[PATCH 3/6] xfs: log EFIs for all btree blocks being used to stage a btree

Darrick J. Wong
2023-07-27T22:24:38Z

We need to log EFIs for every extent that we allocate for the purpose of
staging a new btree so that if we fail then the blocks will be freed
during log recovery. Add a function to relog the EFIs, so that repair
can relog them all every time it creates a new btree block, which will
help us to avoid pinning the log tail.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
fs/xfs/scrub/newbt.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++
fs/xfs/scrub/newbt.h | 4 +
fs/xfs/scrub/repair.c | 10 +++
fs/xfs/scrub/repair.h | 1
4 files changed, 162 insertions(+)

diff --git a/fs/xfs/scrub/newbt.c b/fs/xfs/scrub/newbt.c
index 2eceac52f2834..cbfe2ffada635 100644
--- a/fs/xfs/scrub/newbt.c
+++ b/fs/xfs/scrub/newbt.c
@@ -13,12 +13,14 @@
#include "xfs_btree_staging.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
+#include "xfs_log.h"
#include "xfs_sb.h"
#include "xfs_inode.h"
#include "xfs_alloc.h"
#include "xfs_rmap.h"
#include "xfs_ag.h"
#include "xfs_defer.h"
+#include "xfs_extfree_item.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/trace.h"
@@ -124,6 +126,139 @@ xrep_newbt_init_bare(
XFS_AG_RESV_NONE);
}

+/*
+ * Set up automatic reaping of the blocks reserved for btree reconstruction in
+ * case we crash by logging a deferred free item for each extent we allocate so
+ * that we can get all of the space back if we crash before we can commit the
+ * new btree. This function returns a token that can be used to cancel
+ * automatic reaping if repair is successful.
+ */
+static int
+xrep_newbt_schedule_autoreap(
+ struct xrep_newbt *xnr,
+ struct xrep_newbt_resv *resv)
+{
+ struct xfs_extent_free_item efi_item = {
+ .xefi_blockcount = resv->len,
+ .xefi_owner = xnr->oinfo.oi_owner,
+ .xefi_flags = XFS_EFI_SKIP_DISCARD,
+ .xefi_pag = resv->pag,
+ };
+ struct xfs_scrub *sc = xnr->sc;
+ struct xfs_log_item *lip;
+ LIST_HEAD(items);
+
+ ASSERT(xnr->oinfo.oi_offset == 0);
+
+ efi_item.xefi_startblock = XFS_AGB_TO_FSB(sc->mp, resv->pag->pag_agno,
+ resv->agbno);
+ if (xnr->oinfo.oi_flags & XFS_OWNER_INFO_ATTR_FORK)
+ efi_item.xefi_flags |= XFS_EFI_ATTR_FORK;
+ if (xnr->oinfo.oi_flags & XFS_OWNER_INFO_BMBT_BLOCK)
+ efi_item.xefi_flags |= XFS_EFI_BMBT_BLOCK;
+
+ INIT_LIST_HEAD(&efi_item.xefi_list);
+ list_add(&efi_item.xefi_list, &items);
+
+ xfs_perag_intent_hold(resv->pag);
+ lip = xfs_extent_free_defer_type.create_intent(sc->tp, &items, 1,
+ false);
+ ASSERT(lip != NULL && !IS_ERR(lip));
+
+ resv->efi = lip;
+ return 0;
+}
+
+/*
+ * Earlier, we logged EFIs for the extents that we allocated to hold the new
+ * btree so that we could automatically roll back those allocations if the
+ * system crashed. Now we log an EFD to cancel the EFI, either because the
+ * repair succeeded and the new blocks are in use; or because the repair was
+ * cancelled and we're about to free the extents directly.
+ */
+static inline void
+xrep_newbt_finish_autoreap(
+ struct xfs_scrub *sc,
+ struct xrep_newbt_resv *resv)
+{
+ struct xfs_efd_log_item *efdp;
+ struct xfs_extent *extp;
+ struct xfs_log_item *efd_lip;
+
+ efd_lip = xfs_extent_free_defer_type.create_done(sc->tp, resv->efi, 1);
+ efdp = container_of(efd_lip, struct xfs_efd_log_item, efd_item);
+ extp = efdp->efd_format.efd_extents;
+ extp->ext_start = XFS_AGB_TO_FSB(sc->mp, resv->pag->pag_agno,
+ resv->agbno);
+ extp->ext_len = resv->len;
+ efdp->efd_next_extent++;
+ set_bit(XFS_LI_DIRTY, &efd_lip->li_flags);
+ xfs_perag_intent_rele(resv->pag);
+}
+
+/* Abort an EFI logged for a new btree block reservation. */
+static inline void
+xrep_newbt_cancel_autoreap(
+ struct xrep_newbt_resv *resv)
+{
+ xfs_extent_free_defer_type.abort_intent(resv->efi);
+ xfs_perag_intent_rele(resv->pag);
+}
+
+/*
+ * Relog the EFIs attached to a staging btree so that we don't pin the log
+ * tail. Same logic as xfs_defer_relog.
+ */
+int
+xrep_newbt_relog_autoreap(
+ struct xrep_newbt *xnr)
+{
+ struct xrep_newbt_resv *resv;
+ unsigned int efi_bytes = 0;
+
+ list_for_each_entry(resv, &xnr->resv_list, list) {
+ /*
+ * If the log intent item for this deferred op is in a
+ * different checkpoint, relog it to keep the log tail moving
+ * forward. We're ok with this being racy because an incorrect
+ * decision means we'll be a little slower at pushing the tail.
+ */
+ if (!resv->efi || xfs_log_item_in_current_chkpt(resv->efi))
+ continue;
+
+ resv->efi = xfs_trans_item_relog(resv->efi, xnr->sc->tp);
+
+ /*
+ * If free space is very fragmented, it's possible that the new
+ * btree will be allocated a large number of small extents.
+ * On an active system, it's possible that so many of those
+ * EFIs will need relogging here that doing them all in one
+ * transaction will overflow the reservation.
+ *
+ * Each allocation for the new btree (xrep_newbt_resv) points
+ * to a unique single-mapping EFI, so each relog operation logs
+ * a single-mapping EFD followed by a new EFI. Each single
+ * mapping EF[ID] item consumes about 128 bytes, so we'll
+ * assume 256 bytes per relog. Roll if we consume more than
+ * half of the transaction reservation.
+ */
+ efi_bytes += 256;
+ if (efi_bytes > xnr->sc->tp->t_log_res / 2) {
+ int error;
+
+ error = xrep_roll_trans(xnr->sc);
+ if (error)
+ return error;
+
+ efi_bytes = 0;
+ }
+ }
+
+ if (xnr->sc->tp->t_flags & XFS_TRANS_DIRTY)
+ return xrep_roll_trans(xnr->sc);
+ return 0;
+}
+
/*
* Designate specific blocks to be used to build our new btree. @pag must be
* a passive reference.
@@ -136,6 +271,7 @@ xrep_newbt_add_blocks(
xfs_extlen_t len)
{
struct xrep_newbt_resv *resv;
+ int error;

