This patch adds -drive cache=directsync for O_DIRECT | O_SYNC host file
I/O with no disk write cache presented to the guest.
This mode is useful when guests may not be sending flushes when
appropriate and therefore leave data at risk in case of power failure.
When cache=directsync is used, write operations are only completed to
the guest when data is safely on disk.
This new mode is like cache=writethrough but it bypasses the host page
cache.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch introduces bdrv_parse_cache_flags() which sets open flags
given a cache mode. Previously this was duplicated in blockdev.c and
qemu-img.c.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Fix code format to make checkpatch.pl happy.
Signed-off-by: Robert Wang <wdongxu@linux.vnet.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
If we're already in a coroutine, there is no reason to use the synchronous
version of block layer functions when a coroutine one exists. This makes
bdrv_read/write/flush use bdrv_co_* when used inside a coroutine.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The purpose of AsyncContexts was to protect qcow and qcow2 against reentrancy
during an emulated bdrv_read/write (which includes a qemu_aio_wait() call and
can run AIO callbacks of different requests if it weren't for AsyncContexts).
Now both qcow and qcow2 are protected by CoMutexes and AsyncContexts can be
removed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
In order to be able to call bdrv_co_readv/writev for drivers that don't
implement the functions natively, add an emulation that uses the AIO functions
to implement them.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Use the bdrv_co_readv/writev callbacks to implement bdrv_aio_readv/writev and
bdrv_read/write if a driver provides the coroutine version instead of the
synchronous or AIO version.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add new block driver callbacks bdrv_co_readv/writev, which work on a
QEMUIOVector like bdrv_aio_*, but don't need a callback. The function may only
be called inside a coroutine, so a block driver implementing this interface can
yield instead of blocking during I/O.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Commit aea2a33c made bdrv_eject() obey the locked flag. Correct for
medium eject (eject_flag set), incorrect for medium load (eject_flag
clear). See MMC-5 Table 341 "Actions for Lock/Unlock/Eject".
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Callees always return 0, except for FreeBSD's cdrom_eject(), which
returns -ENOTSUP when the device is in a terminally wedged state.
The only caller is bdrv_eject(), and it maps -ENOTSUP to 0 since
commit 4be9762a.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
BlockDriverState members change_cb and change_opaque are initially
null. The device model may set them, with bdrv_set_change_cb(). If
the device model gets detached (hot unplug), they're left dangling.
Only safe because device hot unplug automatically destroys the
BlockDriverState. But that's a questionable feature, best not to rely
on it.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
qemu-img.c wants to count allocated file size of image. Previously it
counts a single bs->file by 'stat' or Window API. As VMDK introduces
multiple file support, the operation becomes format specific with
platform specific meanwhile.
The functions are moved to block/raw-{posix,win32}.c and qemu-img.c calls
bdrv_get_allocated_file_size to count the bs. And also added VMDK code
to count his own extents.
Signed-off-by: Fam Zheng <famcool@gmail.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Block drivers that don't support creating images don't have a size option. Fail
gracefully instead of segfaulting when trying to access the option's value.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Change BDRV_O_NOCACHE to only imply bypassing the host OS file cache,
but no writeback semantics. All existing callers are changed to also
specify BDRV_O_CACHE_WB to give them writeback semantics.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
No users of bdrv_get_type_hint() left. bdrv_set_type_hint() can make
the media removable by side effect. Make that explicit.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
query-block's specification documents response member "type" with
values "hd", "cdrom", "floppy", "unknown".
Its value is unreliable: a block device used as floppy has type
"floppy" if created with if=floppy, but type "hd" if created with
if=none.
That's because with if=none, the type is at best a declaration of
intent: the drive can be connected to any guest device. Its type is
really the guest device's business. Reporting it here is wrong.
No known user of QMP uses "type". It's unlikely that any unknown
users exist, because its value is useless unless you know how the
block device was created. But then you also know the true value.
