> On Jul 21, 2015, at 7:31 AM, Brian Foster <bfoster@xxxxxxxxxx> wrote: > >> On Thu, Jul 16, 2015 at 01:20:30PM -0500, Eric Sandeen wrote: >> My prior commit, aaf90a2 xfs_copy: fix copy of hard 4k devices >> causes xfs_copy to emit a CRC error warning when copying a >> CRC filesystem. >> >> This is because we are now reading the maximum sector size, >> and attempting to verify the CRC based on that (likely incorrect) >> length. >> >> In xfs_db, we currently just don't verify this read, so it's >> not a problem. In xfs_copy, we almost certainly want to verify. >> >> So, first do the maximal read with no verifier; once it's read, >> drop that buffer, and re-read with the proper sector size and >> verifier. >> >> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx> >> --- >> >> diff --git a/copy/xfs_copy.c b/copy/xfs_copy.c >> index 44a32e8..fd96e15 100644 >> --- a/copy/xfs_copy.c >> +++ b/copy/xfs_copy.c >> @@ -654,11 +654,17 @@ main(int argc, char **argv) >> >> memset(&mbuf, 0, sizeof(xfs_mount_t)); >> libxfs_buftarg_init(&mbuf, xargs.ddev, xargs.logdev, xargs.rtdev); >> + /* We don't yet know the sector size, so read maximal size */ >> sbp = libxfs_readbuf(mbuf.m_ddev_targp, XFS_SB_DADDR, >> - 1 << (XFS_MAX_SECTORSIZE_LOG - BBSHIFT), >> - 0, &xfs_sb_buf_ops); >> + 1 << (XFS_MAX_SECTORSIZE_LOG - BBSHIFT), 0, NULL); >> sb = &mbuf.m_sb; >> libxfs_sb_from_disk(sb, XFS_BUF_TO_SBP(sbp)); >> + /* Do it again, now with proper length and verifier */ >> + libxfs_putbuf(sbp); >> + libxfs_purgebuf(sbp); > > Why the purge? On a quick look, it looks like the buffer cache code > would handle this if the buffer size changes. > > Hmm, is it to ensure the verification occurs if the buffer size doesn't > actually change? If so, I'd suggest to enhance the comment. :) > Without the purge, a re-read of a different size at the same offset seems to cause cache mismatch problems. Eric > Brian > >> + sbp = libxfs_readbuf(mbuf.m_ddev_targp, XFS_SB_DADDR, >> + 1 << (sb->sb_sectlog - BBSHIFT), >> + 0, &xfs_sb_buf_ops); >> >> /* >> * For now, V5 superblock filesystems are not supported without -d; >> >> _______________________________________________ >> xfs mailing list >> xfs@xxxxxxxxxxx >> http://oss.sgi.com/mailman/listinfo/xfs > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
