When using O_DIRECT, qcow2 snapshots didn't work any more for me. In the
process of creating the snapshot, qcow2 tries to pwrite some new information
(e.g. new L1 table) which will often end up being after the old end of the
image file. Now pwrite tries to align things and reads the old contents of the
file, read returns 0 because there is nothing to read after the end of file and
pwrite is stuck in an endless loop.
This patch allows to pread beyond the end of an image file. Whenever the
given offset is after the end of the image file, the read succeeds and fills
the buffer with zeros.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Problem: It is impossible to feed filenames with the character colon because
qemu interprets such names as a protocol. For example filename scsi:0, is
interpreted as a protocol by name "scsi".
This patch allows user to espace colon characters. For example the above
filename can now be expressed either as 'scsi\:0' or as file:scsi:0
anything following the "file:" tag is interpreted verbatin. However if "file:"
tag is omitted then any colon characters in the string must be escaped using
backslash.
Here are couple of examples:
scsi\:0\:abc is a local file scsi:0:abc
http\://myweb is a local file by name http://myweb
file:scsi:0:abc is a local file scsi:0:abc
file:http://myweb is a local file by name http://myweb
Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
When we open a file, we first attempt to open it read-write, then fall back
to read-only. Unfortunately we reuse the flags from the previous attempt,
so both attempts try to open the file with write permissions, and fail.
Fix by clearing the O_RDWR flag from the previous attempt.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
The flags argument to raw_common_open() contain bits defined by the BDRV_O_*
namespace, not the posix O_* namespace.
Adjust to use the correct constants.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Rename raw_ioctl and raw_aio_ioctl to hdev_ioctl and hdev_aio_ioctl as they
are only used for the host device. Also only add them to the method table
for the cases where we need them (generic hdev if linux and linux CDROM)
instead of declaring stubs and always add them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Add a bdrv_probe_device method to all BlockDriver instances implementing
host devices to move matching of host device types into the actual drivers.
For now we keep exacly the old matching behaviour based on the devices names,
although we really should have better detetion methods based on device
information in the future.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Instead of declaring one BlockDriver for all host devices declared one
for each type: a generic one for normal disk devices, a Linux floppy
driver and a CDROM driver for Linux and FreeBSD. This gets rid of a lot
of messy ifdefs and switching based on the type in the various removal
device methods.
block.c grows a new method to find the correct host device driver based
on OS-sepcific criteria, which will later into the actual drivers in a
later patch in this series.
Signed-off-by: Christoph Hellwig <hch@lst.de>
raw_open and hdev_open contain the same basic logic. Add a new
raw_open_common helper containing the guts of the open routine
and call it from raw_open and hdev_open.
We use the new open_flags field in BDRVRawState to allow passing
additional open flags to raw_open_common from both.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Both the Linux floppy and the FreeBSD CDROM host device need to store
the open flags so that they can re-open the device later. Store the
open flags unconditionally to remove the ifdef mess and simply the
calling conventions for the later patches in the series.
Signed-off-by: Christoph Hellwig <hch@lst.de>
This patch adds a small help text to each of the options in the block drivers
which can be displayed by using qemu-img create -f fmt -o ?
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Now that we have a separate aio pool structure we can remove those
aio pool details from BlockDriver.
Every driver supporting AIO now needs to declare a static AIOPool
with the aiocb size and the cancellation method. This cleans up the
current code considerably and will make it cleaner and more obvious
to support two different aio implementations behind a single
BlockDriver.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
We do need hdev_create unconditionally on all platforms so that qemu-img
create support for host device works on all platforms.
Also relax the check to allow character devices in addition to block
devices. On many Unix platforms block devices have buffered block
nodes and unbuffered character device nodes, and on FreeBSD the block
nodes don't even exist anymore. Also on Linux we do support the
/dev/sgN scsi passthrough devices through the host device driver,
and probably the old-style /dev/raw/rawN raw devices although I haven't
tested that.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
raw_pread_aligned currently returns the raw return value from
lseek/read, which is always -1 in case of an error. But the
callers higher up the stack expect it to return the negated
errno just like raw_pwrite_aligned.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Now we can make use of the newly introduced option structures. Instead of
having bdrv_create carry more and more parameters (which are format specific in
most cases), just pass a option structure as defined by the driver itself.
bdrv_create2() contains an emulation of the old interface to simplify the
transition.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
