Messages in this thread | | | Date | Mon, 20 Mar 2006 00:20:37 -0700 | From | Andreas Dilger <> | Subject | Re: [Ext2-devel] [PATCH 1/4] ext2/3: Extends the max file size(ext2 in kernel) |
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On Mar 18, 2006 22:01 +0900, sho@tnes.nec.co.jp wrote: > The unit of ext2/ext3_inode.i_blocks is sector(512B) and the variable > size is 4bytes, so it limits the max file size to 2TB. > I found that i_blocks is always counted with rounding up to the file > system block size and does not have fractions. So we can change the > unit of ext2/ext3_inode.i_blocks from sector to block size. > This change extends the maximum file size as below. > > - Add new compatible flag "EXT2_FEATURE_INCOMPAT_LARGE_BLOCK". > It indicates that the file size is extended. > > - If the flag is set in the super block, ext2_inode.i_blocks is > translated into the number of sectors and set to i_blocks of VFS > inode. And, if not, ext2_inode.i_blocks is passed to i_blocks > of VFS inode as it is. > > - If the flag is set, the limit of the max file size defined in > ext2_max_size() is set to block size * 2G-1(2^31-1).
Instead of breaking all filesystems that need to create large files, the patch should instead set "i_flags | EXT2_LARGEBLK_FL" only on inodes that are larger than 2TB and use "blocksize" i_blocks on those files.
This preserves compatibility with existing filesystems and doesn't impose any breakage opon an existing filesystem for anyone who wants to use this feature.
Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc.
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