[PATCHSET v29.4 08/13] xfs: online repair of inode unlinked state

[PATCHSET v29.4 08/13] xfs: online repair of inode unlinked state

[Darrick J. Wong]

Hi all,

This series adds some logic to the inode scrubbers so that they can
detect and deal with consistency errors between the link count and the
per-inode unlinked list state.  The helpers needed to do this are
presented here because they are a prequisite for rebuildng directories,
since we need to get a rebuilt non-empty directory off the unlinked
list.

Note that this patchset does not provide comprehensive reconstruction of
the AGI unlinked list; that is coming in a subsequent patchset.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-unlinked-inode-state
---
Commits in this patchset:
 * xfs: ensure unlinked list state is consistent with nlink during scrub
 * xfs: update the unlinked list when repairing link counts
---
 fs/xfs/scrub/inode.c         |   19 ++++++++++++++++++
 fs/xfs/scrub/inode_repair.c  |   45 ++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/nlinks_repair.c |   42 +++++++++++++++++++++++++++++++--------
 fs/xfs/xfs_inode.c           |    5 +----
 fs/xfs/xfs_inode.h           |    2 ++
 5 files changed, 100 insertions(+), 13 deletions(-)

[PATCH 1/2] xfs: ensure unlinked list state is consistent with nlink during scrub

[Darrick J. Wong]

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

Now that we have the means to tell if an inode is on an unlinked inode
list or not, we can check that an inode with zero link count is on the
unlinked list; and an inode that has nonzero link count is not on that
list.  Make repair clean things up too.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/inode.c        |   19 ++++++++++++++++++
 fs/xfs/scrub/inode_repair.c |   45 +++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_inode.c          |    5 +----
 fs/xfs/xfs_inode.h          |    2 ++
 4 files changed, 67 insertions(+), 4 deletions(-)


diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
index 6e2fe2d6250b3..d32716fb2fecf 100644
--- a/fs/xfs/scrub/inode.c
+++ b/fs/xfs/scrub/inode.c
@@ -739,6 +739,23 @@ xchk_inode_check_reflink_iflag(
 		xchk_ino_set_corrupt(sc, ino);
 }
 
+/*
+ * If this inode has zero link count, it must be on the unlinked list.  If
+ * it has nonzero link count, it must not be on the unlinked list.
+ */
+STATIC void
+xchk_inode_check_unlinked(
+	struct xfs_scrub	*sc)
+{
+	if (VFS_I(sc->ip)->i_nlink == 0) {
+		if (!xfs_inode_on_unlinked_list(sc->ip))
+			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+	} else {
+		if (xfs_inode_on_unlinked_list(sc->ip))
+			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+	}
+}
+
 /* Scrub an inode. */
 int
 xchk_inode(
@@ -771,6 +788,8 @@ xchk_inode(
 	if (S_ISREG(VFS_I(sc->ip)->i_mode))
 		xchk_inode_check_reflink_iflag(sc, sc->ip->i_ino);
 
+	xchk_inode_check_unlinked(sc);
+
 	xchk_inode_xref(sc, sc->ip->i_ino, &di);
 out:
 	return error;
diff --git a/fs/xfs/scrub/inode_repair.c b/fs/xfs/scrub/inode_repair.c
index eab380e95ef40..2105026d178a2 100644
--- a/fs/xfs/scrub/inode_repair.c
+++ b/fs/xfs/scrub/inode_repair.c
@@ -1697,6 +1697,46 @@ xrep_inode_problems(
 	return xrep_roll_trans(sc);
 }
 
