A number of different places across the code base use CONFIG_UUID. Some
of them are soft dependency, some are not built if libuuid is not
available, some come with dummy fallback, some throws runtime error.

It is hard to maintain, and hard to reason for users.

Since UUID is a simple standard with only a small number of operations,
it is cleaner to have a central support in libqemuutil. This patch adds
qemu_uuid_* functions that all uuid users in the code base can
rely on. Except for qemu_uuid_generate which is new code, all other
functions are just copy from existing fallbacks from other files.

Note that qemu_uuid_parse is moved without updating the function
signature to use QemuUUID, to keep this patch simple.
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NJeff Cody <jcody@redhat.com>
Message-Id: <1474432046-325-2-git-send-email-famz@redhat.com>

This commit moves the initialization of the QemuOptsList qemu_iscsi_opts
struct out of block/iscsi.c in order to allow the iscsi module to be
dynamically loaded.
Signed-off-by: NColin Lord <clord@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1471008424-16465-2-git-send-email-clord@redhat.com
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>

Another step towards killing off sector-based block APIs.

Unlike write_zeroes, where we can be handed unaligned requests
and must fail gracefully with -ENOTSUP for a fallback, we are
guaranteed that discard requests are always aligned because the
block layer already ignored unaligned head/tail.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1468624988-423-13-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Now that the block layer honors max_request, we don't need to
bother with an EINVAL on overlarge requests, but can instead
assert that requests are well-behaved.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1468607524-19021-7-git-send-email-eblake@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

until now the allocation map was used only as a hint if a cluster
is allocated or not. If a block was not allocated (or Qemu had
no info about the allocation status) a get_block_status call was
issued to check the allocation status and possibly avoid
a subsequent read of unallocated sectors. If a block known to be
allocated the get_block_status call was omitted. In the other case
a get_block_status call was issued before every read to avoid
the necessity for a consistent allocation map. To avoid the
potential overhead of calling get_block_status for each and
every read request this took only place for the bigger requests.

This patch enhances this mechanism to cache the allocation
status and avoid calling get_block_status for blocks where
the allocation status has been queried before. This allows
for bypassing the read request even for smaller requests and
additionally omits calling get_block_status for known to be
unallocated blocks.
Signed-off-by: NPeter Lieven <pl@kamp.de>
Message-Id: <1468831940-15556-3-git-send-email-pl@kamp.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

when setting clusters as alloacted the boundaries have
to be expanded. As Paolo pointed out the calculation of
the number of clusters is wrong:

Suppose cluster_sectors is 2, sector_num = 1, nb_sectors = 6:

In the "mark allocated" case, you want to set 0..8, i.e.
cluster_num=0, nb_clusters=4.

   0--.--2--.--4--.--6--.--8
   <--|_________________|-->  (<--> = expanded)

Instead you are setting nb_clusters=3, so that 6..8 is not marked.

   0--.--2--.--4--.--6--.--8
   <--|______________|!!!     (! = wrong)

Cc: qemu-stable@nongnu.org
Reported-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NPeter Lieven <pl@kamp.de>
Message-Id: <1468831940-15556-2-git-send-email-pl@kamp.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In practice the entry argument is always known at creation time, and
it is confusing that sometimes qemu_coroutine_enter is used with a
non-NULL argument to re-enter a coroutine (this happens in
block/sheepdog.c and tests/test-coroutine.c).  So pass the opaque value
at creation time, for consistency with e.g. aio_bh_new.

Mostly done with the following semantic patch:

@ entry1 @
expression entry, arg, co;
@@
- co = qemu_coroutine_create(entry);
+ co = qemu_coroutine_create(entry, arg);
  ...
- qemu_coroutine_enter(co, arg);
+ qemu_coroutine_enter(co);

@ entry2 @
expression entry, arg;
identifier co;
@@
- Coroutine *co = qemu_coroutine_create(entry);
+ Coroutine *co = qemu_coroutine_create(entry, arg);
  ...
- qemu_coroutine_enter(co, arg);
+ qemu_coroutine_enter(co);

@ entry3 @
expression entry, arg;
@@
- qemu_coroutine_enter(qemu_coroutine_create(entry), arg);
+ qemu_coroutine_enter(qemu_coroutine_create(entry, arg));

@ reentry @
expression co;
@@
- qemu_coroutine_enter(co, NULL);
+ qemu_coroutine_enter(co);

except for the aforementioned few places where the semantic patch
stumbled (as expected) and for test_co_queue, which would otherwise
produce an uninitialized variable warning.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Tracked down with an ugly, brittle and probably buggy Perl script.

Also move includes converted to <...> up so they get included before
ours where that's obviously okay.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Tested-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

Using int for values that are only used as booleans is confusing.
While at it, rearrange a couple of members so that all the bools
are contiguous.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

It makes more sense to have ALL block size limit constraints
in the same struct.  Improve the documentation while at it.

Simplify a couple of conditionals, now that we have audited and
documented that request_alignment is always non-zero.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Sector-based limits are awkward to think about; in our on-going
quest to move to byte-based interfaces, convert max_discard and
discard_alignment.  Rename them, using 'pdiscard' as an aid to
track which remaining discard interfaces need conversion, and so
that the compiler will help us catch the change in semantics
across any rebased code.  The BlockLimits type is now completely
byte-based; and in iscsi.c, sector_limits_lun2qemu() is no
longer needed.

pdiscard_alignment is made unsigned (we use power-of-2 alignments
as bitmasks, where unsigned is easier to think about) while
leaving max_pdiscard signed (since we still have an 'int'
interface); this is comparable to what commit cf081fca did for
write zeroes limits.  We may later want to make everything an
unsigned 64-bit limit - but that requires a bigger code audit.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Sector-based limits are awkward to think about; in our on-going
quest to move to byte-based interfaces, convert max_transfer_length
and opt_transfer_length.  Rename them (dropping the _length suffix)
so that the compiler will help us catch the change in semantics
across any rebased code, and improve the documentation.  Use unsigned
values, so that we don't have to worry about negative values and
so that bit-twiddling is easier; however, we are still constrained
by 2^31 of signed int in most APIs.

When a value comes from an external source (iscsi and raw-posix),
sanitize the results to ensure that opt_transfer is a power of 2.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

We want to eventually stick request_alignment alongside other
BlockLimits, but first, we must ensure it is populated at the
same time as all other limits, rather than being a special case
that is set only when a block is first opened.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

The function sector_limits_lun2qemu() returns a value in units of
the block layer's 512-byte sector, and can be as large as
0x40000000, which is much larger than the block layer's inherent
limit of BDRV_REQUEST_MAX_SECTORS.  The block layer already
handles '0' as a synonym to the inherent limit, and it is nicer
to return this value than it is to calculate an arbitrary
maximum, for two reasons: we want to ensure that the block layer
continues to special-case '0' as 'no limit beyond the inherent
limits'; and we want to be able to someday expand the block
layer to allow 64-bit limits, where auditing for uses of
BDRV_REQUEST_MAX_SECTORS will help us make sure we aren't
artificially constraining iscsi to old block layer limits.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Commit 94d047a3 added an assertion the the request alignment check.
This introduced 2 issues:
 a) A off-by-one error since a request of BDRV_REQUEST_MAX_SECTORS
    is actually allowed.
 b) The bdrv_get_block_status call in the read path to check the allocation
    status requests up to INT_MAX sectors which triggers the assertion.

Fixes: 94d047a3Signed-off-by: NPeter Lieven <pl@kamp.de>
Message-Id: <1466414680-18383-1-git-send-email-pl@kamp.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Another step on our continuing quest to switch to byte-based
interfaces.

As this is the first byte-based iscsi interface, convert
is_request_lun_aligned() into two versions, one for sectors
and one for bytes.  Also, change from outright -EINVAL failure
on an unaligned request, to instead failing with -ENOTSUP to
trigger a read-modify-write fallback, particularly since the
block layer should be honoring bs->request_alignment to avoid
-EINVAL on read/write requests.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Another step towards removing sector-based interfaces: convert
the maximum write and minimum alignment values from sectors to
bytes.  Rename the variables to let the compiler check that all
users are converted to the new semantics.