Fixing the broken value risks breaking (hypothetical!) clients that
somehow rely on the current behavior. Not fixing the value risks
breaking (hypothetical!) clients that rely on the value to be
accurate. Can't entirely avoid hypothetical lossage. Change the
value to be always "unknown".
This makes "info block" always report "type=unknown". Pointless.
Change it to not report the type.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The code changed here is an unused data type name (evt_flush_occurred).
Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
The block layer caches the device size to avoid doing lseek(fd, 0,
SEEK_END) every time this value is needed. For removable media the
device size becomes stale if a new medium is inserted. This patch
simply prevents device size caching for removable media.
A smarter solution is to update the cached device size when a new medium
is inserted. Given that there are currently bugs with CD-ROM media
change I do not want to implement that approach until we've gotten
things correct first.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
It can be handy to know when the guest locks/unlocks the CD-ROM tray.
This trace event makes that possible.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When removing a drive from the host-side via drive_del we currently have
the following path:
drive_del
qemu_aio_flush()
bdrv_close() // zaps bs->drv, which makes any subsequent I/O get
// dropped. Works as designed
drive_uninit()
bdrv_delete() // frees the bs. Since the device is still connected to
// bs, any subsequent I/O is a use-after-free.
The value of bs->drv becomes unpredictable on free. As long as it
remains null, I/O still gets dropped, however it could become non-null
at any point after the free resulting SEGVs or other QEMU state
corruption.
To resolve this issue as simply as possible, we can chose to not
actually delete the BlockDriverState pointer. Since bdrv_close()
handles setting the drv pointer to NULL, we just need to remove the
BlockDriverState from the QLIST that is used to enumerate the block
devices. This is currently handled within bdrv_delete, so move this
into its own function, bdrv_make_anon().
The result is that we can now invoke drive_del, this closes the file
descriptors and sets BlockDriverState->drv to NULL which prevents futher
IO to the device, and since we do not free BlockDriverState, we don't
have to worry about the copy retained in the block devices.
We also don't attempt to remove the qdev property since we are no longer
deleting the BlockDriverState on drives with associated drives. This
also allows for removing Drives with no devices associated either.
Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
If the block device has been closed, we no longer have a medium to submit
IO against, check for this before submitting io. This prevents a segfault
further in the code where we dereference elements of the block driver.
Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add a trace event for bdrv_aio_flush() to complement the existing
bdrv_aio_readv() and bdrv_aio_writev() events.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Other geometry guessing functions already reside in block.c.
Remove some unused or debugging only fields.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Set block device in use during block migration, disallow drive_del and
bdrv_truncate for in use devices.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Certain operations such as drive_del or resize cannot be performed
while external users (eg. block migration) reference the block device.
Add a flag to indicate that.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Extend the change_cb callback with a reason argument, and use it
to tell drivers about size changes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The backing format should be honored during image creation. For some
reason we currently use the image format to open the backing file. This
fails when the backing file has a different format than the image being
created. Keep the image and backing format drivers completely separate.
Also print the backing filename if there is an error opening the backing
file instead of the image filename.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Acked-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Avoid a warning with GCC 4.6.0:
/src/qemu/block.c: In function 'bdrv_img_create':
/src/qemu/block.c:2862:25: error: variable 'fmt' set but not used [-Werror=unused-but-set-variable]
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Add a new bdrv_discard method to free blocks in a mapping image, and a new
drive property to set the granularity for these discard. If no discard
granularity support is set discard support is disabled.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Kevin suggested to have bdrv_img_create() return proper -errno values
on error.
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch re-factors img_create() moving the code doing the actual
work into block.c where it can be shared with QEMU. This is needed to
be able to create images from QEMU to be used for live snapshots.
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Backing filenames may contain a protocol. The code currently doesn't
consider this case and produces filenames that embed "<protocol>:".
Don't combine filenames if the backing filename contains a protocol.
Based on an earlier patch by Anthony Liguori <aliguori@us.ibm.com>.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The bdrv_find_protocol() function returns NULL if an unknown protocol
name is given. It returns the "file" protocol when the filename
contains no protocol at all. This makes it difficult to distinguish
between paths which contain a protocol and those which do not.
