xfs: handle ENOMEM correctly during initialisation of perag structures

Add proper error handling in case an error occurs while initializing
new perag structures for a mount point.  The mount structure is
restored to its previous state by deleting and freeing any perag
structures added during the call.

Signed-off-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 17 insertions, 4 deletions

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 049dbc71c28e..be643e588067 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -432,11 +432,13 @@ xfs_initialize_perag(
         xfs_agnumber_t  *maxagi)
 {
         xfs_agnumber_t  index, max_metadata;
+        xfs_agnumber_t  first_initialised = 0;
         xfs_perag_t     *pag;
         xfs_agino_t     agino;
         xfs_ino_t       ino;
         xfs_sb_t        *sbp = &mp->m_sb;
         xfs_ino_t       max_inum = XFS_MAXINUMBER_32;
+        int             error = -ENOMEM;
 
         /* Check to see if the filesystem can overflow 32 bit inodes */
         agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
@@ -453,17 +455,20 @@ xfs_initialize_perag(
                         xfs_perag_put(pag);
                         continue;
                 }
+                if (!first_initialised)
+                        first_initialised = index;
                 pag = kmem_zalloc(sizeof(*pag), KM_MAYFAIL);
                 if (!pag)
-                        return -ENOMEM;
+                        goto out_unwind;
                 if (radix_tree_preload(GFP_NOFS))
-                        return -ENOMEM;
+                        goto out_unwind;
                 spin_lock(&mp->m_perag_lock);
                 if (radix_tree_insert(&mp->m_perag_tree, index, pag)) {
                         BUG();
                         spin_unlock(&mp->m_perag_lock);
-                        kmem_free(pag);
-                        return -EEXIST;
+                        radix_tree_preload_end();
+                        error = -EEXIST;
+                        goto out_unwind;
                 }
                 pag->pag_agno = index;
                 pag->pag_mount = mp;
@@ -523,6 +528,14 @@ xfs_initialize_perag(
         if (maxagi)
                 *maxagi = index;
         return 0;
+
+out_unwind:
+        kmem_free(pag);
+        for (; index > first_initialised; index--) {
+                pag = radix_tree_delete(&mp->m_perag_tree, index);
+                kmem_free(pag);
+        }
+        return error;
 }
 
 void