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Message-Id: <20250506090427.2549456-16-john.g.garry@oracle.com> Date: Tue, 6 May 2025 09:04:25 +0000 From: John Garry <john.g.garry@...cle.com> To: brauner@...nel.org, djwong@...nel.org, hch@....de, viro@...iv.linux.org.uk, jack@...e.cz, cem@...nel.org Cc: linux-fsdevel@...r.kernel.org, dchinner@...hat.com, linux-xfs@...r.kernel.org, linux-kernel@...r.kernel.org, ojaswin@...ux.ibm.com, ritesh.list@...il.com, martin.petersen@...cle.com, linux-ext4@...r.kernel.org, linux-block@...r.kernel.org, catherine.hoang@...cle.com, linux-api@...r.kernel.org, John Garry <john.g.garry@...cle.com> Subject: [PATCH v12 15/17] xfs: add xfs_calc_atomic_write_unit_max() Now that CoW-based atomic writes are supported, update the max size of an atomic write for the data device. The limit of a CoW-based atomic write will be the limit of the number of logitems which can fit into a single transaction. In addition, the max atomic write size needs to be aligned to the agsize. Limit the size of atomic writes to the greatest power-of-two factor of the agsize so that allocations for an atomic write will always be aligned compatibly with the alignment requirements of the storage. Function xfs_atomic_write_logitems() is added to find the limit the number of log items which can fit in a single transaction. Amend the max atomic write computation to create a new transaction reservation type, and compute the maximum size of an atomic write completion (in fsblocks) based on this new transaction reservation. Initially, tr_atomic_write is a clone of tr_itruncate, which provides a reasonable level of parallelism. In the next patch, we'll add a mount option so that sysadmins can configure their own limits. [djwong: use a new reservation type for atomic write ioends, refactor group limit calculations] Reviewed-by: Darrick J. Wong <djwong@...nel.org> Signed-off-by: Darrick J. Wong <djwong@...nel.org> [jpg: rounddown power-of-2 always] Reviewed-by: Christoph Hellwig <hch@....de> Signed-off-by: John Garry <john.g.garry@...cle.com> --- fs/xfs/libxfs/xfs_trans_resv.c | 94 ++++++++++++++++++++++++++++++++++ fs/xfs/libxfs/xfs_trans_resv.h | 2 + fs/xfs/xfs_mount.c | 83 ++++++++++++++++++++++++++++++ fs/xfs/xfs_mount.h | 6 +++ fs/xfs/xfs_reflink.c | 16 ++++++ fs/xfs/xfs_reflink.h | 2 + fs/xfs/xfs_trace.h | 60 ++++++++++++++++++++++ 7 files changed, 263 insertions(+) diff --git a/fs/xfs/libxfs/xfs_trans_resv.c b/fs/xfs/libxfs/xfs_trans_resv.c index a841432abf83..e73c09fbd24c 100644 --- a/fs/xfs/libxfs/xfs_trans_resv.c +++ b/fs/xfs/libxfs/xfs_trans_resv.c @@ -22,6 +22,12 @@ #include "xfs_rtbitmap.h" #include "xfs_attr_item.h" #include "xfs_log.h" +#include "xfs_defer.h" +#include "xfs_bmap_item.h" +#include "xfs_extfree_item.h" +#include "xfs_rmap_item.h" +#include "xfs_refcount_item.h" +#include "xfs_trace.h" #define _ALLOC true #define _FREE false @@ -1394,3 +1400,91 @@ xfs_trans_resv_calc( */ xfs_calc_default_atomic_ioend_reservation(mp, resp); } + +/* + * Return the per-extent and fixed transaction reservation sizes needed to + * complete an atomic write. + */ +STATIC unsigned int +xfs_calc_atomic_write_ioend_geometry( + struct xfs_mount *mp, + unsigned int *step_size) +{ + const unsigned int efi = xfs_efi_log_space(1); + const unsigned int efd = xfs_efd_log_space(1); + const unsigned int rui = xfs_rui_log_space(1); + const unsigned int rud = xfs_rud_log_space(); + const unsigned int cui = xfs_cui_log_space(1); + const unsigned int cud = xfs_cud_log_space(); + const