ext4: Don't allow nonextenst mount option for large filesystem From: "Aneesh Kumar K.V" 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 Signed-off-by: Mingming Cao Signed-off-by: "Theodore Ts'o" --- fs/ext4/super.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) Index: linux-2.6.26-rc9/fs/ext4/super.c =================================================================== --- linux-2.6.26-rc9.orig/fs/ext4/super.c 2008-07-11 16:05:15.000000000 -0700 +++ linux-2.6.26-rc9/fs/ext4/super.c 2008-07-11 16:05:16.000000000 -0700 @@ -1004,6 +1004,7 @@ static int parse_options (char *options, 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: