[PATCH 094/110] xfs: support in-memory btrees

Darrick J. Wong
2024-03-26T03:52:57Z

From: Darrick J. Wong <djwong@kernel.org>

Source kernel commit: a095686a2383526d7315197e2419d84ee8470217

Adapt the generic btree cursor code to be able to create a btree whose
buffers come from a (presumably in-memory) buftarg with a header block
that's specific to in-memory btrees. We'll connect this to other parts
of online scrub in the next patches.

Note that in-memory btrees always have a block size matching the system
memory page size for efficiency reasons. There are also a few things we
need to do to finalize a btree update; that's covered in the next patch.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
include/libxfs.h | 2
include/xfs_mount.h | 5 +
include/xfs_trace.h | 7 +
libxfs/Makefile | 2
libxfs/buf_mem.c | 13 ++
libxfs/buf_mem.h | 2
libxfs/libxfs_api_defs.h | 1
libxfs/libxfs_io.h | 10 ++
libxfs/libxfs_priv.h | 3 +
libxfs/xfs_btree.c | 257 +++++++++++++++++++++++++++++++++++++++-------
libxfs/xfs_btree.h | 7 +
libxfs/xfs_btree_mem.c | 227 +++++++++++++++++++++++++++++++++++++++++
libxfs/xfs_btree_mem.h | 72 +++++++++++++
13 files changed, 571 insertions(+), 37 deletions(-)
create mode 100644 libxfs/xfs_btree_mem.c
create mode 100644 libxfs/xfs_btree_mem.h

diff --git a/include/libxfs.h b/include/libxfs.h
index 60d3b7968775..563c40e5745e 100644
--- a/include/libxfs.h
+++ b/include/libxfs.h
@@ -9,6 +9,8 @@

/* For userspace XFS_RT is always defined */
#define CONFIG_XFS_RT
+/* Ditto in-memory btrees */
+#define CONFIG_XFS_BTREE_IN_MEM

#include "libxfs_api_defs.h"
#include "platform_defs.h"
diff --git a/include/xfs_mount.h b/include/xfs_mount.h
index 98d5b199de8c..9c492b8f5e4c 100644
--- a/include/xfs_mount.h
+++ b/include/xfs_mount.h
@@ -301,4 +301,9 @@ struct xfs_defer_drain { /* empty */ };
static inline void xfs_perag_intent_hold(struct xfs_perag *pag) {}
static inline void xfs_perag_intent_rele(struct xfs_perag *pag) {}

+static inline void libxfs_buftarg_drain(struct xfs_buftarg *btp)
+{
+ cache_purge(btp->bcache);
+}
+
#endif /* __XFS_MOUNT_H__ */
diff --git a/include/xfs_trace.h b/include/xfs_trace.h
index df25dc2a9d62..6c8eeff1e62a 100644
--- a/include/xfs_trace.h
+++ b/include/xfs_trace.h
@@ -6,6 +6,13 @@
#ifndef __TRACE_H__
#define __TRACE_H__

+#define trace_xfbtree_init(...) ((void) 0)
+#define trace_xfbtree_create_root_buf(...) ((void) 0)
+#define trace_xfbtree_alloc_block(...) ((void) 0)
+#define trace_xfbtree_free_block(...) ((void) 0)
+#define trace_xfbtree_trans_cancel_buf(...) ((void) 0)
+#define trace_xfbtree_trans_commit_buf(...) ((void) 0)
+
#define trace_xfs_agfl_reset(a,b,c,d) ((void) 0)
#define trace_xfs_agfl_free_defer(a,b,c,d,e) ((void) 0)
#define trace_xfs_alloc_cur_check(...) ((void) 0)
diff --git a/libxfs/Makefile b/libxfs/Makefile
index 8f501fc39f7e..1e6e549fe8eb 100644
--- a/libxfs/Makefile
+++ b/libxfs/Makefile
@@ -37,6 +37,7 @@ HFILES = \
xfs_bmap.h \
xfs_bmap_btree.h \
xfs_btree.h \
+ xfs_btree_mem.h \
xfs_btree_staging.h \
xfs_attr_remote.h \
xfs_cksum.h \
@@ -81,6 +82,7 @@ CFILES = buf_mem.c \
xfs_bmap.c \
xfs_bmap_btree.c \
xfs_btree.c \
+ xfs_btree_mem.c \
xfs_btree_staging.c \
xfs_da_btree.c \
xfs_defer.c \
diff --git a/libxfs/buf_mem.c b/libxfs/buf_mem.c
index 7c8fa1d2cdcd..769cce23f3f3 100644
--- a/libxfs/buf_mem.c
+++ b/libxfs/buf_mem.c
@@ -233,3 +233,16 @@ xmbuf_unmap_page(
munmap(bp->b_addr, BBTOB(bp->b_length));
bp->b_addr = NULL;
}
+
+/* Is this a valid daddr within the buftarg? */
+bool
+xmbuf_verify_daddr(
+ struct xfs_buftarg *btp,
+ xfs_daddr_t daddr)
+{
+ struct xfile *xf = btp->bt_xfile;
+
+ ASSERT(xfs_buftarg_is_mem(btp));
+
+ return daddr < (xf->partition_bytes >> BBSHIFT);
+}
diff --git a/libxfs/buf_mem.h b/libxfs/buf_mem.h
index d2be2c4240b6..d40f9f9df8f1 100644
--- a/libxfs/buf_mem.h
+++ b/libxfs/buf_mem.h
@@ -23,4 +23,6 @@ void xmbuf_free(struct xfs_buftarg *btp);
int xmbuf_map_page(struct xfs_buf *bp);
void xmbuf_unmap_page(struct xfs_buf *bp);

