resv->tr_atomic_ioend = M_RES(mp)->tr_atomic_ioend; 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); }
