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-rw-r--r--Documentation/filesystems/caching/netfs-api.txt18
1 files changed, 17 insertions, 1 deletions
diff --git a/Documentation/filesystems/caching/netfs-api.txt b/Documentation/filesystems/caching/netfs-api.txt
index 26c1dd5a6a2..11a0a40ce44 100644
--- a/Documentation/filesystems/caching/netfs-api.txt
+++ b/Documentation/filesystems/caching/netfs-api.txt
@@ -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
==============