Commit Graph

203 Commits

Author SHA1 Message Date
Daniel P. Berrange f42cf447e2 block: move trace probes into bdrv_co_preadv|pwritev
There are trace probes in bdrv_co_readv|writev, however, the
block drivers are being gradually moved over to using the
bdrv_co_preadv|pwritev functions instead. As a result some
block drivers miss the current probes. Move the probes
into bdrv_co_preadv|pwritev instead, so that they are triggered
by more (all?) I/O code paths.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170804105036.11879-1-berrange@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-08-07 09:39:35 +01:00
Peter Maydell 718d7f4f9c -----BEGIN PGP SIGNATURE-----
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Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging

# gpg: Signature made Mon 17 Jul 2017 16:40:18 BST
# gpg:                using RSA key 0x9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>"
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>"
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha/tags/block-pull-request:
  block: fix shadowed variable in bdrv_co_pdiscard
  util/aio-win32: Only select on what we are actually waiting for

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2017-07-18 13:09:51 +01:00
Denis V. Lunev 593ed6f0a3 block: fix shadowed variable in bdrv_co_pdiscard
We've had a shadowed 'ret' variable, which risks returning the wrong
value, introduced in commit b9c64947.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20170710150559.30163-1-den@openvz.org
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-07-17 15:58:37 +01:00
Paolo Bonzini 61124f03ab block: invoke .bdrv_drain callback in coroutine context and from AioContext
This will let the callback take a CoMutex in the next patch.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170629132749.997-8-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-07-17 11:28:15 +08:00
Vladimir Sementsov-Ogievskiy d6883bc968 block/dirty-bitmap: add readonly field to BdrvDirtyBitmap
It will be needed in following commits for persistent bitmaps.
If bitmap is loaded from read-only storage (and we can't mark it
"in use" in this storage) corresponding BdrvDirtyBitmap should be
read-only.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 20170628120530.31251-11-vsementsov@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11 17:44:58 +02:00
Eric Blake 51b0a48888 block: Make bdrv_is_allocated_above() byte-based
We are gradually moving away from sector-based interfaces, towards
byte-based.  In the common case, allocation is unlikely to ever use
values that are not naturally sector-aligned, but it is possible
that byte-based values will let us be more precise about allocation
at the end of an unaligned file that can do byte-based access.

Changing the signature of the function to use int64_t *pnum ensures
that the compiler enforces that all callers are updated.  For now,
the io.c layer still assert()s that all callers are sector-aligned,
but that can be relaxed when a later patch implements byte-based
block status.  Therefore, for the most part this patch is just the
addition of scaling at the callers followed by inverse scaling at
bdrv_is_allocated().  But some code, particularly stream_run(),
gets a lot simpler because it no longer has to mess with sectors.
Leave comments where we can further simplify by switching to
byte-based iterations, once later patches eliminate the need for
sector-aligned operations.

For ease of review, bdrv_is_allocated() was tackled separately.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-07-10 13:18:07 +02:00
Eric Blake c00716beb3 block: Minimize raw use of bds->total_sectors
bdrv_is_allocated_above() was relying on intermediate->total_sectors,
which is a field that can have stale contents depending on the value
of intermediate->has_variable_length.  An audit shows that we are safe
(we were first calling through bdrv_co_get_block_status() which in
turn calls bdrv_nb_sectors() and therefore just refreshed the current
length), but it's nicer to favor our accessor functions to avoid having
to repeat such an audit, even if it means refresh_total_sectors() is
called more frequently.

Suggested-by: John Snow <jsnow@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-07-10 13:18:07 +02:00
Eric Blake d6a644bbfe block: Make bdrv_is_allocated() byte-based
We are gradually moving away from sector-based interfaces, towards
byte-based.  In the common case, allocation is unlikely to ever use
values that are not naturally sector-aligned, but it is possible
that byte-based values will let us be more precise about allocation
at the end of an unaligned file that can do byte-based access.

Changing the signature of the function to use int64_t *pnum ensures
that the compiler enforces that all callers are updated.  For now,
the io.c layer still assert()s that all callers are sector-aligned
on input and that *pnum is sector-aligned on return to the caller,
but that can be relaxed when a later patch implements byte-based
block status.  Therefore, this code adds usages like
DIV_ROUND_UP(,BDRV_SECTOR_SIZE) to callers that still want aligned
values, where the call might reasonbly give non-aligned results
in the future; on the other hand, no rounding is needed for callers
that should just continue to work with byte alignment.

