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io/channel: introduce qio_channel_pwrite{v,}_all()

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Add positioned write helpers that retry on short writes, matching
the pread_all family from the previous patch.

  qio_channel_pwritev_all()  -- retry loop; returns 0 on success,
                                 -1 on error.
  qio_channel_pwrite_all()   -- single-buffer convenience wrapper.

Signed-off-by: Junjie Cao <junjie.cao@intel.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/qemu-devel/20260413214549.926435-3-junjie.cao@intel.com
Signed-off-by: Fabiano Rosas <farosas@suse.de>
This commit is contained in:
Junjie Cao
2026-04-14 05:45:47 +08:00
committed by Fabiano Rosas
parent 2dd53f732b
commit 40bf7bbcf4
2 changed files with 89 additions and 0 deletions
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41
include/io/channel.h
View File

@@ -598,6 +598,47 @@ ssize_t qio_channel_pwritev(QIOChannel *ioc, const struct iovec *iov,
ssize_t qio_channel_pwrite(QIOChannel *ioc, void *buf, size_t buflen,
off_t offset, Error **errp);
/**
* qio_channel_pwritev_all:
* @ioc: the channel object
* @iov: the array of memory regions to write data from
* @niov: the length of the @iov array
* @offset: the starting offset in the channel to write to
* @errp: pointer to a NULL-initialized error object
*
* Writes @iov, possibly blocking or (if the channel is non-blocking)
* yielding from the current coroutine multiple times until the entire
* content is written. Otherwise behaves as qio_channel_pwritev().
*
* Returns: 0 if all bytes were written, or -1 on error
*/
int coroutine_mixed_fn qio_channel_pwritev_all(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
off_t offset,
Error **errp);
/**
* qio_channel_pwrite_all:
* @ioc: the channel object
* @buf: the memory region to write data from
* @buflen: the number of bytes to write from @buf
* @offset: the starting offset in the channel to write to
* @errp: pointer to a NULL-initialized error object
*
* Writes @buflen bytes from @buf, possibly blocking or (if the
* channel is non-blocking) yielding from the current coroutine
* multiple times until the entire content is written. Otherwise
* behaves as qio_channel_pwrite().
*
* Returns: 0 if all bytes were written, or -1 on error
*/
int coroutine_mixed_fn qio_channel_pwrite_all(QIOChannel *ioc,
const void *buf,
size_t buflen,
off_t offset,
Error **errp);
/**
* qio_channel_preadv
* @ioc: the channel object

48
io/channel.c
View File

@@ -478,6 +478,54 @@ ssize_t qio_channel_pwrite(QIOChannel *ioc, void *buf, size_t buflen,
return qio_channel_pwritev(ioc, &iov, 1, offset, errp);
}
int coroutine_mixed_fn qio_channel_pwritev_all(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
off_t offset,
Error **errp)
{
int ret = -1;
struct iovec *local_iov = g_new(struct iovec, niov);
struct iovec *local_iov_head = local_iov;
unsigned int nlocal_iov = niov;
nlocal_iov = iov_copy(local_iov, nlocal_iov,
iov, niov,
0, iov_size(iov, niov));
while (nlocal_iov > 0) {
ssize_t len;
len = qio_channel_pwritev(ioc, local_iov, nlocal_iov, offset, errp);
if (len == QIO_CHANNEL_ERR_BLOCK) {
qio_channel_wait_cond(ioc, G_IO_OUT);
continue;
}
if (len < 0) {
goto cleanup;
}
offset += len;
iov_discard_front(&local_iov, &nlocal_iov, len);
}
ret = 0;
cleanup:
g_free(local_iov_head);
return ret;
}
int coroutine_mixed_fn qio_channel_pwrite_all(QIOChannel *ioc,
const void *buf,
size_t buflen,
off_t offset,
Error **errp)
{
struct iovec iov = { .iov_base = (char *)buf, .iov_len = buflen };
return qio_channel_pwritev_all(ioc, &iov, 1, offset, errp);
}
ssize_t qio_channel_preadv(QIOChannel *ioc, const struct iovec *iov,
size_t niov, off_t offset, Error **errp)
{