Messages in this thread | | | From | "Takashi Sato" <> | Subject | Re: stat64 for over 2TB file returned invalid st_blocks | Date | Fri, 2 Dec 2005 22:18:04 +0900 |
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Hi,
> > Hi all, > > > > I found a problem at stat64 on 32bit architecture. > > > > When I called stat64 for a file which is larger than 2TB, stat64 > > returned an invalid number of blocks at st_blocks on 32bit > > architecture, although it returned a valid number of blocks on 64bit > > architecture(ia64). > > For jfs, it's a bigger problem than just stat64. When writing the inode > to disk, jfs calculates the number of blocks from the 32-bit value: > dip->di_nblocks = cpu_to_le64(PBLK2LBLK(ip->i_sb, ip->i_blocks)) > > So it won't only report the wrong number of blocks, but it will actually > store the wrong number. :-(
I also found another problem on generic quota code. In dquot_transfer(), the file usage is calculated from i_blocks via inode_get_bytes(). If the file is over 2TB, the change of usage is less than expected.
To solve this problem, I think inode.i_blocks should be 8 byte.
>> 2. Change the type of architecture dependent stat64.st_blocks in >> include/asm/asm-*/stat.h from unsigned long to unsigned long long. >> I tried modifying only stat64 of 32bit architecture >> (include/asm-i386/stat.h). > >This changes the API, but the structure does suggest that the 4-byte pad >should be used for the high-order bytes of st_blocks, so that's not >really a problem. A correct fix would replace __pad4 with >st_blocks_high (or something like that) and ensure that the high-order >word was stored there. Your proposed fix would only be correct on >little-endian hardware, as Jörn pointed out.
Thank you for your advice. I'll research for glibc and consider how to implement. By the way I think, as Avi Kivity said, it's always little-endian on i386, is it correct?
-- Takashi Sato
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