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26458409a9
Pull vfs cachefiles updates from Christian Brauner:
"This contains improvements for on-demand cachefiles.
If the daemon crashes and the on-demand cachefiles fd is unexpectedly
closed in-flight requests and subsequent read operations associated
with the fd will fail with EIO. This causes issues in various
scenarios as this failure is currently unrecoverable.
The work contained in this pull request introduces a failover mode and
enables the daemon to recover in-flight requested-related objects. A
restarted daemon will be able to process requests as usual.
This requires that in-flight requests are stored during daemon crash
or while the daemon is offline. In addition, a handle to
/dev/cachefiles needs to be stored.
This can be done by e.g., systemd's fdstore (cf. [1]) which enables
the restarted daemon to recover state.
Three new states are introduced in this patchset:
(1) CLOSE
Object is closed by the daemon.
(2) OPEN
Object is open and ready for processing. IOW, the open request
has been handled successfully.
(3) REOPENING
Object has been previously closed and is now reopened due to a
read request.
A restarted daemon can recover the /dev/cachefiles fd from systemd's
fdstore and writes "restore" to the device. This causes the object
state to be reset from CLOSE to REOPENING and reinitializes the
object.
The daemon may now handle the open request. Any in-flight operations
are restored and handled avoiding interruptions for users"
Link: https://systemd.io/FILE_DESCRIPTOR_STORE [1]
* tag 'vfs-6.8.cachefiles' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
cachefiles: add restore command to recover inflight ondemand read requests
cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode
cachefiles: resend an open request if the read request's object is closed
cachefiles: extract ondemand info field from cachefiles_object
cachefiles: introduce object ondemand state
Linux kernel
============
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
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Please read the Documentation/process/changes.rst file, as it contains the
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