We know that the kernel implements a slow fallback code path for
BLKZEROOUT, so if BDRV_REQ_NO_FALLBACK is given, we shouldn't call it.
The other operations we call in the context of .bdrv_co_pwrite_zeroes
should usually be quick, so no modification should be needed for them.
If we ever notice that there are additional problematic cases, we can
still make these conditional as well.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Acked-by: Eric Blake <eblake@redhat.com>
* Add 'drop-cache=on|off' option to file-posix.c. The default is on.
Disabling the option fixes a QEMU 3.0.0 performance regression when live
migrating on the same host with cache.direct=off.
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Merge remote-tracking branch 'remotes/stefanha/tags/block-pull-request' into staging
Pull request
* Add 'drop-cache=on|off' option to file-posix.c. The default is on.
Disabling the option fixes a QEMU 3.0.0 performance regression when live
migrating on the same host with cache.direct=off.
# gpg: Signature made Wed 13 Mar 2019 11:07:48 GMT
# gpg: using RSA key 9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg: aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35 775A 9CA4 ABB3 81AB 73C8
* remotes/stefanha/tags/block-pull-request:
file-posix: add drop-cache=on|off option
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Commit dd577a26ff ("block/file-posix:
implement bdrv_co_invalidate_cache() on Linux") introduced page cache
invalidation so that cache.direct=off live migration is safe on Linux.
The invalidation takes a significant amount of time when the file is
large and present in the page cache. Normally this is not the case for
cross-host live migration but it can happen when migrating between QEMU
processes on the same host.
On same-host migration we don't need to invalidate pages for correctness
anyway, so an option to skip page cache invalidation is useful. I
investigated optimizing invalidation and detecting same-host migration,
but both are hard to achieve so a user-visible option will suffice.
As a bonus this option means that the cache invalidation feature will
now be detectable by libvirt via QMP schema introspection.
Suggested-by: Neil Skrypuch <neil@tembosocial.com>
Tested-by: Neil Skrypuch <neil@tembosocial.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20190307164941.3322-1-stefanha@redhat.com
Message-Id: <20190307164941.3322-1-stefanha@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
If we reopen a BlockDriverState and there is an option that is present
in bs->options but missing from the new set of options then we have to
return an error unless the driver is able to reset it to its default
value.
This patch adds a new 'mutable_opts' field to BlockDriver. This is
a list of runtime options that can be modified during reopen. If an
option in this list is unspecified on reopen then it must be reset (or
return an error).
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Until now, with auto-read-only=on we tried to open the file read-write
first and if that failed, read-only was tried. This is actually not good
enough for libvirt, which gives QEMU SELinux permissions for read-write
only as soon as it actually intends to write to the image. So we need to
be able to switch between read-only and read-write at runtime.
This patch makes auto-read-only dynamic, i.e. the file is opened
read-only as long as no user of the node has requested write
permissions, but it is automatically reopened read-write as soon as the
first writer is attached. Conversely, if the last writer goes away, the
file is reopened read-only again.
bs->read_only is no longer set for auto-read-only=on files even if the
file descriptor is opened read-only because it will be transparently
upgraded as soon as a writer is attached. This changes the output of
qemu-iotests 232.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
In order to be able to dynamically reopen the file read-only or
read-write, depending on the users that are attached, we need to be able
to switch to a different file descriptor during the permission change.
This interacts with reopen, which also creates a new file descriptor and
performs permission changes internally. In this case, the permission
change code must reuse the reopen file descriptor instead of creating a
third one.
In turn, reopen can drop its code to copy file locks to the new file
descriptor because that is now done when applying the new permissions.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
There is no reason why we can take locks on the new file descriptor only
in raw_reopen_commit() where error handling isn't possible any more.
Instead, we can already do this in raw_reopen_prepare().
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We'll want to access the file descriptor in the reopen_state while
processing permission changes in the context of the repoen.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Most files that have TABs only contain a handful of them. Change
them to spaces so that we don't confuse people.
disas, standard-headers, linux-headers and libdecnumber are imported
from other projects and probably should be exempted from the check.
Outside those, after this patch the following files still contain both
8-space and TAB sequences at the beginning of the line. Many of them
have a majority of TABs, or were initially committed with all tabs.
bsd-user/i386/target_syscall.h
bsd-user/x86_64/target_syscall.h
crypto/aes.c
hw/audio/fmopl.c
hw/audio/fmopl.h
hw/block/tc58128.c
hw/display/cirrus_vga.c
hw/display/xenfb.c
hw/dma/etraxfs_dma.c
hw/intc/sh_intc.c
hw/misc/mst_fpga.c
hw/net/pcnet.c
hw/sh4/sh7750.c
hw/timer/m48t59.c
hw/timer/sh_timer.c
include/crypto/aes.h
include/disas/bfd.h
include/hw/sh4/sh.h
libdecnumber/decNumber.c
linux-headers/asm-generic/unistd.h
linux-headers/linux/kvm.h
linux-user/alpha/target_syscall.h
linux-user/arm/nwfpe/double_cpdo.c
linux-user/arm/nwfpe/fpa11_cpdt.c
linux-user/arm/nwfpe/fpa11_cprt.c
linux-user/arm/nwfpe/fpa11.h
linux-user/flat.h
linux-user/flatload.c
linux-user/i386/target_syscall.h
linux-user/ppc/target_syscall.h
linux-user/sparc/target_syscall.h
linux-user/syscall.c
linux-user/syscall_defs.h
linux-user/x86_64/target_syscall.h
slirp/cksum.c
slirp/if.c
slirp/ip.h
slirp/ip_icmp.c
slirp/ip_icmp.h
slirp/ip_input.c
slirp/ip_output.c
slirp/mbuf.c
slirp/misc.c
slirp/sbuf.c
slirp/socket.c
slirp/socket.h
slirp/tcp_input.c
slirp/tcpip.h
slirp/tcp_output.c
slirp/tcp_subr.c
slirp/tcp_timer.c
slirp/tftp.c
slirp/udp.c
slirp/udp.h
target/cris/cpu.h
target/cris/mmu.c
target/cris/op_helper.c
target/sh4/helper.c
target/sh4/op_helper.c
target/sh4/translate.c
tcg/sparc/tcg-target.inc.c
tests/tcg/cris/check_addo.c
tests/tcg/cris/check_moveq.c
tests/tcg/cris/check_swap.c
tests/tcg/multiarch/test-mmap.c
ui/vnc-enc-hextile-template.h
ui/vnc-enc-zywrle.h
util/envlist.c
util/readline.c
The following have only TABs:
bsd-user/i386/target_signal.h
bsd-user/sparc64/target_signal.h
bsd-user/sparc64/target_syscall.h
bsd-user/sparc/target_signal.h
bsd-user/sparc/target_syscall.h
bsd-user/x86_64/target_signal.h
crypto/desrfb.c
hw/audio/intel-hda-defs.h
hw/core/uboot_image.h
hw/sh4/sh7750_regnames.c
hw/sh4/sh7750_regs.h
include/hw/cris/etraxfs_dma.h
linux-user/alpha/termbits.h
linux-user/arm/nwfpe/fpopcode.h
linux-user/arm/nwfpe/fpsr.h
linux-user/arm/syscall_nr.h
linux-user/arm/target_signal.h
linux-user/cris/target_signal.h
linux-user/i386/target_signal.h
linux-user/linux_loop.h
linux-user/m68k/target_signal.h
linux-user/microblaze/target_signal.h
linux-user/mips64/target_signal.h
linux-user/mips/target_signal.h
linux-user/mips/target_syscall.h
linux-user/mips/termbits.h
linux-user/ppc/target_signal.h
linux-user/sh4/target_signal.h
linux-user/sh4/termbits.h
linux-user/sparc64/target_syscall.h
linux-user/sparc/target_signal.h
linux-user/x86_64/target_signal.h
linux-user/x86_64/termbits.h
pc-bios/optionrom/optionrom.h
slirp/mbuf.h
slirp/misc.h
slirp/sbuf.h
slirp/tcp.h
slirp/tcp_timer.h
slirp/tcp_var.h
target/i386/svm.h
target/sparc/asi.h
target/xtensa/core-dc232b/xtensa-modules.inc.c
target/xtensa/core-dc233c/xtensa-modules.inc.c
target/xtensa/core-de212/core-isa.h
target/xtensa/core-de212/xtensa-modules.inc.c
target/xtensa/core-fsf/xtensa-modules.inc.c
target/xtensa/core-sample_controller/core-isa.h
target/xtensa/core-sample_controller/xtensa-modules.inc.c
target/xtensa/core-test_kc705_be/core-isa.h
target/xtensa/core-test_kc705_be/xtensa-modules.inc.c
tests/tcg/cris/check_abs.c
tests/tcg/cris/check_addc.c
tests/tcg/cris/check_addcm.c
tests/tcg/cris/check_addoq.c
tests/tcg/cris/check_bound.c
tests/tcg/cris/check_ftag.c
tests/tcg/cris/check_int64.c
tests/tcg/cris/check_lz.c
tests/tcg/cris/check_openpf5.c
tests/tcg/cris/check_sigalrm.c
tests/tcg/cris/crisutils.h
tests/tcg/cris/sys.c
tests/tcg/i386/test-i386-ssse3.c
ui/vgafont.h
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20181213223737.11793-3-pbonzini@redhat.com>
Reviewed-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Acked-by: Eric Blake <eblake@redhat.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Stefan Markovic <smarkovic@wavecomp.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
aio_worker() doesn't add anything interesting, it's only a useless
indirection. Call the handler function directly instead.
As we know that this handler function is only called from coroutine
context and the coroutine stays around until the worker thread finishes,
we can keep RawPosixAIOData on the stack.
This was the last user of aio_worker(), so the function goes away now.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
No real reason to keep using the callback based mechanism here when the
rest of the file-posix driver is coroutine based. Changing it brings
ioctls more in line with how other request types work.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
aio_worker() doesn't add anything interesting, it's only a useless
indirection. Call the handler function directly instead.
As we know that this handler function is only called from coroutine
context and the coroutine stays around until the worker thread finishes,
we can keep RawPosixAIOData on the stack.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
aio_worker() for reads and writes isn't boring enough yet. It still does
some postprocessing for handling short reads and turning the result into
the right return value.
However, there is no reason why handle_aiocb_rw() couldn't do the same,
and even without duplicating code between the read and write path. So
move the code there.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
aio_worker() doesn't add anything interesting, it's only a useless
indirection. Call the handler function directly instead.
As we know that this handler function is only called from coroutine
context and the coroutine stays around until the worker thread finishes,
we can keep RawPosixAIOData on the stack.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
aio_worker() doesn't add anything interesting, it's only a useless
indirection. Call the handler function directly instead.
As we know that this handler function is only called from coroutine
context and the coroutine stays around until the worker thread finishes,
we can keep RawPosixAIOData on the stack.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
aio_worker() doesn't add anything interesting, it's only a useless
indirection. Call the handler function directly instead.
As we know that this handler function is only called from coroutine
context and the coroutine stays around until the worker thread finishes,
we can keep RawPosixAIOData on the stack.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
aio_worker() doesn't add anything interesting, it's only a useless
indirection. Call the handler function directly instead.
As we know that this handler function is only called from coroutine
context and the coroutine stays around until the worker thread finishes,
we can keep RawPosixAIOData on the stack.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
aio_worker() doesn't add anything interesting, it's only a useless
indirection. Call the handler function directly instead.
As we know that this handler function is only called from coroutine
context and the coroutine stays around until the worker thread finishes,
we can keep RawPosixAIOData on the stack.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Getting the thread pool of the AioContext of a block node and scheduling
some work in it is an operation that is already done twice, and we'll
get more instances. Factor it out into a separate function.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
RawPosixAIOData contains a lot of fields for several separate operations
that are to be processed in a worker thread and that need different
parameters. The struct is currently rather unorganised, with unions that
cover some, but not all operations, and even one #define for field names
instead of a union.
Clean this up to have some common fields and a single union. As a side
effect, on x86_64 the struct shrinks from 72 to 48 bytes.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
s->locked_shared_perm is the set of bits locked in the file, which is
the inverse of the permissions actually shared. So we need to pass them
as they are to raw_apply_lock_bytes() instead of inverting them again.
Reported-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The lock_fd field is not strictly necessary because transferring locked
bytes from old fd to the new one shouldn't fail anyway. This spares the
user one fd per image.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
If we know we've already locked the bytes, don't do it again; similarly
don't unlock a byte if we haven't locked it. This doesn't change the
behavior, but fixes a corner case explained below.
Libvirt had an error handling bug that an image can get its (ownership,
file mode, SELinux) permissions changed (RHBZ 1584982) by mistake behind
QEMU. Specifically, an image in use by Libvirt VM has:
$ ls -lhZ b.img
-rw-r--r--. qemu qemu system_u:object_r:svirt_image_t:s0:c600,c690 b.img
Trying to attach it a second time won't work because of image locking.
And after the error, it becomes:
$ ls -lhZ b.img
-rw-r--r--. root root system_u:object_r:virt_image_t:s0 b.img
Then, we won't be able to do OFD lock operations with the existing fd.
In other words, the code such as in blk_detach_dev:
blk_set_perm(blk, 0, BLK_PERM_ALL, &error_abort);
can abort() QEMU, out of environmental changes.
This patch is an easy fix to this and the change is regardlessly
reasonable, so do it.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Use error_report for situations that affect user operation (i.e. we're
actually returning error), and warn_report/warn_report_err when some
less critical error happened but the user operation can still carry on.
For raw_normalize_devicepath, add Error parameter to propagate to
its callers.
Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
If read-only=off, but auto-read-only=on is given, open the file
read-write if we have the permissions, but instead of erroring out for
read-only files, just degrade to read-only.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
The file-posix code is used for the "file", "host_device" and
"host_cdrom" drivers, and it allows reopening images. However the only
option that is actually processed is "x-check-cache-dropped", and
changes in all other options (e.g. "filename") are silently ignored:
(qemu) qemu-io virtio0 "reopen -o file.filename=no-such-file"
While we could allow changing some of the other options, let's keep
things as they are for now but return an error if the user tries to
change any of them.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The default value of x-check-cache-dropped is false. There's no reason
to use the previous value as a default in raw_reopen_prepare() because
bdrv_reopen_queue_child() already takes care of putting the old
options in the BDRVReopenState.options QDict.
If x-check-cache-dropped was previously set but is now missing from
the reopen QDict then it should be reset to false.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Image locking errors happening at device initialization time doesn't say
which file cannot be locked, for instance,
-device scsi-disk,drive=drive-1: Failed to get shared "write" lock
Is another process using the image?
could refer to either the overlay image or its backing image.
Hoist the error_append_hint to the caller of raw_check_lock_bytes where
file name is known, and include it in the error hint.
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The BLKDISCARD ioctl doesn't guarantee that the discarded blocks read as
all-zero afterwards, so don't try to abuse it for zero writing. We try
to only use this if BLKDISCARDZEROES tells us that it is safe, but this
is unreliable on older kernels and a constant 0 in newer kernels. In
other words, this code path is never actually used with newer kernels,
so we don't even try to unmap while writing zeros.
This patch removes the abuse of discard for writing zeroes from
file-posix and instead adds a new function that uses interfaces that are
actually meant to deallocate and zero out at the same time. Only if
those fail, it falls back to zeroing out without unmap. We never fall
back to a discard operation any more that may or may not result in
zeros.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
In ed6e2161 ("linux-aio: properly bubble up errors from initialzation"),
I only added a bdrv_attach_aio_context callback for the bdrv_file
driver. There are several other drivers that use the shared
aio_plug callback, though, and they will trip the assertion added to
aio_get_linux_aio because they did not call aio_setup_linux_aio first.
Add the appropriate callback definition to the affected driver
definitions.
