[PATCH] ext4: retry failed direct IO allocations

On a 256M filesystem, doing this in a loop:

        xfs_io -F -f -d -c 'pwrite 0 64m' test
        rm -f test

eventually leads to ENOSPC.  (the xfs_io command does a
64m direct IO write to the file "test")

As with other block allocation callers, it looks like we need to
potentially retry the allocations on the initial ENOSPC.
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -3378,6 +3378,7 @@ static ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
 	ssize_t ret;
 	int orphan = 0;
 	size_t count = iov_length(iov, nr_segs);
+	int retries = 0;
 
 	if (rw == WRITE) {
 		loff_t final_size = offset + count;
@@ -3400,9 +3401,12 @@ static ssize_t ext4_ind_direct_IO(int rw, struct kiocb *iocb,
 		}
 	}
 
+retry:
 	ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
 				 offset, nr_segs,
 				 ext4_get_block, NULL);
+	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
+		goto retry;
 
 	if (orphan) {
 		int err;