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Diffstat (limited to 'Documentation/filesystems/caching/netfs-api.txt')
| -rw-r--r-- | Documentation/filesystems/caching/netfs-api.txt | 46 |
1 files changed, 38 insertions, 8 deletions
diff --git a/Documentation/filesystems/caching/netfs-api.txt b/Documentation/filesystems/caching/netfs-api.txt index 7cc6bf2871eb..97e6c0ecc5ef 100644 --- a/Documentation/filesystems/caching/netfs-api.txt +++ b/Documentation/filesystems/caching/netfs-api.txt @@ -35,8 +35,9 @@ This document contains the following sections: (12) Index and data file update (13) Miscellaneous cookie operations (14) Cookie unregistration - (15) Index and data file invalidation - (16) FS-Cache specific page flags. + (15) Index invalidation + (16) Data file invalidation + (17) FS-Cache specific page flags. ============================= @@ -767,13 +768,42 @@ the cookies for "child" indices, objects and pages have been relinquished first. -================================ -INDEX AND DATA FILE INVALIDATION -================================ +================== +INDEX INVALIDATION +================== + +There is no direct way to invalidate an index subtree. To do this, the caller +should relinquish and retire the cookie they have, and then acquire a new one. + + +====================== +DATA FILE INVALIDATION +====================== + +Sometimes it will be necessary to invalidate an object that contains data. +Typically this will be necessary when the server tells the netfs of a foreign +change - at which point the netfs has to throw away all the state it had for an +inode and reload from the server. + +To indicate that a cache object should be invalidated, the following function +can be called: + + void fscache_invalidate(struct fscache_cookie *cookie); + +This can be called with spinlocks held as it defers the work to a thread pool. +All extant storage, retrieval and attribute change ops at this point are +cancelled and discarded. Some future operations will be rejected until the +cache has had a chance to insert a barrier in the operations queue. After +that, operations will be queued again behind the invalidation operation. + +The invalidation operation will perform an attribute change operation and an +auxiliary data update operation as it is very likely these will have changed. + +Using the following function, the netfs can wait for the invalidation operation +to have reached a point at which it can start submitting ordinary operations +once again: -There is no direct way to invalidate an index subtree or a data file. To do -this, the caller should relinquish and retire the cookie they have, and then -acquire a new one. + void fscache_wait_on_invalidate(struct fscache_cookie *cookie); =========================== |