The maximum remains an int as long as BDRV_REQUEST_MAX_SECTORS
is constrained by INT_MAX (this means that we can't even
support a 2G write_zeroes, but just under it) - changing
operation lengths to unsigned or to 64-bits is a much bigger
audit, and debatable if we even want to do it (since at the
core, a 32-bit platform will still have ssize_t as its
underlying limit on write()).

Meanwhile, alignment is changed to 'uint32_t', since it makes no
sense to have an alignment larger than the maximum write, and
less painful to use an unsigned type with well-defined behavior
in bit operations than to have to worry about what happens if
a driver mistakenly supplies a negative alignment.

Add an assert that no one was trying to use sectors to get a
write zeroes larger than 2G, and therefore that a later conversion
to bytes won't be impacted by keeping the limit at 32 bits.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

If hardware does not advertise a minimum zero/discard
alignment, we still want to guarantee that the block layer
will align requests to our blocks, rather than the arbitrary
512-byte BDRV sector size.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

at least in the path via virtio-blk the maximum size is not
restricted.

Cc: qemu-stable@nongnu.org
Signed-off-by: NPeter Lieven <pl@kamp.de>
Message-Id: <1464080368-29584-1-git-send-email-pl@kamp.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NVadim Rozenfeld <vrozenfe@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The block layer has a couple of cases where it can lose
Force Unit Access semantics when writing a large block of
zeroes, such that the request returns before the zeroes
have been guaranteed to land on underlying media.

SCSI does not support FUA during WRITESAME(10/16); FUA is only
supported if it falls back to WRITE(10/16).  But where the
underlying device is new enough to not need a fallback, it
means that any upper layer request with FUA semantics was
silently ignoring BDRV_REQ_FUA.

Conversely, NBD has situations where it can support FUA but not
ZERO_WRITE; when that happens, the generic block layer fallback
to bdrv_driver_pwritev() (or the older bdrv_co_writev() in qemu
2.6) was losing the FUA flag.

The problem of losing flags unrelated to ZERO_WRITE has been
latent in bdrv_co_do_write_zeroes() since commit aa7bfbff, but
back then, it did not matter because there was no FUA flag.  It
became observable when commit 93f5e6d8 paved the way for flags
that can impact correctness, when we should have been using
bdrv_co_writev_flags() with modified flags.  Compare to commit
9eeb6dd1, which got flag manipulation right in
bdrv_co_do_zero_pwritev().

Symptoms: I tested with qemu-io with default writethrough cache
(which is supposed to use FUA semantics on every write), and
targetted an NBD client connected to a server that intentionally
did not advertise NBD_FLAG_SEND_FUA.  When doing 'write 0 512',
the NBD client sent two operations (NBD_CMD_WRITE then
NBD_CMD_FLUSH) to get the fallback FUA semantics; but when doing
'write -z 0 512', the NBD client sent only NBD_CMD_WRITE.

The fix is do to a cleanup bdrv_co_flush() at the end of the
operation if any step in the middle relied on a BDS that does
not natively support FUA for that step (note that we don't
need to flush after every operation, if the operation is broken
into chunks based on bounce-buffer sizing).  Each BDS gains a
new flag .supported_zero_flags, which parallels the use of
.supported_write_flags but only when accessing a zero write
operation (the flags MUST be different, because of SCSI having
different semantics based on WRITE vs. WRITESAME; and also
because BDRV_REQ_MAY_UNMAP only makes sense on zero writes).

Also fix some documentation to describe -ENOTSUP semantics,
particularly since iscsi depends on those semantics.

