block/raw-posix: fix launching with failed disks
Since commit c25f53b06e
("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>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
parent
c095348b91
commit
22d182e82b
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@ -272,6 +272,31 @@ static int probe_physical_blocksize(int fd, unsigned int *blk_size)
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#endif
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#endif
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}
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}
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/* Check if read is allowed with given memory buffer and length.
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*
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* This function is used to check O_DIRECT memory buffer and request alignment.
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*/
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static bool raw_is_io_aligned(int fd, void *buf, size_t len)
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{
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ssize_t ret = pread(fd, buf, len, 0);
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if (ret >= 0) {
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return true;
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}
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#ifdef __linux__
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/* The Linux kernel returns EINVAL for misaligned O_DIRECT reads. Ignore
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* other errors (e.g. real I/O error), which could happen on a failed
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* drive, since we only care about probing alignment.
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*/
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if (errno != EINVAL) {
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return true;
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}
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#endif
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return false;
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}
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static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
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static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
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{
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{
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BDRVRawState *s = bs->opaque;
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BDRVRawState *s = bs->opaque;
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@ -307,7 +332,7 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
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size_t align;
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size_t align;
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buf = qemu_memalign(MAX_BLOCKSIZE, 2 * MAX_BLOCKSIZE);
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buf = qemu_memalign(MAX_BLOCKSIZE, 2 * MAX_BLOCKSIZE);
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for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {
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for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {
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if (pread(fd, buf + align, MAX_BLOCKSIZE, 0) >= 0) {
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if (raw_is_io_aligned(fd, buf + align, MAX_BLOCKSIZE)) {
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s->buf_align = align;
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s->buf_align = align;
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break;
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break;
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}
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}
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@ -319,7 +344,7 @@ static void raw_probe_alignment(BlockDriverState *bs, int fd, Error **errp)
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size_t align;
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size_t align;
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buf = qemu_memalign(s->buf_align, MAX_BLOCKSIZE);
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buf = qemu_memalign(s->buf_align, MAX_BLOCKSIZE);
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for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {
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for (align = 512; align <= MAX_BLOCKSIZE; align <<= 1) {
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if (pread(fd, buf, align, 0) >= 0) {
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if (raw_is_io_aligned(fd, buf, align)) {
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bs->request_alignment = align;
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bs->request_alignment = align;
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break;
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break;
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}
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}
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