From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Reconstruct the refcount data from the rmap btree.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
fs/xfs/Makefile | 1
fs/xfs/scrub/refcount_repair.c | 567 ++++++++++++++++++++++++++++++++++++++++
fs/xfs/scrub/repair.h | 2
fs/xfs/scrub/scrub.c | 2
fs/xfs/scrub/trace.h | 11 -
5 files changed, 577 insertions(+), 6 deletions(-)
create mode 100644 fs/xfs/scrub/refcount_repair.c
diff --git a/fs/xfs/Makefile b/fs/xfs/Makefile
index ff11d48e8089..76dde01bf918 100644
--- a/fs/xfs/Makefile
+++ b/fs/xfs/Makefile
@@ -169,6 +169,7 @@ xfs-y += $(addprefix scrub/, \
array.o \
bitmap.o \
ialloc_repair.o \
+ refcount_repair.o \
repair.o \
)
endif
diff --git a/fs/xfs/scrub/refcount_repair.c b/fs/xfs/scrub/refcount_repair.c
new file mode 100644
index 000000000000..8b19e2b809ea
--- /dev/null
+++ b/fs/xfs/scrub/refcount_repair.c
@@ -0,0 +1,567 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_shared.h"
+#include "xfs_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_btree.h"
+#include "xfs_bit.h"
+#include "xfs_log_format.h"
+#include "xfs_trans.h"
+#include "xfs_sb.h"
+#include "xfs_itable.h"
+#include "xfs_alloc.h"
+#include "xfs_ialloc.h"
+#include "xfs_rmap.h"
+#include "xfs_rmap_btree.h"
+#include "xfs_refcount.h"
+#include "xfs_refcount_btree.h"
+#include "xfs_error.h"
+#include "scrub/xfs_scrub.h"
+#include "scrub/scrub.h"
+#include "scrub/common.h"
+#include "scrub/btree.h"
+#include "scrub/trace.h"
+#include "scrub/repair.h"
+#include "scrub/bitmap.h"
+#include "scrub/array.h"
+
+/*
+ * Rebuilding the Reference Count Btree
+ * ====================================
+ *
+ * This algorithm is "borrowed" from xfs_repair. Imagine the rmap
+ * entries as rectangles representing extents of physical blocks, and
+ * that the rectangles can be laid down to allow them to overlap each
+ * other; then we know that we must emit a refcnt btree entry wherever
+ * the amount of overlap changes, i.e. the emission stimulus is
+ * level-triggered:
+ *
+ * - ---
+ * -- ----- ---- --- ------
+ * -- ---- ----------- ---- ---------
+ * -------------------------------- -----------
+ * ^ ^ ^^ ^^ ^ ^^ ^^^ ^^^^ ^ ^^ ^ ^ ^
+ * 2 1 23 21 3 43 234 2123 1 01 2 3 0
+ *
+ * For our purposes, a rmap is a tuple (startblock, len, fileoff, owner).
+ *
+ * Note that in the actual refcnt btree we don't store the refcount < 2
+ * cases because the bnobt tells us which blocks are free; single-use
+ * blocks aren't recorded in the bnobt or the refcntbt. If the rmapbt
+ * supports storing multiple entries covering a given block we could
+ * theoretically dispense with the refcntbt and simply count rmaps, but
+ * that's inefficient in the (hot) write path, so we'll take the cost of
+ * the extra tree to save time. Also there's no guarantee that rmap
+ * will be enabled.
+ *
+ * Given an array of rmaps sorted by physical block number, a starting
+ * physical block (sp), a bag to hold rmaps that cover sp, and the next
+ * physical block where the level changes (np), we can reconstruct the
+ * refcount btree as follows:
+ *
+ * While there are still unprocessed rmaps in the array,
+ * - Set sp to the physical block (pblk) of the next unprocessed rmap.
+ * - Add to the bag all rmaps in the array where startblock == sp.
+ * - Set np to the physical block where the bag size will change. This
+ * is the minimum of (the pblk of the next unprocessed rmap) and
+ * (startblock + len of each rmap in the bag).
+ * - Record the bag size as old_bag_size.
