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From: Juan Quintela <quintela@redhat.com>
In-Reply-To: <AANLkTi=hXxgsjn4DOumRoQS-kt+p+wmnuPY0tbNoNoJz@mail.gmail.com>
	(Blue Swirl's message of "Tue, 4 Jan 2011 19:06:54 +0000")
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Date: Tue, 04 Jan 2011 20:23:11 +0100
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Subject: [Qemu-devel] Re: [PATCH 5/5] drive_open: Add invalidate option for
	block devices
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To: Blue Swirl <blauwirbel@gmail.com>
Cc: qemu-devel@nongnu.org

Blue Swirl <blauwirbel@gmail.com> wrote:
> On Tue, Jan 4, 2011 at 2:33 PM, Juan Quintela <quintela@redhat.com> wrote:
>> Linux allows to invalidate block devices. =C2=A0This is needed for the i=
ncoming
>> migration part.
>>
>> Signed-off-by: Juan Quintela <quintela@redhat.com>
>> ---
>> =C2=A0block.h =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 | =C2=A0 =C2=A02 ++
>> =C2=A0block/raw-posix.c | =C2=A0 24 ++++++++++++++++++++++++
>> =C2=A0blockdev.c =C2=A0 =C2=A0 =C2=A0 =C2=A0| =C2=A0 =C2=A09 +++++----
>> =C2=A03 files changed, 31 insertions(+), 4 deletions(-)
>>
>> diff --git a/block.h b/block.h
>> index f923add..5ac96a5 100644
>> --- a/block.h
>> +++ b/block.h
>> @@ -34,6 +34,8 @@ typedef struct QEMUSnapshotInfo {
>> =C2=A0#define BDRV_O_NATIVE_AIO =C2=A00x0080 /* use native AIO instead o=
f the thread pool */
>> =C2=A0#define BDRV_O_NO_BACKING =C2=A00x0100 /* don't open the backing f=
ile */
>> =C2=A0#define BDRV_O_NO_FLUSH =C2=A0 =C2=A00x0200 /* disable flushing on=
 this disk */
>> +#define BDRV_O_INVALIDATE =C2=A00x0400 /* invalidate buffer cache for t=
his device.
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 re-read things from=
 server */
>>
>> =C2=A0#define BDRV_O_CACHE_MASK =C2=A0(BDRV_O_NOCACHE | BDRV_O_CACHE_WB =
| BDRV_O_NO_FLUSH)
>>
>> diff --git a/block/raw-posix.c b/block/raw-posix.c
>> index 6b72470..9439cf1 100644
>> --- a/block/raw-posix.c
>> +++ b/block/raw-posix.c
>> @@ -51,6 +51,7 @@
>> =C2=A0#include <sys/param.h>
>> =C2=A0#include <linux/cdrom.h>
>> =C2=A0#include <linux/fd.h>
>> +#include <linux/fs.h>
>> =C2=A0#endif
>> =C2=A0#if defined (__FreeBSD__) || defined(__FreeBSD_kernel__)
>> =C2=A0#include <signal.h>
>> @@ -168,6 +169,29 @@ static int raw_open_common(BlockDriverState *bs, co=
nst char *filename,
>> =C2=A0 =C2=A0 s->fd =3D fd;
>> =C2=A0 =C2=A0 s->aligned_buf =3D NULL;
>>
>> +#ifdef __linux__
>> + =C2=A0 =C2=A0if ((bdrv_flags & BDRV_O_INVALIDATE)) {
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0struct stat buf;
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0int res;
>> +
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0res =3D fstat(fd, &buf);
>> +
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0if (res < 0) {
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0return -errno;
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0}
>> +
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0if (S_ISBLK(buf.st_mode)) {
>> + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0printf("we are in a block dev=
ice: %s\n", filename);
>
> Leftover debugging?

ouch, yes.

thanks for the spotting.

Later, Juan.