[PATCH 19/21] Unionfs: Properly handle stale inodes passed to unionfs_permission

["Josef 'Jeff' Sipek" <jsipek@cs.sunysb.edu>]

From: Erez Zadok <ezk@cs.sunysb.edu>

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
---
 fs/unionfs/inode.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index edd226f..5c452b6 100644
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -843,8 +843,21 @@ static int unionfs_permission(struct inode *inode, int mask,
 	const int is_file = !S_ISDIR(inode->i_mode);
 	const int write_mask = (mask & MAY_WRITE) && !(mask & MAY_READ);
 
+	unionfs_read_lock(inode->i_sb);
+
 	bstart = ibstart(inode);
 	bend = ibend(inode);
+	if (bstart < 0 || bend < 0) {
+		/*
+		 * With branch-management, we can get a stale inode here.
+		 * If so, we return ESTALE back to link_path_walk, which
+		 * would discard the dcache entry and re-lookup the
+		 * dentry+inode.  This should be equivalent to issuing
+		 * __unionfs_d_revalidate_chain on nd.dentry here.
+		 */
+		err = -ESTALE;	/* force revalidate */
+		goto out;
+	}
 
 	for (bindex = bstart; bindex <= bend; bindex++) {
 		hidden_inode = unionfs_lower_inode_idx(inode, bindex);
@@ -881,6 +894,7 @@ static int unionfs_permission(struct inode *inode, int mask,
 	}
 
 out:
+	unionfs_read_unlock(inode->i_sb);
 	return err;
 }
 
-- 
1.5.0.3.268.g3dda

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