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new primitive: iov_iter_for_each_range() 

For kvec and bvec: feeds segments to given callback as long as it
returns 0.  For iovec and pipe: fails.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2017-02-18 01:44:03 -05:00
parent 6d1ff4d6f3
commit 09cf698a59
2 changed files with 26 additions and 0 deletions
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4
include/linux/uio.h
View File

@ -244,4 +244,8 @@ int compat_import_iovec(int type, const struct compat_iovec __user * uvector,
int import_single_range(int type, void __user *buf, size_t len,
struct iovec *iov, struct iov_iter *i);
int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
int (*f)(struct kvec *vec, void *context),
void *context);
#endif

22
lib/iov_iter.c
View File

@ -1446,3 +1446,25 @@ int import_single_range(int rw, void __user *buf, size_t len,
return 0;
}
EXPORT_SYMBOL(import_single_range);
int iov_iter_for_each_range(struct iov_iter *i, size_t bytes,
int (*f)(struct kvec *vec, void *context),
void *context)
{
struct kvec w;
int err = -EINVAL;
if (!bytes)
return 0;
iterate_all_kinds(i, bytes, v, -EINVAL, ({
w.iov_base = kmap(v.bv_page) + v.bv_offset;
w.iov_len = v.bv_len;
err = f(&w, context);
kunmap(v.bv_page);
err;}), ({
w = v;
err = f(&w, context);})
)
return err;
}
EXPORT_SYMBOL(iov_iter_for_each_range);