---

yaml
---
r: 210896
b: refs/heads/master
c: 692ebd1
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 371d217ee1ff8b418b8f73fb2a34990f951ec2d4
+refs/heads/master: 692ebd17c2905313fff3c504c249c6a0faad16ec

trunk/fs/fs-writeback.c

@@ -52,8 +52,6 @@ struct wb_writeback_work {
 #define CREATE_TRACE_POINTS
 #include <trace/events/writeback.h>
 
-#define inode_to_bdi(inode)	((inode)->i_mapping->backing_dev_info)
-
 /*
  * We don't actually have pdflush, but this one is exported though /proc...
  */
@@ -71,6 +69,27 @@ int writeback_in_progress(struct backing_dev_info *bdi)
 	return test_bit(BDI_writeback_running, &bdi->state);
 }
 
+static inline struct backing_dev_info *inode_to_bdi(struct inode *inode)
+{
+	struct super_block *sb = inode->i_sb;
+	struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
+
+	/*
+	 * For inodes on standard filesystems, we use superblock's bdi. For
+	 * inodes on virtual filesystems, we want to use inode mapping's bdi
+	 * because they can possibly point to something useful (think about
+	 * block_dev filesystem).
+	 */
+	if (sb->s_bdi && sb->s_bdi != &noop_backing_dev_info) {
+		/* Some device inodes could play dirty tricks. Catch them... */
+		WARN(bdi != sb->s_bdi && bdi_cap_writeback_dirty(bdi),
+			"Dirtiable inode bdi %s != sb bdi %s\n",
+			bdi->name, sb->s_bdi->name);
+		return sb->s_bdi;
+	}
+	return bdi;
+}
+
 static void bdi_queue_work(struct backing_dev_info *bdi,
 		struct wb_writeback_work *work)
 {