On Fri 14-05-10 16:41:45, Dave Chinner wrote: ... > Well, the "RESERVE" callout I proposed should mean that the > allocation that follows the copy should never fail with ENOSPC. i.e. > if there isn't space, the RESERVE call will fail with ENOSPC, not > the actual ALLOCATE call that occurs after the data is copied. > > Basically I was thinking that in the XFS case, RESERVE would scan the > range for holes, and reserve all blocks needed to fill all the holes > in the range. Then the ALLOCATE call would mark them all delalloc. > The space reservation and delalloc is done in a single call right > now, but splitting them is not hard... But this would mean that you would have to implement at least a basic delayed allocation support for filesystems like ext2, ext3, udf, vfat, etc. They currently do not have a way to provide a functionality you require from RESERVE call... Not that it would be so hard to do - I actually have some patches for ext2/3 doing that because of problems with ENOSPC during mmaped writes but it's not completely trivial either. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
