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-rw-r--r--fs/char_dev.c4
-rw-r--r--fs/fs-writeback.c23
2 files changed, 24 insertions, 3 deletions
diff --git a/fs/char_dev.c b/fs/char_dev.c
index f80a4f25123..143d393881c 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -40,7 +40,9 @@ struct backing_dev_info directly_mappable_cdev_bdi = {
#endif
/* permit direct mmap, for read, write or exec */
BDI_CAP_MAP_DIRECT |
- BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP),
+ BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP |
+ /* no writeback happens */
+ BDI_CAP_NO_ACCT_AND_WRITEBACK),
};
static struct kobj_map *cdev_map;
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 81e086d8aa5..5581122bd2c 100644
--- a/fs/fs-writeback.c
+++ b/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)
{