On Tue, Jan 15 2008, Jens Axboe wrote: > On Mon, Jan 14 2008, Jens Axboe wrote: > > On Mon, Jan 14 2008, Chris Mason wrote: > > > Hello everyone, > > > > > > Here is a modified version of Jens' patch. The basic idea is to push > > > the mapping maintenance out of loop and down into the filesystem (ext2 > > > in this case). > > > > > > Two new address_space operations are added, one to map > > > extents and the other to provide call backs into the FS as io is > > > completed. > > > > > > Still TODO for this patch: > > > > > > * Add exclusion between filling holes and readers. This is partly > > > implemented, when a hole is filled by the FS, the extent is flagged as > > > having a hole. The idea is to check this flag before trying to read > > > the blocks and just send back all zeros. > > > > > > The flag would be cleared when the blocks filling the hole have been > > > written. > > > > > > * Exclude page cache readers and writers > > > > > > * Add a way for the FS to request a commit before telling the higher > > > layers the IO is complete. This way we can make sure metadata related > > > to holes is on disk before claiming the IO is really done. COW based > > > filesystems will also needed it. > > > > > > * Change loop to use fast mapping only when the new address_space op is > > > provided (whoops, forgot about this until just now) > > > > > > * A few other bits for COW, not really relevant until there > > > is...something COW using it. > > > > Looks pretty good. Essentially the loop side is 100% the same, it just > > offloads the extent ownership to the fs (where it belongs). So I like > > it. Attaching a small cleanup/fixup patch for loop, don't think it needs > > further explanations. > > > > One suggestion - free_extent_map(), I would call that put_extent_map() > > instead. > > I split and merged the patch into five bits (added ext3 support), so > perhaps that would be easier for people to read/review. Attached and > also exist in the loop-extent_map branch here: > > http://git.kernel.dk/?p=linux-2.6-block.git;a=shortlog;h=loop-extent_map Seems my ext3 version doesn't work, it craps out in ext3_get_blocks_handle() triggering this bug: J_ASSERT(handle != NULL || create == 0); I'll see if I can fix that, being fairly fs ignorant... -- Jens Axboe - 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
