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authorCarlos Maiolino <cmaiolino@redhat.com>2012-09-20 10:32:36 -0300
committerBen Myers <bpm@sgi.com>2012-09-26 15:42:42 -0500
commit8aea3ff411b2ce8fe7b46644298ed243a920eb24 (patch)
tree19a8f40bf1f8b8f48d1d77d29fb87020d8c17f81 /fs/xfs
parentc3a58fecdd1934a8538ada9073107625f5151687 (diff)
xfs: Fix m_agirotor reset during AG selection
xfs_ialloc_next_ag() currently resets m_agirotor when it is equal to m_maxagi: if (++mp->m_agirotor == mp->m_maxagi) mp->m_agirotor = 0; But, if for some reason mp->m_maxagi changes to a lower value than current m_agirotor, this condition will never be true, causing m_agirotor to exceed the maximum allowed value (m_maxagi). This implies mainly during lookups for xfs_perag structs in its radix tree, since the agno value used for the lookup is based on m_agirotor. An out-of-range m_agirotor may cause a lookup failure which in case will return NULL. As an example, the value of m_maxagi is decreased during inode64->inode32 remount process, case where I've found this problem. Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Mark Tinguely <tinguely@sgi.com> Signed-off-by: Ben Myers <bpm@sgi.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/xfs_ialloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/xfs/xfs_ialloc.c b/fs/xfs/xfs_ialloc.c
index 5aceb3f8ecd..445bf1aef31 100644
--- a/fs/xfs/xfs_ialloc.c
+++ b/fs/xfs/xfs_ialloc.c
@@ -431,7 +431,7 @@ xfs_ialloc_next_ag(
spin_lock(&mp->m_agirotor_lock);
agno = mp->m_agirotor;
- if (++mp->m_agirotor == mp->m_maxagi)
+ if (++mp->m_agirotor >= mp->m_maxagi)
mp->m_agirotor = 0;
spin_unlock(&mp->m_agirotor_lock);