+ *
+ * - While the bag isn't empty,
+ * - Remove from the bag all rmaps where startblock + len == np.
+ * - Add to the bag all rmaps in the array where startblock == np.
+ * - If the bag size isn't old_bag_size, store the refcount entry
+ * (sp, np - sp, bag_size) in the refcnt btree.
+ * - If the bag is empty, break out of the inner loop.
+ * - Set old_bag_size to the bag size
+ * - Set sp = np.
+ * - Set np to the physical block where the bag size will change.
+ * This is the minimum of (the pblk of the next unprocessed rmap)
+ * and (startblock + len of each rmap in the bag).
+ *
+ * Like all the other repairers, we make a list of all the refcount
+ * records we need, then reinitialize the refcount btree root and
+ * insert all the records.
+ */
+
+/* The only parts of the rmap that we care about for computing refcounts. */
+struct xrep_refc_rmap {
+ xfs_agblock_t startblock;
+ xfs_extlen_t blockcount;
+} __attribute__((packed));
+
+/* Smallest possible representation of a refcount extent. */
+struct xrep_refc_extent {
+ xfs_agblock_t startblock;
+ xfs_extlen_t blockcount;
+ xfs_nlink_t refcount;
+} __attribute__((packed));
+
+struct xrep_refc {
+ struct xfbma *rmap_bag; /* rmaps we're tracking */
+ struct xfbma *refcount_records; /* refcount extents */
+ struct xfs_bitmap *btlist; /* old refcountbt blocks */
+ struct xfs_scrub *sc;
+ xfs_extlen_t btblocks; /* # of refcountbt blocks */
+};
+
+/* Grab the next (abbreviated) rmap record from the rmapbt. */
+STATIC int
+xrep_refc_next_rrm(
+ struct xfs_btree_cur *cur,
+ struct xrep_refc *rr,
+ struct xrep_refc_rmap *rrm,
+ bool *have_rec)
+{
+ struct xfs_rmap_irec rmap;
+ struct xfs_mount *mp = cur->bc_mp;
+ xfs_fsblock_t fsbno;
+ int have_gt;
+ int error = 0;
+
+ *have_rec = false;
+ /*
+ * Loop through the remaining rmaps. Remember CoW staging
+ * extents and the refcountbt blocks from the old tree for later
+ * disposal. We can only share written data fork extents, so
+ * keep looping until we find an rmap for one.
+ */
+ do {
+ if (xchk_should_terminate(rr->sc, &error))
+ goto out_error;
+
+ error = xfs_btree_increment(cur, 0, &have_gt);
+ if (error)
+ goto out_error;
+ if (!have_gt)
+ return 0;
+
+ error = xfs_rmap_get_rec(cur, &rmap, &have_gt);
+ if (error)
+ goto out_error;
+ XFS_WANT_CORRUPTED_GOTO(mp, have_gt == 1, out_error);
+
+ if (rmap.rm_owner == XFS_RMAP_OWN_COW) {
+ struct xrep_refc_extent ext = {
+ .startblock = rmap.rm_startblock +
+ XFS_REFC_COW_START,
+ .blockcount = rmap.rm_blockcount,
+ .refcount = 1,
+ };
+
+ /* Pass CoW staging extents right through. */
+ error = xfbma_append(rr->refcount_records, &ext);
+ if (error)
+ goto out_error;
+ } else if (rmap.rm_owner == XFS_RMAP_OWN_REFC) {
+ /* refcountbt block, dump it when we're done. */
+ rr->btblocks += rmap.rm_blockcount;
+ fsbno = XFS_AGB_TO_FSB(cur->bc_mp,
+ cur->bc_private.a.agno,
+ rmap.rm_startblock);
+ error = xfs_bitmap_set(rr->btlist, fsbno,
+ rmap.rm_blockcount);
+ if (error)
+ goto out_error;
+ }
