Date:   Thu, 31 Mar 2022 00:51:55 +0000
From:   Jonathan Lassoff <jof@...jof.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
        linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v2] Add FAT messages to printk index

On Fri, 25 Mar 2022 at 20:18, Andrew Morton <akpm@...ux-foundation.org> wrote:
> It would be nice to see some before-and-after sample output to help
> reviewers understand this proposal.

By diffing the output of the debugfs interface
(/sys/kernel/debug/printk/index/vmlinux), it looks like this:

--- before
+++ after
-<-1> fs/fat/misc.c:56 fat_msg "%sFAT-fs (%s): %pV\n"
+<3> fs/fat/dir.c:1323 fat_add_entries "%sFAT-fs (%s): Corrupted
directory (i_pos %lld)"
+<4> fs/fat/dir.c:1066 fat_remove_entries "%sFAT-fs (%s): Couldn't
remove the long name slots"
+<4> fs/fat/dir.c:173 uni16_to_x8 "%sFAT-fs (%s): filename was
truncated while converting."
+<3> fs/fat/dir.c:102 fat__get_entry "%sFAT-fs (%s): Directory
bread(block %llu) failed"
+<3> fs/fat/fatent.c:110 fat_ent_bread "%sFAT-fs (%s): FAT read failed
(blocknr %llu)"
+<3> fs/fat/fatent.c:97 fat12_ent_bread "%sFAT-fs (%s): FAT read
failed (blocknr %llu)"
+<6> fs/fat/inode.c:1889 fat_fill_super "%sFAT-fs (%s): Can't find a
valid FAT filesystem"
+<4> fs/fat/inode.c:1878 fat_fill_super "%sFAT-fs (%s): mounting with
\"discard\" option, but the device does not support discard"
+<3> fs/fat/inode.c:1871 fat_fill_super "%sFAT-fs (%s): get root inode failed"
+<3> fs/fat/inode.c:1837 fat_fill_super "%sFAT-fs (%s): IO charset %s not found"
+<3> fs/fat/inode.c:1829 fat_fill_super "%sFAT-fs (%s): codepage %s not found"
+<3> fs/fat/inode.c:1794 fat_fill_super "%sFAT-fs (%s): count of
clusters too big (%u)"
+<3> fs/fat/inode.c:1766 fat_fill_super "%sFAT-fs (%s): bogus number
of directory entries (%u)"
+<4> fs/fat/inode.c:1738 fat_fill_super "%sFAT-fs (%s): Invalid FSINFO
signature: 0x%08x, 0x%08x (sector = %lu)"
+<3> fs/fat/inode.c:1731 fat_fill_super "%sFAT-fs (%s): bread failed,
FSINFO block (sector = %lu)"
+<3> fs/fat/inode.c:1688 fat_fill_super "%sFAT-fs (%s): unable to read
boot sector (logical sector size = %lu)"
+<3> fs/fat/inode.c:1680 fat_fill_super "%sFAT-fs (%s): unable to set
blocksize %u"
+<3> fs/fat/inode.c:1671 fat_fill_super "%sFAT-fs (%s): logical sector
size too small for device (logical sector size = %u)"
+<3> fs/fat/inode.c:1650 fat_fill_super "%sFAT-fs (%s): unable to read
boot sector"
+<6> fs/fat/inode.c:1580 fat_read_static_bpb "%sFAT-fs (%s): This
looks like a DOS 1.x volume; assuming default BPB values"
+<4> fs/fat/inode.c:1573 fat_read_static_bpb "%sFAT-fs (%s): This
looks like a DOS 1.x volume, but isn't a recognized floppy size (%llu
sectors)"
+<3> fs/fat/inode.c:1559 fat_read_static_bpb "%sFAT-fs (%s): %s; DOS
2.x BPB is non-zero"
+<3> fs/fat/inode.c:1548 fat_read_static_bpb "%sFAT-fs (%s): %s; no
bootstrapping code"
+<3> fs/fat/inode.c:1525 fat_read_bpb "%sFAT-fs (%s): bogus number of
FAT sectors"
+<3> fs/fat/inode.c:1511 fat_read_bpb "%sFAT-fs (%s): bogus logical
sector size %u"
+<3> fs/fat/inode.c:1502 fat_read_bpb "%sFAT-fs (%s): invalid media
value (0x%02x)"
+<3> fs/fat/inode.c:1491 fat_read_bpb "%sFAT-fs (%s): bogus number of
FAT structure"
+<3> fs/fat/inode.c:1485 fat_read_bpb "%sFAT-fs (%s): bogus number of
reserved sectors"
+<4> fs/fat/inode.c:1366 parse_options "%sFAT-fs (%s): utf8 is not a
recommended IO charset for FAT filesystems, filesystem will be case
sensitive!"
+<3> fs/fat/inode.c:1355 parse_options "%sFAT-fs (%s): Unrecognized
mount option \"%s\" or missing value"
+<6> fs/fat/inode.c:1349 parse_options "%sFAT-fs (%s): \"%s\" option
is obsolete, not supported now"
+<3> fs/fat/inode.c:869 __fat_write_inode "%sFAT-fs (%s): unable to
read inode block for updating (i_pos %lld)"
+<3> fs/fat/inode.c:690 fat_set_state "%sFAT-fs (%s): unable to read
boot sector to mark fs as dirty"
+<4> fs/fat/inode.c:682 fat_set_state "%sFAT-fs (%s): Volume was not
properly unmounted. Some data may be corrupt. Please run fsck."
+<4> fs/fat/inode.c:643 fat_free_eofblocks "%sFAT-fs (%s): Failed to
update on disk inode for unused fallocated blocks, inode could be
corrupted. Please run fsck"
+<3> fs/fat/misc.c:86 fat_clusters_flush "%sFAT-fs (%s): Invalid
FSINFO signature: 0x%08x, 0x%08x (sector = %lu)"
+<3> fs/fat/misc.c:79 fat_clusters_flush "%sFAT-fs (%s): bread failed
in fat_clusters_flush"
+<3> fs/fat/misc.c:39 __fat_fs_error "%sFAT-fs (%s): Filesystem has
been set read-only"
+<3> fs/fat/misc.c:31 __fat_fs_error "%sFAT-fs (%s): error, %pV"
+<3> fs/fat/nfs.c:225 fat_rebuild_parent "%sFAT-fs (%s): unable to
read cluster of parent directory"
+<3> fs/fat/nfs.c:73 __fat_nfs_get_inode "%sFAT-fs (%s): unable to
read block(%llu) for building NFS inode"

> > Reported-by: kernel test robot <lkp@...el.com>
>
> We'll need a Signed-off-by: for this, please.
> Documentation/process/submitting-patches.rst describes this.

*facepalm*
Sorry about that and thanks for some patience.... I'm still a total newbie.

In some of the other subsystems, I've gotten some resistance to
mentioning a "semi-stable interface" (with regard to the existing
debugfs interface, since it's not actually making any stability
guarantees), so I'd like to follow up again with a [PATCH v4] that
rewords the message and includes a Signed-off-by:

-- jof

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