Down the road, we may want to add a driver where its
.bdrv_co_pwritev() honors all three of BDRV_REQ_FUA,
BDRV_REQ_ZERO_WRITE, and BDRV_REQ_MAY_UNMAP, and advertise
this via bs->supported_write_flags for blocks opened by that
driver; such a driver should NOT supply .bdrv_co_write_zeroes
nor .supported_zero_flags.  But none of the drivers touched
in this patch want to do that (the act of writing zeroes is
different enough from normal writes to deserve a second
callback).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Pre-patch, .supported_write_flags lives at the driver level, which
means we are blindly declaring that all block devices using a
given driver will either equally support FUA, or that we need a
fallback at the block layer.  But there are drivers where FUA
support is a per-block decision: the NBD block driver is dependent
on the remote server advertising NBD_FLAG_SEND_FUA (and has
fallback code to duplicate the flush that the block layer would do
if NBD had not set .supported_write_flags); and the iscsi block
driver is dependent on the mode sense bits advertised by the
underlying device (and is currently silently ignoring FUA requests
if the underlying device does not support FUA).

The fix is to make supported flags as a per-BDS option, set during
.bdrv_open().  This patch moves the variable and fixes NBD and iscsi
to set it only conditionally; later patches will then further
simplify the NBD driver to quit duplicating work done at the block
layer, as well as tackle the fact that SCSI does not support FUA
semantics on WRITESAME(10/16) but only on WRITE(10/16).
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>
Acked-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

This is a function that simply calls into the block driver for doing a
write, providing the byte granularity interface we want to eventually
have everywhere, and using whatever interface that driver supports.

This one is a bit more interesting than the version for reads: It adds
support for .bdrv_co_writev_flags() everywhere, so that drivers
implementing this function can drop .bdrv_co_writev() now.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NFam Zheng <famz@redhat.com>

This replaces the existing hack in the iscsi driver that sent the FUA
bit in writethrough mode and ignored the following flush in order to
optimise the number of roundtrips (see commit 73b5394e).
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

Whether a write cache is used or not is a decision that concerns the
user (e.g. the guest device) rather than the backend. It was already
logically part of the BB level as bdrv_move_feature_fields() always kept
it on top of the BDS tree; with this patch, the core of it (the actual
flag and the additional flushes) is also implemented there.

Direct callers of bdrv_open() must pass BDRV_O_CACHE_WB now if bs
doesn't have a BlockBackend attached.
Signed-off-by: NKevin Wolf <kwolf@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>

The iSCSI driver currently accepts the CHAP password in plain text
as a block driver property. This change adds a new "password-secret"
property that accepts the ID of a QCryptoSecret instance.

  $QEMU \
     -object secret,id=sec0,filename=/home/berrange/example.pw \
     -drive driver=iscsi,url=iscsi://example.com/target-foo/lun1,\
            user=dan,password-secret=sec0
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>
Message-id: 1453385961-10718-4-git-send-email-berrange@redhat.com
Signed-off-by: NJeff Cody <jcody@redhat.com>

Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-id: 1453780743-16806-6-git-send-email-famz@redhat.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>

The added parameter can be used to return the BDS pointer which the
valid offset is referring to. Its value should be ignored unless
BDRV_BLOCK_OFFSET_VALID in ret is set.

Until block drivers fill in the right value, let's clear it explicitly
right before calling .bdrv_get_block_status.

The "bs->file" condition in bdrv_co_get_block_status is kept now to keep iotest
case 102 passing, and will be fixed once all drivers return the right file
pointer.
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-id: 1453780743-16806-2-git-send-email-famz@redhat.com
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NMax Reitz <mreitz@redhat.com>

Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.

This commit was created with scripts/clean-includes.
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

When play with Dell MD3000 target, for sure it
is a TYPE_DISK, but readcapacity16 would fail.
Then we find that readcapacity10 succeeded. It
looks like the target just support readcapacity10
even through it is a TYPE_DISK or have some
TYPE_ROM characteristics.

