Revert "mke2fs: prevent creation of unmountable ext4 with large flex_bg count"

This reverts commit d988201ef9cb6f7b521e544061976ab4270a3f89.

The problem with this commit is that causes common small file system
configurations to fail.  For example:

    mke2fs -O flex_bg -b 4096 -I 1024 -F /tmp/tt 79106
    mke2fs 1.42.11 (09-Jul-2014)
    /tmp/tt: Invalid argument passed to ext2 library while setting
             up superblock

This check in ext2fs_initialize() was added to prevent the metadata
from being allocated beyond the end of the filesystem, but it is
also causing a wide range of failures for small filesystems.

We'll address this in a different way, by using a smarter algorithm
for deciding the layout of metadata blocks for the last flex block
group.

Reported-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/lib/ext2fs/initialize.c b/lib/ext2fs/initialize.c
index de358fd..36c94a9 100644 (file)
--- a/lib/ext2fs/initialize.c
+++ b/lib/ext2fs/initialize.c
@@ -91,10 +91,8 @@ errcode_t ext2fs_initialize(const char *name, int flags,
        unsigned int    rem;
        unsigned int    overhead = 0;
        unsigned int    ipg;
-       unsigned int    flexbg_size;
        dgrp_t          i;
        blk64_t         free_blocks;
-       blk64_t         flexbg_overhead;
        blk_t           numblocks;
        int             rsv_gdt;
        int             csum_flag;
@@ -421,28 +419,6 @@ ipg_retry:
        }
 
        /*
-        * Calculate the flex_bg related metadata blocks count.
-        * It includes the boot block, the super block,
-        * the block group descriptors, the reserved gdt blocks,
-        * the block bitmaps, the inode bitmaps and the inode tables.
-        * This is a simple check, so that the backup superblock and
-        * other feature related blocks are not considered.
-        */
-       flexbg_size = 1 << fs->super->s_log_groups_per_flex;
-       flexbg_overhead = super->s_first_data_block + 1 +
-               fs->desc_blocks + super->s_reserved_gdt_blocks +
-               (__u64)flexbg_size * (2 + fs->inode_blocks_per_group);
-
-       /*
-        * Disallow creating ext4 which breaks flex_bg metadata layout
-        * obviously.
-        */
-       if (flexbg_overhead > ext2fs_blocks_count(fs->super)) {
-               retval = EXT2_ET_INVALID_ARGUMENT;
-               goto cleanup;
-       }
-
-       /*
         * At this point we know how big the filesystem will be.  So
         * we can do any and all allocations that depend on the block
         * count.