[PATCH v4] xfs_logprint: Fix super block buffer interpretation issue

Chi Zhiling
2024-10-13T04:30:47Z

From: Chi Zhiling <chizhiling@kylinos.cn>

When using xfs_logprint to interpret the buffer of the super block, the
icount will always be 6360863066640355328 (0x5846534200001000). This is
because the offset of icount is incorrect, causing xfs_logprint to
misinterpret the MAGIC number as icount.
This patch fixes the offset value of the SB counters in xfs_logprint.

Before this patch:
icount: 6360863066640355328 ifree: 5242880 fdblks: 0 frext: 0

After this patch:
icount: 10240 ifree: 4906 fdblks: 37 frext: 0

Suggested-by: Darrick J. Wong <djwong@kernel.org>
Suggested-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Chi Zhiling <chizhiling@kylinos.cn>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
---
logprint/log_misc.c | 17 +++++------------
1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/logprint/log_misc.c b/logprint/log_misc.c
index 8e86ac34..803e4d2f 100644
--- a/logprint/log_misc.c
+++ b/logprint/log_misc.c
@@ -282,22 +282,15 @@ xlog_print_trans_buffer(char **ptr, int len, int *i, int num_ops)
if (be32_to_cpu(head->oh_len) < 4*8) {
printf(_("Out of space\n"));
} else {
- __be64 a, b;
+ struct xfs_dsb *dsb = (struct xfs_dsb *) *ptr;

printf("\n");
- /*
- * memmove because *ptr may not be 8-byte aligned
- */
- memmove(&a, *ptr, sizeof(__be64));
- memmove(&b, *ptr+8, sizeof(__be64));
printf(_("icount: %llu ifree: %llu "),
- (unsigned long long) be64_to_cpu(a),
- (unsigned long long) be64_to_cpu(b));
- memmove(&a, *ptr+16, sizeof(__be64));
- memmove(&b, *ptr+24, sizeof(__be64));
+ (unsigned long long) get_unaligned_be64(dsb->sb_icount),
+ (unsigned long long) get_unaligned_be64(dsb->sb_ifree));
printf(_("fdblks: %llu frext: %llu\n"),
- (unsigned long long) be64_to_cpu(a),
- (unsigned long long) be64_to_cpu(b));
+ (unsigned long long) get_unaligned_be64(dsb->sb_fdblocks),
+ (unsigned long long) get_unaligned_be64(dsb->sb_frextents));
}
super_block = 0;
} else if (be32_to_cpu(*(__be32 *)(*ptr)) == XFS_AGI_MAGIC) {
--

2.43.0