[PATCH v3 0/4] xfs: close crash window in attr dabtree inactivation

[PATCH v3 0/4] xfs: close crash window in attr dabtree inactivation

[Long Li]

Problem
-------

xfs_attr3_node_inactive() cancels all child blocks in the attr dabtree
via xfs_trans_binval(), relying on a subsequent full attr bmap truncation
in xfs_attr_inactive() to ensure log recovery never reaches the root
node.  The child block cancellations and the bmap truncation are
committed in separate transactions, creating a narrow but real crash
window.

If the system shuts down after the cancellations commit but before the
bmap truncation commits, the attr bmap survives recovery intact and
xlog_recover_process_iunlinks() retries inactivation.  It attempts to
read the root node via the attr bmap: if the root node was not replayed,
reading the unreplayed root block maybe triggers a metadata verification
failure immediately; if it was replayed, following its child pointers to
unreplayed child blocks triggers the same failure.

Zhang Yi previously attempted to solve this problem [1], but Dave gave
different advice. Following the approach suggested by Dave Chinner in
review.

[1] https://patchwork.kernel.org/project/xfs/patch/20230613030434.2944173-3-yi.zhang@huaweicloud.com/

Fix
---

The fix addresses the atomicity gap at two levels:

(1) In xfs_attr3_node_inactive(), each child block invalidation and the
    removal of its reference from the parent node are placed in the same
    transaction, so no parent node ever holds a pointer to a cancelled
    block at any crash point.  After all children are removed, the empty
    root node is converted to an empty leaf in the same transaction.
    This conversion is necessary because xfs_da3_node_verify() rejects
    a node block with count == 0, whereas xfs_attr3_leaf_verify()
    explicitly allows it during recovery to accommodate the transient
    state from the shortform-to-leaf promotion path.

(2) In xfs_attr_inactive(), the attr fork is truncated in two phases.
    First the child extents are removed.  Then the root block is
    invalidated and the attr bmap is truncated to zero in a single
    transaction.  These two operations in the second phase must be
    atomic: as long as the attr bmap has any non-zero length, recovery
    can follow it to the root block, so the root block invalidation must
    commit together with the bmap-to-zero truncation.


Changes
-------

v2->v3:
 1) Rewrite Description of xfs_attr3_node_entry_remove and xfs_attr3_leaf_init.
 2) Fixed corner case issue where root leaf block has remote value block.
 3) Reduced the return exit of xfs_attr3_root_inactive().

v1->v2:
 1) Rename xfs_da3_node_entry_remove to xfs_attr3_node_entry_remove.
 2) Initializing the structure value when declaring a structure in a function.
 3) An assertion is added to xfs_attr3_leaf_init to check whether tp is not null.
 4) Fixed syntax style issues.

Long Li (4):
  xfs: only assert new size for datafork during truncate extents
  xfs: factor out xfs_attr3_node_entry_remove
  xfs: factor out xfs_attr3_leaf_init
  xfs: close crash window in attr dabtree inactivation

 fs/xfs/libxfs/xfs_attr_leaf.c | 22 ++++++++
 fs/xfs/libxfs/xfs_attr_leaf.h |  3 ++
 fs/xfs/libxfs/xfs_da_btree.c  | 53 +++++++++++++++----
 fs/xfs/libxfs/xfs_da_btree.h  |  2 +
 fs/xfs/xfs_attr_inactive.c    | 99 +++++++++++++++++++++--------------
 fs/xfs/xfs_inode.c            |  3 +-
 6 files changed, 130 insertions(+), 52 deletions(-)

-- 
2.39.2

[PATCH v3 1/4] xfs: only assert new size for datafork during truncate extents

[Long Li]

The assertion functions properly because we currently only truncate the
attr to a zero size. Any other new size of the attr is not preempted.
Make this assertion is specific to the datafork, preparing for
subsequent patches to truncate the attribute to a non-zero size.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Long Li <leo.lilong@huawei.com>
---
 fs/xfs/xfs_inode.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 50c0404f9064..beaa26ec62da 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1048,7 +1048,8 @@ xfs_itruncate_extents_flags(
 	xfs_assert_ilocked(ip, XFS_ILOCK_EXCL);
 	if (icount_read(VFS_I(ip)))
 		xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL);
-	ASSERT(new_size <= XFS_ISIZE(ip));
+	if (whichfork == XFS_DATA_FORK)
+		ASSERT(new_size <= XFS_ISIZE(ip));
 	ASSERT(tp->t_flags & XFS_TRANS_PERM_LOG_RES);
 	ASSERT(ip->i_itemp != NULL);
 	ASSERT(ip->i_itemp->ili_lock_flags == 0);
-- 
2.39.2