+bool xmbuf_verify_daddr(struct xfs_buftarg *btp, xfs_daddr_t daddr);
+
#endif /* __XFS_BUF_MEM_H__ */
diff --git a/libxfs/libxfs_api_defs.h b/libxfs/libxfs_api_defs.h
index 0e72944bc9aa..fe8a0dc40269 100644
--- a/libxfs/libxfs_api_defs.h
+++ b/libxfs/libxfs_api_defs.h
@@ -76,6 +76,7 @@
#define xfs_buf_read_uncached libxfs_buf_read_uncached
#define xfs_buf_relse libxfs_buf_relse
#define xfs_buf_unlock libxfs_buf_unlock
+#define xfs_buftarg_drain libxfs_buftarg_drain
#define xfs_bunmapi libxfs_bunmapi
#define xfs_bwrite libxfs_bwrite
#define xfs_calc_dquots_per_chunk libxfs_calc_dquots_per_chunk
diff --git a/libxfs/libxfs_io.h b/libxfs/libxfs_io.h
index ae3c4a9484c7..82d86f1d1b37 100644
--- a/libxfs/libxfs_io.h
+++ b/libxfs/libxfs_io.h
@@ -282,4 +282,14 @@ xfs_buf_delwri_queue_here(struct xfs_buf *bp, struct list_head *buffer_list)
int xfs_buf_delwri_submit(struct list_head *buffer_list);
void xfs_buf_delwri_cancel(struct list_head *list);

+xfs_daddr_t xfs_buftarg_nr_sectors(struct xfs_buftarg *btp);
+
+static inline bool
+xfs_buftarg_verify_daddr(
+ struct xfs_buftarg *btp,
+ xfs_daddr_t daddr)
+{
+ return daddr < xfs_buftarg_nr_sectors(btp);
+}
+
#endif /* __LIBXFS_IO_H__ */
diff --git a/libxfs/libxfs_priv.h b/libxfs/libxfs_priv.h
index aee85c155abf..865b8d0f4e1a 100644
--- a/libxfs/libxfs_priv.h
+++ b/libxfs/libxfs_priv.h
@@ -38,6 +38,7 @@
#define __LIBXFS_INTERNAL_XFS_H__

#define CONFIG_XFS_RT
+#define CONFIG_XFS_BTREE_IN_MEM

#include "libxfs_api_defs.h"
#include "platform_defs.h"
@@ -391,7 +392,9 @@ void __xfs_buf_mark_corrupt(struct xfs_buf *bp, xfs_failaddr_t fa);

/* no readahead, need to avoid set-but-unused var warnings. */
#define xfs_buf_readahead(a,d,c,ops) ({ \
+ void *__a = a; \
xfs_daddr_t __d = d; \
+ __a = __a; \
__d = __d; /* no set-but-unused warning */ \
})
#define xfs_buf_readahead_map(a,b,c,ops) ((void) 0) /* no readahead */
diff --git a/libxfs/xfs_btree.c b/libxfs/xfs_btree.c
index 5fd966a63371..a91441b46847 100644
--- a/libxfs/xfs_btree.c
+++ b/libxfs/xfs_btree.c
@@ -25,6 +25,9 @@
#include "xfs_rmap_btree.h"
#include "xfs_refcount_btree.h"
#include "xfs_health.h"
+#include "xfile.h"
+#include "buf_mem.h"
+#include "xfs_btree_mem.h"

/*
* Btree magic numbers.
@@ -72,6 +75,25 @@ xfs_btree_check_fsblock_siblings(
return NULL;
}

