On Sat, Feb 26, 2011 at 09:20:55AM +0200, Amir Goldstein wrote: > Just to be clear, my alternative suggestion to on-disk format change was: > > __u32 s_log_block_size; /* Block size */ > - __s32 s_log_frag_size; /* Fragment size */ > + __s32 s_log_cluster_size; /* Allocation cluster size */ > - __u32 s_blocks_per_group; /* # Blocks per group */ > + __u32 s_clusters_per_group; /* # Clusters per group */ > - __u32 s_frags_per_group; /* # Fragments per group */ > + __u32 s_blocks_per_group; /* # Blocks per group */ > __u32 s_inodes_per_group; /* # Inodes per group */ > > This way, old kernels see a sane value in what used to be > s_blocks_per_group (32K) and new kernels (even without the BIGALLOC > feature) make sure to write correct values in both new > s_blocks_per_group and s_clusters_per_group (old s_blocks_per_group) Unfortunately, that's likely to confuse old kernels even more, since s_blocks_per_group is used to calculate the number of block groups, i.e. s_blocks_count / s_blocks_per_group. In BIGALLOC mode, the number of block groups go down, and so if we change s_blocks_per_group to s_clusters_per_group, it's likely to cause much mischief, for example in ext4_check_descriptors(). - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
