From 865cc3e9cc0b1d4b81c10d53174bced76decf888 Mon Sep 17 00:00:00 2001 From: Bob Peterson Date: Tue, 18 May 2021 09:14:31 -0400 Subject: gfs2: fix a deadlock on withdraw-during-mount Before this patch, gfs2 would deadlock because of the following sequence during mount: mount gfs2_fill_super gfs2_make_fs_rw <--- Detects IO error with glock kthread_stop(sdp->sd_quotad_process); <--- Blocked waiting for quotad to finish logd Detects IO error and the need to withdraw calls gfs2_withdraw gfs2_make_fs_ro kthread_stop(sdp->sd_quotad_process); <--- Blocked waiting for quotad to finish gfs2_quotad gfs2_statfs_sync gfs2_glock_wait <---- Blocked waiting for statfs glock to be granted glock_work_func do_xmote <---Detects IO error, can't release glock: blocked on withdraw glops->go_inval glock_blocked_by_withdraw requeue glock work & exit <--- work requeued, blocked by withdraw This patch makes a special exception for the statfs system inode glock, which allows the statfs glock UNLOCK to proceed normally. That allows the quotad daemon to exit during the withdraw, which allows the logd daemon to exit during the withdraw, which allows the mount to exit. Signed-off-by: Bob Peterson Signed-off-by: Andreas Gruenbacher --- fs/gfs2/glock.c | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) (limited to 'fs/gfs2') diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c index 8c547db210fb..797949e784cc 100644 --- a/fs/gfs2/glock.c +++ b/fs/gfs2/glock.c @@ -582,6 +582,16 @@ out_locked: spin_unlock(&gl->gl_lockref.lock); } +static bool is_system_glock(struct gfs2_glock *gl) +{ + struct gfs2_sbd *sdp = gl->gl_name.ln_sbd; + struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode); + + if (gl == m_ip->i_gl) + return true; + return false; +} + /** * do_xmote - Calls the DLM to change the state of a lock * @gl: The lock state @@ -671,17 +681,25 @@ skip_inval: * to see sd_log_error and withdraw, and in the meantime, requeue the * work for later. * + * We make a special exception for some system glocks, such as the + * system statfs inode glock, which needs to be granted before the + * gfs2_quotad daemon can exit, and that exit needs to finish before + * we can unmount the withdrawn file system. + * * However, if we're just unlocking the lock (say, for unmount, when * gfs2_gl_hash_clear calls clear_glock) and recovery is complete * then it's okay to tell dlm to unlock it. */ if (unlikely(sdp->sd_log_error && !gfs2_withdrawn(sdp))) gfs2_withdraw_delayed(sdp); - if (glock_blocked_by_withdraw(gl)) { - if (target != LM_ST_UNLOCKED || - test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags)) { + if (glock_blocked_by_withdraw(gl) && + (target != LM_ST_UNLOCKED || + test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags))) { + if (!is_system_glock(gl)) { gfs2_glock_queue_work(gl, GL_GLOCK_DFT_HOLD); goto out; + } else { + clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags); } } -- cgit v1.2.3-58-ga151