[PATCH v3 2/4] xfs: factor out xfs_attr3_node_entry_remove

[Long Li]

Factor out wrapper xfs_attr3_node_entry_remove function, which
exported for external use.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Long Li <leo.lilong@huawei.com>
---
 fs/xfs/libxfs/xfs_da_btree.c | 53 ++++++++++++++++++++++++++++--------
 fs/xfs/libxfs/xfs_da_btree.h |  2 ++
 2 files changed, 44 insertions(+), 11 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_da_btree.c b/fs/xfs/libxfs/xfs_da_btree.c
index 09d4c17b3e7b..ad801b7bd2dd 100644
--- a/fs/xfs/libxfs/xfs_da_btree.c
+++ b/fs/xfs/libxfs/xfs_da_btree.c
@@ -1506,21 +1506,20 @@ xfs_da3_fixhashpath(
 }
 
 /*
- * Remove an entry from an intermediate node.
+ * Internal implementation to remove an entry from an intermediate node.
  */
 STATIC void
-xfs_da3_node_remove(
-	struct xfs_da_state	*state,
-	struct xfs_da_state_blk	*drop_blk)
+__xfs_da3_node_remove(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	struct xfs_da_geometry  *geo,
+	struct xfs_da_state_blk *drop_blk)
 {
 	struct xfs_da_intnode	*node;
 	struct xfs_da3_icnode_hdr nodehdr;
 	struct xfs_da_node_entry *btree;
 	int			index;
 	int			tmp;
-	struct xfs_inode	*dp = state->args->dp;
-
-	trace_xfs_da_node_remove(state->args);
 
 	node = drop_blk->bp->b_addr;
 	xfs_da3_node_hdr_from_disk(dp->i_mount, &nodehdr, node);
@@ -1536,17 +1535,17 @@ xfs_da3_node_remove(
 		tmp  = nodehdr.count - index - 1;
 		tmp *= (uint)sizeof(xfs_da_node_entry_t);
 		memmove(&btree[index], &btree[index + 1], tmp);
-		xfs_trans_log_buf(state->args->trans, drop_blk->bp,
+		xfs_trans_log_buf(tp, drop_blk->bp,
 		    XFS_DA_LOGRANGE(node, &btree[index], tmp));
 		index = nodehdr.count - 1;
 	}
 	memset(&btree[index], 0, sizeof(xfs_da_node_entry_t));
-	xfs_trans_log_buf(state->args->trans, drop_blk->bp,
+	xfs_trans_log_buf(tp, drop_blk->bp,
 	    XFS_DA_LOGRANGE(node, &btree[index], sizeof(btree[index])));
 	nodehdr.count -= 1;
 	xfs_da3_node_hdr_to_disk(dp->i_mount, node, &nodehdr);
-	xfs_trans_log_buf(state->args->trans, drop_blk->bp,
-	    XFS_DA_LOGRANGE(node, &node->hdr, state->args->geo->node_hdr_size));
+	xfs_trans_log_buf(tp, drop_blk->bp,
+	    XFS_DA_LOGRANGE(node, &node->hdr, geo->node_hdr_size));
 
 	/*
 	 * Copy the last hash value from the block to propagate upwards.
@@ -1554,6 +1553,38 @@ xfs_da3_node_remove(
 	drop_blk->hashval = be32_to_cpu(btree[index - 1].hashval);
 }
 
