block/ssh: Add basic .bdrv_truncate()

libssh2 does not seem to offer real truncation support, so we can only
grow files -- but that is better than nothing.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180214204915.7980-4-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2018-02-14 21:49:15 +01:00
parent bd8e0e32da
commit 624f3006b8

View File

@ -1220,6 +1220,29 @@ static int64_t ssh_getlength(BlockDriverState *bs)
return length;
}
static int ssh_truncate(BlockDriverState *bs, int64_t offset,
PreallocMode prealloc, Error **errp)
{
BDRVSSHState *s = bs->opaque;
if (prealloc != PREALLOC_MODE_OFF) {
error_setg(errp, "Unsupported preallocation mode '%s'",
PreallocMode_str(prealloc));
return -ENOTSUP;
}
if (offset < s->attrs.filesize) {
error_setg(errp, "ssh driver does not support shrinking files");
return -ENOTSUP;
}
if (offset == s->attrs.filesize) {
return 0;
}
return ssh_grow_file(s, offset, errp);
}
static BlockDriver bdrv_ssh = {
.format_name = "ssh",
.protocol_name = "ssh",
@ -1232,6 +1255,7 @@ static BlockDriver bdrv_ssh = {
.bdrv_co_readv = ssh_co_readv,
.bdrv_co_writev = ssh_co_writev,
.bdrv_getlength = ssh_getlength,
.bdrv_truncate = ssh_truncate,
.bdrv_co_flush_to_disk = ssh_co_flush,
.create_opts = &ssh_create_opts,
};