+static inline xfs_failaddr_t
+xfs_btree_check_memblock_siblings(
+ struct xfs_buftarg *btp,
+ xfbno_t bno,
+ __be64 dsibling)
+{
+ xfbno_t sibling;
+
+ if (dsibling == cpu_to_be64(NULLFSBLOCK))
+ return NULL;
+
+ sibling = be64_to_cpu(dsibling);
+ if (sibling == bno)
+ return __this_address;
+ if (!xmbuf_verify_daddr(btp, xfbno_to_daddr(sibling)))
+ return __this_address;
+ return NULL;
+}
+
static inline xfs_failaddr_t
xfs_btree_check_agblock_siblings(
struct xfs_perag *pag,
@@ -161,6 +183,34 @@ __xfs_btree_check_fsblock(
return fa;
}

+/*
+ * Check an in-memory btree block header. Return the address of the failing
+ * check, or NULL if everything is ok.
+ */
+static xfs_failaddr_t
+__xfs_btree_check_memblock(
+ struct xfs_btree_cur *cur,
+ struct xfs_btree_block *block,
+ int level,
+ struct xfs_buf *bp)
+{
+ struct xfs_buftarg *btp = cur->bc_mem.xfbtree->target;
+ xfs_failaddr_t fa;
+ xfbno_t bno;
+
+ fa = __xfs_btree_check_lblock_hdr(cur, block, level, bp);
+ if (fa)
+ return fa;
+
+ bno = xfs_daddr_to_xfbno(xfs_buf_daddr(bp));
+ fa = xfs_btree_check_memblock_siblings(btp, bno,
+ block->bb_u.l.bb_leftsib);
+ if (!fa)
+ fa = xfs_btree_check_memblock_siblings(btp, bno,
+ block->bb_u.l.bb_rightsib);
+ return fa;
+}
+
/*
* Check a short btree block header. Return the address of the failing check,
* or NULL if everything is ok.
@@ -213,9 +263,17 @@ __xfs_btree_check_block(
int level,
struct xfs_buf *bp)
{
- if (cur->bc_ops->type == XFS_BTREE_TYPE_AG)
+ switch (cur->bc_ops->type) {
+ case XFS_BTREE_TYPE_MEM:
+ return __xfs_btree_check_memblock(cur, block, level, bp);
+ case XFS_BTREE_TYPE_AG:
return __xfs_btree_check_agblock(cur, block, level, bp);
- return __xfs_btree_check_fsblock(cur, block, level, bp);
+ case XFS_BTREE_TYPE_INODE:
+ return __xfs_btree_check_fsblock(cur, block, level, bp);
+ default:
+ ASSERT(0);
+ return __this_address;
+ }
}

static inline unsigned int xfs_btree_block_errtag(struct xfs_btree_cur *cur)
@@ -259,14 +317,22 @@ __xfs_btree_check_ptr(
if (level <= 0)
return -EFSCORRUPTED;

- if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE) {
+ switch (cur->bc_ops->type) {
+ case XFS_BTREE_TYPE_MEM:
+ if (!xfbtree_verify_bno(cur->bc_mem.xfbtree,
+ be64_to_cpu((&ptr->l)[index])))
+ return -EFSCORRUPTED;
+ break;
+ case XFS_BTREE_TYPE_INODE:
if (!xfs_verify_fsbno(cur->bc_mp,
be64_to_cpu((&ptr->l)[index])))
return -EFSCORRUPTED;
- } else {
+ break;
+ case XFS_BTREE_TYPE_AG:
if (!xfs_verify_agbno(cur->bc_ag.pag,
be32_to_cpu((&ptr->s)[index])))
return -EFSCORRUPTED;
+ break;
}

return 0;
@@ -287,17 +353,26 @@ xfs_btree_check_ptr(

error = __xfs_btree_check_ptr(cur, ptr, index, level);
if (error) {
- if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE) {
+ switch (cur->bc_ops->type) {
+ case XFS_BTREE_TYPE_MEM:
+ xfs_err(cur->bc_mp,
+"In-memory: Corrupt %sbt flags 0x%x pointer at level %d index %d fa %pS.",
+ cur->bc_ops->name, cur->bc_flags, level, index,
+ __this_address);
+ break;
+ case XFS_BTREE_TYPE_INODE:
xfs_err(cur->bc_mp,
"Inode %llu fork %d: Corrupt %sbt pointer at level %d index %d.",
cur->bc_ino.ip->i_ino,
cur->bc_ino.whichfork, cur->bc_ops->name,
level, index);
- } else {
+ break;
+ case XFS_BTREE_TYPE_AG:
xfs_err(cur->bc_mp,
"AG %u: Corrupt %sbt pointer at level %d index %d.",
cur->bc_ag.pag->pag_agno, cur->bc_ops->name,
level, index);
+ break;
}
xfs_btree_mark_sick(cur);
}
@@ -454,11 +529,35 @@ xfs_btree_del_cursor(
case XFS_BTREE_TYPE_INODE:
/* nothing to do */
break;
+ case XFS_BTREE_TYPE_MEM:
+ if (cur->bc_mem.pag)
+ xfs_perag_put(cur->bc_mem.pag);
+ break;
}

kmem_cache_free(cur->bc_cache, cur);
}

+/* Return the buffer target for this btree's buffer. */
+static inline struct xfs_buftarg *
+xfs_btree_buftarg(
+ struct xfs_btree_cur *cur)
+{
+ if (cur->bc_ops->type == XFS_BTREE_TYPE_MEM)
+ return cur->bc_mem.xfbtree->target;
+ return cur->bc_mp->m_ddev_targp;
+}
+
+/* Return the block size (in units of 512b sectors) for this btree. */
+static inline unsigned int
+xfs_btree_bbsize(
+ struct xfs_btree_cur *cur)
+{
+ if (cur->bc_ops->type == XFS_BTREE_TYPE_MEM)
+ return XFBNO_BBSIZE;
+ return cur->bc_mp->m_bsize;
+}
+
/*
* Duplicate the btree cursor.
* Allocate a new one, copy the record, re-get the buffers.
@@ -502,10 +601,11 @@ xfs_btree_dup_cursor(
new->bc_levels[i].ra = cur->bc_levels[i].ra;
bp = cur->bc_levels[i].bp;
if (bp) {
- error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
- xfs_buf_daddr(bp), mp->m_bsize,
- 0, &bp,
- cur->bc_ops->buf_ops);
+ error = xfs_trans_read_buf(mp, tp,
+ xfs_btree_buftarg(cur),
+ xfs_buf_daddr(bp),
+ xfs_btree_bbsize(cur), 0, &bp,
+ cur->bc_ops->buf_ops);
if (xfs_metadata_is_sick(error))
xfs_btree_mark_sick(new);
if (error) {
@@ -882,6 +982,32 @@ xfs_btree_readahead_fsblock(
return rval;
}

+STATIC int
+xfs_btree_readahead_memblock(
+ struct xfs_btree_cur *cur,
+ int lr,
+ struct xfs_btree_block *block)
+{
+ struct xfs_buftarg *btp = cur->bc_mem.xfbtree->target;
+ xfbno_t left = be64_to_cpu(block->bb_u.l.bb_leftsib);
+ xfbno_t right = be64_to_cpu(block->bb_u.l.bb_rightsib);
+ int rval = 0;
+
+ if ((lr & XFS_BTCUR_LEFTRA) && left != NULLFSBLOCK) {
+ xfs_buf_readahead(btp, xfbno_to_daddr(left), XFBNO_BBSIZE,
+ cur->bc_ops->buf_ops);
+ rval++;
+ }
+
+ if ((lr & XFS_BTCUR_RIGHTRA) && right != NULLFSBLOCK) {
+ xfs_buf_readahead(btp, xfbno_to_daddr(right), XFBNO_BBSIZE,
+ cur->bc_ops->buf_ops);
+ rval++;
+ }
+
+ return rval;
+}
+
STATIC int
xfs_btree_readahead_agblock(
struct xfs_btree_cur *cur,
@@ -936,9 +1062,17 @@ xfs_btree_readahead(
cur->bc_levels[lev].ra |= lr;
block = XFS_BUF_TO_BLOCK(cur->bc_levels[lev].bp);

- if (cur->bc_ops->ptr_len == XFS_BTREE_LONG_PTR_LEN)
+ switch (cur->bc_ops->type) {
+ case XFS_BTREE_TYPE_AG:
+ return xfs_btree_readahead_agblock(cur, lr, block);
+ case XFS_BTREE_TYPE_INODE:
return xfs_btree_readahead_fsblock(cur, lr, block);
- return xfs_btree_readahead_agblock(cur, lr, block);
+ case XFS_BTREE_TYPE_MEM:
+ return xfs_btree_readahead_memblock(cur, lr, block);
+ default:
+ ASSERT(0);
+ return 0;
+ }
}

STATIC int
@@ -947,23 +1081,24 @@ xfs_btree_ptr_to_daddr(
const union xfs_btree_ptr *ptr,
xfs_daddr_t *daddr)
{
- xfs_fsblock_t fsbno;
- xfs_agblock_t agbno;
int error;

error = xfs_btree_check_ptr(cur, ptr, 0, 1);
if (error)
return error;

- if (cur->bc_ops->ptr_len == XFS_BTREE_LONG_PTR_LEN) {
- fsbno = be64_to_cpu(ptr->l);
- *daddr = XFS_FSB_TO_DADDR(cur->bc_mp, fsbno);
- } else {
- agbno = be32_to_cpu(ptr->s);
+ switch (cur->bc_ops->type) {
+ case XFS_BTREE_TYPE_AG:
*daddr = XFS_AGB_TO_DADDR(cur->bc_mp, cur->bc_ag.pag->pag_agno,
- agbno);
+ be32_to_cpu(ptr->s));
+ break;
+ case XFS_BTREE_TYPE_INODE:
+ *daddr = XFS_FSB_TO_DADDR(cur->bc_mp, be64_to_cpu(ptr->l));
+ break;
+ case XFS_BTREE_TYPE_MEM:
+ *daddr = xfbno_to_daddr(be64_to_cpu(ptr->l));
+ break;
}
-
return 0;
}

@@ -983,8 +1118,9 @@ xfs_btree_readahead_ptr(

if (xfs_btree_ptr_to_daddr(cur, ptr, &daddr))
return;
- xfs_buf_readahead(cur->bc_mp->m_ddev_targp, daddr,
- cur->bc_mp->m_bsize * count, cur->bc_ops->buf_ops);
+ xfs_buf_readahead(xfs_btree_buftarg(cur), daddr,
+ xfs_btree_bbsize(cur) * count,
+ cur->bc_ops->buf_ops);
}

/*
@@ -1169,9 +1305,17 @@ static inline __u64
xfs_btree_owner(
struct xfs_btree_cur *cur)
{
- if (cur->bc_ops->type == XFS_BTREE_TYPE_INODE)
+ switch (cur->bc_ops->type) {
+ case XFS_BTREE_TYPE_MEM:
+ return cur->bc_mem.xfbtree->owner;
+ case XFS_BTREE_TYPE_INODE:
return cur->bc_ino.ip->i_ino;
- return cur->bc_ag.pag->pag_agno;
+ case XFS_BTREE_TYPE_AG:
+ return cur->bc_ag.pag->pag_agno;
+ default:
+ ASSERT(0);
+ return 0;
+ }
}

void
@@ -1215,12 +1359,18 @@ xfs_btree_buf_to_ptr(
struct xfs_buf *bp,
union xfs_btree_ptr *ptr)
{
- if (cur->bc_ops->ptr_len == XFS_BTREE_LONG_PTR_LEN)
- ptr->l = cpu_to_be64(XFS_DADDR_TO_FSB(cur->bc_mp,
- xfs_buf_daddr(bp)));
- else {
+ switch (cur->bc_ops->type) {
+ case XFS_BTREE_TYPE_AG:
ptr->s = cpu_to_be32(xfs_daddr_to_agbno(cur->bc_mp,
xfs_buf_daddr(bp)));
+ break;
+ case XFS_BTREE_TYPE_INODE:
+ ptr->l = cpu_to_be64(XFS_DADDR_TO_FSB(cur->bc_mp,
+ xfs_buf_daddr(bp)));
+ break;
+ case XFS_BTREE_TYPE_MEM:
+ ptr->l = cpu_to_be64(xfs_daddr_to_xfbno(xfs_buf_daddr(bp)));
+ break;
}
}

@@ -1239,15 +1389,14 @@ xfs_btree_get_buf_block(
struct xfs_btree_block **block,
struct xfs_buf **bpp)
{
- struct xfs_mount *mp = cur->bc_mp;
- xfs_daddr_t d;
- int error;
+ xfs_daddr_t d;
+ int error;

error = xfs_btree_ptr_to_daddr(cur, ptr, &d);
if (error)
return error;
- error = xfs_trans_get_buf(cur->bc_tp, mp->m_ddev_targp, d, mp->m_bsize,
- 0, bpp);
+ error = xfs_trans_get_buf(cur->bc_tp, xfs_btree_buftarg(cur), d,
+ xfs_btree_bbsize(cur), 0, bpp);
if (error)
return error;

@@ -1278,9 +1427,9 @@ xfs_btree_read_buf_block(
error = xfs_btree_ptr_to_daddr(cur, ptr, &d);
if (error)
return error;
- error = xfs_trans_read_buf(mp, cur->bc_tp, mp->m_ddev_targp, d,
- mp->m_bsize, flags, bpp,
- cur->bc_ops->buf_ops);
+ error = xfs_trans_read_buf(mp, cur->bc_tp, xfs_btree_buftarg(cur), d,
+ xfs_btree_bbsize(cur), flags, bpp,
+ cur->bc_ops->buf_ops);
if (xfs_metadata_is_sick(error))
xfs_btree_mark_sick(cur);
if (error)
@@ -4579,6 +4728,8 @@ xfs_btree_fsblock_verify(
xfs_fsblock_t fsb;
xfs_failaddr_t fa;