+/*
+ * Remove an entry from an intermediate node.
+ */
+STATIC void
+xfs_da3_node_remove(
+	struct xfs_da_state	*state,
+	struct xfs_da_state_blk	*drop_blk)
+{
+	trace_xfs_da_node_remove(state->args);
+
+	__xfs_da3_node_remove(state->args->trans, state->args->dp,
+			state->args->geo, drop_blk);
+}
+
+/*
+ * Remove an entry from an intermediate attr node at the specified index.
+ */
+void
+xfs_attr3_node_entry_remove(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	struct xfs_buf		*bp,
+	int			index)
+{
+	struct xfs_da_state_blk blk = {
+		.index		= index,
+		.bp		= bp,
+	};
+
+	__xfs_da3_node_remove(tp, dp, dp->i_mount->m_attr_geo, &blk);
+}
+
 /*
  * Unbalance the elements between two intermediate nodes,
  * move all Btree elements from one node into another.
diff --git a/fs/xfs/libxfs/xfs_da_btree.h b/fs/xfs/libxfs/xfs_da_btree.h
index 354d5d65043e..afcf2d3c7a21 100644
--- a/fs/xfs/libxfs/xfs_da_btree.h
+++ b/fs/xfs/libxfs/xfs_da_btree.h
@@ -184,6 +184,8 @@ int	xfs_da3_split(xfs_da_state_t *state);
 int	xfs_da3_join(xfs_da_state_t *state);
 void	xfs_da3_fixhashpath(struct xfs_da_state *state,
 			    struct xfs_da_state_path *path_to_to_fix);
+void	xfs_attr3_node_entry_remove(struct xfs_trans *tp, struct xfs_inode *dp,
+			    struct xfs_buf *bp, int index);
 
 /*
  * Routines used for finding things in the Btree.
-- 
2.39.2

[PATCH v3 3/4] xfs: factor out xfs_attr3_leaf_init

[Long Li]

Factor out wrapper xfs_attr3_leaf_init function, which exported for
external use.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Long Li <leo.lilong@huawei.com>
---
 fs/xfs/libxfs/xfs_attr_leaf.c | 22 ++++++++++++++++++++++
 fs/xfs/libxfs/xfs_attr_leaf.h |  3 +++
 2 files changed, 25 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 47f48ae555c0..2b78041e8672 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -1415,6 +1415,28 @@ xfs_attr3_leaf_create(
 	return 0;
 }
 
+/*
+ * Reinitialize an existing attr fork block as an empty leaf, and attach
+ * the buffer to tp.
+ */
+int
+xfs_attr3_leaf_init(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	xfs_dablk_t		blkno)
+{
+	struct xfs_buf		*bp = NULL;
+	struct xfs_da_args	args = {
+		.trans		= tp,
+		.dp		= dp,
+		.owner		= dp->i_ino,
+		.geo		= dp->i_mount->m_attr_geo,
+	};
+
+	ASSERT(tp != NULL);
+
+	return xfs_attr3_leaf_create(&args, blkno, &bp);
+}
 /*
  * Split the leaf node, rebalance, then add the new entry.
  *
diff --git a/fs/xfs/libxfs/xfs_attr_leaf.h b/fs/xfs/libxfs/xfs_attr_leaf.h
index aca46da2bc50..72639efe6ac3 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.h
+++ b/fs/xfs/libxfs/xfs_attr_leaf.h
@@ -87,6 +87,9 @@ int	xfs_attr3_leaf_list_int(struct xfs_buf *bp,
 /*
  * Routines used for shrinking the Btree.
  */
+
+int	xfs_attr3_leaf_init(struct xfs_trans *tp, struct xfs_inode *dp,
+				xfs_dablk_t blkno);
 int	xfs_attr3_leaf_toosmall(struct xfs_da_state *state, int *retval);
 void	xfs_attr3_leaf_unbalance(struct xfs_da_state *state,
 				       struct xfs_da_state_blk *drop_blk,
-- 
2.39.2

[PATCH v3 4/4] xfs: close crash window in attr dabtree inactivation

[Long Li]

When inactivating an inode with node-format extended attributes,
xfs_attr3_node_inactive() invalidates all child leaf/node blocks via
xfs_trans_binval(), but intentionally does not remove the corresponding
entries from their parent node blocks.  The implicit assumption is that
xfs_attr_inactive() will truncate the entire attr fork to zero extents
afterwards, so log recovery will never reach the root node and follow
those stale pointers.

However, if a log shutdown occurs after the leaf/node block cancellations
commit but before the attr bmap truncation commits, this assumption
breaks.  Recovery replays the attr bmap intact (the inode still has
attr fork extents), but suppresses replay of all cancelled leaf/node
blocks, maybe leaving them as stale data on disk.  On the next mount,
xlog_recover_process_iunlinks() retries inactivation and attempts to
read the root node via the attr bmap. If the root node was not replayed,
reading the unreplayed root block triggers a metadata verification
failure immediately; if it was replayed, following its child pointers
to unreplayed child blocks triggers the same failure:

