fuse_lowlevel: Set bufsize if HAVE_SPLICE is not define and avoid race

These are several buf size fixes

1) Set bufsize when HAVE_SPLICE is not defined. Addresses
https://github.com/libfuse/libfuse/issues/1184

2) Check in the read retry condition for bufsize, i.e. the value
passed to read and not for the buf->mem_size. Using buf->mem_size
can be startup racy. Additionally we now also set bufsize on
allocation to avoid these races.

3) Allocation and value assigned needs to follow the pattern

bufsize = se->bufsize;
buf_alloc(bufsize, internal)
buf->mem_size = bufsize;

I.e. bufsize has to be retrieved first, as se->bufsize might
change at anytime - the value used for allocation and
must not differ from the value actually used.

This also tries to set large sizes in passthrough_hp, to catch
issues in xfstests - though requires to set
/proc/sys/fs/fuse/max_pages_limit

Signed-off-by: Bernd Schubert <bschubert@ddn.com>

0 files changed, 0 insertions, 0 deletions