diff options
Diffstat (limited to 'Documentation/filesystems/caching/object.txt')
| -rw-r--r-- | Documentation/filesystems/caching/object.txt | 29 |
1 files changed, 18 insertions, 11 deletions
diff --git a/Documentation/filesystems/caching/object.txt b/Documentation/filesystems/caching/object.txt index e8b0a35d8fe..100ff41127e 100644 --- a/Documentation/filesystems/caching/object.txt +++ b/Documentation/filesystems/caching/object.txt @@ -127,9 +127,9 @@ fscache_enqueue_object()). PROVISION OF CPU TIME --------------------- -The work to be done by the various states is given CPU time by the threads of -the slow work facility (see Documentation/slow-work.txt). This is used in -preference to the workqueue facility because: +The work to be done by the various states was given CPU time by the threads of +the slow work facility. This was used in preference to the workqueue facility +because: (1) Threads may be completely occupied for very long periods of time by a particular work item. These state actions may be doing sequences of @@ -216,7 +216,14 @@ servicing netfs requests: The normal running state. In this state, requests the netfs makes will be passed on to the cache. - (6) State FSCACHE_OBJECT_UPDATING. + (6) State FSCACHE_OBJECT_INVALIDATING. + + The object is undergoing invalidation. When the state comes here, it + discards all pending read, write and attribute change operations as it is + going to clear out the cache entirely and reinitialise it. It will then + continue to the FSCACHE_OBJECT_UPDATING state. + + (7) State FSCACHE_OBJECT_UPDATING. The state machine comes here to update the object in the cache from the netfs's records. This involves updating the auxiliary data that is used @@ -225,13 +232,13 @@ servicing netfs requests: And there are terminal states in which an object cleans itself up, deallocates memory and potentially deletes stuff from disk: - (7) State FSCACHE_OBJECT_LC_DYING. + (8) State FSCACHE_OBJECT_LC_DYING. The object comes here if it is dying because of a lookup or creation error. This would be due to a disk error or system error of some sort. Temporary data is cleaned up, and the parent is released. - (8) State FSCACHE_OBJECT_DYING. + (9) State FSCACHE_OBJECT_DYING. The object comes here if it is dying due to an error, because its parent cookie has been relinquished by the netfs or because the cache is being @@ -241,27 +248,27 @@ memory and potentially deletes stuff from disk: can destroy themselves. This object waits for all its children to go away before advancing to the next state. - (9) State FSCACHE_OBJECT_ABORT_INIT. +(10) State FSCACHE_OBJECT_ABORT_INIT. The object comes to this state if it was waiting on its parent in FSCACHE_OBJECT_INIT, but its parent died. The object will destroy itself so that the parent may proceed from the FSCACHE_OBJECT_DYING state. -(10) State FSCACHE_OBJECT_RELEASING. -(11) State FSCACHE_OBJECT_RECYCLING. +(11) State FSCACHE_OBJECT_RELEASING. +(12) State FSCACHE_OBJECT_RECYCLING. The object comes to one of these two states when dying once it is rid of all its children, if it is dying because the netfs relinquished its cookie. In the first state, the cached data is expected to persist, and in the second it will be deleted. -(12) State FSCACHE_OBJECT_WITHDRAWING. +(13) State FSCACHE_OBJECT_WITHDRAWING. The object transits to this state if the cache decides it wants to withdraw the object from service, perhaps to make space, but also due to error or just because the whole cache is being withdrawn. -(13) State FSCACHE_OBJECT_DEAD. +(14) State FSCACHE_OBJECT_DEAD. The object transits to this state when the in-memory object record is ready to be deleted. The object processor shouldn't ever see an object in |