[pve-devel] applied: [PATCH kvm 2/2] glusterfs: allow partial reads

[Wolfgang Bumiller]

---
Upstream bug: https://bugs.launchpad.net/qemu/+bug/1644754
This patch was also sent upstream as an RFC patch with an additional
description. For now it should be good enough. If partial reads were
an actual issue we'd see a lot more qemu-generated I/O errors with
glusterfs. This is also more consistent with other block driver backends.

 .../pve/0047-glusterfs-allow-partial-reads.patch   | 78 ++++++++++++++++++++++
 debian/patches/series                              |  1 +
 2 files changed, 79 insertions(+)
 create mode 100644 debian/patches/pve/0047-glusterfs-allow-partial-reads.patch

diff --git a/debian/patches/pve/0047-glusterfs-allow-partial-reads.patch b/debian/patches/pve/0047-glusterfs-allow-partial-reads.patch
new file mode 100644
index 0000000..12ba4b0
--- /dev/null
+++ b/debian/patches/pve/0047-glusterfs-allow-partial-reads.patch
@@ -0,0 +1,78 @@
+From e9a50006a7f86adacff211fbd98d5b3ad79f22ef Mon Sep 17 00:00:00 2001
+From: Wolfgang Bumiller <w.bumiller at proxmox.com>
+Date: Wed, 30 Nov 2016 10:27:47 +0100
+Subject: [PATCH 47/47] glusterfs: allow partial reads
+
+This should deal with qemu bug #1644754 until upstream
+decides which way to go. The general direction seems to be
+away from sector based block APIs and with that in mind, and
+when comparing to other network block backends (eg. nfs)
+treating partial reads as errors doesn't seem to make much
+sense.
+---
+ block/gluster.c | 10 +++++++++-
+ 1 file changed, 9 insertions(+), 1 deletion(-)
+
+diff --git a/block/gluster.c b/block/gluster.c
+index 6dcf926..17c51ed 100644
+--- a/block/gluster.c
++++ b/block/gluster.c
+@@ -39,6 +39,7 @@ typedef struct GlusterAIOCB {
+     QEMUBH *bh;
+     Coroutine *coroutine;
+     AioContext *aio_context;
++    bool is_write;
+ } GlusterAIOCB;
+ 
+ typedef struct BDRVGlusterState {
+@@ -623,8 +624,10 @@ 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 */
+     }
+ 
+     acb->bh = aio_bh_new(acb->aio_context, qemu_gluster_complete_aio, acb);
+@@ -861,6 +864,7 @@ static coroutine_fn int qemu_gluster_co_pwrite_zeroes(BlockDriverState *bs,
+     acb.ret = 0;
+     acb.coroutine = qemu_coroutine_self();
+     acb.aio_context = bdrv_get_aio_context(bs);
++    acb.is_write = true;
+ 
+     ret = glfs_zerofill_async(s->fd, offset, size, gluster_finish_aiocb, &acb);
+     if (ret < 0) {
+@@ -979,9 +983,11 @@ static coroutine_fn int qemu_gluster_co_rw(BlockDriverState *bs,
+     acb.aio_context = bdrv_get_aio_context(bs);
+ 
+     if (write) {
++        acb.is_write = true;
+         ret = glfs_pwritev_async(s->fd, qiov->iov, qiov->niov, offset, 0,
+                                  gluster_finish_aiocb, &acb);
+     } else {
++        acb.is_write = false;
+         ret = glfs_preadv_async(s->fd, qiov->iov, qiov->niov, offset, 0,
+                                 gluster_finish_aiocb, &acb);
+     }
+@@ -1044,6 +1050,7 @@ static coroutine_fn int qemu_gluster_co_flush_to_disk(BlockDriverState *bs)
+     acb.ret = 0;
+     acb.coroutine = qemu_coroutine_self();
+     acb.aio_context = bdrv_get_aio_context(bs);
++    acb.is_write = true;
+ 
+     ret = glfs_fsync_async(s->fd, gluster_finish_aiocb, &acb);
+     if (ret < 0) {
+@@ -1090,6 +1097,7 @@ static coroutine_fn int qemu_gluster_co_pdiscard(BlockDriverState *bs,
+     acb.ret = 0;
+     acb.coroutine = qemu_coroutine_self();
+     acb.aio_context = bdrv_get_aio_context(bs);
++    acb.is_write = true;
+ 
+     ret = glfs_discard_async(s->fd, offset, size, gluster_finish_aiocb, &acb);
+     if (ret < 0) {
+-- 
+2.1.4
+
diff --git a/debian/patches/series b/debian/patches/series
index 4ae72b0..bc87c7a 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -44,6 +44,7 @@ pve/0043-vma-sizes-passed-to-blk_co_preadv-should-be-bytes-no.patch
 pve/0044-glusterfs-daemonize.patch
 pve/0045-qmp_delete_drive_snapshot-add-aiocontext.patch
 pve/0046-convert-savevm-async-to-threads.patch
+pve/0047-glusterfs-allow-partial-reads.patch
 #see https://bugs.launchpad.net/qemu/+bug/1488363?comments=all
 extra/x86-lapic-Load-LAPIC-state-at-post_load.patch
 extra/0001-Revert-target-i386-disable-LINT0-after-reset.patch
-- 
2.1.4