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io: implement io_pwritev/preadv for QIOChannelFile

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The upcoming 'mapped-ram' feature will require qemu to write data to
(and restore from) specific offsets of the migration file.

Add a minimal implementation of pwritev/preadv and expose them via the
io_pwritev and io_preadv interfaces.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: "Daniel P. Berrangé" <berrange@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20240229153017.2221-5-farosas@suse.de
Signed-off-by: Peter Xu <peterx@redhat.com>
This commit is contained in:
Nikolay Borisov 2024-02-29 12:29:58 -03:00 committed by Peter Xu
parent f1cfe39418
commit 0478b030fa
1 changed files with 56 additions and 0 deletions
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56
io/channel-file.c
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@ -146,6 +146,58 @@ static ssize_t qio_channel_file_writev(QIOChannel *ioc,
return ret;
}
#ifdef CONFIG_PREADV
static ssize_t qio_channel_file_preadv(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
off_t offset,
Error **errp)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
ssize_t ret;
retry:
ret = preadv(fioc->fd, iov, niov, offset);
if (ret < 0) {
if (errno == EAGAIN) {
return QIO_CHANNEL_ERR_BLOCK;
}
if (errno == EINTR) {
goto retry;
}
error_setg_errno(errp, errno, "Unable to read from file");
return -1;
}
return ret;
}
static ssize_t qio_channel_file_pwritev(QIOChannel *ioc,
const struct iovec *iov,
size_t niov,
off_t offset,
Error **errp)
{
QIOChannelFile *fioc = QIO_CHANNEL_FILE(ioc);
ssize_t ret;
retry:
ret = pwritev(fioc->fd, iov, niov, offset);
if (ret <= 0) {
if (errno == EAGAIN) {
return QIO_CHANNEL_ERR_BLOCK;
}
if (errno == EINTR) {
goto retry;
}
error_setg_errno(errp, errno, "Unable to write to file");
return -1;
}
return ret;
}
#endif /* CONFIG_PREADV */
static int qio_channel_file_set_blocking(QIOChannel *ioc,
bool enabled,
Error **errp)
@ -231,6 +283,10 @@ static void qio_channel_file_class_init(ObjectClass *klass,
ioc_klass->io_writev = qio_channel_file_writev;
ioc_klass->io_readv = qio_channel_file_readv;
ioc_klass->io_set_blocking = qio_channel_file_set_blocking;
#ifdef CONFIG_PREADV
ioc_klass->io_pwritev = qio_channel_file_pwritev;
ioc_klass->io_preadv = qio_channel_file_preadv;
#endif
ioc_klass->io_seek = qio_channel_file_seek;
ioc_klass->io_close = qio_channel_file_close;
ioc_klass->io_create_watch = qio_channel_file_create_watch;