Add set/end/wait_on_page_fscache() as aliases of set/end/wait_page_private_2(). These allow a page to marked with PG_fscache, the flag to be removed and waiters woken and waiting for the flag to be cleared. A ref on the page is also taken and dropped. [Linus suggested putting the fscache-themed functions into the caching-specific headers rather than pagemap.h[1]] Changes: v5: - Mirror the changes to the core routines[2]. 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 Link: https://lore.kernel.org/r/161539536093.286939.5076448803512118764.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v4 Link: https://lore.kernel.org/r/2499407.1616505440@xxxxxxxxxxxxxxxxxxxxxx/ [2] Link: https://lore.kernel.org/r/161653793873.2770958.12157243390965814502.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v5 --- include/linux/netfs.h | 57 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) diff --git a/include/linux/netfs.h b/include/linux/netfs.h index cc1102040488..8479d63406f7 100644 --- a/include/linux/netfs.h +++ b/include/linux/netfs.h @@ -26,4 +26,61 @@ #define TestSetPageFsCache(page) TestSetPagePrivate2((page)) #define TestClearPageFsCache(page) TestClearPagePrivate2((page)) +/** + * set_page_fscache - Set PG_fscache on a page and take a ref + * @page: The page. + * + * Set the PG_fscache (PG_private_2) flag on a page and take the reference + * needed for the VM to handle its lifetime correctly. This sets the flag and + * takes the reference unconditionally, so care must be taken not to set the + * flag again if it's already set. + */ +static inline void set_page_fscache(struct page *page) +{ + set_page_private_2(page); +} + +/** + * end_page_fscache - Clear PG_fscache and release any waiters + * @page: The page + * + * Clear the PG_fscache (PG_private_2) bit on a page and wake up any sleepers + * waiting for this. The page ref held for PG_private_2 being set is released. + * + * This is, for example, used 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 end_page_fscache(struct page *page) +{ + end_page_private_2(page); +} + +/** + * wait_on_page_fscache - Wait for PG_fscache to be cleared on a page + * @page: The page to wait on + * + * Wait for PG_fscache (aka PG_private_2) to be cleared on a page. + */ +static inline void wait_on_page_fscache(struct page *page) +{ + wait_on_page_private_2(page); +} + +/** + * wait_on_page_fscache_killable - Wait for PG_fscache to be cleared on a page + * @page: The page to wait on + * + * Wait for PG_fscache (aka PG_private_2) to be cleared on a page or until a + * fatal signal is received by the calling task. + * + * Return: + * - 0 if successful. + * - -EINTR if a fatal signal was encountered. + */ +static inline int wait_on_page_fscache_killable(struct page *page) +{ + return wait_on_page_private_2_killable(page); +} + #endif /* _LINUX_NETFS_H */
