When a backing file is opened such that (1) a protocol is directly
used as the block driver and (2) the block driver has bdrv_file_open,
bdrv_open_backing_file segfaults. The problem arises because
bdrv_open_common returns without setting bd->backing_hd->file.
To effect (1), you seem to have to use the -F flag in qemu-img. There
are several block drivers that satisfy (2), such as "file" and "nbd".
Here are some concrete examples:
#!/bin/bash
echo Test file format
./qemu-img create -f file base.file 1m
./qemu-img create -f qcow2 -F file -o backing_file=base.file\
file-overlay.qcow2
./qemu-img convert -O raw file-overlay.qcow2 file-convert.raw
echo Test nbd format
SOCK=$PWD/nbd.sock
./qemu-img create -f raw base.raw 1m
./qemu-nbd -t -k $SOCK base.raw &
trap "kill $!" EXIT
while ! test -e $SOCK; do sleep 1; done
./qemu-img create -f qcow2 -F nbd -o backing_file=nbd:unix:$SOCK\
nbd-overlay.qcow2
./qemu-img convert -O raw nbd-overlay.qcow2 nbd-convert.raw
Without this patch, the two qemu-img convert commands segfault.
This is a regression that was introduced in v1.7 by
dbecebddfa.
Signed-off-by: Peter Feiner <peter@gridcentric.ca>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
It should be possible to use a format as a driver for a file which in
turn requires another file, i.e., nesting file formats.
Allowing nested file formats results in e.g. qcow2 BlockDriverStates
never being directly passed to bdrv_open_common() from bdrv_file_open(),
but instead being handed through bdrv_open(). This changes the error
message when trying to give a filename to qcow2, i.e. trying to use it
as a driver for the protocol level. Therefore, change the reference
output of I/O test 051 accordingly.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Using bdrv_open_image() instead of bdrv_file_open() directly in
bdrv_open() is easier.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add a common function for opening images to be used for block drivers
specified through BlockdevRefs in an option QDict. The difference from
bdrv_file_open() is that this function may invoke bdrv_open() instead,
allowing auto-detection of the driver to be used; and second, it
automatically extracts the BlockdevRef from the option QDict.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
blkdebug and blkverify will, in order to retain compatibility, not
support the field "file" implicitly through bdrv_open(). In order to be
able to use those drivers without giving a filename anyway, it is
necessary to be able to have block devices without files implicitly
opened by bdrv_open(). This is the case, if there was neither a file
name, a reference to an existing block device to use as a file nor
options specific to the file.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
With that now being possible, bdrv_open() should try to extract a block
device reference from the options and pass it to bdrv_file_open().
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Allow specifying a reference to an existing block device (by name) for
bdrv_file_open() instead of a filename and/or options.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
during testing around with 4k LUNs a bad target implementation
triggert an -EIO in iscsi_get_block_status, but it got never caught
resulting in an infinite loop.
CC: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Since cc0681c454 ("block: Enable the new
throttling code in the block layer.") bdrv_drain_all() no longer spins.
The code used to look as follows:
do {
busy = qemu_aio_wait();
/* FIXME: We do not have timer support here, so this is effectively
* a busy wait.
*/
QTAILQ_FOREACH(bs, &bdrv_states, list) {
while (qemu_co_enter_next(&bs->throttled_reqs)) {
busy = true;
}
}
} while (busy);
Note that throttle requests are kicked but I/O throttling limits are
still in effect. The loop spins until the vm_clock time allows the
request to make progress and complete.
The new throttling code introduced bdrv_start_throttled_reqs(). This
function not only kicks throttled requests but also temporarily disables
throttling so requests can run.
The outdated FIXME comment can be removed. Also drop the busy = true
assignment since we overwrite it immediately afterwards.
Reviewed-by: Alex Bligh <alex@alex.org.uk>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Leaving the backing file open although it is not needed anymore can
cause problems if it is opened through a block driver which allows
exclusive access only and if the create function of the block driver
used for the top image (the one being created) tries to close and reopen
the image file (which will include opening the backing file a second
time).
In particular, this will happen with a backing file opened through
qemu-nbd and using qcow2 as the top image file format (which reopens the
image to flush it to disk).
