BDRV_O_FILE is only used to communicate between bdrv_file_open and bdrv_open.
It affects two things:  first bdrv_open only searches for protocols using
find_protocol instead of all image formats and host drivers.  We can easily
move that to the caller and pass the found driver to bdrv_open.  Second
it is used to not force a read-write open of a snapshot file.  But we never
use bdrv_file_open to open snapshots and this behaviour doesn't make sense
to start with.

qemu-io abused the BDRV_O_FILE for it's growable option, switch it to
using bdrv_file_open to make sure we only open files as growable were
we can actually support that.

This patch requires Kevin's "[PATCH] Replace calls of old bdrv_open" to
be applied first.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

What is known today as bdrv_open2 becomes the new bdrv_open. All remaining
callers of the old function are converted to the new one. In some places they
even know the right format, so they should have used bdrv_open2 from the
beginning.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Block drivers can trigger a blkdebug event whenever they reach a place where it
could be useful to inject an error for testing/debugging purposes.

Rules are read from a blkdebug config file and describe which action is taken
when an event is triggered. For now this is only injecting an error (with a few
options) or changing the state (which is an integer). Rules can be declared to
be active only in a specific state; this way later rules can distiguish on
which path we came to trigger their event.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Previously multiwrite_user_cb was never called if a request in the multiwrite
batch failed right away because it did set mcb->error immediately. Make it look
more like a normal callback to fix this.
Reported-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

When two requests of the same multiwrite batch fail, the callback of all
requests in that batch were called twice. This could have any kind of nasty
effects, in my case it lead to use after free and eventually a segfault.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

Signed-off-by: NShahar Havivi <shaharh@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Open backing file read-only where possible
Upgrade backing file to read-write during commit, back to read-only after commit
  If upgrade fail, back to read-only. If also fail, "disconnect" the drive.
Signed-off-by: NNaphtali Sprei <nsprei@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

It's not needed to check the return of qobject_from_jsonf()
anymore, as an assert() has been added there.
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Clean up the current mess about figuring out which flags to pass to the
driver.  BDRV_O_FILE, BDRV_O_SNAPSHOT and BDRV_O_NO_BACKING are flags
only used by the block layer internally so filter them out directly.
Previously BDRV_O_NO_BACKING could accidentally be passed to the drivers,
but wasn't ever used.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

This commit introduces the bdrv_mon_event() function, which
should be called by block subsystems (eg. IDE) when a I/O
error occurs, so that an QMP event is emitted.

The following information is currently provided in the event:

- device name
- operation (ie. "read" or "write")
- action taken (eg. "stop")

Event example:

{ "event": "BLOCK_IO_ERROR",
    "data": { "device": "ide0-hd1",
              "operation": "write",
              "action": "stop" },
    "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

This will manage dirty counter for each device and will allow to get the
dirty counter from above.
Signed-off-by: NLiran Schour <lirans@il.ibm.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

If we go over the maximum number of iovecs support by syscall we get
back EINVAL from the kernel which translate to I/O errors for the guest.

Add a MAX_IOV defintion for platforms that don't have it.  For now we use
the same 1024 define that's used on Linux and various other platforms,
but until the windows block backend implements some kind of vectored I/O
it doesn't matter.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Win32 suffers from a very big memory leak when dealing with SCSI devices.
Each read/write request allocates memory with qemu_memalign (ie
VirtualAlloc) but frees it with qemu_free (ie free).
Pair all qemu_memalign() calls with qemu_vfree() to prevent such leaks.
Signed-off-by: NHerve Poussineau <hpoussin@reactos.org>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Check the whitelist as early as possible instead of continuing the
setup, and move all the error handling code to the end of the
function.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NNaphtali Sprei <nsprei@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Don't assume -EIO but return the real error.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

This reverts commit 0076bc0c.

Kevin Wolf pointed out that this breaks the mingw32 build.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

If we go over the maximum number of iovecs support by syscall we get
back EINVAL from the kernel which translate to I/O errors for the guest.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Signed-off-by: NNaphtali Sprei <nsprei@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Clean-up a little bit the RW related bits of BDRV_O_FLAGS. BDRV_O_RDONLY gone (and so is BDRV_O_ACCESS). Default value for bdrv_flags (0/zero) is READ-ONLY. Need to explicitly request READ-WRITE.

Instead of using the field 'readonly' of the BlockDriverState struct for passing the request,
pass the request in the flags parameter to the function.
Signed-off-by: NNaphtali Sprei <nsprei@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

The backing device is only modified from bdrv_commit.  So instead of
flushing it every time bdrv_flush is called for the front-end device
only flush it after we're written data to it in bdrv_commit.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Introduce the functions needed to change the backing file of an image. The
function is implemented for qcow2.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

If an image references a backing file that doesn't exist, qemu-img info fails
to open this image. Exactly in this case the info would be valuable, though:
the user might want to find out which file is missing.