For the most part this patch is just the addition of scaling at the
callers followed by inverse scaling at bdrv_is_allocated().  But
some code, particularly bdrv_commit(), gets a lot simpler because it
no longer has to mess with sectors; also, it is now possible to pass
NULL if the caller does not care how much of the image is allocated
beyond the initial offset.  Leave comments where we can further
simplify once a later patch eliminates the need for sector-aligned
requests through bdrv_is_allocated().

For ease of review, bdrv_is_allocated_above() will be tackled
separately.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-07-10 13:18:07 +02:00
Eric Blake e8a81e9cad block: Drop unused bdrv_round_sectors_to_clusters()
Now that the last user [mirror_iteration()] has converted to using
bytes, we no longer need a function to round sectors to clusters.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-07-10 13:18:06 +02:00
Eric Blake 81c219ac6c block: Guarantee that *file is set on bdrv_get_block_status()
We document that *file is valid if the return is not an error and
includes BDRV_BLOCK_OFFSET_VALID, but forgot to obey this contract
when a driver (such as blkdebug) lacks a callback.  Messed up in
commit 67a0fd2 (v2.6), when we added the file parameter.

Enhance qemu-iotest 177 to cover this, using a sequence that would
print garbage or even SEGV, because it was dererefencing through
uninitialized memory.  [The resulting test output shows that we
have less-than-ideal block status from the blkdebug driver, but
that's a separate fix coming up soon.]

Setting *file on all paths that return BDRV_BLOCK_OFFSET_VALID is
enough to fix the crash, but we can go one step further: always
setting *file, even on error, means that a broken caller that
blindly dereferences file without checking for error is now more
likely to get a reliable SEGV instead of randomly acting on garbage,
making it easier to diagnose such buggy callers.  Adding an
assertion that file is set where expected doesn't hurt either.

CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-07-10 13:18:05 +02:00
Eric Blake c61e684e44 block: Exploit BDRV_BLOCK_EOF for larger zero blocks
When we have a BDS with unallocated clusters, but asking the status
of its underlying bs->file or backing layer encounters an end-of-file
condition, we know that the rest of the unallocated area will read as
zeroes.  However, pre-patch, this required two separate calls to
bdrv_get_block_status(), as the first call stops at the point where
the underlying file ends.  Thanks to BDRV_BLOCK_EOF, we can now widen
the results of the primary status if the secondary status already
includes BDRV_BLOCK_ZERO.

In turn, this fixes a TODO mentioned in iotest 154, where we can now
see that all sectors in a partial cluster at the end of a file read
as zero when coupling the shorter backing file's status along with our
knowledge that the remaining sectors came from an unallocated cluster.

Also, note that the loop in bdrv_co_get_block_status_above() had an
inefficent exit: in cases where the active layer sets BDRV_BLOCK_ZERO
but does NOT set BDRV_BLOCK_ALLOCATED (namely, where we know we read
zeroes merely because our unallocated clusters lie beyond the backing
file's shorter length), we still ended up probing the backing layer
even though we already had a good answer.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170505021500.19315-3-eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-30 21:48:06 +08:00
Eric Blake fb0d8654ff block: Add BDRV_BLOCK_EOF to bdrv_get_block_status()
Just as the block layer already sets BDRV_BLOCK_ALLOCATED as a
shortcut for subsequent operations, there are also some optimizations
that are made easier if we can quickly tell that *pnum will advance
us to the end of a file, via a new BDRV_BLOCK_EOF which gets set
by the block layer.

This just plumbs up the new bit; subsequent patches will make use
of it.

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20170505021500.19315-2-eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-30 21:48:06 +08:00
Manos Pitsidianakis f5a5ca7969 block: change variable names in BlockDriverState
Change the 'int count' parameter in *pwrite_zeros, *pdiscard related
functions (and some others) to 'int bytes', as they both refer to bytes.
This helps with code legibility.

