ext4: add more paranoia checking in ext4_expand_extra_isize handling

[linux-block.git] / fs / ext4 / super.c

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 7796e2ffc29425444d7eb65ecf48c88b572b675e..71af8780d4ee118c2ef93e0d6ae3e988f154bd46 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3545,12 +3545,15 @@ static void ext4_clamp_want_extra_isize(struct super_block *sb)
 {
        struct ext4_sb_info *sbi = EXT4_SB(sb);
        struct ext4_super_block *es = sbi->s_es;
+       unsigned def_extra_isize = sizeof(struct ext4_inode) -
+                                               EXT4_GOOD_OLD_INODE_SIZE;
 
-       /* determine the minimum size of new large inodes, if present */
-       if (sbi->s_inode_size > EXT4_GOOD_OLD_INODE_SIZE &&
-           sbi->s_want_extra_isize == 0) {
-               sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
-                                                    EXT4_GOOD_OLD_INODE_SIZE;
+       if (sbi->s_inode_size == EXT4_GOOD_OLD_INODE_SIZE) {
+               sbi->s_want_extra_isize = 0;
+               return;
+       }
+       if (sbi->s_want_extra_isize < 4) {
+               sbi->s_want_extra_isize = def_extra_isize;
                if (ext4_has_feature_extra_isize(sb)) {
                        if (sbi->s_want_extra_isize <
                            le16_to_cpu(es->s_want_extra_isize))
@@ -3563,10 +3566,10 @@ static void ext4_clamp_want_extra_isize(struct super_block *sb)
                }
        }
        /* Check if enough inode space is available */
-       if (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize >
-                                                       sbi->s_inode_size) {
-               sbi->s_want_extra_isize = sizeof(struct ext4_inode) -
-                                                      EXT4_GOOD_OLD_INODE_SIZE;
+       if ((sbi->s_want_extra_isize > sbi->s_inode_size) ||
+           (EXT4_GOOD_OLD_INODE_SIZE + sbi->s_want_extra_isize >
+                                                       sbi->s_inode_size)) {
+               sbi->s_want_extra_isize = def_extra_isize;
                ext4_msg(sb, KERN_INFO,
                         "required extra inode space not available");
        }