diff options
Diffstat (limited to 'Documentation/filesystems/caching/netfs-api.txt')
| -rw-r--r-- | Documentation/filesystems/caching/netfs-api.txt | 37 |
1 files changed, 31 insertions, 6 deletions
diff --git a/Documentation/filesystems/caching/netfs-api.txt b/Documentation/filesystems/caching/netfs-api.txt index 97e6c0ecc5e..11a0a40ce44 100644 --- a/Documentation/filesystems/caching/netfs-api.txt +++ b/Documentation/filesystems/caching/netfs-api.txt @@ -32,7 +32,7 @@ This document contains the following sections: (9) Setting the data file size (10) Page alloc/read/write (11) Page uncaching - (12) Index and data file update + (12) Index and data file consistency (13) Miscellaneous cookie operations (14) Cookie unregistration (15) Index invalidation @@ -433,7 +433,7 @@ to the caller. The attribute adjustment excludes read and write operations. ===================== -PAGE READ/ALLOC/WRITE +PAGE ALLOC/READ/WRITE ===================== And the sixth step is to store and retrieve pages in the cache. There are @@ -499,7 +499,7 @@ Else if there's a copy of the page resident in the cache: (*) An argument that's 0 on success or negative for an error code. If an error occurs, it should be assumed that the page contains no usable - data. + data. fscache_readpages_cancel() may need to be called. end_io_func() will be called in process context if the read is results in an error, but it might be called in interrupt context if the read is @@ -623,6 +623,22 @@ some of the pages being read and some being allocated. Those pages will have been marked appropriately and will need uncaching. +CANCELLATION OF UNREAD PAGES +---------------------------- + +If one or more pages are passed to fscache_read_or_alloc_pages() but not then +read from the cache and also not read from the underlying filesystem then +those pages will need to have any marks and reservations removed. This can be +done by calling: + + void fscache_readpages_cancel(struct fscache_cookie *cookie, + struct list_head *pages); + +prior to returning to the caller. The cookie argument should be as passed to +fscache_read_or_alloc_pages(). Every page in the pages list will be examined +and any that have PG_fscache set will be uncached. + + ============== PAGE UNCACHING ============== @@ -690,9 +706,18 @@ written to the cache and for the cache to finish with the page generally. No error is returned. -========================== -INDEX AND DATA FILE UPDATE -========================== +=============================== +INDEX AND DATA FILE CONSISTENCY +=============================== + +To find out whether auxiliary data for an object is up to data within the +cache, the following function can be called: + + int fscache_check_consistency(struct fscache_cookie *cookie) + +This will call back to the netfs to check whether the auxiliary data associated +with a cookie is correct. It returns 0 if it is and -ESTALE if it isn't; it +may also return -ENOMEM and -ERESTARTSYS. To request an update of the index data for an index or other object, the following function should be called: |