 XFS (pmem0): Metadata corruption detected at
 xfs_da3_node_read_verify+0x53/0x220, xfs_da3_node block 0x78
 XFS (pmem0): Unmount and run xfs_repair
 XFS (pmem0): First 128 bytes of corrupted metadata buffer:
 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
 XFS (pmem0): metadata I/O error in "xfs_da_read_buf+0x104/0x190" at daddr 0x78 len 8 error 117

Fix this in two places:

In xfs_attr3_node_inactive(), after calling xfs_trans_binval() on a
child block, immediately remove the entry that references it from the
parent node in the same transaction.  This eliminates the window where
the parent holds a pointer to a cancelled block.  Once all children are
removed, the now-empty root node is converted to a leaf block within the
same transaction. This node-to-leaf conversion is necessary for crash
safety. If the system shutdown after the empty node is written to the
log but before the second-phase bmap truncation commits, log recovery
will attempt to verify the root block on disk. xfs_da3_node_verify()
does not permit a node block with count == 0; such a block will fail
verification and trigger a metadata corruption shutdown. on the other
hand, leaf blocks are allowed to have this transient state.

In xfs_attr_inactive(), split the attr fork truncation into two explicit
phases.  First, truncate all extents beyond the root block (the child
extents whose parent references have already been removed above).
Second, invalidate the root block and truncate the attr bmap to zero in
a single transaction.  The two operations in the second phase must be
atomic: as long as the attr bmap has any non-zero length, recovery can
follow it to the root block, so the root block invalidation must commit
together with the bmap-to-zero truncation.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: <stable@vger.kernel.org>
Signed-off-by: Long Li <leo.lilong@huawei.com>
---
 fs/xfs/xfs_attr_inactive.c | 99 +++++++++++++++++++++++---------------
 1 file changed, 59 insertions(+), 40 deletions(-)

diff --git a/fs/xfs/xfs_attr_inactive.c b/fs/xfs/xfs_attr_inactive.c
index 92331991f9fd..a5b69c0fbfd0 100644
--- a/fs/xfs/xfs_attr_inactive.c
+++ b/fs/xfs/xfs_attr_inactive.c
@@ -140,7 +140,7 @@ xfs_attr3_node_inactive(
 	xfs_daddr_t		parent_blkno, child_blkno;
 	struct xfs_buf		*child_bp;
 	struct xfs_da3_icnode_hdr ichdr;
-	int			error, i;
+	int			error;
 
 	/*
 	 * Since this code is recursive (gasp!) we must protect ourselves.
@@ -152,7 +152,7 @@ xfs_attr3_node_inactive(
 		return -EFSCORRUPTED;
 	}
 
-	xfs_da3_node_hdr_from_disk(dp->i_mount, &ichdr, bp->b_addr);
+	xfs_da3_node_hdr_from_disk(mp, &ichdr, bp->b_addr);
 	parent_blkno = xfs_buf_daddr(bp);
 	if (!ichdr.count) {
 		xfs_trans_brelse(*trans, bp);
@@ -167,7 +167,7 @@ xfs_attr3_node_inactive(
 	 * over the leaves removing all of them.  If this is higher up
 	 * in the tree, recurse downward.
 	 */
-	for (i = 0; i < ichdr.count; i++) {
+	while (ichdr.count > 0) {
 		/*
 		 * Read the subsidiary block to see what we have to work with.
 		 * Don't do this in a transaction.  This is a depth-first
@@ -218,29 +218,32 @@ xfs_attr3_node_inactive(
 		xfs_trans_binval(*trans, child_bp);
 		child_bp = NULL;
 
-		/*
-		 * If we're not done, re-read the parent to get the next
-		 * child block number.
-		 */
-		if (i + 1 < ichdr.count) {
-			struct xfs_da3_icnode_hdr phdr;
+		error = xfs_da3_node_read_mapped(*trans, dp,
+				parent_blkno, &bp, XFS_ATTR_FORK);
+		if (error)
+			return error;
 
