1 files changed, 15 insertions, 7 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index d11d0289f3d2..6dcee88c2e5d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -404,20 +404,28 @@ static loff_t block_llseek(struct file *file, loff_t offset, int origin)
  *      NULL first argument is nfsd_sync_dir() and that's not a directory.
  */
  
-static int block_fsync(struct file *filp, struct dentry *dentry, int datasync)
+int blkdev_fsync(struct file *filp, struct dentry *dentry, int datasync)
 {
-        struct block_device *bdev = I_BDEV(filp->f_mapping->host);
+        struct inode *bd_inode = filp->f_mapping->host;
+        struct block_device *bdev = I_BDEV(bd_inode);
         int error;
 
-        error = sync_blockdev(bdev);
-        if (error)
-                return error;
-        
+        /*
+         * There is no need to serialise calls to blkdev_issue_flush with
+         * i_mutex and doing so causes performance issues with concurrent
+         * O_SYNC writers to a block device.
+         */
+        mutex_unlock(&bd_inode->i_mutex);
+
         error = blkdev_issue_flush(bdev, NULL);
         if (error == -EOPNOTSUPP)
                 error = 0;
+
+        mutex_lock(&bd_inode->i_mutex);
+
         return error;
 }
+EXPORT_SYMBOL(blkdev_fsync);
 
 /*
  * pseudo-fs
@@ -1481,7 +1489,7 @@ const struct file_operations def_blk_fops = {
         .aio_read       = generic_file_aio_read,
         .aio_write      = blkdev_aio_write,
         .mmap           = generic_file_mmap,
-        .fsync          = block_fsync,
+        .fsync          = blkdev_fsync,
         .unlocked_ioctl = block_ioctl,
 #ifdef CONFIG_COMPAT
         .compat_ioctl   = compat_blkdev_ioctl,