ext4: make sure ext4_has_free_blocks returns 0 for ENOSPC

From: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Fix ext4_has_free_blocks() to return 0 when we don't have enough space.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

 fs/ext4/balloc.c |    3 +++
 1 file changed, 3 insertions(+)

Index: linux-2.6.27-rc3/fs/ext4/balloc.c
===================================================================
--- linux-2.6.27-rc3.orig/fs/ext4/balloc.c	2008-08-18 11:38:07.000000000 -0700
+++ linux-2.6.27-rc3/fs/ext4/balloc.c	2008-08-18 11:40:12.000000000 -0700
@@ -1626,6 +1626,9 @@ ext4_fsblk_t ext4_has_free_blocks(struct
 		free_blocks =
 			percpu_counter_sum_and_set(&sbi->s_freeblocks_counter);
 #endif
+	if (free_blocks <= root_blocks)
+		/* we don't have free space */
+		return 0;
 	if (free_blocks - root_blocks < nblocks)
 		return free_blocks - root_blocks;
 	return nblocks;