On Feb 11, 2005 20:52 +0000, Stephen C. Tweedie wrote:
> /*
> * Maximal file size. There is a direct, and {,double-,triple-}indirect
> * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
> * We need to be 1 filesystem block less than the 2^32 sector limit.
> */
>
> Trouble is, that limit *should* be an i_blocks limit, because i_blocks
> is still 32-bits, and (more importantly) is multiplied by the fs
> blocksize / 512 in stat(2) to return st_blocks in 512-byte chunks.
> Overflow 2^32 sectors in i_blocks and stat(2) wraps.I agree. The problem AFAIR is that the i_blocks accounting is done in the quota code, so it was a challenge to get it right, and the i_size limit was easier to do. Until now I don't think anyone has created dense 2TB files, so the sparse limit was enough. Fixing this to count i_blocks correctly would also allow us to have larger sparse files (up to the indirect limit). Note also that there was a patch to extend i_blocks floating around (pretty small hack to use one of the reserved fields), and it might make sense to get this into the kernel before we actually need it. > But i_blocks includes indirect blocks as well as data, so for a > non-sparse file we wrap stat(2) st_blocks well before the file is > 2^32*512 bytes long. Yet ext3_max_size() doesn't understand this: > it simply caps the size with > > if (res > (512LL << 32) - (1 << bits)) > res = (512LL << 32) - (1 << bits); So, for the quick fix we could reduce this by the number of expected [td]indirect blocks and submit that to 2.4 also. Cheers, Andreas -- Andreas Dilger http://sourceforge.net/projects/ext2resize/ http://members.shaw.ca/adilger/ http://members.shaw.ca/golinux/
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