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 <[email protected]> > --- > 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.
> + */
> +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?
> + 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().
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