Add unlock_page_fscache() as an alias of unlock_page_private_2(). This allows a page 'locked' with PG_fscache to be unlocked. Add wait_on_page_fscache() to wait for PG_fscache to be unlocked. [Linus suggested putting the fscache-themed functions into the caching-specific headers rather than pagemap.h[1]] Signed-off-by: David Howells <dhowells@xxxxxxxxxx> cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> cc: linux-mm@xxxxxxxxx cc: linux-cachefs@xxxxxxxxxx cc: linux-afs@xxxxxxxxxxxxxxxxxxx cc: linux-nfs@xxxxxxxxxxxxxxx cc: linux-cifs@xxxxxxxxxxxxxxx cc: ceph-devel@xxxxxxxxxxxxxxx cc: v9fs-developer@xxxxxxxxxxxxxxxxxxxxx cc: linux-fsdevel@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/r/1330473.1612974547@xxxxxxxxxxxxxxxxxxxxxx/ Link: https://lore.kernel.org/r/CAHk-=wjgA-74ddehziVk=XAEMTKswPu1Yw4uaro1R3ibs27ztw@xxxxxxxxxxxxxx/ [1] Link: https://lore.kernel.org/r/161340393568.1303470.4997526899111310530.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v3 --- include/linux/netfs.h | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/include/linux/netfs.h b/include/linux/netfs.h index cc1102040488..5ed8c6dc7453 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -26,4 +26,33 @@ #define TestSetPageFsCache(page) TestSetPagePrivate2((page)) #define TestClearPageFsCache(page) TestClearPagePrivate2((page)) +/** + * unlock_page_fscache - Unlock a page that's locked with PG_fscache + * @page: The page + * + * Unlocks a page that's locked with PG_fscache and wakes up sleepers in + * wait_on_page_fscache(). This page bit is used by the netfs helpers when a + * netfs page is being written to a local disk cache, thereby allowing writes + * to the cache for the same page to be serialised. + */ +static inline void unlock_page_fscache(struct page *page) +{ + unlock_page_private_2(page); +} + +/** + * wait_on_page_fscache - Wait for PG_fscache to be cleared on a page + * @page: The page + * + * Wait for the PG_fscache (PG_private_2) page bit to be removed from a page. + * This is, for example, used to handle a netfs page being written to a local + * disk cache, thereby allowing writes to the cache for the same page to be + * serialised. + */ +static inline void wait_on_page_fscache(struct page *page) +{ + if (PageFsCache(page)) + wait_on_page_bit(compound_head(page), PG_fscache); +} + #endif /* _LINUX_NETFS_H */
