On Wed, 1 Dec 2010, Hugh Dickins wrote: > On Wed, 1 Dec 2010, Andrew Morton wrote: > > On Wed, 01 Dec 2010 15:10:50 -0500 > > Trond Myklebust <Trond.Myklebust@xxxxxxxxxx> wrote: > > > > > --- a/include/linux/fs.h > > > +++ b/include/linux/fs.h > > > @@ -602,6 +602,7 @@ struct address_space_operations { > > > sector_t (*bmap)(struct address_space *, sector_t); > > > void (*invalidatepage) (struct page *, unsigned long); > > > int (*releasepage) (struct page *, gfp_t); > > > + void (*freepage)(struct page *); > > > ssize_t (*direct_IO)(int, struct kiocb *, const struct iovec *iov, > > > loff_t offset, unsigned long nr_segs); > > > int (*get_xip_mem)(struct address_space *, pgoff_t, int, > > > > It would be good to think about and then clearly spell out exactly what > > state the page is in here. It is locked, and I assume clean and not > > under writeback. What about its refcount, freezedness status and > > eligibility for lookups? > > > > And as Hugh pointed out, some callees might needs the address_space* > > although we can perhaps defer that until such a callee turns up. > > If/when that happens we might have a problem though: if this locked > > page is no longer attached to the address_space then what now pins the > > address_space, protecting it from inode reclaim? > > That's an excellent point and trumps mine: it would be actively wrong > to provide the struct address_space *mapping arg I was asking for. > (Bet someone then tries stashing it away via page->private though.) Hmm, thinking further along the same lines: can we even guarantee that the filesystem module is still loaded at that point? i.e. might mapping->freepage now be pointing off into the garbage heap? Hugh -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html