[Cluster-devel] [PATCH] gfs2: clear journal live bit in gfs2_log_flush

[Bob Peterson <rpeterso@redhat.com>]

----- Original Message -----
> When gfs2 was unmounting filesystems or changing them to read-only it
> was clearing the SDF_JOURNAL_LIVE bit before the final log flush.  This
> caused a race.  If an inode glock got demoted in the gap between
> clearing the bit and the shutdown flush, it would be unable to reserve
> log space to clear out the acive items list in inode_go_sync, causing an
> error in inode_go_inval because the glock was still dirty.
> 
> To solve this, the SDF_JOURNAL_LIVE bit is now cleared inside the
> shutdown log flush.  This means that, because of the locking on the log
> blocks, either inode_go_sync will be able to reserve space to clean the
> glock before the shutdown flush, or the shutdown flush will clean the
> glock itself, before inode_go_sync fails to reserve the space. Either
> way, the glock will be clean before inode_go_inval.
> 
> Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
> ---
>  fs/gfs2/log.c   | 3 +++
>  fs/gfs2/super.c | 4 ----
>  2 files changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/gfs2/log.c b/fs/gfs2/log.c
> index 536e7a6..0ff028c 100644
> --- a/fs/gfs2/log.c
> +++ b/fs/gfs2/log.c
> @@ -716,6 +716,9 @@ void gfs2_log_flush(struct gfs2_sbd *sdp, struct
> gfs2_glock *gl,
>  	}
>  	trace_gfs2_log_flush(sdp, 1);
>  
> +	if (type == SHUTDOWN_FLUSH)
> +		clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
> +
>  	sdp->sd_log_flush_head = sdp->sd_log_head;
>  	sdp->sd_log_flush_wrapped = 0;
>  	tr = sdp->sd_log_tr;
> diff --git a/fs/gfs2/super.c b/fs/gfs2/super.c
> index 894fb01..e55c9b6 100644
> --- a/fs/gfs2/super.c
> +++ b/fs/gfs2/super.c
> @@ -842,10 +842,6 @@ static int gfs2_make_fs_ro(struct gfs2_sbd *sdp)
>  	gfs2_quota_sync(sdp->sd_vfs, 0);
>  	gfs2_statfs_sync(sdp->sd_vfs, 0);
>  
> -	down_write(&sdp->sd_log_flush_lock);
> -	clear_bit(SDF_JOURNAL_LIVE, &sdp->sd_flags);
> -	up_write(&sdp->sd_log_flush_lock);
> -
>  	gfs2_log_flush(sdp, NULL, SHUTDOWN_FLUSH);
>  	wait_event(sdp->sd_reserving_log_wait, atomic_read(&sdp->sd_reserving_log)
>  	== 0);
>  	gfs2_assert_warn(sdp, atomic_read(&sdp->sd_log_blks_free) ==
>  	sdp->sd_jdesc->jd_blocks);
> --
> 1.8.3.1
> 
> 
Hi,

Thanks. This is now applied to the for-next branch of the linux-gfs2 tree:
https://git.kernel.org/cgit/linux/kernel/git/gfs2/linux-gfs2.git/commit/fs/gfs2?h=for-next&id=3ceb22a7b7a1e50658cce8c43d942e9f31f654bd

Regards,

Bob Peterson
Red Hat File Systems