-			error = xfs_da3_node_read_mapped(*trans, dp,
-					parent_blkno, &bp, XFS_ATTR_FORK);
+		/*
+		 * Remove entry from parent node, prevents being indexed to.
+		 */
+		xfs_attr3_node_entry_remove(*trans, dp, bp, 0);
+
+		xfs_da3_node_hdr_from_disk(mp, &ichdr, bp->b_addr);
+		bp = NULL;
+
+		if (ichdr.count > 0) {
+			/*
+			 * If we're not done, get the next child block number.
+			 */
+			child_fsb = be32_to_cpu(ichdr.btree[0].before);
+
+			/*
+			 * Atomically commit the whole invalidate stuff.
+			 */
+			error = xfs_trans_roll_inode(trans, dp);
 			if (error)
 				return error;
-			xfs_da3_node_hdr_from_disk(dp->i_mount, &phdr,
-						  bp->b_addr);
-			child_fsb = be32_to_cpu(phdr.btree[i + 1].before);
-			xfs_trans_brelse(*trans, bp);
-			bp = NULL;
 		}
-		/*
-		 * Atomically commit the whole invalidate stuff.
-		 */
-		error = xfs_trans_roll_inode(trans, dp);
-		if (error)
-			return  error;
 	}
 
 	return 0;
@@ -257,10 +260,8 @@ xfs_attr3_root_inactive(
 	struct xfs_trans	**trans,
 	struct xfs_inode	*dp)
 {
-	struct xfs_mount	*mp = dp->i_mount;
 	struct xfs_da_blkinfo	*info;
 	struct xfs_buf		*bp;
-	xfs_daddr_t		blkno;
 	int			error;
 
 	/*
@@ -272,7 +273,6 @@ xfs_attr3_root_inactive(
 	error = xfs_da3_node_read(*trans, dp, 0, &bp, XFS_ATTR_FORK);
 	if (error)
 		return error;
-	blkno = xfs_buf_daddr(bp);
 
 	/*
 	 * Invalidate the tree, even if the "tree" is only a single leaf block.
@@ -283,10 +283,26 @@ xfs_attr3_root_inactive(
 	case cpu_to_be16(XFS_DA_NODE_MAGIC):
 	case cpu_to_be16(XFS_DA3_NODE_MAGIC):
 		error = xfs_attr3_node_inactive(trans, dp, bp, 1);
+		/*
+		 * Empty root node block are not allowed, convert it to leaf.
+		 */
+		if (!error)
+			error = xfs_attr3_leaf_init(*trans, dp, 0);
+		if (!error)
+			error = xfs_trans_roll_inode(trans, dp);
 		break;
 	case cpu_to_be16(XFS_ATTR_LEAF_MAGIC):
 	case cpu_to_be16(XFS_ATTR3_LEAF_MAGIC):
 		error = xfs_attr3_leaf_inactive(trans, dp, bp);
+		/*
+		 * Reinit the leaf before truncating extents so that a crash
+		 * mid-truncation leaves an empty leaf rather than one with
+		 * entries that may reference freed remote value blocks.
+		 */
+		if (!error)
+			error = xfs_attr3_leaf_init(*trans, dp, 0);
+		if (!error)
+			error = xfs_trans_roll_inode(trans, dp);
 		break;
 	default:
 		xfs_dirattr_mark_sick(dp, XFS_ATTR_FORK);
@@ -295,21 +311,6 @@ xfs_attr3_root_inactive(
 		xfs_trans_brelse(*trans, bp);
 		break;
 	}
-	if (error)
-		return error;
-
-	/*
-	 * Invalidate the incore copy of the root block.
-	 */
-	error = xfs_trans_get_buf(*trans, mp->m_ddev_targp, blkno,
-			XFS_FSB_TO_BB(mp, mp->m_attr_geo->fsbcount), 0, &bp);
-	if (error)
-		return error;
-	xfs_trans_binval(*trans, bp);	/* remove from cache */
-	/*
-	 * Commit the invalidate and start the next transaction.
-	 */
-	error = xfs_trans_roll_inode(trans, dp);
 
 	return error;
 }
@@ -328,6 +329,7 @@ xfs_attr_inactive(
 {
 	struct xfs_trans	*trans;
 	struct xfs_mount	*mp;
+	struct xfs_buf          *bp;
 	int			lock_mode = XFS_ILOCK_SHARED;
 	int			error = 0;
 
@@ -363,10 +365,27 @@ xfs_attr_inactive(
 	 * removal below.
 	 */
 	if (dp->i_af.if_nextents > 0) {
+		/*
+		 * Invalidate and truncate all blocks but leave the root block.
+		 */
 		error = xfs_attr3_root_inactive(&trans, dp);
 		if (error)
 			goto out_cancel;
 
