1 files changed, 26 insertions, 2 deletions

diff --git a/fs/sync.c b/fs/sync.c
index ba76b9623e7e..c38ec163da6c 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -7,6 +7,7 @@
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/namei.h>
 #include <linux/sched.h>
 #include <linux/writeback.h>
 #include <linux/syscalls.h>
@@ -33,7 +34,7 @@ static int __sync_filesystem(struct super_block *sb, int wait)
          * This should be safe, as we require bdi backing to actually
          * write out data in the first place
          */
-        if (!sb->s_bdi || sb->s_bdi == &noop_backing_dev_info)
+        if (sb->s_bdi == &noop_backing_dev_info)
                 return 0;
 
         if (sb->s_qcop && sb->s_qcop->quota_sync)
@@ -79,7 +80,7 @@ EXPORT_SYMBOL_GPL(sync_filesystem);
 
 static void sync_one_sb(struct super_block *sb, void *arg)
 {
-        if (!(sb->s_flags & MS_RDONLY) && sb->s_bdi)
+        if (!(sb->s_flags & MS_RDONLY))
                 __sync_filesystem(sb, *(int *)arg);
 }
 /*
@@ -128,6 +129,29 @@ void emergency_sync(void)
         }
 }
 
+/*
+ * sync a single super
+ */
+SYSCALL_DEFINE1(syncfs, int, fd)
+{
+        struct file *file;
+        struct super_block *sb;
+        int ret;
+        int fput_needed;
+
+        file = fget_light(fd, &fput_needed);
+        if (!file)
+                return -EBADF;
+        sb = file->f_dentry->d_sb;
+
+        down_read(&sb->s_umount);
+        ret = sync_filesystem(sb);
+        up_read(&sb->s_umount);
+
+        fput_light(file, fput_needed);
+        return ret;
+}
+
 /**
  * vfs_fsync_range - helper to sync a range of data & metadata to disk
  * @file:               file to sync