| Message ID | 20220825152425.6296-3-logang@deltatee.com |
|---|---|
| State | New |
| Headers | show |
| Series | Userspace P2PDMA with O_DIRECT NVMe devices | expand |
On Thu, Aug 25, 2022 at 09:24:19AM -0600, Logan Gunthorpe wrote: > Add iov_iter_get_pages_flags() and iov_iter_get_pages_alloc_flags() > which take a flags argument that is passed to get_user_pages_fast(). > > This is so that FOLL_PCI_P2PDMA can be passed when appropriate. Any reason why iov_iter_get_pages2 doesn't call iov_iter_get_pages_flags and same for the __alloc version? Also with the "main" version now having the 2 postfix, we can just use the iov_iter_get_pages name for the flags version, and maybe eventually just convert all users over to it.
On 8/25/22 08:24, Logan Gunthorpe wrote: > Add iov_iter_get_pages_flags() and iov_iter_get_pages_alloc_flags() > which take a flags argument that is passed to get_user_pages_fast(). > > This is so that FOLL_PCI_P2PDMA can be passed when appropriate. > > Signed-off-by: Logan Gunthorpe <logang@deltatee.com> > --- > include/linux/uio.h | 6 ++++++ > lib/iov_iter.c | 40 ++++++++++++++++++++++++++++++++++++---- > 2 files changed, 42 insertions(+), 4 deletions(-) > Yes. I also don't object to Christoph's additional request to refactor and rename around iov_iter_get_pages2() and such, but this version here is perfectly good, so please feel free to add: Reviewed-by: John Hubbard <jhubbard@nvidia.com> Looking ahead, interestingly enough, it turns out that this approach to the wrappers is really pretty close to what I posted in patch 4/7 of my "convert most filesystems to pin_user_pages_fast()" series [1]. Instead of passing gup_flags through, I tried to avoid that (because FOLL_PIN is, as a mild design preference, supposed to remain internal to gup.c), but given that you need to do it, I think I can just build on top of your approach, and pass in FOLL_PIN via your new gup_flags arg. Along those lines, I've copied you in on "New topic branch for block + gup work?", let's see what happens over there. [1] https://lore.kernel.org/r/20220831041843.973026-1-jhubbard@nvidia.com thanks,
On 2022-09-05 17:21, John Hubbard wrote: > Looking ahead, interestingly enough, it turns out that this approach to > the wrappers is really pretty close to what I posted in patch 4/7 of my > "convert most filesystems to pin_user_pages_fast()" series [1]. Instead > of passing gup_flags through, I tried to avoid that (because FOLL_PIN > is, as a mild design preference, supposed to remain internal to gup.c), > but given that you need to do it, I think I can just build on top of > your approach, and pass in FOLL_PIN via your new gup_flags arg. Seems to me like we could just provide the one exported function with a flag then use an static inline helper for the pin version. That would help keep the FOLL_PIN flag contained as you like. > Along those lines, I've copied you in on "New topic branch for block + > gup work?", let's see what happens over there. > > [1] https://lore.kernel.org/r/20220831041843.973026-1-jhubbard@nvidia.com Thanks for the review. All the feedback makes sense. I'll apply all the changes from you and Christoph for the next version. I'm happy to base the next version off of any other changes to the iov functions. I suspect my patches can hold off a cycle or two more while we do it. Let me know if you'd like some help making the conversions, I'm also fine to do some work to aid with the effort. Thanks, Logan
diff --git a/include/linux/uio.h b/include/linux/uio.h index 5896af36199c..76ba69edb8c5 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -247,8 +247,14 @@ void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count); void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray, loff_t start, size_t count); +ssize_t iov_iter_get_pages_flags(struct iov_iter *i, struct page **pages, + size_t maxsize, unsigned maxpages, size_t *start, + unsigned int gup_flags); ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages, size_t maxsize, unsigned maxpages, size_t *start); +ssize_t iov_iter_get_pages_alloc_flags(struct iov_iter *i, + struct page ***pages, size_t maxsize, size_t *start, + unsigned int gup_flags); ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages, size_t maxsize, size_t *start); int iov_iter_npages(const struct iov_iter *i, int maxpages); diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 4b7fce72e3e5..dedb78f3c655 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1427,7 +1427,8 @@ static struct page *first_bvec_segment(const struct iov_iter *i, static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages, size_t maxsize, - unsigned int maxpages, size_t *start) + unsigned int maxpages, size_t *start, + unsigned int gup_flags) { unsigned int n; @@ -1439,7 +1440,6 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i, maxsize = MAX_RW_COUNT; if (likely(user_backed_iter(i))) { - unsigned int gup_flags = 0; unsigned long addr; int res; @@ -1497,10 +1497,24 @@ ssize_t iov_iter_get_pages2(struct iov_iter *i, return 0; BUG_ON(!pages); - return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start); + return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, + start, 0); } EXPORT_SYMBOL(iov_iter_get_pages2); +ssize_t iov_iter_get_pages_flags(struct iov_iter *i, struct page **pages, + size_t maxsize, unsigned maxpages, size_t *start, + unsigned int gup_flags) +{ + if (!maxpages) + return 0; + BUG_ON(!pages); + + return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, + start, gup_flags); +} +EXPORT_SYMBOL_GPL(iov_iter_get_pages_flags); + ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages, size_t maxsize, size_t *start) @@ -1509,7 +1523,7 @@ ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, *pages = NULL; - len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start); + len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start, 0); if (len <= 0) { kvfree(*pages); *pages = NULL; @@ -1518,6 +1532,24 @@ ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, } EXPORT_SYMBOL(iov_iter_get_pages_alloc2); +ssize_t iov_iter_get_pages_alloc_flags(struct iov_iter *i, + struct page ***pages, size_t maxsize, + size_t *start, unsigned int gup_flags) +{ + ssize_t len; + + *pages = NULL; + + len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start, + gup_flags); + if (len <= 0) { + kvfree(*pages); + *pages = NULL; + } + return len; +} +EXPORT_SYMBOL_GPL(iov_iter_get_pages_alloc_flags); + size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i) {
Add iov_iter_get_pages_flags() and iov_iter_get_pages_alloc_flags() which take a flags argument that is passed to get_user_pages_fast(). This is so that FOLL_PCI_P2PDMA can be passed when appropriate. Signed-off-by: Logan Gunthorpe <logang@deltatee.com> --- include/linux/uio.h | 6 ++++++ lib/iov_iter.c | 40 ++++++++++++++++++++++++++++++++++++---- 2 files changed, 42 insertions(+), 4 deletions(-)