+ ASSERT(!xfs_buftarg_is_mem(bp->b_target));
+
/* numrecs verification */
if (be16_to_cpu(block->bb_numrecs) > max_recs)
return __this_address;
@@ -4593,6 +4744,36 @@ xfs_btree_fsblock_verify(
return fa;
}

+/* Verify an in-memory btree block. */
+xfs_failaddr_t
+xfs_btree_memblock_verify(
+ struct xfs_buf *bp,
+ unsigned int max_recs)
+{
+ struct xfs_btree_block *block = XFS_BUF_TO_BLOCK(bp);
+ struct xfs_buftarg *btp = bp->b_target;
+ xfs_failaddr_t fa;
+ xfbno_t bno;
+
+ ASSERT(xfs_buftarg_is_mem(bp->b_target));
+
+ /* numrecs verification */
+ if (be16_to_cpu(block->bb_numrecs) > max_recs)
+ return __this_address;
+
+ /* sibling pointer verification */
+ bno = xfs_daddr_to_xfbno(xfs_buf_daddr(bp));
+ fa = xfs_btree_check_memblock_siblings(btp, bno,
+ block->bb_u.l.bb_leftsib);
+ if (fa)
+ return fa;
+ fa = xfs_btree_check_memblock_siblings(btp, bno,
+ block->bb_u.l.bb_rightsib);
+ if (fa)
+ return fa;
+
+ return NULL;
+}
/**
* xfs_btree_agblock_v5hdr_verify() -- verify the v5 fields of a short-format
* btree block
@@ -4634,6 +4815,8 @@ xfs_btree_agblock_verify(
xfs_agblock_t agbno;
xfs_failaddr_t fa;

+ ASSERT(!xfs_buftarg_is_mem(bp->b_target));
+
/* numrecs verification */
if (be16_to_cpu(block->bb_numrecs) > max_recs)
return __this_address;
diff --git a/libxfs/xfs_btree.h b/libxfs/xfs_btree.h
index bacd67cc8ced..f93374278aa1 100644
--- a/libxfs/xfs_btree.h
+++ b/libxfs/xfs_btree.h
@@ -112,6 +112,7 @@ static inline enum xbtree_key_contig xbtree_key_contig(uint64_t x, uint64_t y)
enum xfs_btree_type {
XFS_BTREE_TYPE_AG,
XFS_BTREE_TYPE_INODE,
+ XFS_BTREE_TYPE_MEM,
};

struct xfs_btree_ops {
@@ -281,6 +282,10 @@ struct xfs_btree_cur
struct xfs_buf *agbp;
struct xbtree_afakeroot *afake; /* for staging cursor */
} bc_ag;
+ struct {
+ struct xfbtree *xfbtree;
+ struct xfs_perag *pag;
+ } bc_mem;
};

/* per-format private data */
@@ -455,6 +460,8 @@ xfs_failaddr_t xfs_btree_fsblock_v5hdr_verify(struct xfs_buf *bp,
uint64_t owner);
xfs_failaddr_t xfs_btree_fsblock_verify(struct xfs_buf *bp,
unsigned int max_recs);
+xfs_failaddr_t xfs_btree_memblock_verify(struct xfs_buf *bp,
+ unsigned int max_recs);

