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gfs2: Fix unlikely race in gdlm_put_lock

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In gdlm_put_lock(), there is a small window of time in which the
DFL_UNMOUNT flag has been set but the lockspace hasn't been released,
yet.  In that window, dlm may still call gdlm_ast() and gdlm_bast().
To prevent it from dereferencing freed glock objects, only free the
glock if the lockspace has actually been released.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Andrew Price <anprice@redhat.com>
This commit is contained in:
Andreas Gruenbacher 2025-08-06 23:34:03 +02:00
parent 6ab26555c9
commit 28c4d9bc07
1 changed files with 5 additions and 6 deletions
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11
fs/gfs2/lock_dlm.c
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@ -344,12 +344,6 @@ static void gdlm_put_lock(struct gfs2_glock *gl)
gfs2_sbstats_inc(gl, GFS2_LKS_DCOUNT);
gfs2_update_request_times(gl);
/* don't want to call dlm if we've unmounted the lock protocol */
if (test_bit(DFL_UNMOUNT, &ls->ls_recover_flags)) {
gfs2_glock_free(gl);
return;
}
/*
* When the lockspace is released, all remaining glocks will be
* unlocked automatically. This is more efficient than unlocking them
@ -379,6 +373,11 @@ static void gdlm_put_lock(struct gfs2_glock *gl)
goto again;
}
if (error == -ENODEV) {
gfs2_glock_free(gl);
return;
}
if (error) {
fs_err(sdp, "gdlm_unlock %x,%llx err=%d\n",
gl->gl_name.ln_type,