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-rw-r--r--Documentation/filesystems/caching/netfs-api.txt18
-rw-r--r--fs/fscache/page.c16
-rw-r--r--include/linux/fscache.h22
3 files changed, 55 insertions, 1 deletions
diff --git a/Documentation/filesystems/caching/netfs-api.txt b/Documentation/filesystems/caching/netfs-api.txt
index 26c1dd5a6a21..11a0a40ce445 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
==============
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 793e3d5ca4b5..8702b732109a 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -701,6 +701,22 @@ nobufs:
EXPORT_SYMBOL(__fscache_alloc_page);
/*
+ * Unmark pages allocate in the readahead code path (via:
+ * fscache_readpages_or_alloc) after delegating to the base filesystem
+ */
+void __fscache_readpages_cancel(struct fscache_cookie *cookie,
+ struct list_head *pages)
+{
+ struct page *page;
+
+ list_for_each_entry(page, pages, lru) {
+ if (PageFsCache(page))
+ __fscache_uncache_page(cookie, page);
+ }
+}
+EXPORT_SYMBOL(__fscache_readpages_cancel);
+
+/*
* release a write op reference
*/
static void fscache_release_write_op(struct fscache_operation *_op)
diff --git a/include/linux/fscache.h b/include/linux/fscache.h
index d984aff32a11..19b46458e4e8 100644
--- a/include/linux/fscache.h
+++ b/include/linux/fscache.h
@@ -209,6 +209,8 @@ extern bool __fscache_maybe_release_page(struct fscache_cookie *, struct page *,
gfp_t);
extern void __fscache_uncache_all_inode_pages(struct fscache_cookie *,
struct inode *);
+extern void __fscache_readpages_cancel(struct fscache_cookie *cookie,
+ struct list_head *pages);
/**
* fscache_register_netfs - Register a filesystem as desiring caching services
@@ -590,6 +592,26 @@ int fscache_alloc_page(struct fscache_cookie *cookie,
}
/**
+ * fscache_readpages_cancel - Cancel read/alloc on pages
+ * @cookie: The cookie representing the inode's cache object.
+ * @pages: The netfs pages that we canceled write on in readpages()
+ *
+ * Uncache/unreserve the pages reserved earlier in readpages() via
+ * fscache_readpages_or_alloc() and similar. In most successful caches in
+ * readpages() this doesn't do anything. In cases when the underlying netfs's
+ * readahead failed we need to clean up the pagelist (unmark and uncache).
+ *
+ * This function may sleep as it may have to clean up disk state.
+ */
+static inline
+void fscache_readpages_cancel(struct fscache_cookie *cookie,
+ struct list_head *pages)
+{
+ if (fscache_cookie_valid(cookie))
+ __fscache_readpages_cancel(cookie, pages);
+}
+
+/**
* fscache_write_page - Request storage of a page in the cache
* @cookie: The cookie representing the cache object
* @page: The netfs page to store