diff options
| -rw-r--r-- | Documentation/filesystems/caching/netfs-api.txt | 18 | ||||
| -rw-r--r-- | fs/fscache/page.c | 16 | ||||
| -rw-r--r-- | include/linux/fscache.h | 22 |
3 files changed, 55 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 ============== diff --git a/fs/fscache/page.c b/fs/fscache/page.c index 793e3d5ca4b..8702b732109 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 d984aff32a1..19b46458e4e 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 |