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linux-aio: Allow reads beyond the end of growable images

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This is the linux-aio version of commits 22afa7b5 (raw-posix, synchronous) and
ba1d1afd (posix-aio-compat). Reads now produce zeros after the end of file
instead of failing or resulting in short reads, making linux-aio compatible
with the behaviour of synchronous raw-posix requests and posix-aio-compat.

The problem can be reproduced like this:

dd if=/dev/zero of=/tmp/test.raw bs=1 count=1234
./qemu-io -k -n -g -c 'read -p 1024 512' /tmp/test.raw

Previously, the result of this was 'read failed: Invalid argument', now the
read completes successfully.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
This commit is contained in:
Kevin Wolf 2011-10-13 15:42:52 +02:00
parent 1a6e115b19
commit b161e2e4b3
1 changed files with 14 additions and 3 deletions
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17
linux-aio.c
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@ -31,6 +31,8 @@ struct qemu_laiocb {
struct iocb iocb; struct iocb iocb;
ssize_t ret; ssize_t ret;
size_t nbytes; size_t nbytes;
QEMUIOVector *qiov;
bool is_read;
QLIST_ENTRY(qemu_laiocb) node; QLIST_ENTRY(qemu_laiocb) node;
}; };
@ -57,10 +59,17 @@ static void qemu_laio_process_completion(struct qemu_laio_state *s,
ret = laiocb->ret; ret = laiocb->ret;
if (ret != -ECANCELED) { if (ret != -ECANCELED) {
if (ret == laiocb->nbytes) if (ret == laiocb->nbytes) {
ret = 0; ret = 0;
else if (ret >= 0) } else if (ret >= 0) {
ret = -EINVAL; /* Short reads mean EOF, pad with zeros. */
if (laiocb->is_read) {
qemu_iovec_memset_skip(laiocb->qiov, 0,
laiocb->qiov->size - ret, ret);
} else {
ret = -EINVAL;
}
}
laiocb->common.cb(laiocb->common.opaque, ret); laiocb->common.cb(laiocb->common.opaque, ret);
} }
@ -162,6 +171,8 @@ BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
laiocb->nbytes = nb_sectors * 512; laiocb->nbytes = nb_sectors * 512;
laiocb->ctx = s; laiocb->ctx = s;
laiocb->ret = -EINPROGRESS; laiocb->ret = -EINPROGRESS;
laiocb->is_read = (type == QEMU_AIO_READ);
laiocb->qiov = qiov;
iocbs = &laiocb->iocb; iocbs = &laiocb->iocb;