+		error = xfs_itruncate_extents(&trans, dp, XFS_ATTR_FORK,
+				XFS_FSB_TO_B(mp, mp->m_attr_geo->fsbcount));
+		if (error)
+			goto out_cancel;
+
+		/*
+		 * Invalidate and truncate the root block and ensure that the
+		 * operation is completed within a single transaction.
+		 */
+		error = xfs_da_get_buf(trans, dp, 0, &bp, XFS_ATTR_FORK);
+		if (error)
+			goto out_cancel;
+
+		xfs_trans_binval(trans, bp);
 		error = xfs_itruncate_extents(&trans, dp, XFS_ATTR_FORK, 0);
 		if (error)
 			goto out_cancel;
-- 
2.39.2

Re: [PATCH v3 4/4] xfs: close crash window in attr dabtree inactivation

[Darrick J. Wong]

On Tue, Mar 17, 2026 at 09:51:55AM +0800, Long Li wrote:
> When inactivating an inode with node-format extended attributes,
> xfs_attr3_node_inactive() invalidates all child leaf/node blocks via
> xfs_trans_binval(), but intentionally does not remove the corresponding
> entries from their parent node blocks.  The implicit assumption is that
> xfs_attr_inactive() will truncate the entire attr fork to zero extents
> afterwards, so log recovery will never reach the root node and follow
> those stale pointers.
> 
> However, if a log shutdown occurs after the leaf/node block cancellations
> commit but before the attr bmap truncation commits, this assumption
> breaks.  Recovery replays the attr bmap intact (the inode still has
> attr fork extents), but suppresses replay of all cancelled leaf/node
> blocks, maybe leaving them as stale data on disk.  On the next mount,
> xlog_recover_process_iunlinks() retries inactivation and attempts to
> read the root node via the attr bmap. If the root node was not replayed,
> reading the unreplayed root block triggers a metadata verification
> failure immediately; if it was replayed, following its child pointers
> to unreplayed child blocks triggers the same failure:
> 
>  XFS (pmem0): Metadata corruption detected at
>  xfs_da3_node_read_verify+0x53/0x220, xfs_da3_node block 0x78
>  XFS (pmem0): Unmount and run xfs_repair
>  XFS (pmem0): First 128 bytes of corrupted metadata buffer:
>  00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>  XFS (pmem0): metadata I/O error in "xfs_da_read_buf+0x104/0x190" at daddr 0x78 len 8 error 117
> 
> Fix this in two places:
> 
> In xfs_attr3_node_inactive(), after calling xfs_trans_binval() on a
> child block, immediately remove the entry that references it from the
> parent node in the same transaction.  This eliminates the window where
> the parent holds a pointer to a cancelled block.  Once all children are
> removed, the now-empty root node is converted to a leaf block within the
> same transaction. This node-to-leaf conversion is necessary for crash
> safety. If the system shutdown after the empty node is written to the
> log but before the second-phase bmap truncation commits, log recovery
> will attempt to verify the root block on disk. xfs_da3_node_verify()
> does not permit a node block with count == 0; such a block will fail
> verification and trigger a metadata corruption shutdown. on the other
> hand, leaf blocks are allowed to have this transient state.
> 
> In xfs_attr_inactive(), split the attr fork truncation into two explicit
> phases.  First, truncate all extents beyond the root block (the child
> extents whose parent references have already been removed above).
> Second, invalidate the root block and truncate the attr bmap to zero in
> a single transaction.  The two operations in the second phase must be
> atomic: as long as the attr bmap has any non-zero length, recovery can
> follow it to the root block, so the root block invalidation must commit
> together with the bmap-to-zero truncation.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Long Li <leo.lilong@huawei.com>