resv = kmalloc(sizeof(struct xrep_newbt_resv), XCHK_GFP_FLAGS);
if (!resv)
@@ -147,8 +283,16 @@ xrep_newbt_add_blocks(
resv->used = 0;
resv->pag = xfs_perag_hold(pag);

+ error = xrep_newbt_schedule_autoreap(xnr, resv);
+ if (error)
+ goto out_pag;
+
list_add_tail(&resv->list, &xnr->resv_list);
return 0;
+out_pag:
+ xfs_perag_put(resv->pag);
+ kfree(resv);
+ return error;
}

/* Don't let our allocation hint take us beyond this AG */
@@ -326,6 +470,8 @@ xrep_newbt_free_extent(
free_aglen -= resv->used;
}

+ xrep_newbt_finish_autoreap(sc, resv);
+
if (free_aglen == 0)
return 0;

@@ -396,6 +542,7 @@ xrep_newbt_free(
* reservations.
*/
list_for_each_entry_safe(resv, n, &xnr->resv_list, list) {
+ xrep_newbt_cancel_autoreap(resv);
list_del(&resv->list);
xfs_perag_put(resv->pag);
kfree(resv);
diff --git a/fs/xfs/scrub/newbt.h b/fs/xfs/scrub/newbt.h
index ca53271f3a4c6..cf822472f1667 100644
--- a/fs/xfs/scrub/newbt.h
+++ b/fs/xfs/scrub/newbt.h
@@ -12,6 +12,9 @@ struct xrep_newbt_resv {

struct xfs_perag *pag;

+ /* EFI tracking this space reservation */
+ struct xfs_log_item *efi;
+
/* AG block of the extent we reserved. */
xfs_agblock_t agbno;

@@ -58,5 +61,6 @@ void xrep_newbt_cancel(struct xrep_newbt *xnr);
int xrep_newbt_commit(struct xrep_newbt *xnr);
int xrep_newbt_claim_block(struct xfs_btree_cur *cur, struct xrep_newbt *xnr,
union xfs_btree_ptr *ptr);
+int xrep_newbt_relog_autoreap(struct xrep_newbt *xnr);

#endif /* __XFS_SCRUB_NEWBT_H__ */
diff --git a/fs/xfs/scrub/repair.c b/fs/xfs/scrub/repair.c
index 83a1b1437a4fa..c2474cc40d04c 100644
--- a/fs/xfs/scrub/repair.c
+++ b/fs/xfs/scrub/repair.c
@@ -167,6 +167,16 @@ xrep_roll_ag_trans(
return 0;
}

+/* Roll the scrub transaction, holding the primary metadata locked. */
+int
+xrep_roll_trans(
+ struct xfs_scrub *sc)
+{
+ if (!sc->ip)
+ return xrep_roll_ag_trans(sc);
+ return xfs_trans_roll_inode(&sc->tp, sc->ip);
+}
+
/* Finish all deferred work attached to the repair transaction. */
int
xrep_defer_finish(
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index dc89164d10a63..9ea1eb0aae49d 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -20,6 +20,7 @@ static inline int xrep_notsupported(struct xfs_scrub *sc)
int xrep_attempt(struct xfs_scrub *sc);
void xrep_failure(struct xfs_mount *mp);
int xrep_roll_ag_trans(struct xfs_scrub *sc);
+int xrep_roll_trans(struct xfs_scrub *sc);
int xrep_defer_finish(struct xfs_scrub *sc);
bool xrep_ag_has_space(struct xfs_perag *pag, xfs_extlen_t nr_blocks,
enum xfs_ag_resv_type type);