Badari Pulavarty <[EMAIL PROTECTED]> writes: > On Tue, 2005-04-19 at 04:22, Nikita Danilov wrote: >> Badari Pulavarty <[EMAIL PROTECTED]> writes: >> >> [...] >> >> > >> > Yes. Its possible to do what you want to. I am currently working on >> > adding "delayed allocation" support to ext3. As part of that, We >> >> As you most likely already know, Alex Thomas already implemented delayed >> block allocation for ext3. > > Yep. I reviewed Alex Thomas patches for delayed allocation. He handled > all the cases in his code and did NOT use any mpage* routines to do > the work. I was hoping to change the mpage infrastructure to handle > these, so that every filesystem doesn't have to do their thing. >
Just keep in mind that filesystem != ext3. :-) Generic support makes sense only when it is usable by multiple file systems. This is not always possible, e.g., there is no "generic block allocator" for precisely the same reason: disk space allocation policies are tightly intertwined with the rest of file system internals. > >> >> > >> > In order to do the correct accounting, we need to mark a page >> > to indicate if we reserved a block or not. One way to do this, >> > to use page->private to indicate this. But then, all the generic >> >> I believe one can use PG_mappedtodisk bit in page->flags for this >> purpose. There was old Andrew Morton's patch that introduced new bit >> (PG_delalloc?) for this purpose. > > That would be good. But I don't feel like asking for a bit in page > if there is a way to get around it. Clarification: PG_mappedtodisk is already here, it seems you can reuse this already existing bit to implement delayed allocation support. > [...] >> > > Need to think some more. I guess you thought about this more than you > do :) > > Thanks, > Badari > Nikita. - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