+/*
+ * Make sure this inode's unlinked list pointers are consistent with its
+ * link count.
+ */
+STATIC int
+xrep_inode_unlinked(
+	struct xfs_scrub	*sc)
+{
+	unsigned int		nlink = VFS_I(sc->ip)->i_nlink;
+	int			error;
+
+	/*
+	 * If this inode is linked from the directory tree and on the unlinked
+	 * list, remove it from the unlinked list.
+	 */
+	if (nlink > 0 && xfs_inode_on_unlinked_list(sc->ip)) {
+		struct xfs_perag	*pag;
+		int			error;
+
+		pag = xfs_perag_get(sc->mp,
+				XFS_INO_TO_AGNO(sc->mp, sc->ip->i_ino));
+		error = xfs_iunlink_remove(sc->tp, pag, sc->ip);
+		xfs_perag_put(pag);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * If this inode is not linked from the directory tree yet not on the
+	 * unlinked list, put it on the unlinked list.
+	 */
+	if (nlink == 0 && !xfs_inode_on_unlinked_list(sc->ip)) {
+		error = xfs_iunlink(sc->tp, sc->ip);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
 /* Repair an inode's fields. */
 int
 xrep_inode(
@@ -1746,5 +1786,10 @@ xrep_inode(
 			return error;
 	}
 
+	/* Reconnect incore unlinked list */
+	error = xrep_inode_unlinked(sc);
+	if (error)
+		return error;
+
 	return xrep_defer_finish(sc);
 }
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 1eee2f9ad265e..e6588790e39ae 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -42,9 +42,6 @@
 
 struct kmem_cache *xfs_inode_cache;
 
-STATIC int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
-	struct xfs_inode *);
-
 /*
  * helper function to extract extent size hint from inode
  */
@@ -2263,7 +2260,7 @@ xfs_iunlink_remove_inode(
 /*
  * Pull the on-disk inode from the AGI unlinked list.
  */
-STATIC int
+int
 xfs_iunlink_remove(
 	struct xfs_trans	*tp,
 	struct xfs_perag	*pag,
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index c6e0590c39b67..e15634fcb2638 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -613,6 +613,8 @@ extern struct kmem_cache	*xfs_inode_cache;
 bool xfs_inode_needs_inactive(struct xfs_inode *ip);
 
 int xfs_iunlink(struct xfs_trans *tp, struct xfs_inode *ip);
+int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
+		struct xfs_inode *ip);
 
 void xfs_end_io(struct work_struct *work);
 

Re: [PATCH 1/2] xfs: ensure unlinked list state is consistent with nlink during scrub

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

[PATCH 2/2] xfs: update the unlinked list when repairing link counts

[Darrick J. Wong]

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

When we're repairing the link counts of a file, we must ensure either
that the file has zero link count and is on the unlinked list; or that
it has nonzero link count and is not on the unlinked list.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/nlinks_repair.c |   42 +++++++++++++++++++++++++++++++++---------
 1 file changed, 33 insertions(+), 9 deletions(-)


diff --git a/fs/xfs/scrub/nlinks_repair.c b/fs/xfs/scrub/nlinks_repair.c
index b87618322f55b..58cacb8e94c1b 100644
--- a/fs/xfs/scrub/nlinks_repair.c
+++ b/fs/xfs/scrub/nlinks_repair.c
@@ -17,6 +17,7 @@
 #include "xfs_iwalk.h"
 #include "xfs_ialloc.h"
 #include "xfs_sb.h"
+#include "xfs_ag.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/repair.h"
@@ -36,6 +37,20 @@
  * inode is locked.
  */
 
+/* Remove an inode from the unlinked list. */
+STATIC int
+xrep_nlinks_iunlink_remove(
+	struct xfs_scrub	*sc)
+{
+	struct xfs_perag	*pag;
+	int			error;
+
+	pag = xfs_perag_get(sc->mp, XFS_INO_TO_AGNO(sc->mp, sc->ip->i_ino));
+	error = xfs_iunlink_remove(sc->tp, pag, sc->ip);
+	xfs_perag_put(pag);
+	return error;
+}
+
 /*
  * Correct the link count of the given inode.  Because we have to grab locks
  * and resources in a certain order, it's possible that this will be a no-op.
@@ -99,16 +114,25 @@ xrep_nlinks_repair_inode(
 	}
 
