So I've started looking at this patch series, and I'm wondering if it might be better if we collapse these two feature flags: EXT4_FEATURE_RO_COMPAT_METADATA_CSUM and EXT4_FEATURE_INCOMPAT_BG_USE_META_CSUM To a single feature flag, EXT4_FEATURE_INCOMPAT_METADATA_CSUM, which also implies EXT4_FEATURE_RO_COMPAT_GDT_CSUM. (So in the future, when we enable INCOMPAT_CSUM_METADATA, the presense or absence of EXT4_RO_COMPAT_GDT_CSUM won't matter, and in fact mke2fs will skip setting that feature flag altogether. Tune2fs could also drop the GDT_CSUM flag when adding the CSUM_METADATA flag.) The reasoning behind this is that it simplifies the combinatorics we need to test, and it also simplifies our code base. In addition, it's really easy to make tune2fs recalculate the checksums when the feature flag is set, and reculate the block group checksums using the old algorithm when the metadata flag is unset. So if someone wants to mount the file system on a downlevel kernel, it's really not that bad that this feature is an INCOMPAT feature; we can easily downgrade it using tune2fs. In fact, if we wanted to take this to extremes, we could call it EXT4_FEATURE_INCOMPAT_NEW_METADATA, and then let it imply the following feature flags as well: EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER EXT4_FEATURE_RO_COMPAT_LARGE_FILE EXT4_FEATURE_RO_COMPAT_HUGE_FILE EXT4_FEATURE_RO_COMPAT_DIR_NLINK EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE EXT4_FEATURE_INCOMPAT_FILETYPE EXT4_FEATURE_INCOMPAT_FLEX_BG We can add inline functions in fs/ext4/ext4.h and in lib/ext2fs/ext2fs.h to make the source code look a bit simpler. This would help to reduce our testing load, and it would also make the output of dumpe2fs easier to understand... - 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