This patch introduces a BDRV_O_NO_BACKING flag to ignore the backing file when
opening the image. qemu-img info is the first user and provides info now even
if the backing file is invalid.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

  CC    block.o
cc1: warnings being treated as errors
block.c: In function 'bdrv_open2':
block.c:400: error: ignoring return value of 'realpath', declared with attribute warn_unused_result
Signed-off-by: NKirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Each device statistic information is stored in a QDict and
the returned QObject is a QList of all devices.

This commit should not change user output.
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Each block device information is stored in a QDict and the
returned QObject is a QList of all devices.

This commit should not change user output.
Signed-off-by: NLuiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

This switches the dirty bitmap to a true bitmap, reducing its footprint
(specifically in caches). It moreover fixes off-by-one bugs in
set_dirty_bitmap (nb_sectors+1 were marked) and bdrv_get_dirty (limit
check allowed one sector behind end of drive). And is drops redundant
dirty_tracking field from BlockDriverState.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Instead of duplicating the definition of constants or introducing
trivial retrieval functions move the SECTOR constants into the public
block API. This also obsoletes sector_per_block in BlkMigState.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

No functional changes.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

To support live migration without shared storage we need to be able to trace
writes to disk while migrating. This Patch expose dirty block tracking per
device to be polled from upper layer.

Changes from v4:
- Register dirty tracking for each block device.
- Minor coding style issues.
- Block.c will now manage a dirty bitmap per device once
  bdrv_set_dirty_tracking() is called. Bitmap is polled by the upper
  layer (block-migration.c).
Signed-off-by: NLiran Schour <lirans@il.ibm.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

We have code for a quite a few block formats.  While I trust that all
of these formats are useful at least for some people in some
circumstances, some of them are of a kind that friends don't let
friends use in production.

This patch provides an optional block format whitelist, default off.
If a whitelist is configured with --block-drv-whitelist, QEMU proper
can use only whitelisted formats.  Other programs, like qemu-img, are
not affected.

Drivers for formats off the whitelist still participate in format
probing, to ensure all programs probe exactly the same.  Without that,
QEMU proper would be prone to treat images with a format off the
whitelist as raw when the image's format is probed.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

This is a slightly revised patch for adding readonly flag to the -drive command.
Even though this patch is "stand-alone", it assumes a previous related patch (in Anthony staging tree), that passes
the readonly attribute of the drive to the guest OS, applied first.

This enables sharing same image between guests, with readonly access.
Implementaion mark the drive as read_only and changes the flags when actually opening the file.
The readonly attribute of a qcow also passed to it's base file.
For ide that cannot pass the readonly attribute to the guest OS, disallow the readonly flag.

Also, return error code from bdrv_truncate for readonly drive.
Signed-off-by: NNaphtali Sprei <nsprei@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

bdrv_read/write emulation is used as the perfect example why we need something
like AsyncContexts. So maybe they better start using it.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Problem: Our file sys-queue.h is a copy of the BSD file, but there are
some additions and it's not entirely compatible. Because of that, there have
been conflicts with system headers on BSD systems. Some hacks have been
introduced in the commits 15cc9235,
f40d7537,
96555a96 and
3990d09a but the fixes were fragile.

Solution: Avoid the conflict entirely by renaming the functions and the
file. Revert the previous hacks.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

Instead stalling the VCPU while serving a cache flush try to do it
asynchronously.  Use our good old helper thread pool to issue an
asynchronous fdatasync for raw-posix.  Note that while Linux AIO
implements a fdatasync operation it is not useful for us because
it isn't actually implement in asynchronous fashion.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Add a enable_write_cache flag in the block driver state, and use it to
decide if we claim to have a volatile write cache that needs controlled
flushing from the guest.  The flag is off if cache=writethrough is
defined because O_DSYNC guarantees that every write goes to stable
storage, and it is on for cache=none and cache=writeback.

Both scsi-disk and ide now use the new flage, changing from their
defaults of always off (ide) or always on (scsi-disk).
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

One performance problem of qcow2 during the initial image growth are
sequential writes that are not cluster aligned. In this case, when a first
requests requires to allocate a new cluster but writes only to the first
couple of sectors in that cluster, the rest of the cluster is zeroed - just
to be overwritten by the following second request that fills up the cluster.

Let's try to merge sequential write requests to the same cluster, so we can
avoid to write the zero padding to the disk in the first place.

As a nice side effect, also other formats take advantage of dealing with less
and larger requests.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

Now that do have a nicer interface to work against we can add Linux native
AIO support.  It's an extremly thing layer just setting up an iocb for
the io_submit system call in the submission path, and registering an
eventfd with the qemu poll handler to do complete the iocbs directly
from there.

This started out based on Anthony's earlier AIO patch, but after
estimated 42,000 rewrites and just as many build system changes
there's not much left of it.

To enable native kernel aio use the aio=native sub-command on the
drive command line.  I have also added an option to qemu-io to
test the aio support without needing a guest.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>