On 6/4/21 11:13 AM, Max Reitz wrote:
> Hi,
>
> This is the C virtiofsd equivalent to
> https://gitlab.com/virtio-fs/virtiofsd-rs/-/merge_requests/26. As such,
> the summary is pretty much the same:
>
> Storing an O_PATH file descriptor in every lo_inode object means we have
> a lot of FDs open, which is sometimes bad. This series adds an option
> (-o inode_file_handles) that will make virtiofsd attempt to generate a
> file handle for new inodes and store that instead of an FD. When an FD
> is needed for a given inode, we open the handle.
>
> To accomplish this, lo_inode.fd is should not be accessed directly
> anymore, but only through helper functions (mainly lo_inode_fd() and
> lo_inode_open()). A TempFd object is added to hide the difference
> between FDs that are bound to the lo_inode object (and so need not be
> closed after use) and temporary FDs from open_by_handle_at() (which do
> need to be closed after use).
>
> To prevent the problem I spent a long time talking about (if we don’t
> have an FD open for every inode, the inode can be deleted, its ID
> reused, and then the lookup in lo_data.inodes will find the old deleted
> inode), patch 7 adds a second hash table lo_data.inodes_by_handle that
> maps file handles to lo_inode objects. (Because file handles include a
> generation ID, so we can discern between the old and the new inode.)
>
> Patch 9 is completely optional, but I just really felt compelled to
> write it.
>
>
> Max Reitz (9):
> virtiofsd: Add TempFd structure
> virtiofsd: Use lo_inode_open() instead of openat()
> virtiofsd: Add lo_inode_fd() helper
> virtiofsd: Let lo_fd() return a TempFd
> virtiofsd: Let lo_inode_open() return a TempFd
> virtiofsd: Add lo_inode.fhandle
> virtiofsd: Add inodes_by_handle hash table
> virtiofsd: Optionally fill lo_inode.fhandle
> virtiofsd: Add lazy lo_do_find()
>
> tools/virtiofsd/helper.c | 3 +
> tools/virtiofsd/passthrough_ll.c | 809 +++++++++++++++++++++-----
> tools/virtiofsd/passthrough_seccomp.c | 2 +
> 3 files changed, 667 insertions(+), 147 deletions(-)
>
For the series:
Reviewed-by: Connor Kuehl <ckuehl@redhat.com>