[lustre-devel] [PATCH 16/20] lustre: obdclass: lu_ref_add() called in atomic context

[James Simmons]

For the native Linux client testing I turn on lu_ref
debugging. When turned on the following errors occur:

[ 2885.946815] Call Trace:
[ 2885.951240]  dump_stack+0x68/0x9b
[ 2885.956523]  ___might_sleep+0x205/0x260
[ 2885.962245]  lu_ref_add+0x25/0x40 [obdclass]
[ 2885.968442]  vvp_pgcache_current+0x101/0x1a0 [lustre]
[ 2885.975370]  seq_read+0x1ab/0x3c0

and

[ 7042.102529]  dump_stack+0x68/0x9b
[ 7042.107328]  ___might_sleep+0x205/0x260
[ 7042.112647]  lu_ref_add+0x25/0x40 [obdclass]
[ 7042.118385]  mdc_lock_upcall+0x154/0x4d0 [mdc]
[ 7042.124275]  mdc_enqueue_send+0x508/0x580 [mdc]
[ 7042.130225]  ? mdc_lock_lvb_update+0x280/0x280 [mdc]

This is easily fixed with introducing a lu_object_ref_add_atomic()
function.

WC-bug-id: https://jira.whamcloud.com/browse/LU-15014
Lustre-commit: 5a37bc9577d4c871 ("LU-15014 obdclass: lu_ref_add() called in atomic context")
Signed-off-by: James Simmons <jsimmons at infradead.org>
Reviewed-on: https://review.whamcloud.com/44969
Reviewed-by: Patrick Farrell <pfarrell at whamcloud.com>
Reviewed-by: Andreas Dilger <adilger at whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz at whamcloud.com>
Reviewed-by: Oleg Drokin <green at whamcloud.com>
---
 fs/lustre/include/lu_object.h | 7 +++++++
 fs/lustre/llite/vvp_dev.c     | 2 +-
 fs/lustre/mdc/mdc_dev.c       | 2 +-
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/lustre/include/lu_object.h b/fs/lustre/include/lu_object.h
index 84e0489..146398a 100644
--- a/fs/lustre/include/lu_object.h
+++ b/fs/lustre/include/lu_object.h
@@ -829,6 +829,13 @@ static inline u32 lu_object_attr(const struct lu_object *o)
 	return o->lo_header->loh_attr;
 }
 
+static inline void lu_object_ref_add_atomic(struct lu_object *o,
+					    const char *scope,
+					    const void *source)
+{
+	lu_ref_add_atomic(&o->lo_header->loh_reference, scope, source);
+}
+
 static inline void lu_object_ref_add(struct lu_object *o,
 				     const char *scope,
 				     const void *source)
diff --git a/fs/lustre/llite/vvp_dev.c b/fs/lustre/llite/vvp_dev.c
index fda48bb..0c417d8 100644
--- a/fs/lustre/llite/vvp_dev.c
+++ b/fs/lustre/llite/vvp_dev.c
@@ -399,7 +399,7 @@ static struct page *vvp_pgcache_current(struct vvp_seq_private *priv)
 				continue;
 
 			priv->vsp_clob = lu2cl(lu_obj);
-			lu_object_ref_add(lu_obj, "dump", current);
+			lu_object_ref_add_atomic(lu_obj, "dump", current);
 			priv->vsp_page_index = 0;
 		}
 
diff --git a/fs/lustre/mdc/mdc_dev.c b/fs/lustre/mdc/mdc_dev.c
index 4777b47..b2f60ea 100644
--- a/fs/lustre/mdc/mdc_dev.c
+++ b/fs/lustre/mdc/mdc_dev.c
@@ -461,7 +461,7 @@ static void mdc_lock_granted(const struct lu_env *env, struct osc_lock *oscl,
 	/* lock reference taken by ldlm_handle2lock_long() is
 	 * owned by osc_lock and released in osc_lock_detach()
 	 */
-	lu_ref_add(&dlmlock->l_reference, "osc_lock", oscl);
+	lu_ref_add_atomic(&dlmlock->l_reference, "osc_lock", oscl);
 	oscl->ols_has_ref = 1;
 
 	LASSERT(!oscl->ols_dlmlock);
-- 
1.8.3.1