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>

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index 049dbc7..be643e5 100644 (file)
--- 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