The for_each_perag_from() iteration macro relies on sb_agcount to process every perag currently within EOFS from a given starting point. It's perfectly valid to have perag structures beyond sb_agcount, however, such as if a growfs is in progress. If a perag loop happens to race with growfs in this manner, it will actually attempt to process the post-EOFS perag where ->pag_agno == sb_agcount. This is reproduced by xfs/104 and manifests as the following assert failure in superblock write verifier context: XFS: Assertion failed: agno < mp->m_sb.sb_agcount, file: fs/xfs/libxfs/xfs_types.c, line: 22 Update the corresponding macro to only process perags that are within the current sb_agcount. Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx> --- fs/xfs/libxfs/xfs_ag.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/xfs/libxfs/xfs_ag.h b/fs/xfs/libxfs/xfs_ag.h index cf8baae2ba18..b8cc5017efba 100644 --- a/fs/xfs/libxfs/xfs_ag.h +++ b/fs/xfs/libxfs/xfs_ag.h @@ -142,7 +142,7 @@ struct xfs_perag *xfs_perag_next( (pag) = xfs_perag_next((pag), &(agno))) #define for_each_perag_from(mp, agno, pag) \ - for_each_perag_range((mp), (agno), (mp)->m_sb.sb_agcount, (pag)) + for_each_perag_range((mp), (agno), (mp)->m_sb.sb_agcount - 1, (pag)) #define for_each_perag(mp, agno, pag) \ -- 2.31.1