+ } while (XFS_RMAP_NON_INODE_OWNER(rmap.rm_owner) ||
+ xfs_internal_inum(mp, rmap.rm_owner) ||
+ (rmap.rm_flags & (XFS_RMAP_ATTR_FORK | XFS_RMAP_BMBT_BLOCK |
+ XFS_RMAP_UNWRITTEN)));
+
+ rrm->startblock = rmap.rm_startblock;
+ rrm->blockcount = rmap.rm_blockcount;
+ *have_rec = true;
+ return 0;
+
+out_error:
+ return error;
+}
+
+/* Compare two btree extents. */
+static int
+xrep_refc_extent_cmp(
+ const void *a,
+ const void *b)
+{
+ const struct xrep_refc_extent *ap = a;
+ const struct xrep_refc_extent *bp = b;
+
+ if (ap->startblock > bp->startblock)
+ return 1;
+ else if (ap->startblock < bp->startblock)
+ return -1;
+ return 0;
+}
+
+/* Record a reference count extent. */
+STATIC int
+xrep_refc_remember(
+ struct xfs_scrub *sc,
+ struct xrep_refc *rr,
+ xfs_agblock_t agbno,
+ xfs_extlen_t len,
+ xfs_nlink_t refcount)
+{
+ struct xrep_refc_extent rre = {
+ .startblock = agbno,
+ .blockcount = len,
+ .refcount = refcount,
+ };
+
+ trace_xrep_refcount_extent_fn(sc->mp, sc->sa.agno, agbno, len,
+ refcount);
+
+ return xfbma_append(rr->refcount_records, &rre);
+}
+
+#define RRM_NEXT(r) ((r).startblock + (r).blockcount)
+/*
+ * Find the next block where the refcount changes, given the next rmap we
+ * looked at and the ones we're already tracking.
+ */
+static inline xfs_agblock_t
+xrep_refc_next_edge(
+ struct xfbma *rmap_bag,
+ struct xrep_refc_rmap *next_rrm,
+ bool next_valid)
+{
+ struct xrep_refc_rmap rrm;
+ uint64_t i;
+ xfs_agblock_t nbno;
+
+ nbno = next_valid ? next_rrm->startblock : NULLAGBLOCK;
+ foreach_xfbma_item(rmap_bag, i, rrm)
+ nbno = min_t(xfs_agblock_t, nbno, RRM_NEXT(rrm));
+ return nbno;
+}
+
+/* Iterate all the rmap records to generate reference count data. */
+STATIC int
+xrep_refc_generate_refcounts(
+ struct xfs_scrub *sc,
+ struct xrep_refc *rr)
+{
+ struct xrep_refc_rmap rrm;
+ struct xfs_btree_cur *cur;
+ xfs_agblock_t sbno;
+ xfs_agblock_t cbno;
+ xfs_agblock_t nbno;
+ size_t old_stack_sz;
+ size_t stack_sz = 0;
+ bool have;
+ int have_gt;
+ int error;
+
+ /* Start the rmapbt cursor to the left of all records. */
+ cur = xfs_rmapbt_init_cursor(sc->mp, sc->tp, sc->sa.agf_bp,
+ sc->sa.agno);
+ error = xfs_rmap_lookup_le(cur, 0, 0, 0, 0, 0, &have_gt);
+ if (error)
+ goto out;
+ ASSERT(have_gt == 0);
+
+ /* Process reverse mappings into refcount data. */
+ while (xfs_btree_has_more_records(cur)) {
+ /* Push all rmaps with pblk == sbno onto the stack */
+ error = xrep_refc_next_rrm(cur, rr, &rrm, &have);
+ if (error)
+ goto out;
+ if (!have)
+ break;
+ sbno = cbno = rrm.startblock;
+ while (have && rrm.startblock == sbno) {
+ error = xfbma_insert_anywhere(rr->rmap_bag, &rrm);
+ if (error)
+ goto out;
+ stack_sz++;
+ error = xrep_refc_next_rrm(cur, rr, &rrm, &have);
+ if (error)
+ goto out;
+ }
+ error = xfs_btree_decrement(cur, 0, &have_gt);
+ if (error)
+ goto out;
+ XFS_WANT_CORRUPTED_GOTO(sc->mp, have_gt, out);
+
+ /* Set nbno to the bno of the next refcount change */
+ nbno = xrep_refc_next_edge(rr->rmap_bag, &rrm, have);
+ if (nbno == NULLAGBLOCK) {
