From 016a23388cdcb2740deb1379dc408f21c84efb11 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Thu, 7 Jul 2022 18:53:59 +1000 Subject: [PATCH] xfs: Add order IDs to log items in CIL Before we split the ordered CIL up into per cpu lists, we need a mechanism to track the order of the items in the CIL. We need to do this because there are rules around the order in which related items must physically appear in the log even inside a single checkpoint transaction. An example of this is intents - an intent must appear in the log before it's intent done record so that log recovery can cancel the intent correctly. If we have these two records misordered in the CIL, then they will not be recovered correctly by journal replay. We also will not be able to move items to the tail of the CIL list when they are relogged, hence the log items will need some mechanism to allow the correct log item order to be recreated before we write log items to the hournal. Hence we need to have a mechanism for recording global order of transactions in the log items so that we can recover that order from un-ordered per-cpu lists. Do this with a simple monotonic increasing commit counter in the CIL context. Each log item in the transaction gets stamped with the current commit order ID before it is added to the CIL. If the item is already in the CIL, leave it where it is instead of moving it to the tail of the list and instead sort the list before we start the push work. Signed-off-by: Dave Chinner Reviewed-by: Darrick J. Wong --- fs/xfs/xfs_log_cil.c | 39 +++++++++++++++++++++++++++++++-------- fs/xfs/xfs_log_priv.h | 1 + fs/xfs/xfs_trans.h | 1 + 3 files changed, 33 insertions(+), 8 deletions(-) diff --git a/fs/xfs/xfs_log_cil.c b/fs/xfs/xfs_log_cil.c index f02a75d..6bc5408 100644 --- a/fs/xfs/xfs_log_cil.c +++ b/fs/xfs/xfs_log_cil.c @@ -550,6 +550,7 @@ xlog_cil_insert_items( int len = 0; int iovhdr_res = 0, split_res = 0, ctx_res = 0; int space_used; + int order; struct xlog_cil_pcp *cilpcp; ASSERT(tp); @@ -645,23 +646,22 @@ xlog_cil_insert_items( put_cpu_ptr(cilpcp); /* - * Now (re-)position everything modified at the tail of the CIL. + * Now update the order of everything modified in the transaction + * and insert items into the CIL if they aren't already there. * We do this here so we only need to take the CIL lock once during * the transaction commit. */ + order = atomic_inc_return(&ctx->order_id); spin_lock(&cil->xc_cil_lock); list_for_each_entry(lip, &tp->t_items, li_trans) { /* Skip items which aren't dirty in this transaction. */ if (!test_bit(XFS_LI_DIRTY, &lip->li_flags)) continue; - /* - * Only move the item if it isn't already at the tail. This is - * to prevent a transient list_empty() state when reinserting - * an item that is already the only item in the CIL. - */ - if (!list_is_last(&lip->li_cil, &cil->xc_cil)) - list_move_tail(&lip->li_cil, &cil->xc_cil); + lip->li_order_id = order; + if (!list_empty(&lip->li_cil)) + continue; + list_add_tail(&lip->li_cil, &cil->xc_cil); } spin_unlock(&cil->xc_cil_lock); @@ -1083,6 +1083,26 @@ xlog_cil_build_trans_hdr( } /* + * CIL item reordering compare function. We want to order in ascending ID order, + * but we want to leave items with the same ID in the order they were added to + * the list. This is important for operations like reflink where we log 4 order + * dependent intents in a single transaction when we overwrite an existing + * shared extent with a new shared extent. i.e. BUI(unmap), CUI(drop), + * CUI (inc), BUI(remap)... + */ +static int +xlog_cil_order_cmp( + void *priv, + const struct list_head *a, + const struct list_head *b) +{ + struct xfs_log_item *l1 = container_of(a, struct xfs_log_item, li_cil); + struct xfs_log_item *l2 = container_of(b, struct xfs_log_item, li_cil); + + return l1->li_order_id > l2->li_order_id; +} + +/* * Pull all the log vectors off the items in the CIL, and remove the items from * the CIL. We don't need the CIL lock here because it's only needed on the * transaction commit side which is currently locked out by the flush lock. @@ -1101,6 +1121,8 @@ xlog_cil_build_lv_chain( { struct xfs_log_vec *lv = NULL; + list_sort(NULL, &cil->xc_cil, xlog_cil_order_cmp); + while (!list_empty(&cil->xc_cil)) { struct xfs_log_item *item; @@ -1114,6 +1136,7 @@ xlog_cil_build_lv_chain( } list_del_init(&item->li_cil); + item->li_order_id = 0; if (!ctx->lv_chain) ctx->lv_chain = item->li_lv; else diff --git a/fs/xfs/xfs_log_priv.h b/fs/xfs/xfs_log_priv.h index 05a5668..563145e 100644 --- a/fs/xfs/xfs_log_priv.h +++ b/fs/xfs/xfs_log_priv.h @@ -229,6 +229,7 @@ struct xfs_cil_ctx { struct list_head committing; /* ctx committing list */ struct work_struct discard_endio_work; struct work_struct push_work; + atomic_t order_id; }; /* diff --git a/fs/xfs/xfs_trans.h b/fs/xfs/xfs_trans.h index 9561f19..29927ce 100644 --- a/fs/xfs/xfs_trans.h +++ b/fs/xfs/xfs_trans.h @@ -45,6 +45,7 @@ struct xfs_log_item { struct xfs_log_vec *li_lv; /* active log vector */ struct xfs_log_vec *li_lv_shadow; /* standby vector */ xfs_csn_t li_seq; /* CIL commit seq */ + uint32_t li_order_id; /* CIL commit order */ }; /* -- 2.7.4