A new combined tree for storage subsystems

One of the outcomes from this year's Linux Storage and Filesystem Summit was a plan to create a combined tree to help ease the process of integrating changes to various storage subsystems. At the summit, James Bottomley "volunteered" himself to put the tree together, and that came to fruition with his announcement of the tree on September 10. Paralleling the discussion at the summit, there is still the lingering belief that more than just an automatically generated tree may be needed.

The tree currently collects patches from several subsystem trees, scsi, libata, and block, along with patches from the dm quilt repository. It is being automatically pulled and built nightly, much like linux-next. It will also be rebased daily against the mainline which will make it somewhat harder for kernel hackers to use—also like linux-next. Because of that, Dave Chinner didn't really see the storage-tree as being all that useful: "I really don't see a tree like this getting wide use - if I enjoyed the pain of rebasing against throw-away merge trees every day, then I'd already be using linux-next."

Bottomley acknowledged that complaint, noting that using linux-next had been suggested at the summit, but pointed out that the storage-tree is a much smaller target than linux-next: "The diffs to mainline in the current storage tree are still under a megabyte." Bottomley also noted that the summit participants were a bit skeptical that a tree without a "storage maintainer" to oversee it (a la Dave Miller's networking tree) might not prove to solve the problem, which was one of Chinner's concerns as well.

But there are political considerations too. "Unlike net, storage has never had a single maintainer, so it's a bit more political than just doing that by fiat", Bottomley said. Chinner was of the opinion that the summit is the obvious place to have made a decision to appoint a storage maintainer, even if all of the current maintainers of the storage subsystems were not present. But its clear that those who were present wanted to move slowly, as Bottomley described:

The tree is available at git://git.kernel.org/pub/scm/linux/kernel/git/jejb/storage-tree. The nightly diffs from the mainline and log of the pull script are available as well. It is likely to take a bit of time to see if the storage-tree solves the problem with integration of cross-storage-subsystem changes, but it does provide a good starting point.