+ error = -EFSCORRUPTED;
+ goto out;
+ }
+
+ ASSERT(nbno > sbno);
+ old_stack_sz = stack_sz;
+
+ /* While stack isn't empty... */
+ while (stack_sz) {
+ uint64_t i;
+
+ /* Pop all rmaps that end at nbno */
+ foreach_xfbma_item(rr->rmap_bag, i, rrm) {
+ if (RRM_NEXT(rrm) != nbno)
+ continue;
+ error = xfbma_nullify(rr->rmap_bag, i);
+ if (error)
+ goto out;
+ stack_sz--;
+ }
+
+ /* Push array items that start at nbno */
+ error = xrep_refc_next_rrm(cur, rr, &rrm, &have);
+ if (error)
+ goto out;
+ while (have && rrm.startblock == nbno) {
+ error = xfbma_insert_anywhere(rr->rmap_bag, &rrm);
+ if (error)
+ goto out;
+ stack_sz++;
+ error = xrep_refc_next_rrm(cur, rr, &rrm,
+ &have);
+ if (error)
+ goto out;
+ }
+ error = xfs_btree_decrement(cur, 0, &have_gt);
+ if (error)
+ goto out;
+ XFS_WANT_CORRUPTED_GOTO(sc->mp, have_gt, out);
+
+ /* Emit refcount if necessary */
+ ASSERT(nbno > cbno);
+ if (stack_sz != old_stack_sz) {
+ if (old_stack_sz > 1) {
+ error = xrep_refc_remember(sc, rr, cbno,
+ nbno - cbno,
+ old_stack_sz);
+ if (error)
+ goto out;
+ }
+ cbno = nbno;
+ }
+
+ /* Stack empty, go find the next rmap */
+ if (stack_sz == 0)
+ break;
+ old_stack_sz = stack_sz;
+ sbno = nbno;
+
+ /* Set nbno to the bno of the next refcount change */
+ nbno = xrep_refc_next_edge(rr->rmap_bag, &rrm, have);
+ if (nbno == NULLAGBLOCK) {
+ error = -EFSCORRUPTED;
+ goto out;
+ }
+
+ ASSERT(nbno > sbno);
+ }
+ }
+
+ ASSERT(stack_sz == 0);
+out:
+ xfs_btree_del_cursor(cur, error);
+ return error;
+}
+#undef RRM_NEXT
+
+/*
+ * Generate all the reference counts for this AG and a list of the old
+ * refcount btree blocks. Figure out if we have enough free space to
+ * reconstruct the inode btrees. The caller must clean up the lists if
+ * anything goes wrong.
+ */
+STATIC int
+xrep_refc_find_refcounts(
+ struct xfs_scrub *sc,
+ struct xfbma *refcount_records,
+ struct xfs_bitmap *old_refcountbt_blocks)
+{
+ struct xrep_refc rr = {
+ .sc = sc,
+ .refcount_records = refcount_records,
+ .btlist = old_refcountbt_blocks,
+ };
+ struct xfs_mount *mp = sc->mp;
+ xfs_extlen_t blocks;
+ int error;
+
+ /* Set up some storage */
+ rr.rmap_bag = xfbma_init(sizeof(struct xrep_refc_rmap));
+ if (IS_ERR(rr.rmap_bag))
+ return PTR_ERR(rr.rmap_bag);
+
+ /* Generate all the refcount records. */
+ error = xrep_refc_generate_refcounts(sc, &rr);
+ if (error)
+ goto out;
+
+ /* Do we actually have enough space to do this? */
+ blocks = xfs_refcountbt_calc_size(mp, xfbma_length(refcount_records));
+ if (!xrep_ag_has_space(sc->sa.pag, blocks, XFS_AG_RESV_METADATA)) {
+ error = -ENOSPC;
+ goto out;
+ }
+
+out:
+ xfbma_destroy(rr.rmap_bag);
+ return error;
+}
+
+/* Initialize new refcountbt root and implant it into the AGF. */
+STATIC int
+xrep_refc_reset_btree(
+ struct xfs_scrub *sc,
+ int *log_flags)
+{
+ struct xfs_buf *bp;
+ struct xfs_agf *agf;
+ xfs_fsblock_t btfsb;
+ int error;
+
+ agf = XFS_BUF_TO_AGF(sc->sa.agf_bp);
+
+ /* Initialize a new refcountbt root. */
+ error = xrep_alloc_ag_block(sc, &XFS_RMAP_OINFO_REFC, &btfsb,
