locks: keep ref on the inode while locks are held

keeping refs on the inode while there are held locks prevents the
inode from getting pruned away

Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

BUG: 315 (generation number support)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=315

6 files changed, 66 insertions, 7 deletions

diff --git a/xlators/features/locks/src/common.c b/xlators/features/locks/src/common.c
index 08dc451e16e..b9037688a3f 100644
--- a/xlators/features/locks/src/common.c
+++ b/xlators/features/locks/src/common.c
@@ -35,6 +35,7 @@
 #include "common-utils.h"
 
 #include "locks.h"
+#include "common.h"
 
 
 static int
@@ -43,7 +44,7 @@ static void
 __insert_and_merge (pl_inode_t *pl_inode, posix_lock_t *lock);
 
 static pl_dom_list_t *
-allocate_domain(const char *volume)
+allocate_domain (const char *volume)
 {
         pl_dom_list_t *dom = NULL;
 
@@ -95,6 +96,56 @@ found:
         return dom;
 }
 
+
+int
+__pl_inode_is_empty (pl_inode_t *pl_inode)
+{
+        pl_dom_list_t *dom = NULL;
+        int            is_empty = 1;
+
+        if (!list_empty (&pl_inode->ext_list))
+                is_empty = 0;
+
+        list_for_each_entry (dom, &pl_inode->dom_list, inode_list) {
+                if (!list_empty (&dom->entrylk_list))
+                        is_empty = 0;
+
+                if (!list_empty (&dom->inodelk_list))
+                        is_empty = 0;
+        }
+
+        return is_empty;
+}
+
+void
+pl_update_refkeeper (xlator_t *this, inode_t *inode)
+{
+        pl_inode_t *pl_inode  = NULL;
+        int         is_empty  = 0;
+        int         need_unref = 0;
+
+        pl_inode = pl_inode_get (this, inode);
+
+        pthread_mutex_lock (&pl_inode->mutex);
+        {
+                is_empty = __pl_inode_is_empty (pl_inode);
+
+                if (is_empty && pl_inode->refkeeper) {
+                        need_unref = 1;
+                        pl_inode->refkeeper = NULL;
+                }
+
+                if (!is_empty && !pl_inode->refkeeper) {
+                        pl_inode->refkeeper = inode_ref (inode);
+                }
+        }
+        pthread_mutex_unlock (&pl_inode->mutex);
+
+        if (need_unref)
+                inode_unref (inode);
+}
+
+
 pl_inode_t *
 pl_inode_get (xlator_t *this, inode_t *inode)
 {
diff --git a/xlators/features/locks/src/common.h b/xlators/features/locks/src/common.h
index fabe8bd840a..59201c9070a 100644
--- a/xlators/features/locks/src/common.h
+++ b/xlators/features/locks/src/common.h
@@ -65,4 +65,6 @@ void
 grant_blocked_entry_locks (xlator_t *this, pl_inode_t *pl_inode,
 			   pl_entry_lock_t *unlocked, pl_dom_list_t *dom);
 
+void pl_update_refkeeper (xlator_t *this, inode_t *inode);
+
 #endif /* __COMMON_H__ */
diff --git a/xlators/features/locks/src/entrylk.c b/xlators/features/locks/src/entrylk.c
index f1536f8039b..e22a8305d27 100644
--- a/xlators/features/locks/src/entrylk.c
+++ b/xlators/features/locks/src/entrylk.c
@@ -534,6 +534,7 @@ pl_common_entrylk (call_frame_t *frame, xlator_t *this,
 
 	op_ret = 0;
 out:
+        pl_update_refkeeper (this, inode);
 	if (unwind) {
 		STACK_UNWIND_STRICT (entrylk, frame, op_ret, op_errno);
 	}
diff --git a/xlators/features/locks/src/inodelk.c b/xlators/features/locks/src/inodelk.c
index 4c76f64bb80..1cb2c952200 100644
--- a/xlators/features/locks/src/inodelk.c
+++ b/xlators/features/locks/src/inodelk.c
@@ -525,6 +525,7 @@ pl_common_inodelk (call_frame_t *frame, xlator_t *this,
 	op_ret = 0;
 
 unwind:
+        pl_update_refkeeper (this, inode);
 	STACK_UNWIND_STRICT (inodelk, frame, op_ret, op_errno);
 out:
 	return 0;
diff --git a/xlators/features/locks/src/locks.h b/xlators/features/locks/src/locks.h
index 4ad16c714ec..9d030f15e13 100644
--- a/xlators/features/locks/src/locks.h
+++ b/xlators/features/locks/src/locks.h
@@ -86,12 +86,12 @@ struct __pl_rw_req_t {
 typedef struct __pl_rw_req_t pl_rw_req_t;
 
 struct __pl_dom_list_t {
-        const char *domain;
-        struct list_head inode_list;       /* list_head back to pl_inode_t */
-        struct list_head entrylk_list;     /* List of entry locks */
-        struct list_head blocked_entrylks; /* List of all blocked entrylks */
-        struct list_head inodelk_list;     /* List of inode locks */
-        struct list_head blocked_inodelks; /* List of all blocked inodelks */
+        struct list_head   inode_list;       /* list_head back to pl_inode_t */
+        const char        *domain;
+        struct list_head   entrylk_list;     /* List of entry locks */
+        struct list_head   blocked_entrylks; /* List of all blocked entrylks */
+        struct list_head   inodelk_list;     /* List of inode locks */
+        struct list_head   blocked_inodelks; /* List of all blocked inodelks */
 };
 typedef struct __pl_dom_list_t pl_dom_list_t;
 
@@ -123,6 +123,9 @@ struct __pl_inode {
 	struct list_head ext_list;       /* list of fcntl locks */
 	struct list_head rw_list;        /* list of waiting r/w requests */
 	int              mandatory;      /* if mandatory locking is enabled */
+
+        inode_t          *refkeeper;     /* hold refs on an inode while locks are
+                                            held to prevent pruning */
 };
 typedef struct __pl_inode pl_inode_t;
 
diff --git a/xlators/features/locks/src/posix.c b/xlators/features/locks/src/posix.c
index f2e73b9cb25..50958a2ed93 100644
--- a/xlators/features/locks/src/posix.c
+++ b/xlators/features/locks/src/posix.c
@@ -686,6 +686,7 @@ pl_lk (call_frame_t *frame, xlator_t *this,
 	}
 
 unwind:
+        pl_update_refkeeper (this, fd->inode);
 	STACK_UNWIND_STRICT (lk, frame, op_ret, op_errno, flock);
 out:
 	return 0;