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iov_iter: track truncated size

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Remember how many bytes were truncated and reverted back. Because
not reexpanded iterators don't always work well with reverting, we may
need to know that to reexpand ourselves when needed.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Pavel Begunkov 2021-08-23 11:18:44 +01:00 committed by Al Viro
parent e73f0f0ee7
commit 2112ff5ce0
1 changed files with 5 additions and 1 deletions
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6
include/linux/uio.h
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@ -47,6 +47,7 @@ struct iov_iter {
};
loff_t xarray_start;
};
size_t truncated;
};
static inline enum iter_type iov_iter_type(const struct iov_iter *i)
@ -254,8 +255,10 @@ static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
* conversion in assignement is by definition greater than all
* values of size_t, including old i->count.
*/
if (i->count > count)
if (i->count > count) {
i->truncated += i->count - count;
i->count = count;
}
}
/*
@ -264,6 +267,7 @@ static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
*/
static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
{
i->truncated -= count - i->count;
i->count = count;
}