xfs: reinitialise recycled VFS inode correctly

We are going to keep certain on-disk information in the VFS inode
rather than in a separate XFS specific stucture, so we have to be
careful of the VFS code clearing that information when we
re-initialise reclaimable cached inodes during lookup. If we don't
do this, then we lose critical information from the inode and that
results in corruption being detected.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>

1 files changed, 21 insertions, 1 deletions

diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index 7c26f8611891..9ca2865575ab 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -135,6 +135,26 @@ xfs_inode_free(
 }
 
 /*
+ * When we recycle a reclaimable inode, we need to re-initialise the VFS inode
+ * part of the structure. This is made more complex by the fact we store
+ * information about the on-disk values in the VFS inode and so we can't just
+ * overwrite it's values unconditionally. Hence we save the parameters we
+ * need to retain across reinitialisation, and rewrite them into the VFS inode
+ * after resetting it's state even if resetting fails.
+ */
+static int
+xfs_reinit_inode(
+        struct xfs_mount        *mp,
+        struct inode            *inode)
+{
+        int             error;
+
+        error = inode_init_always(mp->m_super, inode);
+
+        return error;
+}
+
+/*
  * Check the validity of the inode we just found it the cache
  */
 static int
@@ -208,7 +228,7 @@ xfs_iget_cache_hit(
                 spin_unlock(&ip->i_flags_lock);
                 rcu_read_unlock();
 
-                error = inode_init_always(mp->m_super, inode);
+                error = xfs_reinit_inode(mp, inode);
                 if (error) {
                         /*
                          * Re-initializing the inode failed, and we are in deep