jffs2: Erase pending blocks in GC pass, avoid invalid -EIO return

jffs2_garbage_collect_pass() would previously return -EAGAIN if it
couldn't find anything to garbage collect from, and there were blocks on
the erase_pending_list. If the blocks were actually in the process of
being erased, though, then they wouldn't be on that list. Check for
nr_erasing_blocks being non-zero instead.

Fix jffs2_reserve_space() to wait for the in-progress erases to
complete, when jffs2_garbage_collect_pass() returns -EAGAIN.

And fix jffs2_erase_succeeded() to actually wake up the erase_wait wq
that jffs2_reserve_space() is now using.
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

fs/jffs2/erase.c

@@ -172,6 +172,7 @@ static void jffs2_erase_succeeded(struct jffs2_sb_info *c, struct jffs2_eraseblo
 	mutex_unlock(&c->erase_free_sem);
 	/* Ensure that kupdated calls us again to mark them clean */
 	jffs2_erase_pending_trigger(c);
+	wake_up(&c->erase_wait);
 }
 
 static void jffs2_erase_failed(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, uint32_t bad_offset)

fs/jffs2/gc.c

@@ -214,6 +214,19 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
 		return ret;
 	}
 
+	/* If there are any blocks which need erasing, erase them now */
+	if (!list_empty(&c->erase_complete_list) ||
+	    !list_empty(&c->erase_pending_list)) {
+		spin_unlock(&c->erase_completion_lock);
+		D1(printk(KERN_DEBUG "jffs2_garbage_collect_pass() erasing pending blocks\n"));
+		if (jffs2_erase_pending_blocks(c, 1)) {
+			mutex_unlock(&c->alloc_sem);
+			return 0;
+		}
+		D1(printk(KERN_DEBUG "No progress from erasing blocks; doing GC anyway\n"));
+		spin_lock(&c->erase_completion_lock);
+	}
+
 	/* First, work out which block we're garbage-collecting */
 	jeb = c->gcblock;
 
@@ -222,7 +235,7 @@ int jffs2_garbage_collect_pass(struct jffs2_sb_info *c)
 
 	if (!jeb) {
 		/* Couldn't find a free block. But maybe we can just erase one and make 'progress'? */
-		if (!list_empty(&c->erase_pending_list)) {
+		if (c->nr_erasing_blocks) {
 			spin_unlock(&c->erase_completion_lock);
 			mutex_unlock(&c->alloc_sem);
 			return -EAGAIN;

fs/jffs2/nodemgmt.c

@@ -116,9 +116,21 @@ int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize,
 
 			ret = jffs2_garbage_collect_pass(c);
 
-			if (ret == -EAGAIN)
-				jffs2_erase_pending_blocks(c, 1);
-			else if (ret)
+			if (ret == -EAGAIN) {
+				spin_lock(&c->erase_completion_lock);
+				if (c->nr_erasing_blocks &&
+				    list_empty(&c->erase_pending_list) &&
+				    list_empty(&c->erase_complete_list)) {
+					DECLARE_WAITQUEUE(wait, current);
+					set_current_state(TASK_UNINTERRUPTIBLE);
+					add_wait_queue(&c->erase_wait, &wait);
+					D1(printk(KERN_DEBUG "%s waiting for erase to complete\n", __func__));
+					spin_unlock(&c->erase_completion_lock);
+
+					schedule();
+				} else
+					spin_unlock(&c->erase_completion_lock);
+			} else if (ret)
 				return ret;
 
 			cond_resched();