Looks good, lemme run that through QA one more time...
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> ---
>  fs/xfs/xfs_attr_inactive.c | 99 +++++++++++++++++++++++---------------
>  1 file changed, 59 insertions(+), 40 deletions(-)
> 
> diff --git a/fs/xfs/xfs_attr_inactive.c b/fs/xfs/xfs_attr_inactive.c
> index 92331991f9fd..a5b69c0fbfd0 100644
> --- a/fs/xfs/xfs_attr_inactive.c
> +++ b/fs/xfs/xfs_attr_inactive.c
> @@ -140,7 +140,7 @@ xfs_attr3_node_inactive(
>  	xfs_daddr_t		parent_blkno, child_blkno;
>  	struct xfs_buf		*child_bp;
>  	struct xfs_da3_icnode_hdr ichdr;
> -	int			error, i;
> +	int			error;
>  
>  	/*
>  	 * Since this code is recursive (gasp!) we must protect ourselves.
> @@ -152,7 +152,7 @@ xfs_attr3_node_inactive(
>  		return -EFSCORRUPTED;
>  	}
>  
> -	xfs_da3_node_hdr_from_disk(dp->i_mount, &ichdr, bp->b_addr);
> +	xfs_da3_node_hdr_from_disk(mp, &ichdr, bp->b_addr);
>  	parent_blkno = xfs_buf_daddr(bp);
>  	if (!ichdr.count) {
>  		xfs_trans_brelse(*trans, bp);
> @@ -167,7 +167,7 @@ xfs_attr3_node_inactive(
>  	 * over the leaves removing all of them.  If this is higher up
>  	 * in the tree, recurse downward.
>  	 */
> -	for (i = 0; i < ichdr.count; i++) {
> +	while (ichdr.count > 0) {
>  		/*
>  		 * Read the subsidiary block to see what we have to work with.
>  		 * Don't do this in a transaction.  This is a depth-first
> @@ -218,29 +218,32 @@ xfs_attr3_node_inactive(
>  		xfs_trans_binval(*trans, child_bp);
>  		child_bp = NULL;
>  
> -		/*
> -		 * If we're not done, re-read the parent to get the next
> -		 * child block number.
> -		 */
> -		if (i + 1 < ichdr.count) {
> -			struct xfs_da3_icnode_hdr phdr;
> +		error = xfs_da3_node_read_mapped(*trans, dp,
> +				parent_blkno, &bp, XFS_ATTR_FORK);
> +		if (error)
> +			return error;
>  
> -			error = xfs_da3_node_read_mapped(*trans, dp,
> -					parent_blkno, &bp, XFS_ATTR_FORK);
> +		/*
> +		 * Remove entry from parent node, prevents being indexed to.
> +		 */
> +		xfs_attr3_node_entry_remove(*trans, dp, bp, 0);
> +
> +		xfs_da3_node_hdr_from_disk(mp, &ichdr, bp->b_addr);
> +		bp = NULL;
> +
> +		if (ichdr.count > 0) {
> +			/*
> +			 * If we're not done, get the next child block number.
> +			 */
> +			child_fsb = be32_to_cpu(ichdr.btree[0].before);
> +
> +			/*
> +			 * Atomically commit the whole invalidate stuff.
> +			 */
> +			error = xfs_trans_roll_inode(trans, dp);
>  			if (error)
>  				return error;
> -			xfs_da3_node_hdr_from_disk(dp->i_mount, &phdr,
> -						  bp->b_addr);
> -			child_fsb = be32_to_cpu(phdr.btree[i + 1].before);
> -			xfs_trans_brelse(*trans, bp);
> -			bp = NULL;
>  		}
> -		/*
> -		 * Atomically commit the whole invalidate stuff.
> -		 */
> -		error = xfs_trans_roll_inode(trans, dp);
> -		if (error)
> -			return  error;
>  	}
>  
>  	return 0;
> @@ -257,10 +260,8 @@ xfs_attr3_root_inactive(
>  	struct xfs_trans	**trans,
>  	struct xfs_inode	*dp)
>  {
> -	struct xfs_mount	*mp = dp->i_mount;
>  	struct xfs_da_blkinfo	*info;
>  	struct xfs_buf		*bp;
> -	xfs_daddr_t		blkno;
>  	int			error;
>  
>  	/*
> @@ -272,7 +273,6 @@ xfs_attr3_root_inactive(
>  	error = xfs_da3_node_read(*trans, dp, 0, &bp, XFS_ATTR_FORK);
>  	if (error)
>  		return error;
> -	blkno = xfs_buf_daddr(bp);
>  
>  	/*
>  	 * Invalidate the tree, even if the "tree" is only a single leaf block.
> @@ -283,10 +283,26 @@ xfs_attr3_root_inactive(
>  	case cpu_to_be16(XFS_DA_NODE_MAGIC):
>  	case cpu_to_be16(XFS_DA3_NODE_MAGIC):
>  		error = xfs_attr3_node_inactive(trans, dp, bp, 1);
> +		/*
> +		 * Empty root node block are not allowed, convert it to leaf.
> +		 */
> +		if (!error)
> +			error = xfs_attr3_leaf_init(*trans, dp, 0);
> +		if (!error)
> +			error = xfs_trans_roll_inode(trans, dp);
>  		break;
>  	case cpu_to_be16(XFS_ATTR_LEAF_MAGIC):
>  	case cpu_to_be16(XFS_ATTR3_LEAF_MAGIC):
>  		error = xfs_attr3_leaf_inactive(trans, dp, bp);
> +		/*
> +		 * Reinit the leaf before truncating extents so that a crash
> +		 * mid-truncation leaves an empty leaf rather than one with
> +		 * entries that may reference freed remote value blocks.
> +		 */
> +		if (!error)
> +			error = xfs_attr3_leaf_init(*trans, dp, 0);
> +		if (!error)
> +			error = xfs_trans_roll_inode(trans, dp);
>  		break;
>  	default:
>  		xfs_dirattr_mark_sick(dp, XFS_ATTR_FORK);
> @@ -295,21 +311,6 @@ xfs_attr3_root_inactive(
>  		xfs_trans_brelse(*trans, bp);
>  		break;
>  	}
> -	if (error)
> -		return error;
> -
> -	/*
> -	 * Invalidate the incore copy of the root block.
> -	 */
> -	error = xfs_trans_get_buf(*trans, mp->m_ddev_targp, blkno,
> -			XFS_FSB_TO_BB(mp, mp->m_attr_geo->fsbcount), 0, &bp);
> -	if (error)
> -		return error;
> -	xfs_trans_binval(*trans, bp);	/* remove from cache */
> -	/*
> -	 * Commit the invalidate and start the next transaction.
> -	 */
> -	error = xfs_trans_roll_inode(trans, dp);
>  
>  	return error;
>  }
> @@ -328,6 +329,7 @@ xfs_attr_inactive(
>  {
>  	struct xfs_trans	*trans;
>  	struct xfs_mount	*mp;
> +	struct xfs_buf          *bp;
>  	int			lock_mode = XFS_ILOCK_SHARED;
>  	int			error = 0;
>  
> @@ -363,10 +365,27 @@ xfs_attr_inactive(
>  	 * removal below.
>  	 */
>  	if (dp->i_af.if_nextents > 0) {
> +		/*
> +		 * Invalidate and truncate all blocks but leave the root block.
> +		 */
>  		error = xfs_attr3_root_inactive(&trans, dp);
>  		if (error)
>  			goto out_cancel;
>  
> +		error = xfs_itruncate_extents(&trans, dp, XFS_ATTR_FORK,
> +				XFS_FSB_TO_B(mp, mp->m_attr_geo->fsbcount));
> +		if (error)
> +			goto out_cancel;
> +
> +		/*
> +		 * Invalidate and truncate the root block and ensure that the
> +		 * operation is completed within a single transaction.
> +		 */
> +		error = xfs_da_get_buf(trans, dp, 0, &bp, XFS_ATTR_FORK);
> +		if (error)
> +			goto out_cancel;
> +
> +		xfs_trans_binval(trans, bp);
>  		error = xfs_itruncate_extents(&trans, dp, XFS_ATTR_FORK, 0);
>  		if (error)
>  			goto out_cancel;
> -- 
> 2.39.2
> 
> 