Signed-off-by: Manos Pitsidianakis <el13635@mail.ntua.gr>
Message-id: 20170609101808.13506-1-el13635@mail.ntua.gr
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-06-26 14:54:46 +02:00
Kevin Wolf c5f1ad429c block: Remove bdrv_aio_readv/writev/flush()
These functions are unused now.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-06-26 14:51:15 +02:00
Stefan Hajnoczi ea17c9d20d block: use BDRV_POLL_WHILE() in bdrv_rw_vmstate()
Calling aio_poll() directly may have been fine previously, but this is
the future, man!  The difference between an aio_poll() loop and
BDRV_POLL_WHILE() is that BDRV_POLL_WHILE() releases the AioContext
around aio_poll().

This allows the IOThread to run fd handlers or BHs to complete the
request.  Failure to release the AioContext causes deadlocks.

Using BDRV_POLL_WHILE() partially fixes a 'savevm' hang with -object
iothread.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-06-26 14:51:13 +02:00
Stefan Hajnoczi dc88a467ec block: count bdrv_co_rw_vmstate() requests
Call bdrv_inc/dec_in_flight() for vmstate reads/writes.  This seems
unnecessary at first glance because vmstate reads/writes are done
synchronously while the guest is stopped.  But we need the bdrv_wakeup()
in bdrv_dec_in_flight() so the main loop sees request completion.
Besides, it's cleaner to count vmstate reads/writes like ordinary
read/write requests.

The bdrv_wakeup() partially fixes a 'savevm' hang with -object iothread.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-06-26 14:51:13 +02:00
Paolo Bonzini 3783fa3dd3 block: protect tracked_requests and flush_queue with reqs_lock
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-14-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-16 07:55:00 +08:00
Paolo Bonzini 47fec59941 block: access write_gen with atomics
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-13-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-16 07:55:00 +08:00
Paolo Bonzini f7946da274 block: use Stat64 for wr_highest_offset
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-12-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-16 07:55:00 +08:00
Paolo Bonzini 850d54a2a9 block: access io_plugged with atomic ops
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-7-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-16 07:55:00 +08:00
Paolo Bonzini e2a6ae7fe5 block: access wakeup with atomic ops
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-6-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-16 07:55:00 +08:00
Paolo Bonzini 20fc71b25c block: access serialising_in_flight with atomic ops
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-5-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-16 07:55:00 +08:00
Paolo Bonzini 414c2ec358 block: access quiesce_counter with atomic ops
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-3-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-16 07:55:00 +08:00
Paolo Bonzini d3faa13e5f block: access copy_on_read with atomic ops
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20170605123908.18777-2-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-06-16 07:55:00 +08:00
Paolo Bonzini f321dcb57f blockjob: introduce block_job_pause/resume_all
Remove use of block_job_pause/resume from outside blockjob.c, thus
making them static.  The new functions are used by the block layer,
so place them in blockjob_int.h.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 20170508141310.8674-5-pbonzini@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
2017-05-24 16:38:51 -04:00
Eric Blake ee29d6adef block: Simplify BDRV_BLOCK_RAW recursion
Since we are already in coroutine context during the body of
bdrv_co_get_block_status(), we can shave off a few layers of
wrappers when recursing to query the protocol when a format driver
returned BDRV_BLOCK_RAW.

Note that we are already using the correct recursion later on in
the same function, when probing whether the protocol layer is sparse
in order to find out if we can add BDRV_BLOCK_ZERO to an existing
BDRV_BLOCK_DATA|BDRV_BLOCK_OFFSET_VALID.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170504173745.27414-1-eblake@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-05-12 10:36:46 -04:00
Denis V. Lunev f13ce1be35 block: fix alignment calculations in bdrv_co_do_zero_pwritev
tail_padding_bytes is calculated wrong. F.e. for
    offset = 0
    bytes = 2048
    align = 512
we will have tail_padding_bytes = 512 which is definitely wrong. The patch
fixes that arithmetics.

Fortunately this problem is harmless, we will have 1 extra allocation and
free thus there is no need to put this into stable. The problem is here
from the very beginning.

Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Stefan Hajnoczi <stefanha@redhat.com>
CC: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-04-27 16:24:01 +02:00
Fam Zheng e914404efb block: Remove NULL check in bdrv_co_flush
Reported by Coverity. We already use bs in bdrv_inc_in_flight before
checking for NULL. It is unnecessary as all callers pass non-NULL bs, so
drop it.

Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-04-27 15:39:50 +02:00
Max Reitz 362b3786eb Revert "block/io: Comment out permission assertions"
This reverts commit e3e0003a8f.

This commit was necessary for the 2.9 release because we were unable to
fix the underlying issue(s) in time. However, we will be for 2.10.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-04-27 15:39:49 +02:00
Fam Zheng 178bd438af block: Walk bs->children carefully in bdrv_drain_recurse
The recursive bdrv_drain_recurse may run a block job completion BH that
drops nodes. The coming changes will make that more likely and use-after-free
would happen without this patch

Stash the bs pointer and use bdrv_ref/bdrv_unref in addition to
QLIST_FOREACH_SAFE to prevent such a case from happening.

Since bdrv_unref accesses global state that is not protected by the AioContext
lock, we cannot use bdrv_ref/bdrv_unref unconditionally.  Fortunately the
protection is not needed in IOThread because only main loop can modify a graph
with the AioContext lock held.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170418143044.12187-2-famz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Tested-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2017-04-18 22:56:28 +08:00
Max Reitz e3e0003a8f block/io: Comment out permission assertions
In case of block migration, there may be writes to BlockBackends that do
not have the write permission taken. Before this issue is fixed (which
is not going to happen in 2.9), we therefore cannot assert that this is
the case.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Tested-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 20170411145050.31290-1-mreitz@redhat.com
Tested-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2017-04-11 16:09:31 +01:00
Fam Zheng 49ca625913 block: Fix bdrv_co_flush early return
bdrv_inc_in_flight and bdrv_dec_in_flight are mandatory for
BDRV_POLL_WHILE to work, even for the shortcut case where flush is
unnecessary. Move the if block to below bdrv_dec_in_flight, and BTW fix
the variable declaration position.

Signed-off-by: Fam Zheng <famz@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
2017-04-11 20:07:15 +08:00
Fam Zheng e92f0e1910 block: Use bdrv_coroutine_enter to start I/O coroutines
BDRV_POLL_WHILE waits for the started I/O by releasing bs's ctx then polling
the main context, which relies on the yielded coroutine continuing on bs->ctx
before notifying qemu_aio_context with bdrv_wakeup().

Thus, using qemu_coroutine_enter to start I/O is wrong because if the coroutine
is entered from main loop, co->ctx will be qemu_aio_context, as a result of the
"release, poll, acquire" loop of BDRV_POLL_WHILE, race conditions happen when
both main thread and the iothread access the same BDS:

  main loop                                iothread
-----------------------------------------------------------------------
  blockdev_snapshot
    aio_context_acquire(bs->ctx)
                                           virtio_scsi_data_plane_handle_cmd
    bdrv_drained_begin(bs->ctx)
    bdrv_flush(bs)
      bdrv_co_flush(bs)                      aio_context_acquire(bs->ctx).enter
        ...
        qemu_coroutine_yield(co)
      BDRV_POLL_WHILE()
        aio_context_release(bs->ctx)
                                             aio_context_acquire(bs->ctx).return
                                               ...
                                                 aio_co_wake(co)
        aio_poll(qemu_aio_context)               ...
          co_schedule_bh_cb()                    ...
            qemu_coroutine_enter(co)             ...

              /* (A) bdrv_co_flush(bs)           /* (B) I/O on bs */
                      continues... */
                                             aio_context_release(bs->ctx)
        aio_context_acquire(bs->ctx)

Note that in above case, bdrv_drained_begin() doesn't do the "release,
poll, acquire" in BDRV_POLL_WHILE, because bs->in_flight == 0.

Fix this by using bdrv_coroutine_enter and enter coroutine in the right
context.

iotests 109 output is updated because the coroutine reenter flow during
mirror job complete is different (now through co_queue_wakeup, instead
of the unconditional qemu_coroutine_switch before), making the end job
len different.

Signed-off-by: Fam Zheng <famz@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
2017-04-11 20:07:15 +08:00
Fam Zheng 14e9559f46 block: Make bdrv_parent_drained_begin/end public
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
2017-04-11 20:07:15 +08:00
Kevin Wolf 1bf03e66fd block: Don't check permissions for copy on read
The assertion is currently failing. We can't require callers to have
write permissions when all they are doing is a read, so comment it out.
Add a FIXME comment in the code so that the check is re-enabled when
copy on read is refactored into its own filter driver.

Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
2017-04-07 14:44:06 +02:00
Kevin Wolf b64aa44195 block: Request block status from *file for BDRV_BLOCK_RAW
This fixes bdrv_co_get_block_status() for the bdrv_mirror_top block
driver, which must fall through to bs->backing instead of bs->file.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
2017-03-13 12:49:33 +01:00
Kevin Wolf c8f6d58edb block: Assertions for resize permission
This adds an assertion that ensures that the necessary resize permission
has been granted before bdrv_truncate() is called.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
2017-02-28 20:47:50 +01:00
Kevin Wolf afa4b29323 block: Assertions for write permissions
This adds assertions that ensure that the necessary write permissions
have been granted before someone attempts to write to a node.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
2017-02-28 20:47:50 +01:00
Kevin Wolf 85c97ca7a1 block: Pass BdrvChild to bdrv_aligned_preadv/pwritev and copy-on-read
This is where we want to check the permissions, so we need to have the
BdrvChild around where they are stored.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
2017-02-28 20:47:50 +01:00
Paolo Bonzini 1ace7ceac5 coroutine-lock: add mutex argument to CoQueue APIs
All that CoQueue needs in order to become thread-safe is help
from an external mutex.  Add this to the API.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170213181244.16297-6-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-02-21 11:39:40 +00:00
Paolo Bonzini b9e413dd37 block: explicitly acquire aiocontext in aio callbacks that need it
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-16-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-02-21 11:39:39 +00:00
Paolo Bonzini 1919631e6b block: explicitly acquire aiocontext in bottom halves that need it
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-15-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-02-21 11:39:39 +00:00
Paolo Bonzini 2f47da5f7f block: explicitly acquire aiocontext in timers that need it
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170213135235.12274-13-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-02-21 11:14:08 +00:00
Paolo Bonzini c2b38b277a block: move AioContext, QEMUTimer, main-loop to libqemuutil
AioContext is fairly self contained, the only dependency is QEMUTimer but
that in turn doesn't need anything else.  So move them out of block-obj-y
to avoid introducing a dependency from io/ to block-obj-y.

main-loop and its dependency iohandler also need to be moved, because
later in this series io/ will call iohandler_get_aio_context.

[Changed copyright "the QEMU team" to "other QEMU contributors" as
suggested by Daniel Berrange and agreed by Paolo.
--Stefan]

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20170213135235.12274-2-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-02-21 11:14:07 +00:00
Paolo Bonzini 8f90b5e91d block: get rid of bdrv_io_unplugged_begin/end
bdrv_io_plug and bdrv_io_unplug are only called (via their
BlockBackend equivalents) after starting asynchronous I/O.
bdrv_drain is not going to be called while they are running,
because---even if a coroutine runs for some reason---it will
only drain in the next iteration of the event loop through
bdrv_co_yield_to_drain.

So this mechanism is unnecessary, get rid of it.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 20161129113334.605-1-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2017-01-16 13:25:17 +00:00
Eric Blake 3482b9bc41 block: Pass unaligned discard requests to drivers
Discard is advisory, so rounding the requests to alignment
boundaries is never semantically wrong from the data that
the guest sees.  But at least the Dell Equallogic iSCSI SANs
has an interesting property that its advertised discard
alignment is 15M, yet documents that discarding a sequence
of 1M slices will eventually result in the 15M page being
marked as discarded, and it is possible to observe which
pages have been discarded.

Between commits 9f1963b and b8d0a980, we converted the block
layer to a byte-based interface that ultimately ignores any
unaligned head or tail based on the driver's advertised
discard granularity, which means that qemu 2.7 refuses to
pass any discard request smaller than 15M down to the Dell
Equallogic hardware.  This is a slight regression in behavior
compared to earlier qemu, where a guest executing discards
in power-of-2 chunks used to be able to get every page
discarded, but is now left with various pages still allocated
because the guest requests did not align with the hardware's
15M pages.

Since the SCSI specification says nothing about a minimum
discard granularity, and only documents the preferred
alignment, it is best if the block layer gives the driver
every bit of information about discard requests, rather than
rounding it to alignment boundaries early.