Factor out a helper function that tests whether or not a filename has a
protocol. The next patch makes use of this function.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Filenames may start with "<protocol>:" to explicitly use a protocol like
nbd. Filenames with unknown protocols are rejected in most of QEMU
except for bdrv_create_file(). Even if a file with an invalid filename
can be created, QEMU cannot use it since all the other relevant
functions reject such paths. Make bdrv_create_file() consistent.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Sectors are marked dirty in the bitmap on AIO submission. This is wrong
since data has not reached storage.
Set a given sector as dirty in the dirty bitmap on AIO completion, so that
reading a sector marked as dirty is guaranteed to return uptodate data.
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Otherwise upper 32 bits of bitmap entries are not correctly calculated.
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This changes bdrv_flush to return 0 on success and -errno in case of failure.
It's a requirement for implementing proper error handle in users of bdrv_flush.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
In order to backup snapshots, created from QCOW2 iamge, we want to copy snapshots out of QCOW2 disk to a seperate storage.
The following patch adds a new option in "qemu-img": qemu-img convert -f qcow2 -O qcow2 -s snapshot_name src_img bck_img.
Right now, it only supports to copy the full snapshot, delta snapshot is on the way.
Changes from V1: all the comments from Kevin are addressed:
Add read-only checking
Fix coding style
Change the name from bdrv_snapshot_load to bdrv_snapshot_load_tmp
Signed-off-by: Disheng Su <edison@cloud.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Observing block layer aio readv/writev operations is useful for
debugging image formats or understanding guest disk I/O patterns.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This reverts commit 79368c81bf.
Conflicts:
block.c
I haven't been able to come up with a solution yet for the corruption caused by
unaligned requests from the IDE disk so revert until a solution can be written.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Arguably we should re-open the backing file with the backing file format and
not with the format of the snapshot image.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_eject() gets called when a device model opens or closes the tray.
If the block driver implements method bdrv_eject(), that method gets
called. Drivers host_cdrom implements it, and it opens and closes the
physical tray, and nothing else. When a device model opens, then
closes the tray, media changes only if the user actively changes the
physical media while the tray is open. This is matches how physical
hardware behaves.
If the block driver doesn't implement method bdrv_eject(), we do
something quite different: opening the tray severs the connection to
the image by calling bdrv_close(), and closing the tray does nothing.
When the device model opens, then closes the tray, media is gone,
unless the user actively inserts another one while the tray is open,
with a suitable change command in the monitor. This isn't how
physical hardware behaves. Rather inconvenient when programs
"helpfully" eject media to give you a chance to change it. The way
bdrv_eject() behaves here turns that chance into a must, which is not
what these programs or their users expect.
Change the default action not to call bdrv_close(). Instead, note the
tray status in new BlockDriverState member tray_open. Use it in
bdrv_is_inserted().
Arguably, the device models should keep track of tray status
themselves. But this is less invasive.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Assuming that any image on a block device is not properly zero-initialized is
actually wrong: Only raw images have this problem. Any other image format
shouldn't care about it, they initialize everything properly themselves.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_commit copies the image to its backing file sector by sector, which
is (surprise!) relatively slow. Let's take a larger buffer and handle more
sectors at once if possible.
With a 1G qcow2 file, this brought the time bdrv_commit takes down from
5:06 min to 1:14 min for me.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Block device change command did not copy BDRV_O_SNAPSHOT flag. Thus
the new image did not have this flag and the file got deleted during
opening.
Fix by copying BDRV_O_SNAPSHOT flag.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
"No such file or directory" is a misleading error message
when a user tries to open a file with wrong permissions.
Cc: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
CVE-2008-2004 described a vulnerability in QEMU whereas a malicious user could
trick the block probing code into accessing arbitrary files in a guest. To
mitigate this, we added an explicit format parameter to -drive which disabling
block probing.
Fast forward to today, and the vast majority of users do not use this parameter.
libvirt does not use this by default nor does virt-manager.