In addition, the BlockDriverState in bdrv_img_create() is used for the
backing file only; it should therefore be made local to the respective
block.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Right now, bdrv_co_do_write_zeroes will only try to align the
beginning of the request. However, it is simpler for many
formats to expect the block layer to separate both the head *and*
the tail. This makes sure that the format's bdrv_co_write_zeroes
function will be called with aligned sector_num and nb_sectors for
the bulk of the request.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Similar to write_zeroes, let the generic code receive a ENOTSUP for
discard operations. Since bdrv_discard has advisory semantics,
we can just swallow the error.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This will be used by the SCSI layer.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This lets bdrv_co_do_rw receive flags, so that it can be used for
zero writes.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
bdrv_co_discard is only covering drivers which have a .bdrv_co_discard()
implementation, but not those with .bdrv_aio_discard(). Not very nice,
and easy to avoid.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
If you open an image temporarily just because you want to check its size
or get it flushed, there's no real reason to open the whole backing file
chain.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
In the case of snapshot=on, don't rely on the backing file path in the
temporary image any more, but override the backing file with the given
set of options. This way, block drivers that don't use a file name can
be accessed with snapshot=on, for example:
-drive file.driver=nbd,file.host=localhost,snapshot=on
Which becomes internally something like:
file.filename=/tmp/vl.AWQZCu,backing.file.driver=nbd,backing.file.host=localhost
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This adds "remove_break" command which is the reverse of blkdebug
command "break": it removes all breakpoints with given tag and resumes
all the requests.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
We have multiple dirty bitmaps in BDS now, switch QAPI to allow query
it (BlockInfo.dirty_bitmaps), and also drop old BlockInfo.dirty.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Previously a BlockDriverState has only one dirty bitmap, so only one
caller (e.g. a block job) can keep track of writing. This changes the
dirty bitmap to a list and creates a BdrvDirtyBitmap for each caller, the
lifecycle is managed with these new functions:
bdrv_create_dirty_bitmap
bdrv_release_dirty_bitmap
Where BdrvDirtyBitmap is a linked list wrapper structure of HBitmap.
In place of bdrv_set_dirty_tracking, a BdrvDirtyBitmap pointer argument
is added to these functions, since each caller has its own dirty bitmap:
bdrv_get_dirty
bdrv_dirty_iter_init
bdrv_get_dirty_count
bdrv_set_dirty and bdrv_reset_dirty prototypes are unchanged but will
internally walk the list of all dirty bitmaps and set them one by one.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
this patch does 2 things:
a) only do additional call outs if BDRV_BLOCK_ZERO is not already set.
b) use the newly introduced bdrv_unallocated_blocks_are_zero()
to return the zero state of an unallocated block. the used callout
to bdrv_has_zero_init() is only valid right after bdrv_create.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
this patch adds a call to completely zero out a block device.
the operation is sped up by checking the block status and
only writing zeroes to the device if they currently do not
return zeroes. optionally the zero writing can be sped up
by setting the flag BDRV_REQ_MAY_UNMAP to emulate the zero
write by unmapping if the driver supports it.
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This adds 2 wrappers to read the unallocated_blocks_are_zero and
can_write_zeroes_with_unmap info from the BDI. The wrappers are
required to check for the existence of a backing_hd and
if the devices are opened with the correct flags.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
If an explicit driver option is present, but doesn't specify a valid
driver, then bdrv_open() should fail instead of probing the format.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
If backing file doesn't exist, the error message is confusing and
misleading:
$ qemu /tmp/a.qcow2
qemu: could not open disk image /tmp/a.qcow2: Could not open file: No
such file or directory
But...
$ ls /tmp/a.qcow2
/tmp/a.qcow2
$ qemu-img info /tmp/a.qcow2
image: /tmp/a.qcow2
file format: qcow2
virtual size: 8.0G (8589934592 bytes)
disk size: 196K
cluster_size: 65536
backing file: /tmp/b.qcow2
Because...
$ ls /tmp/b.qcow2
ls: cannot access /tmp/b.qcow2: No such file or directory
This is not intuitive. It's better to have the missing file's name in
the error message. With this patch:
$ qemu-io -c 'read 0 512' /tmp/a.qcow2
qemu-io: can't open device /tmp/a.qcow2: Could not open backing
file: Could not open '/stor/vm/arch.raw': No such file or directory
no file open, try 'help open'
Which is a little bit better.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Since b94a2610, bdrv_getlength() is omitted when probing image. VMDK
monolithicFlat is broken by that because a file < 512 bytes can't be
read with its total_sectors truncated to 0. This patch round up the size
to BDRV_SECTOR_SIZE, when a image size is not sector aligned.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
error_setg_errno() may overwrite errno; therefore, its value should be
read before calling that function and not afterwards.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The block layer generally keeps the size of an image cached in
bs->total_sectors so that it doesn't have to perform expensive
operations to get the size whenever it needs it.