unsigned int xfs_btree_compute_maxlevels(const unsigned int *limits,
unsigned long long records);
diff --git a/libxfs/xfs_btree_mem.c b/libxfs/xfs_btree_mem.c
new file mode 100644
index 000000000000..31835e065652
--- /dev/null
+++ b/libxfs/xfs_btree_mem.c
@@ -0,0 +1,227 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021-2024 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#include "libxfs_priv.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_trans.h"
+#include "xfs_btree.h"
+#include "xfile.h"
+#include "buf_mem.h"
+#include "xfs_btree_mem.h"
+#include "xfs_ag.h"
+#include "xfs_trace.h"
+
+/* Set the root of an in-memory btree. */
+void
+xfbtree_set_root(
+ struct xfs_btree_cur *cur,
+ const union xfs_btree_ptr *ptr,
+ int inc)
+{
+ ASSERT(cur->bc_ops->type == XFS_BTREE_TYPE_MEM);
+
+ cur->bc_mem.xfbtree->root = *ptr;
+ cur->bc_mem.xfbtree->nlevels += inc;
+}
+
+/* Initialize a pointer from the in-memory btree header. */
+void
+xfbtree_init_ptr_from_cur(
+ struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *ptr)
+{
+ ASSERT(cur->bc_ops->type == XFS_BTREE_TYPE_MEM);
+
+ *ptr = cur->bc_mem.xfbtree->root;
+}
+
+/* Duplicate an in-memory btree cursor. */
+struct xfs_btree_cur *
+xfbtree_dup_cursor(
+ struct xfs_btree_cur *cur)
+{
+ struct xfs_btree_cur *ncur;
+
+ ASSERT(cur->bc_ops->type == XFS_BTREE_TYPE_MEM);
+
+ ncur = xfs_btree_alloc_cursor(cur->bc_mp, cur->bc_tp, cur->bc_ops,
+ cur->bc_maxlevels, cur->bc_cache);
+ ncur->bc_flags = cur->bc_flags;
+ ncur->bc_nlevels = cur->bc_nlevels;
+ ncur->bc_mem.xfbtree = cur->bc_mem.xfbtree;
+
+ if (cur->bc_mem.pag)
+ ncur->bc_mem.pag = xfs_perag_hold(cur->bc_mem.pag);
+
+ return ncur;
+}
+
+/* Close the btree xfile and release all resources. */
+void
+xfbtree_destroy(
+ struct xfbtree *xfbt)
+{
+ xfs_buftarg_drain(xfbt->target);
+}
+
+/* Compute the number of bytes available for records. */
+static inline unsigned int
+xfbtree_rec_bytes(
+ struct xfs_mount *mp,
+ const struct xfs_btree_ops *ops)
+{
+ return XMBUF_BLOCKSIZE - XFS_BTREE_LBLOCK_CRC_LEN;
+}
+
+/* Initialize an empty leaf block as the btree root. */
+STATIC int
+xfbtree_init_leaf_block(
+ struct xfs_mount *mp,
+ struct xfbtree *xfbt,
+ const struct xfs_btree_ops *ops)
+{
+ struct xfs_buf *bp;
+ xfbno_t bno = xfbt->highest_bno++;
+ int error;
+
+ error = xfs_buf_get(xfbt->target, xfbno_to_daddr(bno), XFBNO_BBSIZE,
+ &bp);
+ if (error)
+ return error;
+
+ trace_xfbtree_create_root_buf(xfbt, bp);
+
+ bp->b_ops = ops->buf_ops;
+ xfs_btree_init_buf(mp, bp, ops, 0, 0, xfbt->owner);
+ xfs_buf_relse(bp);
+
+ xfbt->root.l = cpu_to_be64(bno);
+ return 0;
+}
+
+/*
+ * Create an in-memory btree root that can be used with the given xmbuf.
+ * Callers must set xfbt->owner.
+ */
+int
+xfbtree_init(
+ struct xfs_mount *mp,
+ struct xfbtree *xfbt,
+ struct xfs_buftarg *btp,
+ const struct xfs_btree_ops *ops)
+{
+ unsigned int blocklen = xfbtree_rec_bytes(mp, ops);
+ unsigned int keyptr_len;
+ int error;
+
+ /* Requires a long-format CRC-format btree */
+ if (!xfs_has_crc(mp)) {
+ ASSERT(xfs_has_crc(mp));
+ return -EINVAL;
+ }
+ if (ops->ptr_len != XFS_BTREE_LONG_PTR_LEN) {
+ ASSERT(ops->ptr_len == XFS_BTREE_LONG_PTR_LEN);
+ return -EINVAL;
+ }
+
+ memset(xfbt, 0, sizeof(*xfbt));
+ xfbt->target = btp;
+
+ /* Set up min/maxrecs for this btree. */
+ keyptr_len = ops->key_len + sizeof(__be64);
+ xfbt->maxrecs[0] = blocklen / ops->rec_len;
+ xfbt->maxrecs[1] = blocklen / keyptr_len;
+ xfbt->minrecs[0] = xfbt->maxrecs[0] / 2;
+ xfbt->minrecs[1] = xfbt->maxrecs[1] / 2;
+ xfbt->highest_bno = 0;
+ xfbt->nlevels = 1;
+
+ /* Initialize the empty btree. */
+ error = xfbtree_init_leaf_block(mp, xfbt, ops);
+ if (error)
+ goto err_freesp;
+
+ trace_xfbtree_init(mp, xfbt, ops);
+
+ return 0;
+
+err_freesp:
+ xfs_buftarg_drain(xfbt->target);
