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authorAl Viro <viro@zeniv.linux.org.uk>2022-05-22 21:59:25 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2022-08-09 05:37:15 +0300
commitfcb14cb1bdacec5b4374fe161e83fb8208164a85 (patch)
tree06b308b8f6b67c65e0c1e90d2e97e61ae66f232a /include
parentfa9db655d0e112c108fe838809608caf759bdf5e (diff)
downloadlinux-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.h26
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