This patch can give a chance to send
readcapacity16 when readcapacity10 failed.
This patch is not harmful to original pathes
Signed-off-by: NZhu Lingshan <lszhu@suse.com>
Message-Id: <1451359934-9236-1-git-send-email-lszhu@suse.com>
[Don't fall through on UNIT ATTENTION. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

fix:The error message for readcapacity 16 incorrectly mentioned
a readcapacity 10 failure, fixed the error message.
Signed-off-by: NZhu Lingshan <lszhu@suse.com>
Reviewed-by: NJohn Snow <jsnow@redhat.com>
Signed-off-by: NMichael Tokarev <mjt@tls.msk.ru>

Now the callback is not used any more, drop the field along with all
implementations in block drivers, which are iscsi and raw.
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Message-id: 1447064214-29930-8-git-send-email-famz@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

iscsi_ioctl emulates SG_GET_VERSION_NUM and SG_GET_SCSI_ID. Now that
bdrv_ioctl() will be emulated with .bdrv_aio_ioctl, replicate the logic
into iscsi_aio_ioctl to make them consistent.
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Message-id: 1447064214-29930-5-git-send-email-famz@redhat.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

Previously we return -EIO blindly when anything goes wrong. Add a helper
function to parse sense fields and try to make the return code more
meaningful.

This also fixes the default werror configuration (enospc) when we're
using qcow2 on an iscsi lun. The old -EIO not being treated as out of
space error failed to trigger vm stop.
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-Id: <1446699609-11376-1-git-send-email-famz@redhat.com>
[libiscsi 1.9 compatibility - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

All callers pass in false, and the real external ones will switch to
true in coming patches.
Signed-off-by: NFam Zheng <famz@redhat.com>
Reviewed-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NKevin Wolf <kwolf@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

It has been reported that at least tgtd returns a block size of 0
for LUN 0. To avoid running into divide by zero later on and protect
against other problematic block sizes validate the block size right
at connection time.

Cc: qemu-stable@nongnu.org
Reported-by: NAndrey Korolyov <andrey@xdel.ru>
Signed-off-by: NPeter Lieven <pl@kamp.de>
Message-Id: <1439552016-8557-1-git-send-email-pl@kamp.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

RHEL7 and others are stuck with libiscsi 1.9.0 since there
unfortunately was an ABI breakage after that release.
Signed-off-by: NPeter Lieven <pl@kamp.de>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-id: 1435313881-19366-1-git-send-email-pl@kamp.de
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

libiscsi starting with 1.15 will properly support timeout of iscsi
commands. The default will remain no timeout, but this can
be changed via cmdline parameters, e.g.:

qemu -iscsi timeout=30 -drive file=iscsi://...

If a timeout occurs a reconnect is scheduled and the timed out command
will be requeued for processing after a successful reconnect.

The required API call iscsi_set_timeout is present since libiscsi
1.10 which was released in October 2013. However, due to some bugs
in the libiscsi code the use is not recommended before version 1.15.

Please note that this patch bumps the libiscsi requirement to 1.10
to have all function and macros defined. The patch fixes also a
off-by-one error in the NOP timeout calculation which was fixed
while touching these code parts.
Signed-off-by: NPeter Lieven <pl@kamp.de>
Message-id: 1434455107-19328-1-git-send-email-pl@kamp.de
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

During migration, QEMU uses fsync()/fdatasync() on the open file
descriptor for read-write block devices to flush data just before
stopping the VM.

However, fsync() on a scsi-generic device returns -EINVAL which
causes the migration to fail. This patch skips flushing data in case
of an SG device, since submitting SCSI commands directly via an SG
character device (e.g. /dev/sg0) bypasses the page cache completely,
anyway.

Note that fsync() not only flushes the page cache but also the disk
cache. The scsi-generic device never sends flushes, and for
migration it assumes that the same SCSI device is used by the
destination host, so it does not issue any SCSI SYNCHRONIZE CACHE
(10) command.

Finally, remove the bdrv_is_sg() test from iscsi_co_flush() since
this is now redundant (we flush the underlying protocol at the end
of bdrv_co_flush() which, with this patch, we never reach).
Signed-off-by: NDimitris Aragiorgis <dimara@arrikto.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435056300-14924-3-git-send-email-dimara@arrikto.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>

Instead of checking bs->sg use bdrv_is_sg() consistently throughout
the code.
Signed-off-by: NDimitris Aragiorgis <dimara@arrikto.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435056300-14924-2-git-send-email-dimara@arrikto.com
Signed-off-by: NStefan Hajnoczi <stefanha@redhat.com>