+ return error;
+}
+
+/* Allocate a block to our in-memory btree. */
+int
+xfbtree_alloc_block(
+ struct xfs_btree_cur *cur,
+ const union xfs_btree_ptr *start,
+ union xfs_btree_ptr *new,
+ int *stat)
+{
+ struct xfbtree *xfbt = cur->bc_mem.xfbtree;
+ xfbno_t bno = xfbt->highest_bno++;
+
+ ASSERT(cur->bc_ops->type == XFS_BTREE_TYPE_MEM);
+
+ trace_xfbtree_alloc_block(xfbt, cur, bno);
+
+ /* Fail if the block address exceeds the maximum for the buftarg. */
+ if (!xfbtree_verify_bno(xfbt, bno)) {
+ ASSERT(xfbtree_verify_bno(xfbt, bno));
+ *stat = 0;
+ return 0;
+ }
+
+ new->l = cpu_to_be64(bno);
+ *stat = 1;
+ return 0;
+}
+
+/* Free a block from our in-memory btree. */
+int
+xfbtree_free_block(
+ struct xfs_btree_cur *cur,
+ struct xfs_buf *bp)
+{
+ struct xfbtree *xfbt = cur->bc_mem.xfbtree;
+ xfs_daddr_t daddr = xfs_buf_daddr(bp);
+ xfbno_t bno = xfs_daddr_to_xfbno(daddr);
+
+ ASSERT(cur->bc_ops->type == XFS_BTREE_TYPE_MEM);
+
+ trace_xfbtree_free_block(xfbt, cur, bno);
+
+ if (bno + 1 == xfbt->highest_bno)
+ xfbt->highest_bno--;
+
+ return 0;
+}
+
+/* Return the minimum number of records for a btree block. */
+int
+xfbtree_get_minrecs(
+ struct xfs_btree_cur *cur,
+ int level)
+{
+ struct xfbtree *xfbt = cur->bc_mem.xfbtree;
+
+ return xfbt->minrecs[level != 0];
+}
+
+/* Return the maximum number of records for a btree block. */
+int
+xfbtree_get_maxrecs(
+ struct xfs_btree_cur *cur,
+ int level)
+{
+ struct xfbtree *xfbt = cur->bc_mem.xfbtree;
+
+ return xfbt->maxrecs[level != 0];
+}
diff --git a/libxfs/xfs_btree_mem.h b/libxfs/xfs_btree_mem.h
new file mode 100644
index 000000000000..ecc2ceac3ed4
--- /dev/null
+++ b/libxfs/xfs_btree_mem.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021-2024 Oracle. All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_BTREE_MEM_H__
+#define __XFS_BTREE_MEM_H__
+
+typedef uint64_t xfbno_t;
+
+#define XFBNO_BLOCKSIZE (XMBUF_BLOCKSIZE)
+#define XFBNO_BBSHIFT (XMBUF_BLOCKSHIFT - BBSHIFT)
+#define XFBNO_BBSIZE (XFBNO_BLOCKSIZE >> BBSHIFT)
+
+static inline xfs_daddr_t xfbno_to_daddr(xfbno_t blkno)
+{
+ return blkno << XFBNO_BBSHIFT;
+}
+
+static inline xfbno_t xfs_daddr_to_xfbno(xfs_daddr_t daddr)
+{
+ return daddr >> XFBNO_BBSHIFT;
+}
+
+struct xfbtree {
+ /* buffer cache target for this in-memory btree */
+ struct xfs_buftarg *target;
+
+ /* Highest block number that has been written to. */
+ xfbno_t highest_bno;
+
+ /* Owner of this btree. */
+ unsigned long long owner;
+
+ /* Btree header */
+ union xfs_btree_ptr root;
+ unsigned int nlevels;
+
+ /* Minimum and maximum records per block. */
+ unsigned int maxrecs[2];
+ unsigned int minrecs[2];
+};
+
+#ifdef CONFIG_XFS_BTREE_IN_MEM
+static inline bool xfbtree_verify_bno(struct xfbtree *xfbt, xfbno_t bno)
+{
+ return xmbuf_verify_daddr(xfbt->target, xfbno_to_daddr(bno));
+}
+
+void xfbtree_set_root(struct xfs_btree_cur *cur,
+ const union xfs_btree_ptr *ptr, int inc);
+void xfbtree_init_ptr_from_cur(struct xfs_btree_cur *cur,
+ union xfs_btree_ptr *ptr);
+struct xfs_btree_cur *xfbtree_dup_cursor(struct xfs_btree_cur *cur);
+
+int xfbtree_get_minrecs(struct xfs_btree_cur *cur, int level);
+int xfbtree_get_maxrecs(struct xfs_btree_cur *cur, int level);
+
+int xfbtree_alloc_block(struct xfs_btree_cur *cur,
+ const union xfs_btree_ptr *start, union xfs_btree_ptr *ptr,
+ int *stat);
+int xfbtree_free_block(struct xfs_btree_cur *cur, struct xfs_buf *bp);
+
+/* Callers must set xfbt->target and xfbt->owner before calling this */
+int xfbtree_init(struct xfs_mount *mp, struct xfbtree *xfbt,
+ struct xfs_buftarg *btp, const struct xfs_btree_ops *ops);
+void xfbtree_destroy(struct xfbtree *xfbt);
+#else
+# define xfbtree_verify_bno(...) (false)
+#endif /* CONFIG_XFS_BTREE_IN_MEM */
+
+#endif /* __XFS_BTREE_MEM_H__ */