Re: [PATCH] debugfs/logdump.c: Add parameter t to dump sequence commit timestamps

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Jun 17, 2025 at 07:31:35PM +0800, zhanchengbin wrote:
> When filesystem errors occur, inspect journal sequences with parameter t to
>  dump commit timestamps.
> 
> Signed-off-by: zhanchengbin <zhanchengbin@huawei.com>
> ---
>  debugfs/logdump.c | 63 ++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 54 insertions(+), 9 deletions(-)
> 
> diff --git a/debugfs/logdump.c b/debugfs/logdump.c
> index 324ed42..bbe1384 100644
> --- a/debugfs/logdump.c
> +++ b/debugfs/logdump.c
> @@ -47,7 +47,7 @@ enum journal_location {JOURNAL_IS_INTERNAL,
> JOURNAL_IS_EXTERNAL};
> 
>  #define ANY_BLOCK ((blk64_t) -1)
> 
> -static int        dump_all, dump_super, dump_old, dump_contents,
> dump_descriptors;
> +static int        dump_all, dump_super, dump_old, dump_contents,
> dump_descriptors, dump_time;
>  static int64_t        dump_counts;
>  static blk64_t        block_to_dump, bitmap_to_dump, inode_block_to_dump;
>  static unsigned int    group_to_dump, inode_offset_to_dump;
> @@ -67,6 +67,8 @@ static void dump_descriptor_block(FILE *, struct
> journal_source *,
>                    char *, journal_superblock_t *,
>                    unsigned int *, unsigned int, __u32, tid_t);
> 
> +static void dump_commit_time(FILE *out_file, char *buf);
> +
>  static void dump_revoke_block(FILE *, char *, journal_superblock_t *,
>                    unsigned int, unsigned int, tid_t);
> 
> @@ -118,10 +120,11 @@ void do_logdump(int argc, ss_argv_t argv, int sci_idx
> EXT2FS_ATTR((unused)),
>      inode_block_to_dump = ANY_BLOCK;
>      inode_to_dump = -1;
>      dump_counts = -1;
> +    dump_time = 0;

Globals are initialized to zero if not given an explicit value so this
isn't necessary.

>      wrapped_flag = false;
> 
>      reset_getopt();
> -    while ((c = getopt (argc, argv, "ab:ci:f:OsSn:")) != EOF) {
> +    while ((c = getopt (argc, argv, "ab:ci:f:OsSn:t")) != EOF) {
>          switch (c) {
>          case 'a':
>              dump_all++;
> @@ -162,6 +165,9 @@ void do_logdump(int argc, ss_argv_t argv, int sci_idx
> EXT2FS_ATTR((unused)),
>                  return;
>              }
>              break;
> +        case 't':
> +            dump_time++;
> +            break;
>          default:
>              goto print_usage;
>          }
> @@ -521,21 +527,33 @@ static void dump_journal(char *cmdname, FILE
> *out_file,
>                  break;
>          }
> 
> -        if (dump_descriptors) {
> -            fprintf (out_file, "Found expected sequence %u, "
> -                 "type %u (%s) at block %u\n",
> -                 sequence, blocktype,
> -                 type_to_name(blocktype), blocknr);
> -        }
> -
>          switch (blocktype) {
>          case JBD2_DESCRIPTOR_BLOCK:
> +            if (dump_descriptors) {
> +                fprintf (out_file, "Found expected sequence %u, "
> +                     "type %u (%s) at block %u\n",
> +                     sequence, blocktype,
> +                     type_to_name(blocktype), blocknr);
> +            }
> +
>              dump_descriptor_block(out_file, source, buf, jsb,
>                            &blocknr, blocksize, maxlen,
>                            transaction);
>              continue;
> 
>          case JBD2_COMMIT_BLOCK:
> +            if (dump_descriptors) {
> +                fprintf (out_file, "Found expected sequence %u, "
> +                     "type %u (%s) at block %u",
> +                     sequence, blocktype,
> +                     type_to_name(blocktype), blocknr);
> +            }

Why did the "Found expected sequence..." message get moved?

> +
> +            if (dump_time)
> +                dump_commit_time(out_file, buf);
> +
> +            fprintf(out_file, "\n");
> +
>              cur_counts++;
>              transaction++;
>              blocknr++;
> @@ -543,6 +561,13 @@ static void dump_journal(char *cmdname, FILE *out_file,
>              continue;
> 
>          case JBD2_REVOKE_BLOCK:
> +            if (dump_descriptors) {
> +                fprintf (out_file, "Found expected sequence %u, "
> +                     "type %u (%s) at block %u\n",
> +                     sequence, blocktype,
> +                     type_to_name(blocktype), blocknr);
> +            }
> +
>              dump_revoke_block(out_file, buf, jsb,
>                        blocknr, blocksize,
>                        transaction);
> @@ -742,6 +767,26 @@ static void dump_descriptor_block(FILE *out_file,
>      *blockp = blocknr;
>  }
> 
> +static void dump_commit_time(FILE *out_file, char *buf)
> +{
> +    struct commit_header    *header;
> +    __be64        commit_sec;
> +    time_t        timestamp;
> +    struct tm    timeinfo;
> +
> +    header = (struct commit_header*)buf;
> +    commit_sec = be64_to_cpu(header->h_commit_sec);
> +
> +    timestamp = commit_sec;
> +    gmtime_r(&timestamp, &timeinfo);
> +    fprintf(out_file, ", commit at UTC: %04d-%02d-%02d %02d:%02d:%02d",
> +        timeinfo.tm_year + 1900,
> +        timeinfo.tm_mon + 1,
> +        timeinfo.tm_mday,
> +        timeinfo.tm_hour,
> +        timeinfo.tm_min,
> +        timeinfo.tm_sec);

Use ctime_r() to get a locale-appropriate local timestamp string to
print out.  Or asctime_r() if you really need UTC.

--D

> +}
> 
>  static void dump_revoke_block(FILE *out_file, char *buf,
>                    journal_superblock_t *jsb EXT2FS_ATTR((unused)),
> -- 
> 2.33.0
>