On Mon, Dec 08, 2025 at 01:18:55AM +0100, Stefano Brivio wrote: > I happened to touch these functions for a change that turned out to be > unnecessary, but coding style and documentation could still benefit > from some rephrasing and fixes. > > Signed-off-by: Stefano Brivio Reviewed-by: David Gibson > --- > v2: Make description of @offset consistent between iov_from_buf() and > iov_to_buf() > > iov.c | 68 +++++++++++++++++++++++++---------------------------------- > 1 file changed, 29 insertions(+), 39 deletions(-) > > diff --git a/iov.c b/iov.c > index 8c74a59..ad726da 100644 > --- a/iov.c > +++ b/iov.c > @@ -20,24 +20,21 @@ > * Contributions after 2012-01-13 are licensed under the terms of the > * GNU GPL, version 2 or (at your option) any later version. > */ > + > #include > > #include "util.h" > #include "iov.h" > > - > /** > - * iov_skip_bytes() - Skip leading bytes of an IO vector > - * @iov: IO vector > + * iov_skip_bytes() - Find index and offset in iovec array given byte offset > + * @iov: iovec array > * @n: Number of entries in @iov > - * @skip: Number of leading bytes of @iov to skip > - * @offset: Offset of first unskipped byte in its @iov entry > + * @skip: Byte offset: leading bytes of @iov to skip > + * @offset: Offset within matching @iov entry, set on return, can be NULL > * > - * Return: index I of individual struct iovec which contains the byte at @skip > - * bytes into the vector (as though all its buffers were contiguous). > - * If @offset is non-NULL, update it to the offset of that byte within > - * @iov[I] (guaranteed to be less than @iov[I].iov_len) If the whole > - * vector has <= @skip bytes, return @n. > + * Return: index of iovec array containing the @skip byte counted as if buffers > + * were contiguous. If iovec has less than @skip bytes, return @n. > */ > size_t iov_skip_bytes(const struct iovec *iov, size_t n, > size_t skip, size_t *offset) > @@ -57,17 +54,14 @@ size_t iov_skip_bytes(const struct iovec *iov, size_t n, > } > > /** > - * iov_from_buf() - Copy data from a buffer to an I/O vector (struct iovec) > - * efficiently. > - * > - * @iov: Pointer to the array of struct iovec describing the > - * scatter/gather I/O vector. > - * @iov_cnt: Number of elements in the iov array. > - * @offset: Byte offset in the iov array where copying should start. > - * @buf: Pointer to the source buffer containing the data to copy. > - * @bytes: Total number of bytes to copy from buf to iov. > + * iov_from_buf() - Copy from flat buffer to iovec array > + * @iov: Destination iovec array > + * @iov_cnt: Number of elements in the iovec array > + * @offset: Destination offset in @iov counted as if buffers were contiguous > + * @buf: Source buffer > + * @bytes: Bytes to copy > * > - * Return: the number of bytes successfully copied. > + * Return: number of bytes copied > */ > size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt, > size_t offset, const void *buf, size_t bytes) > @@ -78,12 +72,12 @@ size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt, > if (__builtin_constant_p(bytes) && iov_cnt && > offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) { > memcpy((char *)iov[0].iov_base + offset, buf, bytes); > + > return bytes; > } > > i = iov_skip_bytes(iov, iov_cnt, offset, &offset); > > - /* copying data */ > for (copied = 0; copied < bytes && i < iov_cnt; i++) { > size_t len = MIN(iov[i].iov_len - offset, bytes - copied); > > @@ -97,17 +91,14 @@ size_t iov_from_buf(const struct iovec *iov, size_t iov_cnt, > } > > /** > - * iov_to_buf() - Copy data from a scatter/gather I/O vector (struct iovec) to > - * a buffer efficiently. > - * > - * @iov: Pointer to the array of struct iovec describing the scatter/gather > - * I/O vector. > - * @iov_cnt: Number of elements in the iov array. > - * @offset: Offset within the first element of iov from where copying should start. > - * @buf: Pointer to the destination buffer where data will be copied. > - * @bytes: Total number of bytes to copy from iov to buf. > + * iov_to_buf() - Copy from iovec to flat buffer > + * @iov: Source iovec array > + * @iov_cnt: Number of elements in iovec array > + * @offset: Source offset in @iov counted as if buffers were contiguous > + * @buf: Destination buffer > + * @bytes: Bytes to copy > * > - * Return: the number of bytes successfully copied. > + * Return: number of bytes copied > */ > size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt, > size_t offset, void *buf, size_t bytes) > @@ -118,15 +109,17 @@ size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt, > if (__builtin_constant_p(bytes) && iov_cnt && > offset <= iov[0].iov_len && bytes <= iov[0].iov_len - offset) { > memcpy(buf, (char *)iov[0].iov_base + offset, bytes); > + > return bytes; > } > > i = iov_skip_bytes(iov, iov_cnt, offset, &offset); > > - /* copying data */ > for (copied = 0; copied < bytes && i < iov_cnt; i++) { > size_t len = MIN(iov[i].iov_len - offset, bytes - copied); > + > ASSERT(iov[i].iov_base); > + > memcpy((char *)buf + copied, (char *)iov[i].iov_base + offset, > len); > copied += len; > @@ -137,14 +130,11 @@ size_t iov_to_buf(const struct iovec *iov, size_t iov_cnt, > } > > /** > - * iov_size() - Calculate the total size of a scatter/gather I/O vector > - * (struct iovec). > + * iov_size() - Calculate total data size of iovec > + * @iov: Source iovec array > + * @iov_cnt: Number of elements in iovec array > * > - * @iov: Pointer to the array of struct iovec describing the > - * scatter/gather I/O vector. > - * @iov_cnt: Number of elements in the iov array. > - * > - * Return: the total size in bytes. > + * Return: total size in bytes > */ > size_t iov_size(const struct iovec *iov, size_t iov_cnt) > { > -- > 2.43.0 > -- David Gibson (he or they) | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you, not the other way | around. http://www.ozlabs.org/~dgibson