This doesn't work however when using a backend that can change its size
without qemu being aware of it, i.e. passthrough of removable media like
CD-ROMs or floppy disks. For this reason, the caching is disabled when a
removable device is used.
It is obvious that checking whether the _guest_ device has removable
media isn't the right thing to do when we want to know whether the size
of the host backend can change. To make things worse, non-top-level
BlockDriverStates never have any device attached, which makes qemu
assume they are removable, so drv->bdrv_getlength() is always called on
the protocol layer. In the case of raw-posix, this causes unnecessary
lseek() system calls, which turned out to be rather expensive.
This patch completely changes the logic and disables bs->total_sectors
caching only for certain block driver types, for which a size change is
expected: host_cdrom and host_floppy on POSIX, host_device on win32; also
the raw format in case it sits on top of one of these protocols, but in
the common case the nested bdrv_getlength() call on the protocol driver
will use the cache again and avoid an expensive drv->bdrv_getlength()
call.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Since commit 0ebd24e0a2,
bdrv_open_common will throw an error when trying to open a file
read-only with the BDRV_O_COPY_ON_READ flag set.
Although BDRV_O_RDWR is unset for the backing files,
BDRV_O_COPY_ON_READ is still passed on if copy-on-read was requested
for the drive. Let's unset this flag too before opening the backing
file, or bdrv_open_common will fail.
Signed-off-by: Thibaut LAURENT <thibaut.laurent@gmail.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
bdrv_open_backing_file() tries to copy the backing file name using
pstrcpy directly after calling bdrv_open() to open the backing file
without checking whether that was actually successful. If it was not,
ps->backing_hd->file will probably be NULL and qemu will crash.
Fix this by moving pstrcpy after checking whether bdrv_open() succeeded.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Amos Kong <kongjianjun@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
If a read-only device is configured with copy-on-read=on, the old code
only prints a warning and automatically disables copy on read. Make it
a real error for blockdev-add.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
The main intent of this patch is to consolidate the whitelist checks to
a single point in the code instead of spreading it everywhere. This adds
a nicer error message for read-only whitelisting, too, in places where
it was still missing.
The patch also contains a bonus bug fix: By finding the format first in
bdrv_open() and then independently checking against the whitelist only
later, we avoid the case that use of a non-whitelisted format results in
probing rather than an error message. Previously, this could happen when
using the driver=... option.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
This field is used by blkverify to disable external snapshots creation.
It will also be used by block filters like quorum to disable external
snapshot creation.
Signed-off-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
if a raw device like an iscsi target or host device is used
the current implementation makes a second call out to get
the block status of bs->file.
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Add a function for retrieving an ImageInfoSpecific object from a block
driver.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The content filename point to may be erased by qemu_opts_absorb_qdict()
in raw_open_common() in drv->bdrv_file_open()
So it's better to use bs->filename.
Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The content filename point to will be erased by qemu_opts_absorb_qdict()
in raw_open_common() in drv->bdrv_file_open()
So it's better to use bs->filename.
Signed-off-by: Dunrong Huang <riegamaths@gmail.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Some drivers will have driver specifics options but no filename.
This new bool allow the block layer to treat them correctly.
The .bdrv_needs_filename is set in drivers not having .bdrv_parse_filename and
not having .bdrv_open.
The first exception to this rule will be the quorum driver.
Signed-off-by: Benoit Canet <benoit@irqsave.net>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
if the call is invoked through bdrv_is_allocated the caller might
expect *pnum = 0 on error. however, a new implementation of
bdrv_get_block_status might only return a negative exit value on
error while keeping *pnum untouched.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Providing backing.file.filename doesn't override backing file as expected:
$ x86_64-softmmu/qemu-system-x86_64 -drive \
file=/tmp/child.qcow2,backing.file.filename=/tmp/fake.qcow2
qemu-system-x86_64: -drive \
file=/tmp/child.qcow2,backing.file.filename=/tmp/fake.qcow2: could not
open disk image /tmp/child.qcow2: Can't specify 'file' and 'filename'
options at the same time
With
$ qemu-img info /tmp/child.qcow2
image: /tmp/child.qcow2
file format: qcow2
virtual size: 1.0G (1073741824 bytes)
disk size: 196K
cluster_size: 65536
backing file: /tmp/fake.qcow2
This fixes it by calling bdrv_get_full_backing_filename only if
backing.file.filename is not provided. Also save the backing file name
to bs->backing_file so the information is correct with HMP "info block".
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
To read the last sector that is not aligned to sector boundary, current
code for growable backends, since commit 893a8f6 "block: Produce zeros
when protocols reading beyond end of file", drops the data and directly
returns zeroes. That is incorrect.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
