Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: Patch up how we claim metadata blocks for quota purposes
  ext4: Ensure zeroout blocks have no dirty metadata
  ext4: return correct wbc.nr_to_write in ext4_da_writepages
  ext4: Update documentation to correct the inode_readahead_blks option name
  jbd2: don't use __GFP_NOFAIL in journal_init_common()
  ext4: flush delalloc blocks when space is low
  fs-writeback: Add helper function to start writeback if idle
  ext4: Eliminate potential double free on error path
  ext4: fix unsigned long long printk warning in super.c
  ext4, jbd2: Add barriers for file systems with exernal journals
  ext4: replace BUG() with return -EIO in ext4_ext_get_blocks
  ext4: add module aliases for ext2 and ext3
  ext4: Don't ask about supporting ext2/3 in ext4 if ext4 is not configured
  ext4: remove unused #include <linux/version.h>

1 files changed, 17 insertions, 0 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 49bc1b8e8f19..f6c2155e0026 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1187,6 +1187,23 @@ void writeback_inodes_sb(struct super_block *sb)
 EXPORT_SYMBOL(writeback_inodes_sb);
 
 /**
+ * writeback_inodes_sb_if_idle  -       start writeback if none underway
+ * @sb: the superblock
+ *
+ * Invoke writeback_inodes_sb if no writeback is currently underway.
+ * Returns 1 if writeback was started, 0 if not.
+ */
+int writeback_inodes_sb_if_idle(struct super_block *sb)
+{
+        if (!writeback_in_progress(sb->s_bdi)) {
+                writeback_inodes_sb(sb);
+                return 1;
+        } else
+                return 0;
+}
+EXPORT_SYMBOL(writeback_inodes_sb_if_idle);
+
+/**
  * sync_inodes_sb       -       sync sb inode pages
  * @sb: the superblock
  *