Am 28.05.2013 10:27, schrieb Kevin Wolf: > Am 28.05.2013 um 10:18 hat Andreas Färber geschrieben: >> The implementation of the ATA FLUSH command invokes a flush at the block >> layer, which may on raw files on POSIX entail a synchronous fdatasync(). >> This may in some cases take so long that the SLES 11 SP1 guest driver >> reports I/O errors and filesystems get corrupted or remounted read-only. >> >> Avoid this by setting BUSY_STAT, so that the guest is made aware we are >> in the middle of an operation and no ATA commands are attempted to be >> processed concurrently. >> >> Addresses BNC#637297. >> >> Suggested-by: Gonglei (Arei) <arei.gong...@huawei.com> >> Signed-off-by: Andreas Färber <afaer...@suse.de> >> --- >> hw/ide/core.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/hw/ide/core.c b/hw/ide/core.c >> index c7a8041..bf1ff18 100644 >> --- a/hw/ide/core.c >> +++ b/hw/ide/core.c >> @@ -795,6 +795,8 @@ static void ide_flush_cb(void *opaque, int ret) >> { >> IDEState *s = opaque; >> >> + s->status &= ~BUSY_STAT; >> + > > This part is unnecessary, the status is already reset.
Only in the ret >= 0 case though AFAICS? >> if (ret < 0) { >> /* XXX: What sector number to set here? */ >> if (ide_handle_rw_error(s, -ret, BM_STATUS_RETRY_FLUSH)) { >> @@ -814,6 +816,7 @@ void ide_flush_cache(IDEState *s) >> return; >> } >> >> + s->status |= BUSY_STAT; >> bdrv_acct_start(s->bs, &s->acct, 0, BDRV_ACCT_FLUSH); >> bdrv_aio_flush(s->bs, ide_flush_cb, s); >> } > > This should fix the bug, however in an one-off way. I was planning to > fix it by setting BSY for all commands and having an explicit command > completion everywhere. This part is a mess currently in IDE. That's a valid idea, but I had backporting to 0.15 in mind. ;) And doh, I forgot qemu-stable. > The other part why I haven't sent a fix yet is that I don't have a test > case for it. Temporarily add a sleep(31) in qemu_fdatasync()? I was lazy in testing with -snapshot to not corrupt my disk image, which would not trigger the same issue since qcow2-backed AFAIU. > I guess I need to extend blkdebug first before this can be > reliably tested by qtest. It can't, since it's not a pure device emulation issue but depends on the relative timing of filesystem operations and subsequent commands. Andreas -- SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg