On 20.03.2017 12:00, Stefan Hajnoczi wrote: > On Mon, Mar 13, 2017 at 10:40:36PM +0100, Max Reitz wrote: >> Currently, raw_regular_truncate() is intended for setting the size of a >> newly created file. However, we also want to use it for truncating an >> existing file in which case only the newly added space (when growing) >> should be preallocated. >> >> This also means that if resizing failed, we should try to restore the >> original file size. This is important when using preallocation. >> >> Signed-off-by: Max Reitz <mre...@redhat.com> >> --- >> block/file-posix.c | 73 >> ++++++++++++++++++++++++++++++++++++++++++++---------- >> 1 file changed, 60 insertions(+), 13 deletions(-) >> >> diff --git a/block/file-posix.c b/block/file-posix.c >> index 35a9e43f3e..cd229324ba 100644 >> --- a/block/file-posix.c >> +++ b/block/file-posix.c >> @@ -1384,11 +1384,39 @@ static void raw_close(BlockDriverState *bs) >> } >> } >> >> -static int raw_regular_truncate(int fd, int64_t offset, PreallocMode >> prealloc, >> +/** >> + * Truncates the given regular file @fd to @offset and, when growing, fills >> the >> + * new space according to @prealloc. >> + * >> + * @create must be true iff the file is new. In that case, @bs is ignored. >> If >> + * @create is false, @bs must be valid and correspond to the same file as >> @fd. > > Returns: 0 on success, -errno on failure.
Yep, will add.
>> + */
>> +static int raw_regular_truncate(int fd, BlockDriverState *bs, int64_t
>> offset,
>
> The presence of both a file descriptor and a BlockDriverState (actually
> it must be a BDRVRawState) arguments is unusual. It seems bs is needed
> for bdrv_getlength().
>
> How about using fstat(fd, &st) and then dropping bs and create?
Well, I could do that, but bdrv_getlength() is a bit simpler and I don't
see much of an issue with specifying both an fd and a bs.
>> + PreallocMode prealloc, bool create,
>> Error **errp)
>> {
>> int result = 0;
>> - char *buf;
>> + int64_t current_length = 0;
>> + char *buf = NULL;
>> +
>> + assert(create || bs);
>> + if (!create) {
>> + BDRVRawState *s = bs->opaque;
>> + assert(s->fd == fd);
>> + }
>> +
>> + if (!create) {
>> + current_length = bdrv_getlength(bs);
>> + if (current_length < 0) {
>> + error_setg_errno(errp, -current_length,
>> + "Could not inquire current length");
>> + return -current_length;
>> + }
>> +
>> + if (current_length > offset && prealloc != PREALLOC_MODE_OFF) {
>> + return -ENOTSUP;
>> + }
>
> Missing error_setg().
Indeed! Will fix.
Max
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