 	/*
-	 * We did not find any links to this inode.  If the inode agrees, we
-	 * have nothing further to do.  If not, the inode has a nonzero link
-	 * count and we don't have anywhere to graft the child onto.  Dropping
-	 * a live inode's link count to zero can cause unexpected shutdowns in
-	 * inactivation, so leave it alone.
+	 * If this inode is linked from the directory tree and on the unlinked
+	 * list, remove it from the unlinked list.
 	 */
-	if (total_links == 0) {
-		if (actual_nlink != 0)
-			trace_xrep_nlinks_unfixable_inode(mp, ip, &obs);
-		goto out_trans;
+	if (total_links > 0 && xfs_inode_on_unlinked_list(ip)) {
+		error = xrep_nlinks_iunlink_remove(sc);
+		if (error)
+			goto out_trans;
+		dirty = true;
+	}
+
+	/*
+	 * If this inode is not linked from the directory tree yet not on the
+	 * unlinked list, put it on the unlinked list.
+	 */
+	if (total_links == 0 && !xfs_inode_on_unlinked_list(ip)) {
+		error = xfs_iunlink(sc->tp, ip);
+		if (error)
+			goto out_trans;
+		dirty = true;
 	}
 
 	/* Commit the new link count if it changed. */

Re: [PATCH 2/2] xfs: update the unlinked list when repairing link counts

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

[PATCHSET v30.3 08/16] xfs: online repair of inode unlinked state

[Darrick J. Wong]

Hi all,

This series adds some logic to the inode scrubbers so that they can
detect and deal with consistency errors between the link count and the
per-inode unlinked list state.  The helpers needed to do this are
presented here because they are a prequisite for rebuildng directories,
since we need to get a rebuilt non-empty directory off the unlinked
list.

Note that this patchset does not provide comprehensive reconstruction of
the AGI unlinked list; that is coming in a subsequent patchset.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-unlinked-inode-state-6.10
---
Commits in this patchset:
 * xfs: ensure unlinked list state is consistent with nlink during scrub
 * xfs: update the unlinked list when repairing link counts
---
 fs/xfs/scrub/inode.c         |   19 ++++++++++++++++++
 fs/xfs/scrub/inode_repair.c  |   45 ++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/nlinks_repair.c |   42 +++++++++++++++++++++++++++++++--------
 fs/xfs/xfs_inode.c           |    5 +----
 fs/xfs/xfs_inode.h           |    2 ++
 5 files changed, 100 insertions(+), 13 deletions(-)

[PATCH 1/2] xfs: ensure unlinked list state is consistent with nlink during scrub

[Darrick J. Wong]

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

Now that we have the means to tell if an inode is on an unlinked inode
list or not, we can check that an inode with zero link count is on the
unlinked list; and an inode that has nonzero link count is not on that
list.  Make repair clean things up too.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/scrub/inode.c        |   19 ++++++++++++++++++
 fs/xfs/scrub/inode_repair.c |   45 +++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_inode.c          |    5 +----
 fs/xfs/xfs_inode.h          |    2 ++
 4 files changed, 67 insertions(+), 4 deletions(-)


diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
index 6e2fe2d6250b..d32716fb2fec 100644
--- a/fs/xfs/scrub/inode.c
+++ b/fs/xfs/scrub/inode.c
@@ -739,6 +739,23 @@ xchk_inode_check_reflink_iflag(
 		xchk_ino_set_corrupt(sc, ino);
 }
 
+/*
+ * If this inode has zero link count, it must be on the unlinked list.  If
+ * it has nonzero link count, it must not be on the unlinked list.
+ */
+STATIC void
+xchk_inode_check_unlinked(
+	struct xfs_scrub	*sc)
+{
+	if (VFS_I(sc->ip)->i_nlink == 0) {
+		if (!xfs_inode_on_unlinked_list(sc->ip))
+			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+	} else {
+		if (xfs_inode_on_unlinked_list(sc->ip))
+			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+	}
+}
+
 /* Scrub an inode. */
 int
 xchk_inode(
@@ -771,6 +788,8 @@ xchk_inode(
 	if (S_ISREG(VFS_I(sc->ip)->i_mode))
 		xchk_inode_check_reflink_iflag(sc, sc->ip->i_ino);
 
