[ Upstream commit 96b1454f2e ]
Before this patch, sister functions gfs2_make_fs_rw and gfs2_make_fs_ro locked
(held) the freeze glock by calling gfs2_freeze_lock and gfs2_freeze_unlock.
The problem is, not all the callers of gfs2_make_fs_ro should be doing this.
The three callers of gfs2_make_fs_ro are: remount (gfs2_reconfigure),
signal_our_withdraw, and unmount (gfs2_put_super). But when unmounting the
file system we can get into the following circular lock dependency:
deactivate_super
down_write(&s->s_umount); <-------------------------------------- s_umount
deactivate_locked_super
gfs2_kill_sb
kill_block_super
generic_shutdown_super
gfs2_put_super
gfs2_make_fs_ro
gfs2_glock_nq_init sd_freeze_gl
freeze_go_sync
if (freeze glock in SH)
freeze_super (vfs)
down_write(&sb->s_umount); <------- s_umount
This patch moves the hold of the freeze glock outside the two sister rw/ro
functions to their callers, but it doesn't request the glock from
gfs2_put_super, thus eliminating the circular dependency.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
a602e830dd