The code is similar to the implementation of discard and write_zeroes
with UNMAP. However, failure must be propagated up to block.c.
The stale page cache problem can be reproduced as follows:
# modprobe scsi-debug lbpws=1 lbprz=1
# ./qemu-io /dev/sdXX
qemu-io> write -P 0xcc 0 2M
qemu-io> write -z 0 1M
qemu-io> read -P 0x00 0 512
Pattern verification failed at offset 0, 512 bytes
qemu-io> read -v 0 512
00000000: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc ................
...
# ./qemu-io --cache=none /dev/sdXX
qemu-io> write -P 0xcc 0 2M
qemu-io> write -z 0 1M
qemu-io> read -P 0x00 0 512
qemu-io> read -v 0 512
00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
...
And similarly with discard instead of "write -z".
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
See the next commit for the description of the Linux kernel problem
that is worked around in raw_open_common.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Writing zeroes to a file can be done by punching a hole if
MAY_UNMAP is set.
Note that in this case ENOTSUP is not ignored, but makes
the block layer fall back to the generic implementation.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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>
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>
The below patch is needed to compile qemu trunk on FreeBSD with gcc48,
clang will fail.... ;). Host x84_64-freebsd.
Signed-off-by: Andreas Tobler <andreast@FreeBSD.org>
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>
Make use of the error parameter in the opening and creating functions in
block/raw-posix.c.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@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>
Add an Error ** parameter to BlockDriver.bdrv_open and
BlockDriver.bdrv_file_open to allow more specific error messages.
Signed-off-by: Max Reitz <mreitz@redhat.com>
These are created for example with XFS_IOC_ZERO_RANGE.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
For now, bdrv_get_block_status is just another name for bdrv_is_allocated.
The next patches will add more flags.
This also touches all block drivers with a mostly mechanical rename. The
sole exception is cow; because it calls cow_co_is_allocated from the read
code, we keep that function and make cow_co_get_block_status a wrapper.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
.has_zero_init defaults to 1 for all formats and protocols.
this is a dangerous default since this means that all
new added drivers need to manually overwrite it to 0 if
they do not ensure that a device is zero initialized
after bdrv_create().
if a driver needs to explicitly set this value to
1 its easier to verify the correctness in the review process.
during review of the existing drivers it turned out
that ssh and gluster had a wrong default of 1.
both protocols support host_devices as backend
which are not by default zero initialized. this
wrong assumption will lead to possible corruption
if qemu-img convert is used to write to such a backend.
vpc and vmdk also defaulted to 1 altough they support
fixed respectively flat extends. this has to be addresses
in separate patches. both formats as well as the mentioned
ssh and gluster are turned to the default of 0 with this
patch for safety.
a similar problem with the wrong default existed for
iscsi most likely because the driver developer did
oversee the default value of 1.
Signed-off-by: Peter Lieven <pl@kamp.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The raw-posix driver has code to provide a /dev/cdrom on OS X even
though it doesn't really exist. However, since commit c66a6157 the real
filename is dismissed after finding it, so opening /dev/cdrom fails.
Put the filename back into the options QDict to make this work again.
Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Now that each AioContext has a ThreadPool and the main loop AioContext
can be fetched with bdrv_get_aio_context(), we can eliminate the concept
of a global thread pool from thread-pool.c.
The submit functions must take a ThreadPool* argument.
block/raw-posix.c and block/raw-win32.c use
aio_get_thread_pool(bdrv_get_aio_context(bs)) to fetch the main loop's
ThreadPool.
tests/test-thread-pool.c must be updated to reflect the new
thread_pool_submit() function prototypes.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Linux block devices can be set read-only with "blockdev --setro
<device>". The same thing can be done for LVM volumes using "lvchange
--permission r <volume>". This read-only setting is independent of
device node permissions. Therefore the device can still be opened
O_RDWR but actual writes will fail.
This results in odd behavior for QEMU. bdrv_open() is supposed to fail
if a read-only image is being opened with BDRV_O_RDWR. By not failing
for Linux block devices, the guest boots up but every write produces an
I/O error.
This patch checks whether the block device is read-only so that Linux
block devices behave like regular files.
Reported-by: Sibiao Luo <sluo@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Commit eeb6b45d48 (block: raw-posix image
file reopen) broke the build on OpenIndiana.
illumos has no O_ASYNC. Exclude it from flags to be compared
and instead assert that it is not set where defined.
Cf. e61ab1da7e for qemu-ga.
Cc: qemu-stable@nongnu.org (1.3.x)
Cc: Jeff Cody <jcody@redhat.com>
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Andreas Färber <andreas.faerber@web.de>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Fixes the build on OpenBSD among others.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Andreas Färber <andreas.faerber@web.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This is easy with the thread pool, because we can use s->is_xfs and
s->has_discard from the worker function.
QEMU has a widespread assumption that each I/O operation writes less
than 2^32 bytes. This patch doesn't fix it throughout of course,
but it starts correcting struct RawPosixAIOData so that there is
no regression with respect to the synchronous discard implementation.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Block devices use a ioctl instead of fallocate, so add a separate
implementation.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Avoid sending system calls repeatedly if they shall fail. This
does not apply to XFS: if the filesystem-specific ioctl fails,
something weird is happening.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Linux 2.6.38 introduced the filesystem independent interface to
deallocate part of a file. As of Linux 3.7, btrfs, ext4, ocfs2,
tmpfs and xfs support it.
Even though the system calls here are in practice issued on Linux,
the code is structured to allow plugging in alternatives for other Unix
variants. EOPNOTSUPP is used unconditionally in this patch, but it is
supported in both OpenBSD and Mac OS X since forever (see for example
http://lists.debian.org/debian-glibc/2006/02/msg00337.html).
Signed-off-by: Kusanagi Kouichi <slash@ac.auone-net.jp>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The qiov_is_aligned() function checks whether a QEMUIOVector meets a
BlockDriverState's alignment requirements. This is needed by
virtio-blk-data-plane so:
1. Move the function from block/raw-posix.c to block/block.c.
2. Make it public in block/block.h.
3. Rename to bdrv_qiov_is_aligned().
4. Change return type from int to bool.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When the raw-posix aio=thread code was moved from posix-aio-compat.c
to block/raw-posix.c, there was an unintended change to the ioctl code.
The code used to return the ioctl command, which posix_aio_read()
would later morph into a zero. This hack is not necessary anymore,
and in fact breaks scsi-generic (which expects a zero return code).
Remove it.
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The raw_get_aio_fd() function allows virtio-blk-data-plane to get the
file descriptor of a raw image file with Linux AIO enabled. This
interface is really a layering violation that can be resolved once the
block layer is able to run outside the global mutex - at that point
virtio-blk-data-plane will switch from custom Linux AIO code to using
the block layer.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Touching char/char.h basically causes the whole of QEMU to
be rebuilt. Avoid this, it is usually unnecessary.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
clang now warns about an unused function:
CC block/raw-posix.o
block/raw-posix.c:707:26: warning: unused function paio_ioctl
[-Wunused-function]
static BlockDriverAIOCB *paio_ioctl(BlockDriverState *bs, int fd,
^
1 warning generated.
because the only use of paio_ioctl() is inside a #if defined(__linux__)
guard and it is static now.
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
For hdev, floppy, and cdrom, the reopen() handlers are the same as
for the file reopen handler. For floppy and cdrom types, however,
we keep O_NONBLOCK, as in the _open function.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Making the qemu_paiocb specific to raw devices will let us access members
of the BDRVRawState arbitrarily.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is derived from the Supriya Kannery's reopen patches.
This contains the raw-posix driver changes for the bdrv_reopen_*
functions. All changes are staged into a temporary scratch buffer
during the prepare() stage, and copied over to the live structure
during commit(). Upon abort(), all changes are abandoned, and the
live structures are unmodified.
The _prepare() will create an extra fd - either by means of a dup,
if possible, or opening a new fd if not (for instance, access
control changes). Upon _commit(), the original fd is closed and
the new fd is used. Upon _abort(), the duplicate/new fd is closed.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The aligned_buf pointer and aligned_buf size are no longer used in
raw_posix.c, so remove all references to them.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Rather than check for a non-NULL aligned_buf to determine if
raw_aio_submit needs to check for alignment, check for the presence
of BDRV_O_NOCACHE in the bs->open_flags.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Block drivers should ignore BDRV_O_CACHE_WB in .bdrv_open flags,
and in the bs->open_flags.
This patch removes the code, leaving the behaviour behind as if
BDRV_O_CACHE_WB was set.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Code motion, to move parsing of open flags into a helper function.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Move AIO initialization for raw-posix block driver into a helper function.
In addition to just code motion, the aio_ctx pointer is checked for NULL,
prior to calling laio_init(), to make sure laio_init() is only run once.
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch converts all block layer close calls, that correspond
to qemu_open calls, to qemu_close.
Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch converts all block layer open calls to qemu_open.
Note that this adds the O_CLOEXEC flag to the changed open paths
when the O_CLOEXEC macro is defined.
Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Move the declaration of s into the #ifdef sections that actually make
use of it.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Either FIEMAP, or SEEK_DATA+SEEK_HOLE can be used to implement the
is_allocated callback for raw files. On Linux ext4, btrfs and XFS
all support it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Use __APPLE__ and __MACH__ macros instead of CONFIG_COCOA to detect Mac
OS X host. The patch is based on Ben Leslie's patch:
http://patchwork.ozlabs.org/patch/97859/
Signed-off-by: Ben Leslie <benno@benno.id.au>
Signed-off-by: Pavel Borzenkov <pavel.borzenkov@gmail.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Andreas Färber <andreas.faerber@web.de>
