xfs: allow bulkstat to return metadata directories

Allow the V5 bulkstat ioctl to return information about metadata
directory files so that xfs_scrub can find and scrub them, since they
are otherwise ordinary directories.

(Metadata files of course require per-file scrub code and hence do not
need exposure.)

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

4 files changed, 48 insertions, 5 deletions

diff --git a/fs/xfs/libxfs/xfs_fs.h b/fs/xfs/libxfs/xfs_fs.h
index a42c1a33691c..499bea4ea806 100644
--- a/fs/xfs/libxfs/xfs_fs.h
+++ b/fs/xfs/libxfs/xfs_fs.h
@@ -490,9 +490,17 @@ struct xfs_bulk_ireq {
  */
 #define XFS_BULK_IREQ_NREXT64	(1U << 2)
 
+/*
+ * Allow bulkstat to return information about metadata directories.  This
+ * enables xfs_scrub to find them for scanning, as they are otherwise ordinary
+ * directories.
+ */
+#define XFS_BULK_IREQ_METADIR	(1U << 3)
+
 #define XFS_BULK_IREQ_FLAGS_ALL	(XFS_BULK_IREQ_AGNO |	 \
 				 XFS_BULK_IREQ_SPECIAL | \
-				 XFS_BULK_IREQ_NREXT64)
+				 XFS_BULK_IREQ_NREXT64 | \
+				 XFS_BULK_IREQ_METADIR)
 
 /* Operate on the root directory inode. */
 #define XFS_BULK_IREQ_SPECIAL_ROOT	(1)
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 2567fd2a0994..f36fd8db388c 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -233,6 +233,10 @@ xfs_bulk_ireq_setup(
 	if (hdr->flags & XFS_BULK_IREQ_NREXT64)
 		breq->flags |= XFS_IBULK_NREXT64;
 
+	/* Caller wants to see metadata directories in bulkstat output. */
+	if (hdr->flags & XFS_BULK_IREQ_METADIR)
+		breq->flags |= XFS_IBULK_METADIR;
+
 	return 0;
 }
 
@@ -323,6 +327,9 @@ xfs_ioc_inumbers(
 	if (copy_from_user(&hdr, &arg->hdr, sizeof(hdr)))
 		return -EFAULT;
 
+	if (hdr.flags & XFS_BULK_IREQ_METADIR)
+		return -EINVAL;
+
 	error = xfs_bulk_ireq_setup(mp, &hdr, &breq, arg->inumbers);
 	if (error == -ECANCELED)
 		goto out_teardown;
diff --git a/fs/xfs/xfs_itable.c b/fs/xfs/xfs_itable.c
index 37c2b50d877e..1fa1c0564b0c 100644
--- a/fs/xfs/xfs_itable.c
+++ b/fs/xfs/xfs_itable.c
@@ -36,6 +36,14 @@ struct xfs_bstat_chunk {
 	struct xfs_bulkstat	*buf;
 };
 
+static inline bool
+want_metadir_file(
+	struct xfs_inode	*ip,
+	struct xfs_ibulk	*breq)
+{
+	return xfs_is_metadir_inode(ip) && (breq->flags & XFS_IBULK_METADIR);
+}
+
 /*
  * Fill out the bulkstat info for a single inode and report it somewhere.
  *
@@ -69,9 +77,6 @@ xfs_bulkstat_one_int(
 	vfsuid_t		vfsuid;
 	vfsgid_t		vfsgid;
 
-	if (xfs_is_sb_inum(mp, ino))
-		goto out_advance;
-
 	error = xfs_iget(mp, tp, ino,
 			 (XFS_IGET_DONTCACHE | XFS_IGET_UNTRUSTED),
 			 XFS_ILOCK_SHARED, &ip);
@@ -97,8 +102,28 @@ xfs_bulkstat_one_int(
 	vfsuid = i_uid_into_vfsuid(idmap, inode);
 	vfsgid = i_gid_into_vfsgid(idmap, inode);
 
+	/*
+	 * If caller wants files from the metadata directories, push out the
+	 * bare minimum information for enabling scrub.
+	 */
+	if (want_metadir_file(ip, bc->breq)) {
+		memset(buf, 0, sizeof(*buf));
+		buf->bs_ino = ino;
+		buf->bs_gen = inode->i_generation;
+		buf->bs_mode = inode->i_mode & S_IFMT;
+		xfs_bulkstat_health(ip, buf);
+		buf->bs_version = XFS_BULKSTAT_VERSION_V5;
+		xfs_iunlock(ip, XFS_ILOCK_SHARED);
+		xfs_irele(ip);
+
+		error = bc->formatter(bc->breq, buf);
+		if (!error || error == -ECANCELED)
+			goto out_advance;
+		goto out;
+	}
+
 	/* If this is a private inode, don't leak its details to userspace. */
-	if (IS_PRIVATE(inode)) {
+	if (IS_PRIVATE(inode) || xfs_is_sb_inum(mp, ino)) {
 		xfs_iunlock(ip, XFS_ILOCK_SHARED);
 		xfs_irele(ip);
 		error = -EINVAL;
diff --git a/fs/xfs/xfs_itable.h b/fs/xfs/xfs_itable.h
index 1659f13f17a8..f10e8f8f2335 100644
--- a/fs/xfs/xfs_itable.h
+++ b/fs/xfs/xfs_itable.h
@@ -22,6 +22,9 @@ struct xfs_ibulk {
 /* Fill out the bs_extents64 field if set. */
 #define XFS_IBULK_NREXT64	(1U << 1)
 
+/* Signal that we can return metadata directories. */
+#define XFS_IBULK_METADIR	(1U << 2)
+
 /*
  * Advance the user buffer pointer by one record of the given size.  If the
  * buffer is now full, return the appropriate error code.