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gfs2: Fix deadlock dumping resource group glocks 

Commit 0e539ca1bb ("gfs2: Fix NULL pointer dereference in gfs2_rgrp_dump")
introduced additional locking in gfs2_rgrp_go_dump, which is also used for
dumping resource group glocks via debugfs.  However, on that code path, the
glock spin lock is already taken in dump_glock, and taking it again in
gfs2_glock2rgrp leads to deadlock.  This can be reproduced with:

  $ mkfs.gfs2 -O -p lock_nolock /dev/FOO
  $ mount /dev/FOO /mnt/foo
  $ touch /mnt/foo/bar
  $ cat /sys/kernel/debug/gfs2/FOO/glocks

Fix that by not taking the glock spin lock inside the go_dump callback.

Fixes: 0e539ca1bb ("gfs2: Fix NULL pointer dereference in gfs2_rgrp_dump")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Alexander Aring 2020-11-22 18:10:24 -05:00 committed by Andreas Gruenbacher
parent 418baf2c28
commit 16e6281b6b
1 changed files with 1 additions and 1 deletions
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2
fs/gfs2/glops.c
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@ -245,7 +245,7 @@ static void rgrp_go_inval(struct gfs2_glock *gl, int flags)
static void gfs2_rgrp_go_dump(struct seq_file *seq, struct gfs2_glock *gl,
const char *fs_id_buf)
{
struct gfs2_rgrpd *rgd = gfs2_glock2rgrp(gl);
struct gfs2_rgrpd *rgd = gl->gl_object;
if (rgd)
gfs2_rgrp_dump(seq, rgd, fs_id_buf);