Re: [PATCH v3 0/4] xfs: close crash window in attr dabtree inactivation

[Carlos Maiolino]

On Tue, 17 Mar 2026 09:51:51 +0800, Long Li wrote:
> Problem
> -------
> 
> xfs_attr3_node_inactive() cancels all child blocks in the attr dabtree
> via xfs_trans_binval(), relying on a subsequent full attr bmap truncation
> in xfs_attr_inactive() to ensure log recovery never reaches the root
> node.  The child block cancellations and the bmap truncation are
> committed in separate transactions, creating a narrow but real crash
> window.
> 
> [...]

Applied to for-next, thanks!

[1/4] xfs: only assert new size for datafork during truncate extents
      commit: e942498385bf80f4d6d075b47174035545eb6a2e
[2/4] xfs: factor out xfs_attr3_node_entry_remove
      commit: ce4e789cf3561c9fac73cc24445bfed9ea0c514b
[3/4] xfs: factor out xfs_attr3_leaf_init
      commit: e65bb55d7f8c2041c8fdb73cd29b0b4cad4ed847
[4/4] xfs: close crash window in attr dabtree inactivation
      commit: b854e1c4eff3473b6d3a9ae74129ac5c48bc0b61

Best regards,
-- 
Carlos Maiolino <cem@kernel.org>