This is version 2 of a patch series that limits LAYOUTGET invocation to the beginning of the IO paths. It is intended for the pnfs_submit branch, without reversion in a post_submit branch. Patches 1-4 revert direct IO. Commit is already broken, and this series breaks them further. The problem is that the direct IO redefines data->wb_req and data->pages, so that it can only work with the pnfs code if we don't look at those fields. The reverted code should be saved somewhere. I tend to agree with Boaz that keeping it in git is preferable, but I can supply a patch which returns the code ifdef'ed out if tht is preferred. Patches 5-9 do some code cleanup in preperation for the real work. Patches 10-21 implement the change. NOTE that patch 20 changes the calling convention of the layout drivers commit calls. There is no longer a universal lseg for the commit, instead each nfs_page has an lseg attached, with NULL meaning to go through the MDS. Patches 22-26 rework the filelayout commit function, and then do some other code cleanup. The basic idea of these patches is as follows: We attempt to grab a lseg (possibly invoking LAYOUTGET) early in the IO. If we succeed, we refcount and stash it, using it through the rest of the io. If we fail, we revert to straight nfs, even if the area becomes covered by a layout due to other io. The tricky, though hopefully anomalous, case is when we start without the layout, but have it at this particular stage of the IO. We ignore this for the moment at write_pages, which will cause block and object to issue CB_LAYOUTRECALL. At commit, it is tricky to handle, but since block doesn't use commit, and file needs to handle complicated splitting anyway, I just push all complicated decisions of splitting commit between nfs (for IO started without layout) and pnfs to the driver. Fred -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
