On Mon, Apr 23, 2018 at 11:19:40PM -0700, Omar Sandoval wrote: > From: Omar Sandoval <osandov@xxxxxx> > > Hi, Al, > > This is a respin of my linkat() AT_REPLACE series, previously posted > here: > > https://patchwork.kernel.org/patch/9636735/ > https://patchwork.kernel.org/patch/9636733/ > > There are no changes since v2, only a rebase onto v4.17-rc2 and some > minor additions to the commit messages. > > The goal is to allow for updating a file atomically in-place with an > O_TMPFILE like so: > > - open temporary file with O_TMPFILE > - write temporary file contents > - fsync temporary file > - atomically replace permanent location with the temporary file > - fsync parent directory > > Patch 1 implements the VFS support for this flag. The implementation > resembles sys_renameat2(), and I took care to preserve all of the > original error cases and make the new error cases consistent with > rename. > > Previously, we discussed extending renameat2() instead of linkat() for > this, but this makes a mess of rename and also forces us to special-case > the parent directory for O_TMPFILEs in implementations of > i_op->rename(), so I still think linkat() is a better fit. > > Patch 2 adds support for AT_REPLACE to Btrfs. That's the codebase I'm > most familiar with so that's where I started, but it should be > straightforward to implement for other filesystems. v1 of this series > had some incorrect dentry fiddling, so now I just unhash the replaced > dentry for simplicity. > > Please take a look. > > Thanks! Ping, Al, can you take a look?