Most users want block probing so we should try to make it safer.
This patch adds some logic to the raw device which attempts to detect a write
operation to the beginning of a raw device. If the first 4 bytes happen to
match an image file that has a backing file that we support, it scrubs the
signature to all zeros. If a user specifies an explicit format parameter, this
behavior is disabled.
I contend that while a legitimate guest could write such a signature to the
header, we would behave incorrectly anyway upon the next invocation of QEMU.
This simply changes the incorrect behavior to not involve a security
vulnerability.
I've tested this pretty extensively both in the positive and negative case. I'm
not 100% confident in the block layer's ability to deal with zero sized writes
particularly with respect to the aio functions so some additional eyes would be
appreciated.
Even in the case of a single sector write, we have to make sure to invoked the
completion from a bottom half so just removing the zero sized write is not an
option.
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This distinguishes between harmless leaks and real corruption. Hopefully users
better understand what qemu-img check wants to tell them.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
People think that their images are corrupted when in fact there are just some
leaked clusters. Differentiating several error cases should make the messages
more comprehensible.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Don't try to be clever by freeing all temporary data and calling all callbacks
when the return value (an error) is certain. Doing so has at least two
important problems:
* The temporary data that is freed (qiov, possibly zero buffer) is still used
by the requests that have not yet completed.
* Calling the callbacks for all requests in the multiwrite means for the caller
that it may free buffers etc. which are still in use.
Just remember the error value and do the cleanup when all requests have
completed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_aio_writev may call the callback immediately (and it will commonly do so
in error cases). Current code doesn't consider this. For details see the
comment added by this patch.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
BlockDriverState member removable controls whether virtual media
change (monitor commands change, eject) is allowed. It is set when
the "type hint" is BDRV_TYPE_CDROM or BDRV_TYPE_FLOPPY.
The type hint is only set by drive_init(). It sets BDRV_TYPE_FLOPPY
for if=floppy. It sets BDRV_TYPE_CDROM for media=cdrom and if=ide,
scsi, xen, or none.
if=ide and if=scsi work, because the type hint makes it a CD-ROM.
if=xen likewise, I think.
For the same reason, if=none works when it's used by ide-drive or
scsi-disk. For other guest devices, there are problems:
* fdc: you can't change virtual media
$ qemu [...] -drive if=none,id=foo,... -global isa-fdc.driveA=foo
QEMU 0.12.50 monitor - type 'help' for more information
(qemu) eject foo
Device 'foo' is not removable
unless you add media=cdrom, but that makes it readonly.
* virtio: if you add media=cdrom, you can change virtual media. If
you eject, the guest gets I/O errors. If you change, the guest sees
the drive's contents suddenly change.
* scsi-generic: if you add media=cdrom, you can change virtual media.
I didn't test what that does to the guest or the physical device,
but it can't be pretty.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
savevm.c keeps a pointer to the snapshot block device. If you manage
to get that device deleted, the pointer dangles, and the next snapshot
operation will crash & burn. Unplugging a guest device that uses it
does the trick:
$ MALLOC_PERTURB_=234 qemu-system-x86_64 [...]
QEMU 0.12.50 monitor - type 'help' for more information
(qemu) info snapshots
No available block device supports snapshots
(qemu) drive_add auto if=none,file=tmp.qcow2
OK
(qemu) device_add usb-storage,id=foo,drive=none1
(qemu) info snapshots
Snapshot devices: none1
Snapshot list (from none1):
ID TAG VM SIZE DATE VM CLOCK
(qemu) device_del foo
(qemu) info snapshots
Snapshot devices:
Segmentation fault (core dumped)
Move management of that pointer to block.c, and zap it when the device
it points becomes unusable.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
For instance, -device scsi-disk,drive=foo -device scsi-disk,drive=foo
happily creates two SCSI disks connected to the same block device.
It's all downhill from there.
Device usb-storage deliberately attaches twice to the same blockdev,
which fails with the fix in place. Detach before the second attach
there.
