From: Brian Foster Date: Thu, 28 Apr 2022 19:39:03 +0000 (-0400) Subject: xfs: terminate perag iteration reliably on agcount X-Git-Tag: v5.16.0-rc0~28 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=6c18fde82cd02e550fb0c095bd6c6908dcc77747;p=thirdparty%2Fxfsprogs-dev.git xfs: terminate perag iteration reliably on agcount Source kernel commit: 8ed004eb9d07a5d6114db3e97a166707c186262d 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. Fixes: 58d43a7e3263 ("xfs: pass perags around in fsmap data dev functions") Signed-off-by: Brian Foster Reviewed-by: Dave Chinner Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Eric Sandeen --- diff --git a/libxfs/xfs_ag.h b/libxfs/xfs_ag.h index 9cd066943..fae2a38e7 100644 --- a/libxfs/xfs_ag.h +++ b/libxfs/xfs_ag.h @@ -144,7 +144,7 @@ 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) \