From: Darrick J. Wong <djwong@xxxxxxxxxx>
Metadata inodes are private files and therefore cannot be exposed to
userspace. This means no bulkstat, no open-by-handle, no linking them
into the directory tree, and no feeding them to LSMs. As such, we mark
them S_PRIVATE, which stops all that.
While we're at it, put them in a separate lockdep class so that it won't
get confused by "recursive" i_rwsem locking such as what happens when we
write to a rt file and need to allocate from the rt bitmap file.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
fs/xfs/scrub/tempfile.c | 8 ++++++++
fs/xfs/xfs_iops.c | 34 ++++++++++++++++++++++++++++++++--
2 files changed, 40 insertions(+), 2 deletions(-)
diff --git a/fs/xfs/scrub/tempfile.c b/fs/xfs/scrub/tempfile.c
index db3a9a47e1f82..583bbd5a02bc9 100644
--- a/fs/xfs/scrub/tempfile.c
+++ b/fs/xfs/scrub/tempfile.c
@@ -867,6 +867,14 @@ xrep_is_tempfile(
const struct xfs_inode *ip)
{
const struct inode *inode = &ip->i_vnode;
+ struct xfs_mount *mp = ip->i_mount;
+
+ /*
+ * Files in the metadata directory tree also have S_PRIVATE set and
+ * IOP_XATTR unset, so we must distinguish them separately.
+ */
+ if (xfs_has_metadir(mp) && (ip->i_diflags2 & XFS_DIFLAG2_METADIR))
+ return false;
if (IS_PRIVATE(inode) && !(inode->i_opflags & IOP_XATTR))
return true;
diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 90296b3c838aa..461e77dd54e38 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -45,6 +45,15 @@
static struct lock_class_key xfs_nondir_ilock_class;
static struct lock_class_key xfs_dir_ilock_class;
+/*
+ * Metadata directories and files are not exposed to userspace, which means
+ * that they never access any of the VFS IO locks and never experience page
+ * faults. Give them separate locking classes so that lockdep will not
+ * complain about conflicts that cannot happen.
+ */
+static struct lock_class_key xfs_metadata_file_ilock_class;
+static struct lock_class_key xfs_metadata_dir_ilock_class;
+
static int
xfs_initxattrs(
struct inode *inode,
@@ -1291,6 +1300,7 @@ xfs_setup_inode(
{
struct inode *inode = &ip->i_vnode;
gfp_t gfp_mask;
+ bool is_meta = xfs_is_metadata_inode(ip);
inode->i_ino = ip->i_ino;
inode->i_state |= I_NEW;
@@ -1302,6 +1312,16 @@ xfs_setup_inode(
i_size_write(inode, ip->i_disk_size);
xfs_diflags_to_iflags(ip, true);
+ /*
+ * Mark our metadata files as private so that LSMs and the ACL code
+ * don't try to add their own metadata or reason about these files,
+ * and users cannot ever obtain file handles to them.
+ */
+ if (is_meta) {
+ inode->i_flags |= S_PRIVATE;
+ inode->i_opflags &= ~IOP_XATTR;
+ }
+
if (S_ISDIR(inode->i_mode)) {
/*
* We set the i_rwsem class here to avoid potential races with
@@ -1311,9 +1331,19 @@ xfs_setup_inode(
*/
lockdep_set_class(&inode->i_rwsem,
&inode->i_sb->s_type->i_mutex_dir_key);
- lockdep_set_class(&ip->i_lock.mr_lock, &xfs_dir_ilock_class);
+ if (is_meta)
+ lockdep_set_class(&ip->i_lock.mr_lock,
+ &xfs_metadata_dir_ilock_class);
+ else
+ lockdep_set_class(&ip->i_lock.mr_lock,
+ &xfs_dir_ilock_class);
} else {
- lockdep_set_class(&ip->i_lock.mr_lock, &xfs_nondir_ilock_class);
+ if (is_meta)
+ lockdep_set_class(&ip->i_lock.mr_lock,
+ &xfs_metadata_file_ilock_class);
+ else
+ lockdep_set_class(&ip->i_lock.mr_lock,
+ &xfs_nondir_ilock_class);
}
/*
