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SubjectRe: [PATCH V2 2/2] fs: print a message when freezing/unfreezing filesystems
On Wed 14-05-14 00:04:43, Mateusz Guzik wrote:
> This helps hang troubleshooting efforts when only dmesg is available.
>
> While here remove code duplication with MS_RDONLY case and fix a
> whitespace nit.
I'm somewhat undecided here I have to say. On one hand I don't like
printing to kernel log when everything is fine and kernel is operating
normally. On the other hand I've seen quite a few cases where people have
shot themselves in the foot with filesystem freezing so having some trace
of this in the log doesn't seem like a completely bad thing either. What do
other people think?

Honza
> Signed-off-by: Mateusz Guzik <mguzik@redhat.com>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: Josef Bacik <jbacik@fb.com>
> Cc: Jan Kara <jack@suse.cz>
> Cc: Al Viro <viro@ZenIV.linux.org.uk>
> Cc: Eric Sandeen <esandeen@redhat.com>
> Cc: Joe Perches <joe@perches.com>
> ---
> since v1:
> fix copy-pasto which found its way into the patch
> restore curly brackets in MS_RDONLY case
> fs/super.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/fs/super.c b/fs/super.c
> index 017e10a..4dd7356 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -1291,9 +1291,7 @@ int freeze_super(struct super_block *sb)
>
> if (sb->s_flags & MS_RDONLY) {
> /* Nothing to do really... */
> - sb->s_writers.frozen = SB_FREEZE_COMPLETE;
> - up_write(&sb->s_umount);
> - return 0;
> + goto out;
> }
>
> /* From now on, no new normal writers can start */
> @@ -1335,8 +1333,10 @@ int freeze_super(struct super_block *sb)
> * This is just for debugging purposes so that fs can warn if it
> * sees write activity when frozen is set to SB_FREEZE_COMPLETE.
> */
> +out:
> sb->s_writers.frozen = SB_FREEZE_COMPLETE;
> up_write(&sb->s_umount);
> + pr_info("VFS:Filesystem %s frozen\n", sb->s_id);
> return 0;
> }
> EXPORT_SYMBOL(freeze_super);
> @@ -1374,7 +1374,7 @@ out:
> smp_wmb();
> wake_up(&sb->s_writers.wait_unfrozen);
> deactivate_locked_super(sb);
> -
> + pr_info("VFS:Filesystem %s thawed\n", sb->s_id);
> return 0;
> }
> EXPORT_SYMBOL(thaw_super);
> --
> 1.8.3.1
>
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR


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