+ XFS_AG_RESV_METADATA);
+ if (error)
+ return error;
+ error = xrep_init_btblock(sc, btfsb, &bp, XFS_BTNUM_REFC,
+ &xfs_refcountbt_buf_ops);
+ if (error)
+ return error;
+ agf->agf_refcount_root = cpu_to_be32(XFS_FSB_TO_AGBNO(sc->mp, btfsb));
+ agf->agf_refcount_level = cpu_to_be32(1);
+ agf->agf_refcount_blocks = cpu_to_be32(1);
+ *log_flags |= XFS_AGF_REFCOUNT_BLOCKS | XFS_AGF_REFCOUNT_ROOT |
+ XFS_AGF_REFCOUNT_LEVEL;
+
+ return 0;
+}
+
+/* Insert a single record into the refcount btree. */
+STATIC int
+xrep_refc_insert_rec(
+ const void *item,
+ void *priv)
+{
+ const struct xrep_refc_extent *rre = item;
+ struct xfs_refcount_irec refc = {
+ .rc_startblock = rre->startblock,
+ .rc_blockcount = rre->blockcount,
+ .rc_refcount = rre->refcount,
+ };
+ struct xfs_scrub *sc = priv;
+ struct xfs_mount *mp = sc->mp;
+ struct xfs_btree_cur *cur;
+ int have_gt;
+ int error;
+
+ /* Insert into the refcountbt. */
+ cur = xfs_refcountbt_init_cursor(mp, sc->tp, sc->sa.agf_bp,
+ sc->sa.agno);
+ error = xfs_refcount_lookup_eq(cur, rre->startblock, &have_gt);
+ if (error)
+ goto out;
+ XFS_WANT_CORRUPTED_GOTO(mp, have_gt == 0, out);
+ error = xfs_refcount_insert(cur, &refc, &have_gt);
+ if (error)
+ goto out;
+ XFS_WANT_CORRUPTED_GOTO(mp, have_gt == 1, out);
+ xfs_btree_del_cursor(cur, error);
+ return xrep_roll_ag_trans(sc);
+out:
+ xfs_btree_del_cursor(cur, error);
+ return error;
+}
+
+/* Build new refcount btree and dispose of the old one. */
+STATIC int
+xrep_refc_rebuild_tree(
+ struct xfs_scrub *sc,
+ struct xfbma *refcount_records,
+ struct xfs_bitmap *old_refcountbt_blocks)
+{
+ int error;
+
+ /*
+ * Sort the refcount extents by startblock to avoid btree splits when
+ * we rebuild the refcount btree.
+ */
+ error = xfbma_sort(refcount_records, xrep_refc_extent_cmp);
+ if (error)
+ return error;
+
+ /* Free the old refcountbt blocks if they're not in use. */
+ error = xrep_reap_extents(sc, old_refcountbt_blocks,
+ &XFS_RMAP_OINFO_REFC, XFS_AG_RESV_METADATA);
+ if (error)
+ return error;
+
+ /* Add all records. */
+ return xfbma_iter_del(refcount_records, xrep_refc_insert_rec, sc);
+}
+
+/* Rebuild the refcount btree. */
+int
+xrep_refcountbt(
+ struct xfs_scrub *sc)
+{
+ struct xfs_bitmap old_refcountbt_blocks;
+ struct xfbma *refcount_records;
+ struct xfs_mount *mp = sc->mp;
+ int log_flags = 0;
+ int error;
+
+ /* We require the rmapbt to rebuild anything. */
+ if (!xfs_sb_version_hasrmapbt(&mp->m_sb))
+ return -EOPNOTSUPP;
+
+ xchk_perag_get(sc->mp, &sc->sa);
+
+ /* Set up some storage */
+ refcount_records = xfbma_init(sizeof(struct xrep_refc_extent));
+ if (IS_ERR(refcount_records))
+ return PTR_ERR(refcount_records);
+
+ /* Collect all reference counts. */
+ xfs_bitmap_init(&old_refcountbt_blocks);
+ error = xrep_refc_find_refcounts(sc, refcount_records,
+ &old_refcountbt_blocks);
+ if (error)
+ goto out;
+
+ /*
+ * Blow out the old refcount btrees. This is the point at which
+ * we are no longer able to bail out gracefully.
