Hi Kazuya, I am really sorry for late answer. I think you're partly right. my solution is not good, but I still think that your is not good as well. I need to look at this again and more closely, sorry. What do you think about this: ext4_ext_next_allocated_block() should return next allocated block, however instead it in some cases returns EXT_MAX_BLOCK, which points at the last logical block in a file, which however in some cases might be equal to the last not allocated block, not first allocated block in subsequent extent. And boom, we have (next == lblock). So if we want to really return next allocated block (or more specifically, next block which we can not allocate), we should in those cases return EXT_MAX_BLOCK+1. And we should do this in ext4_ext_put_gap_in_cache() as well when there is no extent yet. Also note that as I said EXT_MAX_BLOCK means maximum logical block, however we use it as lenght in ext4_ext_put_gap_in_cache() which does not sound right either. It seems all a little bit messy :-/. I need to look at it and try it to see if it would work, but I think it does make sense. What do you think? Thanks! -Lukas On Tue, 24 May 2011, Kazuya Mio wrote: > Hi Lukas, > How do you think about my comment? > > Regards, > Kazuya Mio > > 2011/05/13 17:55, Kazuya Mio wrote: > > 2011/05/13 15:36, Lukas Czerner wrote: > >> That is because due to defensive programming we planted a lot of > >> BUG_ON's to prevent the length of the gap cache to be zero, but in this > >> case it actually will be zero, because there will be no gap at the end > >> of the file. > > > > Um, I think there is a block (blocksize -1 byte) in gap. > > And this gap should be used for the next block searching. > > According to ext4_ext_in_cache(), len=0 means the special case > > which we have no cache extent, so len=0 should be disallowed. > > > > Moreover, if we create the file which has 2^32-1 offset, > > we can't get extent which starts from this offset with FIEMAP ioctl. > > That's why I think the maximum file size should be 2^32-1 * blocksize. > > > > Regards, > > Kazuya Mio > -- -- 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
