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>
Anthony Liguori