On Fri, Dec 02, 2016 at 01:13:28PM -0600, Eric Blake wrote: > On 12/01/2016 04:59 AM, Wolfgang Bumiller wrote: > > Fixes #1644754. > > > > Signed-off-by: Wolfgang Bumiller <w.bumil...@proxmox.com> > > --- > > I'm not sure what the original rationale was to treat both partial > > reads as well as well as writes as I/O error. (Seems to have happened > > from original glusterfs v1 to v2 series with a note but no reasoning > > for the read side as far as I could see.) > > The general direction lately seems to be to move away from sector > > based block APIs. Also eg. the NFS code allows partial reads. (It > > does, however, have an old patch (c2eb918e3) dedicated to aligning > > sizes to 512 byte boundaries for file creation for compatibility to > > other parts of qemu like qcow2. This already happens in glusterfs, > > though, but if you move a file from a different storage over to > > glusterfs you may end up with a qcow2 file with eg. the L1 table in > > the last 80 bytes of the file aligned to _begin_ at a 512 boundary, > > but not _end_ at one.) > > > > block/gluster.c | 10 +++++++++- > > 1 file changed, 9 insertions(+), 1 deletion(-) > > > > diff --git a/block/gluster.c b/block/gluster.c > > index 891c13b..3db0bf8 100644 > > --- a/block/gluster.c > > +++ b/block/gluster.c > > @@ -41,6 +41,7 @@ typedef struct GlusterAIOCB { > > int ret; > > Coroutine *coroutine; > > AioContext *aio_context; > > + bool is_write; > > } GlusterAIOCB; > > > > typedef struct BDRVGlusterState { > > @@ -716,8 +717,10 @@ static void gluster_finish_aiocb(struct glfs_fd *fd, > > ssize_t ret, void *arg) > > acb->ret = 0; /* Success */ > > } else if (ret < 0) { > > acb->ret = -errno; /* Read/Write failed */ > > + } else if (acb->is_write) { > > + acb->ret = -EIO; /* Partial write - fail it */ > > } else { > > - acb->ret = -EIO; /* Partial read/write - fail it */ > > + acb->ret = 0; /* Success */ > > Does this properly guarantee that the portion beyond EOF reads as zero?
I'd argue this wasn't necessarily the case before either, considering the first check starts with `!ret`: if (!ret || ret == acb->size) { acb->ret = 0; /* Success */ A read right at EOF would return 0 and be treated as success there, no? Iow. it wouldn't zero out the destination buffer as far as I can see. Come to think of it, I'm not too fond of this part of the check for the write case either. > Would it be better to switch to byte-based interfaces rather than > continue to force gluster interaction in 512-byte sector chunks, since > gluster can obviously store files that are not 512-aligned?