uptime: fix a problem with subsequent reads.
When doing subsequent reads of uptime on an open file handle
in the form:
read
lseek 0L, SEEK_SET
read
the second (and later) reads cause that the error
"failed to write to cache" was printed. This
happens for example with "top". top would print the error:
bad data in /proc/uptime
To fix this problem use the whole size of the buffer instead of the d->size
because this is set on the first read.
This behavior was introduced with commit
0ecddf023a4caf8e8d2fe7e9125d777a06c5ec12.
Signed-off-by: Bernhard Miklautz <bernhard.miklautz@shacknet.at>