On Wed, 2021-12-22 at 23:20 +0000, David Howells wrote: > Provide a function to be called from a network filesystem's releasepage > method to indicate that a page has been released that might have been a > reflection of data upon the server - and now that data must be reloaded > from the server or the cache. > > This is used to end an optimisation for empty files, in particular files > that have just been created locally, whereby we know there cannot yet be > any data that we would need to read from the server or the cache. > > Signed-off-by: David Howells <dhowells@xxxxxxxxxx> > cc: linux-cachefs@xxxxxxxxxx > Link: https://lore.kernel.org/r/163819617128.215744.4725572296135656508.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1 > Link: https://lore.kernel.org/r/163906920354.143852.7511819614661372008.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v2 > Link: https://lore.kernel.org/r/163967128061.1823006.611781655060034988.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v3 > --- > > include/linux/fscache.h | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/include/linux/fscache.h b/include/linux/fscache.h > index 18e725671594..28ce258c1f87 100644 > --- a/include/linux/fscache.h > +++ b/include/linux/fscache.h > @@ -607,4 +607,20 @@ static inline void fscache_clear_inode_writeback(struct fscache_cookie *cookie, > } > } > > +/** > + * fscache_note_page_release - Note that a netfs page got released > + * @cookie: The cookie corresponding to the file > + * > + * Note that a page that has been copied to the cache has been released. This > + * means that future reads will need to look in the cache to see if it's there. > + */ > +static inline > +void fscache_note_page_release(struct fscache_cookie *cookie) > +{ > + if (cookie && > + test_bit(FSCACHE_COOKIE_HAVE_DATA, &cookie->flags) && > + test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags)) > + clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags); > +} > + > #endif /* _LINUX_FSCACHE_H */ > > Is this logic correct? FSCACHE_COOKIE_HAVE_DATA gets set in cachefiles_write_complete, but will that ever be called on a cookie that has no data? Will we ever call cachefiles_write at all when there is no data to be written? -- Jeff Layton <jlayton@xxxxxxxxxx>
