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Commit 6528250b authored by Brian Foster's avatar Brian Foster Committed by Dave Chinner
Browse files

xfs: support a crc verification only log record pass 



Log recovery torn write detection uses CRC verification over a range of
the active log to identify torn writes. Since the generic log recovery
pass code implements a superset of the functionality required for CRC
verification, it can be easily modified to support a CRC verification
only pass.

Create a new CRC pass type and update the log record processing helper
to skip everything beyond CRC verification when in this mode. This pass
will be invoked in subsequent patches to implement torn write detection.

Signed-off-by: default avatarBrian Foster <bfoster@redhat.com>
Reviewed-by: default avatarDave Chinner <dchinner@redhat.com>
Signed-off-by: default avatarDave Chinner <david@fromorbit.com>
parent d7f37692

fs/xfs/libxfs/xfs_log_recover.h

+1 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ typedef struct xlog_recover { 
 */

#define	XLOG_BC_TABLE_SIZE	64



#define	XLOG_RECOVER_CRCPASS	0

#define	XLOG_RECOVER_PASS1	1

#define	XLOG_RECOVER_PASS2	2

fs/xfs/xfs_log_recover.c

+19 −5
Original line number Diff line number Diff line
@@ -4159,13 +4159,27 @@ xlog_recover_process( 
	int			error;

	__le32			crc;



	crc = xlog_cksum(log, rhead, dp, be32_to_cpu(rhead->h_len));



	/*

	 * Check the CRC and issue a warning if and only if the CRC in the

	 * header is non-zero. This is an advisory warning and the zero CRC

	 * check prevents warnings from being emitted when upgrading the kernel

	 * from one that does not add CRCs by default.

	 * Nothing else to do if this is a CRC verification pass. Just return

	 * if this a record with a non-zero crc. Unfortunately, mkfs always

	 * sets h_crc to 0 so we must consider this valid even on v5 supers.

	 * Otherwise, return EFSBADCRC on failure so the callers up the stack

	 * know precisely what failed.

	 */

	if (pass == XLOG_RECOVER_CRCPASS) {

		if (rhead->h_crc && crc != le32_to_cpu(rhead->h_crc))

			return -EFSBADCRC;

		return 0;

	}



	/*

	 * We're in the normal recovery path. Issue a warning if and only if the

	 * CRC in the header is non-zero. This is an advisory warning and the

	 * zero CRC check prevents warnings from being emitted when upgrading

	 * the kernel from one that does not add CRCs by default.

	 */

	crc = xlog_cksum(log, rhead, dp, be32_to_cpu(rhead->h_len));

	if (crc != le32_to_cpu(rhead->h_crc)) {

		if (rhead->h_crc || xfs_sb_version_hascrc(&log->l_mp->m_sb)) {

			xfs_alert(log->l_mp,