Also catch attempt to delete while a guest device model is attached.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
To fix https://bugs.launchpad.net/qemu/+bug/597402 where qemu fails to
call unlink() on temporary snapshots due to bs->is_temporary getting clobbered
in bdrv_open_common() after being set in bdrv_open() which calls the former.
We don't need to initialize bs->is_temporary in bdrv_open_common().
Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Before the raw/file split we used to allow filenames with colons for host
device only. While this was more by accident than by design people rely
on it, so we need to bring it back.
So move the host device probing to be before the protocol detection
again.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add new functions that write and flush the written data to disk immediately.
This is what needs to be used for image format metadata to maintain integrity
for cache=... modes that don't use O_DSYNC. (Actually, we only need barriers,
and therefore the functions are defined as such, but flushes is what is
implemented in this patch - we can try to change that later)
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Fix a warning from OpenBSD gcc (3.3.5 (propolice)):
/src/qemu/block.c: In function `bdrv_info_stats_bs':
/src/qemu/block.c:1548: warning: long long int format, long unsigned
int arg (arg 6)
There may be also truncation effects.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This is a more flexible alternative to bdrv_iterate().
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
do_commit() and mux_proc_byte() iterate over the list of drives
defined with drive_init(). This misses host block devices defined by
other means. Such means don't exist now, but will be introduced later
in this series.
Change them to use new bdrv_commit_all(), which iterates over all host
block devices.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
That's where they belong semantically (block device host part), even
though the actions are actually executed by guest device code.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Both bdrv_can_snapshot() and bdrv_has_snapshot() does not work as advertized.
First issue: Their names implies different porpouses, but they do the same thing
and have exactly the same code. Maybe copied and pasted and forgotten?
bdrv_has_snapshot() is called in various places for actually checking if there
is snapshots or not.
Second issue: the way bdrv_can_snapshot() verifies if a block driver supports or
not snapshots does not catch all cases. E.g.: a raw image.
So when do_savevm() is called, first thing it does is to set a global
BlockDriverState to save the VM memory state calling get_bs_snapshots().
static BlockDriverState *get_bs_snapshots(void)
{
BlockDriverState *bs;
DriveInfo *dinfo;
if (bs_snapshots)
return bs_snapshots;
QTAILQ_FOREACH(dinfo, &drives, next) {
bs = dinfo->bdrv;
if (bdrv_can_snapshot(bs))
goto ok;
}
return NULL;
ok:
bs_snapshots = bs;
return bs;
}
bdrv_can_snapshot() may return a BlockDriverState that does not support
snapshots and do_savevm() goes on.
Later on in do_savevm(), we find:
QTAILQ_FOREACH(dinfo, &drives, next) {
bs1 = dinfo->bdrv;
if (bdrv_has_snapshot(bs1)) {
/* Write VM state size only to the image that contains the state */
sn->vm_state_size = (bs == bs1 ? vm_state_size : 0);
ret = bdrv_snapshot_create(bs1, sn);
if (ret < 0) {
monitor_printf(mon, "Error while creating snapshot on '%s'\n",
bdrv_get_device_name(bs1));
}
}
}
bdrv_has_snapshot(bs1) is not checking if the device does support or has
snapshots as explained above. Only in bdrv_snapshot_create() the device is
actually checked for snapshot support.
So, in cases where the first device supports snapshots, and the second does not,
the snapshot on the first will happen anyways. I believe this is not a good
behavior. It should be an all or nothing process.
This patch addresses these issues by making bdrv_can_snapshot() actually do
what it must do and enforces better tests to avoid errors in the middle of
do_savevm(). bdrv_has_snapshot() is removed and replaced by bdrv_can_snapshot()
where appropriate.
bdrv_can_snapshot() was moved from savevm.c to block.c. It makes more sense to me.
The loadvm_state() function was updated too to enforce that when loading a VM at
least all writable devices must support snapshots too.
Signed-off-by: Miguel Di Ciurcio Filho <miguel.filho@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When snapshot handlers are not defined in the format driver, it is
better to call the ones of the protocol driver. This enables us to
implement snapshot support in the protocol driver.