+	xchk_inode_check_unlinked(sc);
+
 	xchk_inode_xref(sc, sc->ip->i_ino, &di);
 out:
 	return error;
diff --git a/fs/xfs/scrub/inode_repair.c b/fs/xfs/scrub/inode_repair.c
index 097afba3043f..c743772a523e 100644
--- a/fs/xfs/scrub/inode_repair.c
+++ b/fs/xfs/scrub/inode_repair.c
@@ -1745,6 +1745,46 @@ xrep_inode_problems(
 	return xrep_roll_trans(sc);
 }
 
+/*
+ * Make sure this inode's unlinked list pointers are consistent with its
+ * link count.
+ */
+STATIC int
+xrep_inode_unlinked(
+	struct xfs_scrub	*sc)
+{
+	unsigned int		nlink = VFS_I(sc->ip)->i_nlink;
+	int			error;
+
+	/*
+	 * If this inode is linked from the directory tree and on the unlinked
+	 * list, remove it from the unlinked list.
+	 */
+	if (nlink > 0 && xfs_inode_on_unlinked_list(sc->ip)) {
+		struct xfs_perag	*pag;
+		int			error;
+
+		pag = xfs_perag_get(sc->mp,
+				XFS_INO_TO_AGNO(sc->mp, sc->ip->i_ino));
+		error = xfs_iunlink_remove(sc->tp, pag, sc->ip);
+		xfs_perag_put(pag);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * If this inode is not linked from the directory tree yet not on the
+	 * unlinked list, put it on the unlinked list.
+	 */
+	if (nlink == 0 && !xfs_inode_on_unlinked_list(sc->ip)) {
+		error = xfs_iunlink(sc->tp, sc->ip);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
 /* Repair an inode's fields. */
 int
 xrep_inode(
@@ -1794,5 +1834,10 @@ xrep_inode(
 			return error;
 	}
 
+	/* Reconnect incore unlinked list */
+	error = xrep_inode_unlinked(sc);
+	if (error)
+		return error;
+
 	return xrep_defer_finish(sc);
 }
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index ac92c0525d9b..b24c0e23d37d 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -42,9 +42,6 @@
 
 struct kmem_cache *xfs_inode_cache;
 
-STATIC int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
-	struct xfs_inode *);
-
 /*
  * helper function to extract extent size hint from inode
  */
@@ -2252,7 +2249,7 @@ xfs_iunlink_remove_inode(
 /*
  * Pull the on-disk inode from the AGI unlinked list.
  */
-STATIC int
+int
 xfs_iunlink_remove(
 	struct xfs_trans	*tp,
 	struct xfs_perag	*pag,
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 596eec715675..8157ae7f8e59 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -617,6 +617,8 @@ extern struct kmem_cache	*xfs_inode_cache;
 bool xfs_inode_needs_inactive(struct xfs_inode *ip);
 
 int xfs_iunlink(struct xfs_trans *tp, struct xfs_inode *ip);
+int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
+		struct xfs_inode *ip);
 
 void xfs_end_io(struct work_struct *work);
 

[PATCHSET v30.1 09/15] xfs: online repair of inode unlinked state

[Darrick J. Wong]

Hi all,

This series adds some logic to the inode scrubbers so that they can
detect and deal with consistency errors between the link count and the
per-inode unlinked list state.  The helpers needed to do this are
presented here because they are a prequisite for rebuildng directories,
since we need to get a rebuilt non-empty directory off the unlinked
list.

