ext4: fix hot spins in mballoc after err_freebuddy and err_freemeta

In ext4_mb_init_backend() 'i' is of type ext4_group_t. Since unsigned, i
>= 0 is always true, so fix hot spins after err_freebuddy: and -meta:
and prevent decrements when zero.

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 3 insertions, 5 deletions

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 11e1fd59acbd..fbec2ef93797 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -2272,13 +2272,13 @@ static int ext4_mb_init_backend(struct super_block *sb)
                 meta_group_info[j] = kzalloc(len, GFP_KERNEL);
                 if (meta_group_info[j] == NULL) {
                         printk(KERN_ERR "EXT4-fs: can't allocate buddy mem\n");
-                        i--;
                         goto err_freebuddy;
                 }
                 desc = ext4_get_group_desc(sb, i, NULL);
                 if (desc == NULL) {
                         printk(KERN_ERR
                                 "EXT4-fs: can't read descriptor %lu\n", i);
+                        i++;
                         goto err_freebuddy;
                 }
                 memset(meta_group_info[j], 0, len);
@@ -2318,13 +2318,11 @@ static int ext4_mb_init_backend(struct super_block *sb)
         return 0;
 
 err_freebuddy:
-        while (i >= 0) {
+        while (i-- > 0)
                 kfree(ext4_get_group_info(sb, i));
-                i--;
-        }
         i = num_meta_group_infos;
 err_freemeta:
-        while (--i >= 0)
+        while (i-- > 0)
                 kfree(sbi->s_group_info[i]);
         iput(sbi->s_buddy_cache);
 err_freesgi: