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authorKevin Wolf <kwolf@redhat.com>2011-10-13 15:42:52 +0200
committerKevin Wolf <kwolf@redhat.com>2011-10-14 10:29:13 +0200
commitb161e2e4b32ac8fb9e6a891eba3da0b825b5d046 (patch)
tree6fce6aa203716a01110062b1563fc82074a2bb66 /linux-aio.c
parent1a6e115b19b0d3831d63bbacb843722070e6674c (diff)
linux-aio: Allow reads beyond the end of growable images
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>
Diffstat (limited to 'linux-aio.c')
-rw-r--r--linux-aio.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/linux-aio.c b/linux-aio.c
index 50da75db1..1c635ef12 100644
--- a/linux-aio.c
+++ b/linux-aio.c
@@ -31,6 +31,8 @@ struct qemu_laiocb {
struct iocb iocb;
ssize_t ret;
size_t nbytes;
+ QEMUIOVector *qiov;
+ bool is_read;
QLIST_ENTRY(qemu_laiocb) node;
};
@@ -57,10 +59,17 @@ static void qemu_laio_process_completion(struct qemu_laio_state *s,
ret = laiocb->ret;
if (ret != -ECANCELED) {
- if (ret == laiocb->nbytes)
+ if (ret == laiocb->nbytes) {
ret = 0;
- else if (ret >= 0)
- ret = -EINVAL;
+ } else if (ret >= 0) {
+ /* 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);
}
@@ -162,6 +171,8 @@ BlockDriverAIOCB *laio_submit(BlockDriverState *bs, void *aio_ctx, int fd,
laiocb->nbytes = nb_sectors * 512;
laiocb->ctx = s;
laiocb->ret = -EINPROGRESS;
+ laiocb->is_read = (type == QEMU_AIO_READ);
+ laiocb->qiov = qiov;
iocbs = &laiocb->iocb;