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由 Eric Sandeen 提交于
This is for bug #850, http://oss.sgi.com/bugzilla/show_bug.cgi?id=850 XFS file system segfaults , repeatedly and 100% reproducable in 2.6.30 , 2.6.31 The above only showed up on a CONFIG_XFS_DEBUG=y kernel, because xfs_bmapi() ASSERTs that it has been asked for at least one map, and it was getting 0. The root cause is that our guesstimated "bufsize" from xfs_file_readdir was fairly small, and the bufsize -= length; in the loop was going negative - except bufsize is a size_t, so it was wrapping to a very large number. Then when we did ra_want = howmany(bufsize + mp->m_dirblksize, mp->m_sb.sb_blocksize) - 1; with that very large number, the (int) ra_want was coming out negative, and a subsequent compare: if (1 + ra_want > map_blocks ... was coming out -true- (negative int compare w/ uint) and we went back to xfs_bmapi() for more, even though we did not need more, and asked for 0 maps, and hit the ASSERT. We have kind of a type mess here, but just keeping bufsize from going negative is probably sufficient to avoid the problem. Signed-off-by: NEric Sandeen <sandeen@sandeen.net> Reviewed-by: NChristoph Hellwig <hch@lst.de> Reviewed-by: NAlex Elder <aelder@sgi.com> Signed-off-by: NAlex Elder <aelder@sgi.com>
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