Note that this patchset does not provide comprehensive reconstruction of
the AGI unlinked list; that is coming in a subsequent patchset.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-unlinked-inode-state
---
Commits in this patchset:
 * xfs: ensure unlinked list state is consistent with nlink during scrub
 * xfs: update the unlinked list when repairing link counts
---
 fs/xfs/scrub/inode.c         |   19 ++++++++++++++++++
 fs/xfs/scrub/inode_repair.c  |   45 ++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/nlinks_repair.c |   42 +++++++++++++++++++++++++++++++--------
 fs/xfs/xfs_inode.c           |    5 +----
 fs/xfs/xfs_inode.h           |    2 ++
 5 files changed, 100 insertions(+), 13 deletions(-)

[PATCH 1/2] xfs: ensure unlinked list state is consistent with nlink during scrub

[Darrick J. Wong]

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

Now that we have the means to tell if an inode is on an unlinked inode
list or not, we can check that an inode with zero link count is on the
unlinked list; and an inode that has nonzero link count is not on that
list.  Make repair clean things up too.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/scrub/inode.c        |   19 ++++++++++++++++++
 fs/xfs/scrub/inode_repair.c |   45 +++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_inode.c          |    5 +----
 fs/xfs/xfs_inode.h          |    2 ++
 4 files changed, 67 insertions(+), 4 deletions(-)


diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
index 6e2fe2d6250b3..d32716fb2fecf 100644
--- a/fs/xfs/scrub/inode.c
+++ b/fs/xfs/scrub/inode.c
@@ -739,6 +739,23 @@ xchk_inode_check_reflink_iflag(
 		xchk_ino_set_corrupt(sc, ino);
 }
 
+/*
+ * If this inode has zero link count, it must be on the unlinked list.  If
+ * it has nonzero link count, it must not be on the unlinked list.
+ */
+STATIC void
+xchk_inode_check_unlinked(
+	struct xfs_scrub	*sc)
+{
+	if (VFS_I(sc->ip)->i_nlink == 0) {
+		if (!xfs_inode_on_unlinked_list(sc->ip))
+			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+	} else {
+		if (xfs_inode_on_unlinked_list(sc->ip))
+			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+	}
+}
+
 /* Scrub an inode. */
 int
 xchk_inode(
@@ -771,6 +788,8 @@ xchk_inode(
 	if (S_ISREG(VFS_I(sc->ip)->i_mode))
 		xchk_inode_check_reflink_iflag(sc, sc->ip->i_ino);
 
+	xchk_inode_check_unlinked(sc);
+
 	xchk_inode_xref(sc, sc->ip->i_ino, &di);
 out:
 	return error;
diff --git a/fs/xfs/scrub/inode_repair.c b/fs/xfs/scrub/inode_repair.c
index 96c5763dc3839..7b8efb6d3539b 100644
--- a/fs/xfs/scrub/inode_repair.c
+++ b/fs/xfs/scrub/inode_repair.c
@@ -1743,6 +1743,46 @@ xrep_inode_problems(
 	return xrep_roll_trans(sc);
 }
 
+/*
+ * Make sure this inode's unlinked list pointers are consistent with its
+ * link count.
+ */
+STATIC int
+xrep_inode_unlinked(
+	struct xfs_scrub	*sc)
+{
+	unsigned int		nlink = VFS_I(sc->ip)->i_nlink;
+	int			error;
+
+	/*
+	 * If this inode is linked from the directory tree and on the unlinked
+	 * list, remove it from the unlinked list.
+	 */
+	if (nlink > 0 && xfs_inode_on_unlinked_list(sc->ip)) {
+		struct xfs_perag	*pag;
+		int			error;
+
+		pag = xfs_perag_get(sc->mp,
+				XFS_INO_TO_AGNO(sc->mp, sc->ip->i_ino));
+		error = xfs_iunlink_remove(sc->tp, pag, sc->ip);
+		xfs_perag_put(pag);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * If this inode is not linked from the directory tree yet not on the
+	 * unlinked list, put it on the unlinked list.
+	 */
+	if (nlink == 0 && !xfs_inode_on_unlinked_list(sc->ip)) {
+		error = xfs_iunlink(sc->tp, sc->ip);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
 /* Repair an inode's fields. */
 int
 xrep_inode(
@@ -1792,5 +1832,10 @@ xrep_inode(
 			return error;
 	}
 
