vfs: fix inode_init_always calling convention

Currently inode_init_always calls into ->destroy_inode if the additional
initialization fails.  That's not only counter-intuitive because
inode_init_always did not allocate the inode structure, but in case of
XFS it's actively harmful as ->destroy_inode might delete the inode from
a radix-tree that has never been added.  This in turn might end up
deleting the inode for the same inum that has been instanciated by
another process and cause lots of cause subtile problems.

Also in the case of re-initializing a reclaimable inode in XFS it would
free an inode we still want to keep alive.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Eric Sandeen <sandeen@sandeen.net>

1 files changed, 5 insertions, 12 deletions

diff --git a/fs/xfs/xfs_iget.c b/fs/xfs/xfs_iget.c
index 5fcec6f020a7..719c85b155f4 100644
--- a/fs/xfs/xfs_iget.c
+++ b/fs/xfs/xfs_iget.c
@@ -64,6 +64,10 @@ xfs_inode_alloc(
 	ip = kmem_zone_alloc(xfs_inode_zone, KM_SLEEP);
 	if (!ip)
 		return NULL;
+	if (inode_init_always(mp->m_super, VFS_I(ip))) {
+		kmem_zone_free(xfs_inode_zone, ip);
+		return NULL;
+	}
 
 	ASSERT(atomic_read(&ip->i_iocount) == 0);
 	ASSERT(atomic_read(&ip->i_pincount) == 0);
@@ -105,17 +109,6 @@ xfs_inode_alloc(
 #ifdef XFS_DIR2_TRACE
 	ip->i_dir_trace = ktrace_alloc(XFS_DIR2_KTRACE_SIZE, KM_NOFS);
 #endif
-	/*
-	* Now initialise the VFS inode. We do this after the xfs_inode
-	* initialisation as internal failures will result in ->destroy_inode
-	* being called and that will pass down through the reclaim path and
-	* free the XFS inode. This path requires the XFS inode to already be
-	* initialised. Hence if this call fails, the xfs_inode has already
-	* been freed and we should not reference it at all in the error
-	* handling.
-	*/
-	if (!inode_init_always(mp->m_super, VFS_I(ip)))
-		return NULL;
 
 	/* prevent anyone from using this yet */
 	VFS_I(ip)->i_state = I_NEW|I_LOCK;
@@ -167,7 +160,7 @@ xfs_iget_cache_hit(
 		 * errors cleanly, then tag it so it can be set up correctly
 		 * later.
 		 */
-		if (!inode_init_always(mp->m_super, VFS_I(ip))) {
+		if (inode_init_always(mp->m_super, VFS_I(ip))) {
 			error = ENOMEM;
 			goto out_error;
 		}