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raw-posix: fix O_DIRECT short reads 

The following O_DIRECT read from a <512 byte file fails:

  $ truncate -s 320 test.img
  $ qemu-io -n -c 'read -P 0 0 512' test.img
  qemu-io: can't open device test.img: Could not read image for determining its format: Invalid argument

Note that qemu-io completes successfully without the -n (O_DIRECT)
option.

This patch fixes qemu-iotests ./check -nocache -vmdk 059.

Cc: qemu-stable@nongnu.org
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2014-08-21 13:44:07 +01:00 committed by Kevin Wolf
parent d832fb4d66
commit 61ed73cff4
1 changed files with 9 additions and 0 deletions
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block/raw-posix.c
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@ -747,6 +747,15 @@ static ssize_t handle_aiocb_rw_linear(RawPosixAIOData *aiocb, char *buf)
} }
if (len == -1 && errno == EINTR) { if (len == -1 && errno == EINTR) {
continue; continue;
} else if (len == -1 && errno == EINVAL &&
(aiocb->bs->open_flags & BDRV_O_NOCACHE) &&
!(aiocb->aio_type & QEMU_AIO_WRITE) &&
offset > 0) {
/* O_DIRECT pread() may fail with EINVAL when offset is unaligned
* after a short read. Assume that O_DIRECT short reads only occur
* at EOF. Therefore this is a short read, not an I/O error.
*/
break;
} else if (len == -1) { } else if (len == -1) {
offset = -errno; offset = -errno;
break; break;