unsigned int bui = xfs_bui_log_space(1); + const unsigned int bud = xfs_bud_log_space(); + + /* + * Maximum overhead to complete an atomic write ioend in software: + * remove data fork extent + remove cow fork extent + map extent into + * data fork. + * + * tx0: Creates a BUI and a CUI and that's all it needs. + * + * tx1: Roll to finish the BUI. Need space for the BUD, an RUI, and + * enough space to relog the CUI (== CUI + CUD). + * + * tx2: Roll again to finish the RUI. Need space for the RUD and space + * to relog the CUI. + * + * tx3: Roll again, need space for the CUD and possibly a new EFI. + * + * tx4: Roll again, need space for an EFD. + * + * If the extent referenced by the pair of BUI/CUI items is not the one + * being currently processed, then we need to reserve space to relog + * both items. + */ + const unsigned int tx0 = bui + cui; + const unsigned int tx1 = bud + rui + cui + cud; + const unsigned int tx2 = rud + cui + cud; + const unsigned int tx3 = cud + efi; + const unsigned int tx4 = efd; + const unsigned int relog = bui + bud + cui + cud; + + const unsigned int per_intent = max(max3(tx0, tx1, tx2), + max3(tx3, tx4, relog)); + + /* Overhead to finish one step of each intent item type */ + const unsigned int f1 = xfs_calc_finish_efi_reservation(mp, 1); + const unsigned int f2 = xfs_calc_finish_rui_reservation(mp, 1); + const unsigned int f3 = xfs_calc_finish_cui_reservation(mp, 1); + const unsigned int f4 = xfs_calc_finish_bui_reservation(mp, 1); + + /* We only finish one item per transaction in a chain */ + *step_size = max(f4, max3(f1, f2, f3)); + + return per_intent; +} + +/* + * Compute the maximum size (in fsblocks) of atomic writes that we can complete + * given the existing log reservations. + */ +xfs_extlen_t +xfs_calc_max_atomic_write_fsblocks( + struct xfs_mount *mp) +{ + const struct xfs_trans_res *resv = &M_RES(mp)->tr_atomic_ioend; + unsigned int per_intent = 0; + unsigned int step_size = 0; + unsigned int ret = 0; + + if (resv->tr_logres > 0) { + per_intent = xfs_calc_atomic_write_ioend_geometry(mp, + &step_size); + + if (resv->tr_logres >= step_size) + ret = (resv->tr_logres - step_size) / per_intent; + } + + trace_xfs_calc_max_atomic_write_fsblocks(mp, per_intent, step_size, + resv->tr_logres, ret); + + return ret; +} diff --git a/fs/xfs/libxfs/xfs_trans_resv.h b/fs/xfs/libxfs/xfs_trans_resv.h index 670045d417a6..a6d303b83688 100644 --- a/fs/xfs/libxfs/xfs_trans_resv.h +++ b/fs/xfs/libxfs/xfs_trans_resv.h @@ -121,4 +121,6 @@ unsigned int xfs_calc_itruncate_reservation_minlogsize(struct xfs_mount *mp); unsigned int xfs_calc_write_reservation_minlogsize(struct xfs_mount *mp); unsigned int xfs_calc_qm_dqalloc_reservation_minlogsize(struct xfs_mount *mp); +xfs_extlen_t xfs_calc_max_atomic_write_fsblocks(struct xfs_mount *mp); + #endif /* __XFS_TRANS_RESV_H__ */ diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c index 00b53f479ece..86089e27b8e7 100644 --- a/fs/xfs/xfs_mount.c +++ b/fs/xfs/xfs_mount.c @@ -666,6 +666,82 @@ xfs_agbtree_compute_maxlevels( mp->m_agbtree_maxlevels = max(levels, mp->m_refc_maxlevels); } +/* Maximum atomic write IO size that the kernel allows. */ +static inline xfs_extlen_t xfs_calc_atomic_write_max(struct xfs_mount *mp) +{ + return rounddown_pow_of_two(XFS_B_TO_FSB(mp, MAX_RW_COUNT)); +} + +static inline unsigned int max_pow_of_two_factor(const unsigned int nr) +{ + return 1 << (ffs(nr) - 1); +} + +/* + * If the data device advertises atomic write support, limit the size of data + * device atomic writes to