+	/* Reconnect incore unlinked list */
+	error = xrep_inode_unlinked(sc);
+	if (error)
+		return error;
+
 	return xrep_defer_finish(sc);
 }
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index f9fcb7761e233..98a01a490adcc 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -42,9 +42,6 @@
 
 struct kmem_cache *xfs_inode_cache;
 
-STATIC int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
-	struct xfs_inode *);
-
 /*
  * helper function to extract extent size hint from inode
  */
@@ -2241,7 +2238,7 @@ xfs_iunlink_remove_inode(
 /*
  * Pull the on-disk inode from the AGI unlinked list.
  */
-STATIC int
+int
 xfs_iunlink_remove(
 	struct xfs_trans	*tp,
 	struct xfs_perag	*pag,
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index 23be8f7521530..22d6fa2fcc676 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -617,6 +617,8 @@ extern struct kmem_cache	*xfs_inode_cache;
 bool xfs_inode_needs_inactive(struct xfs_inode *ip);
 
 int xfs_iunlink(struct xfs_trans *tp, struct xfs_inode *ip);
+int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
+		struct xfs_inode *ip);
 
 void xfs_end_io(struct work_struct *work);
 

[PATCHSET v29.0 21/28] xfs: online repair of inode unlinked state

[Darrick J. Wong]

Hi all,

This series adds some logic to the inode scrubbers so that they can
detect and deal with consistency errors between the link count and the
per-inode unlinked list state.  The helpers needed to do this are
presented here because they are a prequisite for rebuildng directories,
since we need to get a rebuilt non-empty directory off the unlinked
list.

Note that this patchset does not provide comprehensive reconstruction of
the AGI unlinked list; that is coming in a subsequent patchset.

If you're going to start using this code, I strongly recommend pulling
from my git trees, which are linked below.

This has been running on the djcloud for months with no problems.  Enjoy!
Comments and questions are, as always, welcome.

--D

kernel git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfs-linux.git/log/?h=repair-unlinked-inode-state
---
 fs/xfs/scrub/inode.c         |   19 ++++++++++++++++++
 fs/xfs/scrub/inode_repair.c  |   45 ++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/nlinks_repair.c |   42 +++++++++++++++++++++++++++++++--------
 fs/xfs/xfs_inode.c           |    5 +----
 fs/xfs/xfs_inode.h           |    2 ++
 5 files changed, 100 insertions(+), 13 deletions(-)

[PATCH 1/2] xfs: ensure unlinked list state is consistent with nlink during scrub

[Darrick J. Wong]

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

Now that we have the means to tell if an inode is on an unlinked inode
list or not, we can check that an inode with zero link count is on the
unlinked list; and an inode that has nonzero link count is not on that
list.  Make repair clean things up too.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/inode.c        |   19 ++++++++++++++++++
 fs/xfs/scrub/inode_repair.c |   45 +++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/xfs_inode.c          |    5 +----
 fs/xfs/xfs_inode.h          |    2 ++
 4 files changed, 67 insertions(+), 4 deletions(-)


diff --git a/fs/xfs/scrub/inode.c b/fs/xfs/scrub/inode.c
index 6e2fe2d6250b3..d32716fb2fecf 100644
--- a/fs/xfs/scrub/inode.c
+++ b/fs/xfs/scrub/inode.c
@@ -739,6 +739,23 @@ xchk_inode_check_reflink_iflag(
 		xchk_ino_set_corrupt(sc, ino);
 }
 