We need to call bdrv_close() and bdrv_open() handlers of the format
driver before and after bdrv_snapshot_goto() call of the protocol. It is
because the contents of the block driver state may need to be changed
after loading vmstate.
Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch calls the close handler of the block driver before the qemu
process exits.
This is necessary because the sheepdog block driver releases the lock
of VM images in the close handler.
Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
qemu -cdrom /dev/cdrom with an empty CD-ROM drive doesn't work any more because
we try to guess the format and when this fails (because there is no medium) we
exit with an error message.
This patch should restore the old behaviour by assuming raw format for such
drives.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Clean up block.c and use BDRV_SECTOR_SIZE rather than hard coded
numbers (512) when referring to sector size throughout the code.
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
In bdrv_open() there is no need to shift total_size >> 9 just to
multiply it by 512 again just a few lines later, since this is the
only place the variable is used.
Mask with BDRV_SECTOR_MASK to protect against case where we are
passed a corrupted image.
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Previous commit added QMP documentation to the qemu-monitor.hx
file, it's is a copy of this information.
While it's good to keep it near code, maintaining two copies of
the same information is too hard and has little benefit as we
don't expect client writers to consult the code to find how to
use a QMP command.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This patch adds a missing bdrv_delete() call in find_image_format() so that a
SG_IO BlockDriver properly releases the temporary BlockDriverState *bs created
from bdrv_file_open()
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Reported-by: Chris Krumme <chris.krumme@windriver.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch enables protocol drivers to use their create options which
are not supported by the format. For example, protcol drivers can use
a backing_file option with raw format.
Signed-off-by: MORITA Kazutaka <morita.kazutaka@lab.ntt.co.jp>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
With overlapping requests, the total number of sectors is smaller than the sum
of the nb_sectors of both requests.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Usually the guest can tell the host to flush data to disk. In some cases we
don't want to flush though, but try to keep everything in cache.
So let's add a new cache value to -drive that allows us to set the cache
policy to most aggressive, disabling flushes. We call this mode "unsafe",
as guest data is not guaranteed to survive host crashes anymore.
This patch also adds a noop function for aio, so we can do nothing in AIO
fashion.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
This patch adds a special case check for scsi-generic devices in
refresh_total_sectors() to skip the subsequent BlockDriver->bdrv_getlength()
that will be returning -ESPIPE from block/raw-posic.c:raw_getlength() for
BlockDriverState->sg=1 devices.
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch adds a special BlockDriverState->sg check in block.c:find_image_format()
after bdrv_file_open() -> block/raw-posix.c:hdev_open() has been called to determine
if we are dealing with a Linux host scsi-generic device.
The patch then returns the BlockDriver * from bdrv_find_format("raw"), skipping the
subsequent bdrv_read() and rest of find_image_format().
Signed-off-by: Nicholas A. Bellinger <nab@linux-iscsi.org>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The difference between the start sectors of two requests can be larger
than the size of the "int" type, which can lead to a not correctly
sorted multiwrite array and thus spurious I/O errors and filesystem
corruption due to incorrect request merges.
So instead of doing the cute sector arithmetics trick spell out the
exact comparisms.
Spotted by Kevin Wolf based on a testcase from Michael Tokarev.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The special case doesn't really us buy anything. Without it vvfat works more
consistently as a protocol. We get raw on top of vvfat now, which works just
as well as using vvfat directly.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The 'parent' field in the 'query-blockstats' monitor command is
part of the top level block device QDict, not part of the 2nd
level 'stats' QDict.
* block.c: Fix docs for 'parent' field in block stats monitor
command output
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
There is a call to free() where qemu_free() should instead be used.
Signed-off-by: Bruce Rogers <brogers@novell.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When reopening the image, don't guess the driver, but use the same driver as
was used before. This is important if the format=... option was used for that
image.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We can't assume the file protocol for Windows devices, they need the same
detection as other files for which an explicit protocol is not specified.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
They aren't used afterwards nor supposed to be stored by a bdrv_create
handler.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This adds the wr_highest_sector blockstat which implements what is generally
known as the high watermark. It is the highest offset of a sector written to
the respective BlockDriverState since it has been opened.