the greatest power-of-two factor of the AG size so + * that every atomic write unit aligns with the start of every AG. This is + * required so that the per-AG allocations for an atomic write will always be + * aligned compatibly with the alignment requirements of the storage. + * + * If the data device doesn't advertise atomic writes, then there are no + * alignment restrictions and the largest out-of-place write we can do + * ourselves is the number of blocks that user files can allocate from any AG. + */ +static inline xfs_extlen_t xfs_calc_perag_awu_max(struct xfs_mount *mp) +{ + if (mp->m_ddev_targp->bt_bdev_awu_min > 0) + return max_pow_of_two_factor(mp->m_sb.sb_agblocks); + return rounddown_pow_of_two(mp->m_ag_max_usable); +} + +/* + * Reflink on the realtime device requires rtgroups, and atomic writes require + * reflink. + * + * If the realtime device advertises atomic write support, limit the size of + * data device atomic writes to the greatest power-of-two factor of the rtgroup + * size so that every atomic write unit aligns with the start of every rtgroup. + * This is required so that the per-rtgroup allocations for an atomic write + * will always be aligned compatibly with the alignment requirements of the + * storage. + * + * If the rt device doesn't advertise atomic writes, then there are no + * alignment restrictions and the largest out-of-place write we can do + * ourselves is the number of blocks that user files can allocate from any + * rtgroup. + */ +static inline xfs_extlen_t xfs_calc_rtgroup_awu_max(struct xfs_mount *mp) +{ + struct xfs_groups *rgs = &mp->m_groups[XG_TYPE_RTG]; + + if (rgs->blocks == 0) + return 0; + if (mp->m_rtdev_targp && mp->m_rtdev_targp->bt_bdev_awu_min > 0) + return max_pow_of_two_factor(rgs->blocks); + return rounddown_pow_of_two(rgs->blocks); +} + +/* Compute the maximum atomic write unit size for each section. */ +static inline void +xfs_calc_atomic_write_unit_max( + struct xfs_mount *mp) +{ + struct xfs_groups *ags = &mp->m_groups[XG_TYPE_AG]; + struct xfs_groups *rgs = &mp->m_groups[XG_TYPE_RTG]; + + const xfs_extlen_t max_write = xfs_calc_atomic_write_max(mp); + const xfs_extlen_t max_ioend = xfs_reflink_max_atomic_cow(mp); + const xfs_extlen_t max_agsize = xfs_calc_perag_awu_max(mp); + const xfs_extlen_t max_rgsize = xfs_calc_rtgroup_awu_max(mp); + + ags->awu_max = min3(max_write, max_ioend, max_agsize); + rgs->awu_max = min3(max_write, max_ioend, max_rgsize); + + trace_xfs_calc_atomic_write_unit_max(mp, max_write, max_ioend, + max_agsize, max_rgsize); +} + /* Compute maximum possible height for realtime btree types for this fs. */ static inline void xfs_rtbtree_compute_maxlevels( @@ -1082,6 +1158,13 @@ xfs_mountfs( xfs_zone_gc_start(mp); } + /* + * Pre-calculate atomic write unit max. This involves computations + * derived from transaction reservations, so we must do this after the + * log is fully initialized. + */ + xfs_calc_atomic_write_unit_max(mp); + return 0; out_agresv: diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h index e67bc3e91f98..e2abf31438e0 100644 --- a/fs/xfs/xfs_mount.h +++ b/fs/xfs/xfs_mount.h @@ -119,6 +119,12 @@ struct xfs_groups { * SMR hard drives. */ xfs_fsblock_t start_fsb; + + /* + * Maximum length of an atomic write for files stored in this + * collection of allocation groups, in fsblocks. + */ + xfs_extlen_t awu_max; }; struct xfs_freecounter { diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index 218dee76768b..ad3bcb76d805 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -1040,6 +1040,22 @@ xfs_reflink_end_atomic_cow( return error; } +/* Compute the largest atomic write that we can complete through software. */ +xfs_extlen_t +xfs_reflink_max_atomic_cow( + struct xfs_mount *mp) +{ + /* We cannot do any atomic writes without out of place writes. */ + if (!xfs_can_sw_atomic_write(mp)) + return 0; + + /* + * Atomic write limits must always be a power-of-2, according to + * generic_atomic_write_valid. + */ + return rounddown_pow_of_two(xfs_calc_max_atomic_write_fsblocks(mp)); +} + /* * Free all CoW staging blocks that are still referenced by the ondisk refcount * metadata. The ondisk metadata does not track which inode created the diff --git a/fs/xfs/xfs_reflink.h b/fs/xfs/xfs_reflink.h index 412e9b6f2082..36cda724da89 100644 --- a/fs/xfs/xfs_reflink.h +++ b/fs/xfs/xfs_reflink.h @@ -68,4 +68,6 @@ extern int xfs_reflink_update_dest(struct xfs_inode *dest, xfs_off_t newlen, bool xfs_reflink_supports_rextsize(struct xfs_mount *mp, unsigned int rextsize); +xfs_extlen_t xfs_reflink_max_atomic_cow(struct xfs_mount *mp); + #endif /* __XFS_REFLINK_H */ diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h index 9554578c6da4..d5ae00f8e04c 100644 --- a/fs/xfs/xfs_trace.h +++ b/fs/xfs/xfs_trace.h @@ -170,6 +170,66 @@ DEFINE_ATTR_LIST_EVENT(xfs_attr_list_notfound); DEFINE_ATTR_LIST_EVENT(xfs_attr_leaf_list); DEFINE_ATTR_LIST_EVENT(xfs_attr_node_list); +TRACE_EVENT(xfs_calc_atomic_write_unit_max, + TP_PROTO(struct xfs_mount *mp, unsigned int max_write, + unsigned int max_ioend, unsigned int max_agsize, + unsigned int max_rgsize), + TP_ARGS(mp, max_write, max_ioend, max_agsize, max_rgsize), + TP_STRUCT__entry( + __field(dev_t, dev) + __field(unsigned int, max_write) + __field(unsigned int, max_ioend) + __field(unsigned int, max_agsize) + __field(unsigned int, max_rgsize) + __field(unsigned int, data_awu_max) + __field(unsigned int, rt_awu_max) + ), + TP_fast_assign( + __entry->dev = mp->m_super->s_dev; + __entry->max_write = max_write; + __entry->max_ioend = max_ioend; + __entry->max_agsize = max_agsize; + __entry->max_rgsize = max_rgsize; + __entry->data_awu_max = mp->m_groups[XG_TYPE_AG].awu_max; + __entry->rt_awu_max = mp->m_groups[XG_TYPE_RTG].awu_max; + ), + TP_printk("dev %d:%d max_write %u max_ioend %u max_agsize %u max_rgsize %u data_awu_max %u rt_awu_max %u", + MAJOR(__entry->dev), MINOR(__entry->dev), + __entry->max_write, + __entry->max_ioend, + __entry->max_agsize, + __entry->max_rgsize, + __entry->data_awu_max, + __entry->rt_awu_max) +); + +TRACE_EVENT(xfs_calc_max_atomic_write_fsblocks, + TP_PROTO(struct xfs_mount *mp, unsigned int per_intent, + unsigned int step_size, unsigned int logres, + unsigned int blockcount), + TP_ARGS(mp, per_intent, step_size, logres, blockcount), + TP_STRUCT__entry( + __field(dev_t, dev) + __field(unsigned int, per_intent) + __field(unsigned int, step_size) + __field(unsigned int, logres) + __field(unsigned int, blockcount) + ), + TP_fast_assign( + __entry->dev = mp->m_super->s_dev; + __entry->per_intent = per_intent; + __entry->step_size = step_size; + __entry->logres = logres; + __entry->blockcount = blockcount; + ), + TP_printk("dev %d:%d per_intent %u step_size %u logres %u blockcount %u", + MAJOR(__entry->dev), MINOR(__entry->dev), + __entry->per_intent, + __entry->step_size, + __entry->logres, + __entry->blockcount) +); + TRACE_EVENT(xlog_intent_recovery_failed, TP_PROTO(struct xfs_mount *mp, const struct xfs_defer_op_type *ops, int error), -- 2.31.1
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