ext4: Don't allow nonextenst mount option for large filesystem
Aneesh Kumar K.V [Fri, 11 Jul 2008 23:27:31 +0000 (19:27 -0400)]
The block mapped inode format can address only blocks within 2**32. This
causes a number of issues, the biggest of which is that the block
allocator needs to be taught that certain inodes can not utilize block
numbers > 2**32.  So until this is fixed, it is simplest to fail
mounting of file systems with more than 2**32 blocks if the -o noextents
option is given.

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/super.c

index 4e104dd..2bf9cdd 100644 (file)
@@ -1004,6 +1004,7 @@ static int parse_options (char *options, struct super_block *sb,
        int qtype, qfmt;
        char *qname;
 #endif
+       ext4_fsblk_t last_block;
 
        if (!options)
                return 1;
@@ -1326,6 +1327,20 @@ set_qf_format:
                        set_opt (sbi->s_mount_opt, EXTENTS);
                        break;
                case Opt_noextents:
+                       /*
+                        * When e2fsprogs support resizing an already existing
+                        * ext3 file system to greater than 2**32 we need to
+                        * add support to block allocator to handle growing
+                        * already existing block  mapped inode so that blocks
+                        * allocated for them fall within 2**32
+                        */
+                       last_block = ext4_blocks_count(sbi->s_es) - 1;
+                       if (last_block  > 0xffffffffULL) {
+                               printk(KERN_ERR "EXT4-fs: Filesystem too "
+                                               "large to mount with "
+                                               "-o noextents options\n");
+                               return 0;
+                       }
                        clear_opt (sbi->s_mount_opt, EXTENTS);
                        break;
                case Opt_i_version: