[PATCH V6 RESEND 0/5] cachefiles: Introduce failover mechanism for on-demand mode

[Christian Brauner]

On Mon, 20 Nov 2023 12:14:17 +0800, Jia Zhu wrote:
> Changes since v5:
> In cachefiles_daemon_poll(), replace xa_for_each_marked with xas_for_each_marked.
> 
> [Background]
> ============
> In the on-demand read mode, if user daemon unexpectedly closes an on-demand fd
> (for example, due to daemon crashing), subsequent read operations and inflight
> requests relying on these fd will result in a return value of -EIO, indicating
> an I/O error.
> While this situation might be tolerable for individual personal users, it
> becomes a significant concern when it occurs in a real public cloud service
> production environment (like us).  Such I/O errors will be propagated to cloud
> service users, potentially impacting the execution of their jobs and
> compromising the overall stability of the cloud service.  Besides, we have no
> way to recover this.
> 
> [...]

Applied to the vfs.fscache branch of the vfs/vfs.git tree.
Patches in the vfs.fscache branch should appear in linux-next soon.

Please report any outstanding bugs that were missed during review in a
new review to the original patch series allowing us to drop it.

It's encouraged to provide Acked-bys and Reviewed-bys even though the
patch has now been applied. If possible patch trailers will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. If in doubt, please check the listed branch.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs.git
branch: vfs.fscache

[1/5] cachefiles: introduce object ondemand state
      https://git.kernel.org/vfs/vfs/c/357a18d03314
[2/5] cachefiles: extract ondemand info field from cachefiles_object
      https://git.kernel.org/vfs/vfs/c/3c5ecfe16e76
[3/5] cachefiles: resend an open request if the read request's object is closed
      https://git.kernel.org/vfs/vfs/c/0a7e54c1959c
[4/5] cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode
      https://git.kernel.org/vfs/vfs/c/b817e22b2e91
[5/5] cachefiles: add restore command to recover inflight ondemand read requests
      https://git.kernel.org/vfs/vfs/c/e73fa11a356c