+/*
+ * If this inode has zero link count, it must be on the unlinked list.  If
+ * it has nonzero link count, it must not be on the unlinked list.
+ */
+STATIC void
+xchk_inode_check_unlinked(
+	struct xfs_scrub	*sc)
+{
+	if (VFS_I(sc->ip)->i_nlink == 0) {
+		if (!xfs_inode_on_unlinked_list(sc->ip))
+			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+	} else {
+		if (xfs_inode_on_unlinked_list(sc->ip))
+			xchk_ino_set_corrupt(sc, sc->ip->i_ino);
+	}
+}
+
 /* Scrub an inode. */
 int
 xchk_inode(
@@ -771,6 +788,8 @@ xchk_inode(
 	if (S_ISREG(VFS_I(sc->ip)->i_mode))
 		xchk_inode_check_reflink_iflag(sc, sc->ip->i_ino);
 
+	xchk_inode_check_unlinked(sc);
+
 	xchk_inode_xref(sc, sc->ip->i_ino, &di);
 out:
 	return error;
diff --git a/fs/xfs/scrub/inode_repair.c b/fs/xfs/scrub/inode_repair.c
index 549b66ef826a9..50bcc5a4c3df1 100644
--- a/fs/xfs/scrub/inode_repair.c
+++ b/fs/xfs/scrub/inode_repair.c
@@ -1697,6 +1697,46 @@ xrep_inode_problems(
 	return xrep_roll_trans(sc);
 }
 
+/*
+ * Make sure this inode's unlinked list pointers are consistent with its
+ * link count.
+ */
+STATIC int
+xrep_inode_unlinked(
+	struct xfs_scrub	*sc)
+{
+	unsigned int		nlink = VFS_I(sc->ip)->i_nlink;
+	int			error;
+
+	/*
+	 * If this inode is linked from the directory tree and on the unlinked
+	 * list, remove it from the unlinked list.
+	 */
+	if (nlink > 0 && xfs_inode_on_unlinked_list(sc->ip)) {
+		struct xfs_perag	*pag;
+		int			error;
+
+		pag = xfs_perag_get(sc->mp,
+				XFS_INO_TO_AGNO(sc->mp, sc->ip->i_ino));
+		error = xfs_iunlink_remove(sc->tp, pag, sc->ip);
+		xfs_perag_put(pag);
+		if (error)
+			return error;
+	}
+
+	/*
+	 * If this inode is not linked from the directory tree yet not on the
+	 * unlinked list, put it on the unlinked list.
+	 */
+	if (nlink == 0 && !xfs_inode_on_unlinked_list(sc->ip)) {
+		error = xfs_iunlink(sc->tp, sc->ip);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
 /* Repair an inode's fields. */
 int
 xrep_inode(
@@ -1746,5 +1786,10 @@ xrep_inode(
 			return error;
 	}
 
+	/* Reconnect incore unlinked list */
+	error = xrep_inode_unlinked(sc);
+	if (error)
+		return error;
+
 	return xrep_defer_finish(sc);
 }
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 70705e2e30f79..970daeb160b24 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -42,9 +42,6 @@
 
 struct kmem_cache *xfs_inode_cache;
 
-STATIC int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
-	struct xfs_inode *);
-
 /*
  * helper function to extract extent size hint from inode
  */
@@ -2254,7 +2251,7 @@ xfs_iunlink_remove_inode(
 /*
  * Pull the on-disk inode from the AGI unlinked list.
  */
-STATIC int
+int
 xfs_iunlink_remove(
 	struct xfs_trans	*tp,
 	struct xfs_perag	*pag,
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index b6f10ea725857..f11e91c6e2182 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -613,6 +613,8 @@ extern struct kmem_cache	*xfs_inode_cache;
 bool xfs_inode_needs_inactive(struct xfs_inode *ip);
 
 int xfs_iunlink(struct xfs_trans *tp, struct xfs_inode *ip);
+int xfs_iunlink_remove(struct xfs_trans *tp, struct xfs_perag *pag,
+		struct xfs_inode *ip);
 
 void xfs_end_io(struct work_struct *work);