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cifs: Use iterate_and_advance*() routines directly for hashing

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Replace the bespoke cifs iterators of ITER_BVEC and ITER_KVEC to do hashing
with iterate_and_advance_kernel() - a variant on iterate_and_advance() that
only supports kernel-internal ITER_* types and not UBUF/IOVEC types.

The bespoke ITER_XARRAY is left because we don't really want to be calling
crypto_shash_update() under the RCU read lock for large amounts of data;
besides, ITER_XARRAY is going to be phased out.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.com>
cc: Tom Talpey <tom@talpey.com>
cc: Enzo Matsumiya <ematsumiya@suse.de>
cc: linux-cifs@vger.kernel.org
Link: https://lore.kernel.org/r/20240814203850.2240469-24-dhowells@redhat.com/ # v2
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
David Howells
2024-07-26 20:03:07 +01:00
committed by Christian Brauner
parent 8f246b7c0a
commit 2982c8c19b
2 changed files with 70 additions and 86 deletions
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47
include/linux/iov_iter.h
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@@ -328,4 +328,51 @@ size_t iterate_and_advance(struct iov_iter *iter, size_t len, void *priv,
return iterate_and_advance2(iter, len, priv, NULL, ustep, step);
}
/**
* iterate_and_advance_kernel - Iterate over a kernel-internal iterator
* @iter: The iterator to iterate over.
* @len: The amount to iterate over.
* @priv: Data for the step functions.
* @priv2: More data for the step functions.
* @step: Function for other iterators; given kernel addresses.
*
* Iterate over the next part of an iterator, up to the specified length. The
* buffer is presented in segments, which for kernel iteration are broken up by
* physical pages and mapped, with the mapped address being presented.
*
* [!] Note This will only handle BVEC, KVEC, FOLIOQ, XARRAY and DISCARD-type
* iterators; it will not handle UBUF or IOVEC-type iterators.
*
* A step functions, @step, must be provided, one for handling mapped kernel
* addresses and the other is given user addresses which have the potential to
* fault since no pinning is performed.
*
* The step functions are passed the address and length of the segment, @priv,
* @priv2 and the amount of data so far iterated over (which can, for example,
* be added to @priv to point to the right part of a second buffer). The step
* functions should return the amount of the segment they didn't process (ie. 0
* indicates complete processsing).
*
* This function returns the amount of data processed (ie. 0 means nothing was
* processed and the value of @len means processes to completion).
*/
static __always_inline
size_t iterate_and_advance_kernel(struct iov_iter *iter, size_t len, void *priv,
void *priv2, iov_step_f step)
{
if (unlikely(iter->count < len))
len = iter->count;
if (unlikely(!len))
return 0;
if (iov_iter_is_bvec(iter))
return iterate_bvec(iter, len, priv, priv2, step);
if (iov_iter_is_kvec(iter))
return iterate_kvec(iter, len, priv, priv2, step);
if (iov_iter_is_folioq(iter))
return iterate_folioq(iter, len, priv, priv2, step);
if (iov_iter_is_xarray(iter))
return iterate_xarray(iter, len, priv, priv2, step);
return iterate_discard(iter, len, priv, priv2, step);
}
#endif /* _LINUX_IOV_ITER_H */