| Message ID | 20220622041552.737754-26-viro@zeniv.linux.org.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [01/44] 9p: handling Rerror without copy_from_iter_full() | expand |
On Wed, 2022-06-22 at 05:15 +0100, Al Viro wrote: > The differences between those two are > * pipe_get_pages() gets a non-NULL struct page ** value pointing to > preallocated array + array size. > * pipe_get_pages_alloc() gets an address of struct page ** variable that > contains NULL, allocates the array and (on success) stores its address in > that variable. > > Not hard to combine - always pass struct page ***, have > the previous pipe_get_pages_alloc() caller pass ~0U as cap for > array size. > > Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> > --- > lib/iov_iter.c | 49 +++++++++++++++++-------------------------------- > 1 file changed, 17 insertions(+), 32 deletions(-) > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 5c985cf2858e..1c98f2f3a581 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -1187,6 +1187,11 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i) > } > EXPORT_SYMBOL(iov_iter_gap_alignment); > > +static struct page **get_pages_array(size_t n) > +{ > + return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); > +} > + > static inline ssize_t __pipe_get_pages(struct iov_iter *i, > size_t maxsize, > struct page **pages, > @@ -1220,10 +1225,11 @@ static inline ssize_t __pipe_get_pages(struct iov_iter *i, > } > > static ssize_t pipe_get_pages(struct iov_iter *i, > - struct page **pages, size_t maxsize, unsigned maxpages, > + struct page ***pages, size_t maxsize, unsigned maxpages, > size_t *start) > { > unsigned int npages, off; > + struct page **p; > size_t capacity; > > if (!sanity(i)) > @@ -1231,8 +1237,15 @@ static ssize_t pipe_get_pages(struct iov_iter *i, > > *start = off = pipe_npages(i, &npages); > capacity = min(npages, maxpages) * PAGE_SIZE - off; > + maxsize = min(maxsize, capacity); > + p = *pages; > + if (!p) { > + *pages = p = get_pages_array(DIV_ROUND_UP(maxsize + off, PAGE_SIZE)); > + if (!p) > + return -ENOMEM; > + } > > - return __pipe_get_pages(i, min(maxsize, capacity), pages, off); > + return __pipe_get_pages(i, maxsize, p, off); > } > > static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, > @@ -1394,41 +1407,13 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, > return len - *start; > } > if (iov_iter_is_pipe(i)) > - return pipe_get_pages(i, pages, maxsize, maxpages, start); > + return pipe_get_pages(i, &pages, maxsize, maxpages, start); > if (iov_iter_is_xarray(i)) > return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); > return -EFAULT; > } > EXPORT_SYMBOL(iov_iter_get_pages); > > -static struct page **get_pages_array(size_t n) > -{ > - return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); > -} > - > -static ssize_t pipe_get_pages_alloc(struct iov_iter *i, > - struct page ***pages, size_t maxsize, > - size_t *start) > -{ > - struct page **p; > - unsigned int npages, off; > - ssize_t n; > - > - if (!sanity(i)) > - return -EFAULT; > - > - *start = off = pipe_npages(i, &npages); > - n = npages * PAGE_SIZE - off; > - if (maxsize > n) > - maxsize = n; > - else > - npages = DIV_ROUND_UP(maxsize + off, PAGE_SIZE); > - *pages = p = get_pages_array(npages); > - if (!p) > - return -ENOMEM; > - return __pipe_get_pages(i, maxsize, p, off); > -} > - > static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i, > struct page ***pages, size_t maxsize, > size_t *_start_offset) > @@ -1511,7 +1496,7 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i, > return len - *start; > } > if (iov_iter_is_pipe(i)) > - return pipe_get_pages_alloc(i, pages, maxsize, start); > + return pipe_get_pages(i, pages, maxsize, ~0U, start); > if (iov_iter_is_xarray(i)) > return iter_xarray_get_pages_alloc(i, pages, maxsize, start); > return -EFAULT; Reviewed-by: Jeff Layton <jlayton@kernel.org>
diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 5c985cf2858e..1c98f2f3a581 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -1187,6 +1187,11 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i) } EXPORT_SYMBOL(iov_iter_gap_alignment); +static struct page **get_pages_array(size_t n) +{ + return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); +} + static inline ssize_t __pipe_get_pages(struct iov_iter *i, size_t maxsize, struct page **pages, @@ -1220,10 +1225,11 @@ static inline ssize_t __pipe_get_pages(struct iov_iter *i, } static ssize_t pipe_get_pages(struct iov_iter *i, - struct page **pages, size_t maxsize, unsigned maxpages, + struct page ***pages, size_t maxsize, unsigned maxpages, size_t *start) { unsigned int npages, off; + struct page **p; size_t capacity; if (!sanity(i)) @@ -1231,8 +1237,15 @@ static ssize_t pipe_get_pages(struct iov_iter *i, *start = off = pipe_npages(i, &npages); capacity = min(npages, maxpages) * PAGE_SIZE - off; + maxsize = min(maxsize, capacity); + p = *pages; + if (!p) { + *pages = p = get_pages_array(DIV_ROUND_UP(maxsize + off, PAGE_SIZE)); + if (!p) + return -ENOMEM; + } - return __pipe_get_pages(i, min(maxsize, capacity), pages, off); + return __pipe_get_pages(i, maxsize, p, off); } static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa, @@ -1394,41 +1407,13 @@ ssize_t iov_iter_get_pages(struct iov_iter *i, return len - *start; } if (iov_iter_is_pipe(i)) - return pipe_get_pages(i, pages, maxsize, maxpages, start); + return pipe_get_pages(i, &pages, maxsize, maxpages, start); if (iov_iter_is_xarray(i)) return iter_xarray_get_pages(i, pages, maxsize, maxpages, start); return -EFAULT; } EXPORT_SYMBOL(iov_iter_get_pages); -static struct page **get_pages_array(size_t n) -{ - return kvmalloc_array(n, sizeof(struct page *), GFP_KERNEL); -} - -static ssize_t pipe_get_pages_alloc(struct iov_iter *i, - struct page ***pages, size_t maxsize, - size_t *start) -{ - struct page **p; - unsigned int npages, off; - ssize_t n; - - if (!sanity(i)) - return -EFAULT; - - *start = off = pipe_npages(i, &npages); - n = npages * PAGE_SIZE - off; - if (maxsize > n) - maxsize = n; - else - npages = DIV_ROUND_UP(maxsize + off, PAGE_SIZE); - *pages = p = get_pages_array(npages); - if (!p) - return -ENOMEM; - return __pipe_get_pages(i, maxsize, p, off); -} - static ssize_t iter_xarray_get_pages_alloc(struct iov_iter *i, struct page ***pages, size_t maxsize, size_t *_start_offset) @@ -1511,7 +1496,7 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i, return len - *start; } if (iov_iter_is_pipe(i)) - return pipe_get_pages_alloc(i, pages, maxsize, start); + return pipe_get_pages(i, pages, maxsize, ~0U, start); if (iov_iter_is_xarray(i)) return iter_xarray_get_pages_alloc(i, pages, maxsize, start); return -EFAULT;
The differences between those two are * pipe_get_pages() gets a non-NULL struct page ** value pointing to preallocated array + array size. * pipe_get_pages_alloc() gets an address of struct page ** variable that contains NULL, allocates the array and (on success) stores its address in that variable. Not hard to combine - always pass struct page ***, have the previous pipe_get_pages_alloc() caller pass ~0U as cap for array size. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- lib/iov_iter.c | 49 +++++++++++++++++-------------------------------- 1 file changed, 17 insertions(+), 32 deletions(-)