* [Qemu-devel] [PATCH v2 1/2] block/raw-posix: fix launching with failed disks
2015-03-05 21:38 [Qemu-devel] [PATCH v2 0/2] block/raw-posix: fix launching with failed disks Stefan Hajnoczi
@ 2015-03-05 21:38 ` Stefan Hajnoczi
2015-03-05 21:38 ` [Qemu-devel] [PATCH v2 2/2] iotests: add O_DIRECT alignment probing test Stefan Hajnoczi
2015-03-06 12:14 ` [Qemu-devel] [PATCH v2 0/2] block/raw-posix: fix launching with failed disks Kevin Wolf
2 siblings, 0 replies; 4+ messages in thread
From: Stefan Hajnoczi @ 2015-03-05 21:38 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf, Paolo Bonzini, hare, Stefan Hajnoczi
Since commit c25f53b06eba1575d5d0e92a0132455c97825b83 ("raw: Probe
required direct I/O alignment") QEMU has failed to launch if image files
produce I/O errors.
Previously, QEMU would launch successfully and the guest would see the
errors when attempting I/O.
This is a regression and may prevent multipath I/O inside the guest,
where QEMU must launch and let the guest figure out by itself which
disks are online.
Tweak the alignment probing code in raw-posix.c to explicitly look for
EINVAL on Linux instead of bailing. The kernel refuses misaligned
requests with this error code and other error codes can be ignored.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
block/raw-posix.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)
diff --git a/block/raw-posix.c b/block/raw-posix.c
index 3263d2b..f0b4488 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -272,6 +272,31 @@ static int probe_physical_blocksize(int fd, unsigned int *blk_size)
#endif
}
+/* Check if read is allowed with given memory buffer and length.
+ *
+ * This function is used to check O_DIRECT memory buffer and request alignment.
+ */
+static bool raw_is_io_aligned(int fd, void *buf, size_t len)
+{
+ ssize_t ret = pread(fd, buf, len, 0);
+
+ if (ret >= 0) {
+ return true;
+ }
+
+#ifdef __linux__
+ /* The Linux kernel returns EINVAL for misaligned O_DIRECT reads. Ignore
+ * other errors (e.g. real I/O error), which could happen on a failed
+ * drive, since we only care about probing alignment.
+ */
+ if (errno != EINVAL) {
+ return true;
+ }
+#endif
+
+ return false;
+}
+
static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
{
BDRVRawState *s = bs->opaque;
@@ -307,7 +332,7 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
size_t align;
buf = qemu_memalign(MAX_BLOCKSIZE, 2 * MAX_BLOCKSIZE);
for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {
- if (pread(fd, buf + align, MAX_BLOCKSIZE, 0) >= 0) {
+ if (raw_is_io_aligned(fd, buf + align, MAX_BLOCKSIZE)) {
s->buf_align = align;
break;
}
@@ -319,7 +344,7 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
size_t align;
buf = qemu_memalign(s->buf_align, MAX_BLOCKSIZE);
for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {
- if (pread(fd, buf, align, 0) >= 0) {
+ if (raw_is_io_aligned(fd, buf, align)) {
bs->request_alignment = align;
break;
}
--
2.1.0
^ permalink raw reply related [flat|nested] 4+ messages in thread* [Qemu-devel] [PATCH v2 2/2] iotests: add O_DIRECT alignment probing test
2015-03-05 21:38 [Qemu-devel] [PATCH v2 0/2] block/raw-posix: fix launching with failed disks Stefan Hajnoczi
2015-03-05 21:38 ` [Qemu-devel] [PATCH v2 1/2] " Stefan Hajnoczi
@ 2015-03-05 21:38 ` Stefan Hajnoczi
2015-03-06 12:14 ` [Qemu-devel] [PATCH v2 0/2] block/raw-posix: fix launching with failed disks Kevin Wolf
2 siblings, 0 replies; 4+ messages in thread
From: Stefan Hajnoczi @ 2015-03-05 21:38 UTC (permalink / raw)
To: qemu-devel; +Cc: Kevin Wolf, Paolo Bonzini, hare, Stefan Hajnoczi
This test case checks that image files can be opened even if I/O
produces EIO errors. QEMU should not refuse opening failed disks since
the guest may be configured for multipath I/O where accessing failed
disks is expected.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
tests/qemu-iotests/128 | 82 ++++++++++++++++++++++++++++++++++++++++++++++
tests/qemu-iotests/128.out | 5 +++
tests/qemu-iotests/group | 1 +
3 files changed, 88 insertions(+)
create mode 100755 tests/qemu-iotests/128
create mode 100644 tests/qemu-iotests/128.out
diff --git a/tests/qemu-iotests/128 b/tests/qemu-iotests/128
new file mode 100755
index 0000000..249a865
--- /dev/null
+++ b/tests/qemu-iotests/128
@@ -0,0 +1,82 @@
+#!/bin/bash
+#
+# Test that opening O_DIRECT succeeds when image file I/O produces EIO
+#
+# Copyright (C) 2015 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=stefanha@redhat.com
+
+seq=`basename $0`
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1 # failure is the default!
+
+devname="eiodev$$"
+
+_setup_eiodev()
+{
+ # This test should either be run as root or with passwordless sudo
+ for cmd in "" "sudo -n"; do
+ echo "0 $((1024 * 1024 * 1024 / 512)) error" | \
+ $cmd dmsetup create "$devname" 2>/dev/null
+ if [ "$?" -eq 0 ]; then
+ return
+ fi
+ done
+ _notrun "root privileges required to run dmsetup"
+}
+
+_cleanup_eiodev()
+{
+ for cmd in "" "sudo -n"; do
+ $cmd dmsetup remove "$devname" 2>/dev/null
+ if [ "$?" -eq 0 ]; then
+ return
+ fi
+ done
+}
+
+_cleanup()
+{
+ _cleanup_eiodev
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt raw
+_supported_proto file
+_supported_os Linux
+
+_setup_eiodev
+
+TEST_IMG="/dev/mapper/$devname"
+
+echo
+echo "== reading from error device =="
+# Opening image should succeed but the read operation should fail
+$QEMU_IO --format "$IMGFMT" --nocache -c "read 0 65536" "$TEST_IMG" | _filter_qemu_io
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/128.out b/tests/qemu-iotests/128.out
new file mode 100644
index 0000000..4e43f5f
--- /dev/null
+++ b/tests/qemu-iotests/128.out
@@ -0,0 +1,5 @@
+QA output created by 128
+
+== reading from error device ==
+read failed: Input/output error
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 87eec39..71f19d4 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -121,3 +121,4 @@
114 rw auto quick
116 rw auto quick
123 rw auto quick
+128 rw auto quick
--
2.1.0
^ permalink raw reply related [flat|nested] 4+ messages in thread