Rework the block layer discard algorithm to mirror the write
zero algorithm: always peel off any unaligned head or tail
and manage that in isolation, then do the bulk of the request
on an aligned boundary.  The fallback when the driver returns
-ENOTSUP for an unaligned request is to silently ignore that
portion of the discard request; but for devices that can pass
the partial request all the way down to hardware, this can
result in the hardware coalescing requests and discarding
aligned pages after all.

Reported by: Peter Lieven <pl@kamp.de>
CC: qemu-stable@nongnu.org
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-11-22 15:59:23 +01:00
Eric Blake b2f95feec5 block: Let write zeroes fallback work even with small max_transfer
Commit 443668ca rewrote the write_zeroes logic to guarantee that
an unaligned request never crosses a cluster boundary.  But
in the rewrite, the new code assumed that at most one iteration
would be needed to get to an alignment boundary.

However, it is easy to trigger an assertion failure: the Linux
kernel limits loopback devices to advertise a max_transfer of
only 64k.  Any operation that requires falling back to writes
rather than more efficient zeroing must obey max_transfer during
that fallback, which means an unaligned head may require multiple
iterations of the write fallbacks before reaching the aligned
boundaries, when layering a format with clusters larger than 64k
atop the protocol of file access to a loopback device.

Test case:

$ qemu-img create -f qcow2 -o cluster_size=1M file 10M
$ losetup /dev/loop2 /path/to/file
$ qemu-io -f qcow2 /dev/loop2
qemu-io> w 7m 1k
qemu-io> w -z 8003584 2093056

In fairness to Denis (as the original listed author of the culprit
commit), the faulty logic for at most one iteration is probably all
my fault in reworking his idea.  But the solution is to restore what
was in place prior to that commit: when dealing with an unaligned
head or tail, iterate as many times as necessary while fragmenting
the operation at max_transfer boundaries.

Reported-by: Ed Swierk <eswierk@skyportsystems.com>
CC: qemu-stable@nongnu.org
CC: Denis V. Lunev <den@openvz.org>
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-11-22 15:59:22 +01:00
Kevin Wolf e6af1e0854 block: Don't mark node clean after failed flush
Commit 3ff2f67a changed bdrv_co_flush() so that no flush is issues if
the image hasn't been dirtied since the last flush. This is not quite
correct: The condition should be that the image hasn't been dirtied
since the last _successful_ flush. This patch changes the logic
accordingly.

Without this fix, subsequent bdrv_co_flush() calls would return success
without actually doing anything even though the image is still dirty.
The difference is visible in some blkdebug test cases where error
messages incorrectly disappeared after commit 3ff2f67a.

Cc: qemu-stable@nongnu.org
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Denis V. Lunev <den@openvz.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1478300595-10090-1-git-send-email-kwolf@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2016-11-08 16:06:35 +00:00
Alberto Garcia c0778f6693 block: Add bdrv_drain_all_{begin,end}()
bdrv_drain_all() doesn't allow the caller to do anything after all
pending requests have been completed but before block jobs are
resumed.

This patch splits bdrv_drain_all() into _begin() and _end() for that
purpose. It also adds aio_{disable,enable}_external() calls to disable
external clients in the meantime.

An important restriction of this split is that no new block jobs or
BlockDriverStates can be created between the bdrv_drain_all_begin()
and bdrv_drain_all_end() calls. This is not a concern now because
we'll only be using this in bdrv_reopen_multiple(), but it must be
dealt with if we ever have other uses cases in the future.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-10-31 16:51:14 +01:00
Paolo Bonzini c9d1a56174 block: only call aio_poll on the current thread's AioContext
aio_poll is not thread safe; for example bdrv_drain can hang if
the last in-flight I/O operation is completed in the I/O thread after
the main thread has checked bs->in_flight.

The bug remains latent as long as all of it is called within
aio_context_acquire/aio_context_release, but this will change soon.

To fix this, if bdrv_drain is called from outside the I/O thread,
signal the main AioContext through a dummy bottom half.  The event
loop then only runs in the I/O thread.

Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <1477565348-5458-18-git-send-email-pbonzini@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
2016-10-28 21:50:18 +08:00