diff options
| author | Al Viro <viro@zeniv.linux.org.uk> | 2022-05-22 21:59:25 +0300 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2022-08-09 05:37:15 +0300 |
| commit | fcb14cb1bdacec5b4374fe161e83fb8208164a85 (patch) | |
| tree | 06b308b8f6b67c65e0c1e90d2e97e61ae66f232a /include | |
| parent | fa9db655d0e112c108fe838809608caf759bdf5e (diff) | |
| download | linux-fcb14cb1bdacec5b4374fe161e83fb8208164a85.tar.xz | |
new iov_iter flavour - ITER_UBUF
Equivalent of single-segment iovec. Initialized by iov_iter_ubuf(),
checked for by iter_is_ubuf(), otherwise behaves like ITER_IOVEC
ones.
We are going to expose the things like ->write_iter() et.al. to those
in subsequent commits.
New predicate (user_backed_iter()) that is true for ITER_IOVEC and
ITER_UBUF; places like direct-IO handling should use that for
checking that pages we modify after getting them from iov_iter_get_pages()
would need to be dirtied.
DO NOT assume that replacing iter_is_iovec() with user_backed_iter()
will solve all problems - there's code that uses iter_is_iovec() to
decide how to poke around in iov_iter guts and for that the predicate
replacement obviously won't suffice.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/uio.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/uio.h b/include/linux/uio.h index 9a2dc496d535..85bef84fd294 100644 --- a/include/linux/uio.h +++ b/include/linux/uio.h @@ -26,6 +26,7 @@ enum iter_type { ITER_PIPE, ITER_XARRAY, ITER_DISCARD, + ITER_UBUF, }; struct iov_iter_state { @@ -38,6 +39,7 @@ struct iov_iter { u8 iter_type; bool nofault; bool data_source; + bool user_backed; size_t iov_offset; size_t count; union { @@ -46,6 +48,7 @@ struct iov_iter { const struct bio_vec *bvec; struct xarray *xarray; struct pipe_inode_info *pipe; + void __user *ubuf; }; union { unsigned long nr_segs; @@ -70,6 +73,11 @@ static inline void iov_iter_save_state(struct iov_iter *iter, state->nr_segs = iter->nr_segs; } +static inline bool iter_is_ubuf(const struct iov_iter *i) +{ + return iov_iter_type(i) == ITER_UBUF; +} + static inline bool iter_is_iovec(const struct iov_iter *i) { return iov_iter_type(i) == ITER_IOVEC; @@ -105,6 +113,11 @@ static inline unsigned char iov_iter_rw(const struct iov_iter *i) return i->data_source ? WRITE : READ; } +static inline bool user_backed_iter(const struct iov_iter *i) +{ + return i->user_backed; +} + /* * Total number of bytes covered by an iovec. * @@ -322,4 +335,17 @@ ssize_t __import_iovec(int type, const struct iovec __user *uvec, int import_single_range(int type, void __user *buf, size_t len, struct iovec *iov, struct iov_iter *i); +static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction, + void __user *buf, size_t count) +{ + WARN_ON(direction & ~(READ | WRITE)); + *i = (struct iov_iter) { + .iter_type = ITER_UBUF, + .user_backed = true, + .data_source = direction, + .ubuf = buf, + .count = count + }; +} + #endif |