[PATCH 4.6 116/121] xfs: remove xfs_fs_evict_inode()

Greg Kroah-Hartman
2016-06-05T22:03:16Z

From: Dave Chinner <dchinner@redhat.com>

commit 8179c03629de67f515d3ab825b5a9428687d4b85 upstream.

Joe Lawrence reported a list_add corruption with 4.6-rc1 when
testing some custom md administration code that made it's own
block device nodes for the md array. The simple test loop of:

for i in {0..100}; do
mknod --mode=0600 $tmp/tmp_node b $MAJOR $MINOR
mdadm --detail --export $tmp/tmp_node > /dev/null
rm -f $tmp/tmp_node
done

Would produce this warning in bd_acquire() when mdadm opened the
device node:

list_add double add: new=ffff88043831c7b8, prev=ffff8804380287d8, next=ffff88043831c7b8.

And then produce this from bd_forget from kdevtmpfs evicting a block
dev inode:

list_del corruption. prev->next should be ffff8800bb83eb10, but was ffff88043831c7b8

This is a regression caused by commit c19b3b05 ("xfs: mode di_mode
to vfs inode"). The issue is that xfs_inactive() frees the
unlinked inode, and the above commit meant that this freeing zeroed
the mode in the struct inode. The problem is that after evict() has
called ->evict_inode, it expects the i_mode to be intact so that it
can call bd_forget() or cd_forget() to drop the reference to the
block device inode attached to the XFS inode.

In reality, the only thing we do in xfs_fs_evict_inode() that is not
generic is call xfs_inactive(). We can move the xfs_inactive() call
to xfs_fs_destroy_inode() without any problems at all, and this
will leave the VFS inode intact until it is completely done with it.

So, remove xfs_fs_evict_inode(), and do the work it used to do in
->destroy_inode instead.

Reported-by: Joe Lawrence <joe.lawrence@stratus.com>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/xfs_super.c | 28 +++++++---------------------
1 file changed, 7 insertions(+), 21 deletions(-)

--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -928,7 +928,7 @@ xfs_fs_alloc_inode(

/*
* Now that the generic code is guaranteed not to be accessing
- * the linux inode, we can reclaim the inode.
+ * the linux inode, we can inactivate and reclaim the inode.
*/
STATIC void
xfs_fs_destroy_inode(
@@ -938,9 +938,14 @@ xfs_fs_destroy_inode(

trace_xfs_destroy_inode(ip);

- XFS_STATS_INC(ip->i_mount, vn_reclaim);
+ ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
+ XFS_STATS_INC(ip->i_mount, vn_rele);
+ XFS_STATS_INC(ip->i_mount, vn_remove);
+
+ xfs_inactive(ip);

ASSERT(XFS_FORCED_SHUTDOWN(ip->i_mount) || ip->i_delayed_blks == 0);
+ XFS_STATS_INC(ip->i_mount, vn_reclaim);

/*
* We should never get here with one of the reclaim flags already set.
@@ -987,24 +992,6 @@ xfs_fs_inode_init_once(
"xfsino", ip->i_ino);
}

-STATIC void
-xfs_fs_evict_inode(
- struct inode *inode)
-{
- xfs_inode_t *ip = XFS_I(inode);
-
- ASSERT(!rwsem_is_locked(&ip->i_iolock.mr_lock));
-
- trace_xfs_evict_inode(ip);
-
- truncate_inode_pages_final(&inode->i_data);
- clear_inode(inode);
- XFS_STATS_INC(ip->i_mount, vn_rele);
- XFS_STATS_INC(ip->i_mount, vn_remove);
-
- xfs_inactive(ip);
-}
-
/*
* We do an unlocked check for XFS_IDONTCACHE here because we are already
* serialised against cache hits here via the inode->i_lock and igrab() in
@@ -1673,7 +1660,6 @@ xfs_fs_free_cached_objects(
static const struct super_operations xfs_super_operations = {
.alloc_inode = xfs_fs_alloc_inode,
.destroy_inode = xfs_fs_destroy_inode,
- .evict_inode = xfs_fs_evict_inode,
.drop_inode = xfs_fs_drop_inode,
.put_super = xfs_fs_put_super,
.sync_fs = xfs_fs_sync_fs,