On Wed, Sep 26, 2018 at 01:22:28PM +0200, Marcin Niestrój wrote:
>
> I think I was a little bit too early with review :) Below I have some
> comments.
>
> Marcin Niestrój <m.niestroj@xxxxxxxxxxxxxxxx> writes:
>
> > Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> writes:
> >
> >> In ramfs_truncate() "newchunks" denotes the number of chunks we
> >> want to have after the call. We decrease that number while iterating
> >> over the existing chunks and decrease it further with every newly
> >> allocated chunk until "newchunks" is zero.
> >> This is a bit hard to read. Instead we drop the decreasing while
> >> iterating over existing chunks and increase "oldchunks" while allocating
> >> until it reaches "newchunks".
> >>
> >> This is mainly done to make the next patch easier.
> >>
> >> Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> >> ---
> >> fs/ramfs.c | 9 ++++-----
> >> 1 file changed, 4 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/fs/ramfs.c b/fs/ramfs.c
> >> index 09dafe02ae..8ba8d77de9 100644
> >> --- a/fs/ramfs.c
> >> +++ b/fs/ramfs.c
> >> @@ -384,19 +384,18 @@ static int ramfs_truncate(struct device_d *dev, FILE *f, ulong size)
> >> if (!node->data)
> >> return -ENOMEM;
> >> data = node->data;
> >> + newchunks = 1;
>
> What is the reason of this instruction? What if 'size' == 16384 and we
> do it on freshly opened file (with truncate(fd, 16384)? 'newchunk'
> should be 2 in that case, or not?
Yes, you're right. It should be "oldchunks = 1" instead. Then we have:
> if (!data) {
> node->data = ramfs_get_chunk();
> if (!node->data)
> return -ENOMEM;
> data = node->data;
> oldchunks = 1;
> }
!data we have no chunks allocated. We allocate one and set oldchunks to one. When we
do:
> while (newchunks > oldchunks) {
> data->next = ramfs_get_chunk();
> if (!data->next)
> return -ENOMEM;
> data = data->next;
> oldchunks++;
> }
In your example above we execute this loop once, allocate the second chunk, oldchunks
will become two which is the same as newchunks and then we go out.
I hope this is correct now ;)
Sascha
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