Hi Ted, Andreas and the list,
After the bigalloc-feature is completed in ext4, we could have much more
big size of block-group (also bigger continuous space), but the extent
structure of files now limit the extent size below 128MB, which is not
optimal.
We could solve the problem by creating a new extent format to support
larger extent size, which looks like this:
struct ext4_extent2 {
__le64 ee_block; /* first logical block extent covers */
__le64 ee_start; /* starting physical block */
__le32 ee_len; /* number of blocks covered by extent */
__le32 ee_flags; /* flags and future extension */
};
struct ext4_extent2_idx {
__le64 ei_block; /* index covers logical blocks from 'block' */
__le64 ei_leaf; /* pointer to the physical block of the next level */
__le32 ei_flags; /* flags and future extension */
__le32 ei_unused; /* padding */
};
I think we could keep the structure of ext4_extent_header and add new
imcompat flag EXT4_FEATURE_INCOMPAT_EXTENTS2.
The new extent format could support 16TB continuous space and larger volumes.
What's your opinion?
--
--
Best Regard
Robin Dong
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