From: Bob Peterson rpeterso@redhat.com
commit f39e7d3aae2934b1cfdd209b54c508e2552e9531 upstream.
GFS2's freeze/thaw mechanism uses a special freeze glock to control its operation. It does this with a sync glock operation (glops.c) called freeze_go_sync. When the freeze glock is demoted (glock's do_xmote) the glops function causes the file system to be frozen. This is intended. However, GFS2's mount and unmount processes also hold the freeze glock to prevent other processes, perhaps on different cluster nodes, from mounting the frozen file system in read-write mode.
Before this patch, there was no check in freeze_go_sync for whether a freeze in intended or whether the glock demote was caused by a normal unmount. So it was trying to freeze the file system it's trying to unmount, which ends up in a deadlock.
This patch adds an additional check to freeze_go_sync so that demotes of the freeze glock are ignored if they come from the unmount process.
Fixes: 20b329129009 ("gfs2: Fix regression in freeze_go_sync") Signed-off-by: Bob Peterson rpeterso@redhat.com Signed-off-by: Andreas Gruenbacher agruenba@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/gfs2/glops.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/fs/gfs2/glops.c +++ b/fs/gfs2/glops.c @@ -551,7 +551,8 @@ static int freeze_go_sync(struct gfs2_gl * Once thawed, the work func acquires the freeze glock in * SH and everybody goes back to thawed. */ - if (gl->gl_state == LM_ST_SHARED && !gfs2_withdrawn(sdp)) { + if (gl->gl_state == LM_ST_SHARED && !gfs2_withdrawn(sdp) && + !test_bit(SDF_NORECOVERY, &sdp->sd_flags)) { atomic_set(&sdp->sd_freeze_state, SFS_STARTING_FREEZE); error = freeze_super(sdp->sd_vfs); if (error) {