+ */
+ error = xrep_refc_reset_btree(sc, &log_flags);
+ if (error)
+ goto out;
+ xfs_alloc_log_agf(sc->tp, sc->sa.agf_bp, log_flags);
+
+ /* Invalidate all the inobt/finobt blocks in btlist. */
+ error = xrep_invalidate_blocks(sc, &old_refcountbt_blocks);
+ if (error)
+ goto out;
+ error = xrep_roll_ag_trans(sc);
+ if (error)
+ goto out;
+
+ /* Now rebuild the refcount information. */
+ error = xrep_refc_rebuild_tree(sc, refcount_records,
+ &old_refcountbt_blocks);
+ if (error)
+ goto out;
+ sc->reset_perag_resv = true;
+out:
+ xfs_bitmap_destroy(&old_refcountbt_blocks);
+ xfbma_destroy(refcount_records);
+ return error;
+}
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index 8ba72b381bc2..fd7d98040029 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -65,6 +65,7 @@ int xrep_agfl(struct xfs_scrub *sc);
int xrep_agi(struct xfs_scrub *sc);
int xrep_allocbt(struct xfs_scrub *sc);
int xrep_iallocbt(struct xfs_scrub *sc);
+int xrep_refcountbt(struct xfs_scrub *sc);
#else
@@ -101,6 +102,7 @@ xrep_reset_perag_resv(
#define xrep_agi xrep_notsupported
#define xrep_allocbt xrep_notsupported
#define xrep_iallocbt xrep_notsupported
+#define xrep_refcountbt xrep_notsupported
#endif /* CONFIG_XFS_ONLINE_REPAIR */
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 22ad456f5c51..b76a3ecbd7a6 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -265,7 +265,7 @@ static const struct xchk_meta_ops meta_scrub_ops[] = {
.setup = xchk_setup_ag_refcountbt,
.scrub = xchk_refcountbt,
.has = xfs_sb_version_hasreflink,
- .repair = xrep_notsupported,
+ .repair = xrep_refcountbt,
},
[XFS_SCRUB_TYPE_INODE] = { /* inode record */
.type = ST_INODE,
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index a847f9be0c1c..26ed7fb0da63 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -668,8 +668,9 @@ DEFINE_REPAIR_RMAP_EVENT(xrep_bmap_extent_fn);
TRACE_EVENT(xrep_refcount_extent_fn,
TP_PROTO(struct xfs_mount *mp, xfs_agnumber_t agno,
- struct xfs_refcount_irec *irec),
- TP_ARGS(mp, agno, irec),
+ xfs_agblock_t startblock, xfs_extlen_t blockcount,
+ xfs_nlink_t refcount),
+ TP_ARGS(mp, agno, startblock, blockcount, refcount),
TP_STRUCT__entry(
__field(dev_t, dev)
__field(xfs_agnumber_t, agno)
@@ -680,9 +681,9 @@ TRACE_EVENT(xrep_refcount_extent_fn,
TP_fast_assign(
__entry->dev = mp->m_super->s_dev;
__entry->agno = agno;
- __entry->startblock = irec->rc_startblock;
- __entry->blockcount = irec->rc_blockcount;
- __entry->refcount = irec->rc_refcount;
+ __entry->startblock = startblock;
+ __entry->blockcount = blockcount;
+ __entry->refcount = refcount;
),
TP_printk("dev %d:%d agno %u agbno %u len %u refcount %u",
MAJOR(__entry->dev), MINOR(__entry->dev),