The query-blockstat QMP command is extended to add this value to the result,
and also to add the statistics of the underlying protocol in a new "parent"
field. Note that to get the "high watermark" of a qcow2 image, you need to look
into the wr_highest_sector field of the parent (which can be a file, a
host_device, ...). The wr_highest_sector of the qcow2 BlockDriverState itself
is the highest offset on the _virtual_ disk that the guest has written to.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The BlockDriver bdrv_getlength function is called from the I/O code path
when checking that the request falls within the device. Unfortunately
this involves an lseek system call in the raw protocol; every read or
write request will incur this lseek cost.
Jan Kiszka <jan.kiszka@siemens.com> identified this issue and its
latency overhead. This patch caches device length in the existing
total_sectors variable so lseek calls can be avoided for fixed size
devices.
Growable devices fall back to the full bdrv_getlength code path because
I have not added logic to detect extending the size of the device in a
write.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
It is safer to set backing_hd to NULL after deleting it so that any use
after deletion is obvious during development. Happy segfaulting!
This patch should be applied after Kevin Wolf's "vmdk: Convert to
bdrv_open" so that vmdk does not segfault on close.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This fixes the problem that qemu-img's use of no_zero_init only considered the
no_zero_init flag of the format driver, but not of the underlying protocols.
Between the raw/file split and this fix, converting to host devices is broken.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Format drivers shouldn't need to bother with things like file names, but rather
just get an open BlockDriverState for the underlying protocol. This patch
introduces this behaviour for bdrv_open implementation. For protocols which
need to access the filename to open their file/device/connection/... a new
callback bdrv_file_open is introduced which doesn't get an underlying file
opened.
For now, also some of the more obscure formats use bdrv_file_open because they
open() the file themselves instead of using the block.c functions. They need to
be fixed in later patches.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_open contains quite some code that is only useful for opening images (as
opposed to opening files by a protocol), for example snapshots.
This patch splits the code so that we have bdrv_open_file() for files (uses
protocols), bdrv_open() for images (uses format drivers) and bdrv_open_common()
for the code common for opening both images and files.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We're running into various problems because the "raw" file access, which
is used internally by the various image formats is entangled with the
"raw" image format, which maps the VM view 1:1 to a file system.
This patch renames the raw file backends to the file protocol which
is treated like other protocols (e.g. nbd and http) and adds a new
"raw" image format which is just a wrapper around calls to the underlying
protocol.
The patch is surprisingly simple, besides changing the probing logical
in block.c to only look for image formats when using bdrv_open and
renaming of the old raw protocols to file there's almost nothing in there.
For creating images, a new bdrv_create_file is introduced which guesses the
protocol to use. This allows using qemu-img create -f raw (or just using the
default) for both files and host devices. Converting the other format drivers
to use this function to create their images is left for later patches.
The only issues still open are in the handling of the host devices.
Firstly in current qemu we can specifiy the host* format names
on various command line acceping images, but the new code can't
do that without adding some translation. Second the layering breaks
the no_zero_init flag in the BlockDriver used by qemu-img. I'm not
happy how this is done per-driver instead of per-state so I'll
prepare a separate patch to clean this up.
There's some more cleanup opportunity after this patch, e.g. using
separate lists and registration functions for image formats vs
protocols and maybe even host drivers, but this can be done at a
later stage.
Also there's a check for protocol in bdrv_open for the BDRV_O_SNAPSHOT
case that I don't quite understand, but which I fear won't work as
expected - possibly even before this patch.
Note that this patch requires various recent block patches from Kevin
and me, which should all be in his block queue.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
A new iovec array is allocated when creating a merged write request.
This patch ensures that the iovec array is deleted in addition to its
qiov owner.
Reported-by: Leszek Urbanski <tygrys@moo.pl>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