Fixes: ed6e2161 ("linux-aio: properly bubble up errors from initialization")
Reported-by: Farhan Ali <alifm@linux.ibm.com>
Signed-off-by: Nishanth Aravamudan <naravamudan@digitalocean.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20180718211256.29774-1-naravamudan@digitalocean.com
Cc: Eric Blake <eblake@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: John Snow <jsnow@redhat.com>
Cc: Max Reitz <mreitz@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Fam Zheng <famz@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-block@nongnu.org
Cc: qemu-devel@nongnu.org
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Adjust each caller of raw_open_common to specify if they are expecting
host and character devices or not. Tighten expectations of file types upon
open in the common code and refuse types that are not expected.
This has two effects:
(1) Character and block devices are now considered deprecated for the
'file' driver, which expects only S_IFREG, and
(2) no file-posix driver (file, host_cdrom, or host_device) can open
directories now.
I don't think there's a legitimate reason to open directories as if
they were files. This prevents QEMU from opening and attempting to probe
a directory inode, which can break in exciting ways. One of those ways
is lseek on ext4/xfs, which will return 0x7fffffffffffffff as the file
size instead of EISDIR. This can coax QEMU into responding with a
confusing "file too big" instead of "Hey, that's not a file".
See: https://bugs.launchpad.net/qemu/+bug/1739304/
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
A few trace points that can help reveal what is happening in a copy
offloading I/O path.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
With in one module, trace points usually have a common prefix named
after the module name. paio_submit and paio_submit_co are the only two
trace points so far in the two file protocol drivers. As we are adding
more, having a common prefix here is better so that trace points can be
enabled with a glob. Rename them.
Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Pass read flags and write flags separately. This is needed to handle
coming BDRV_REQ_NO_SERIALISING clearly in following patches.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
One of them is a typo. But update both to be more readable.
Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 20180702025836.20957-3-famz@redhat.com
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Closing the FD does not necessarily mean that it is unlocked. Fix this
by relinquishing all permission locks before qemu_close().
Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
raw_apply_lock_bytes() takes a bit mask of "permissions that are NOT
shared".
Also, make the "perm" and "shared" variables uint64_t, because I do not
particularly like using ~ on signed integers (and other permission masks
are usually uint64_t, too).
Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
EINTR should be checked against errno, not ret. While fixing the bug,
collect the branches with a switch block.
Also, change the return value from -ENOSTUP to -ENOSPC when the actual
issue is request range passes EOF, which should be distinguishable from
the case of error == ENOSYS by the caller, so that it could still retry
with other byte ranges, whereas it shouldn't retry anymore upon ENOSYS.
Signed-off-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This simplifies file-posix by implementing the coroutine variants of
the discard and flush BlockDriver callbacks. These were the last
remaining users of paio_submit(), which can be removed now.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
This moves the code to resize an image file to the thread pool to avoid
blocking.
Creating large images with preallocation with blockdev-create is now
actually a background job instead of blocking the monitor (and most
other things) until the preallocation has completed.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
bdrv_truncate() is an operation that can block (even for a quite long
time, depending on the PreallocMode) in I/O paths that shouldn't block.
Convert it to a coroutine_fn so that we have the infrastructure for
drivers to make their .bdrv_co_truncate implementation asynchronous.
This change could potentially introduce new race conditions because
bdrv_truncate() isn't necessarily executed atomically any more. Whether
this is a problem needs to be evaluated for each block driver that
supports truncate:
* file-posix/win32, gluster, iscsi, nfs, rbd, ssh, sheepdog: The
protocol drivers are trivially safe because they don't actually yield
yet, so there is no change in behaviour.
* copy-on-read, crypto, raw-format: Essentially just filter drivers that
pass the request to a child node, no problem.
* qcow2: The implementation modifies metadata, so it needs to hold
s->lock to be safe with concurrent I/O requests. In order to avoid
double locking, this requires pulling the locking out into
preallocate_co() and using qcow2_write_caches() instead of
bdrv_flush().
* qed: Does a single header update, this is fine without locking.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
laio_init() can fail for a couple of reasons, which will lead to a NULL
pointer dereference in laio_attach_aio_context().
To solve this, add a aio_setup_linux_aio() function which is called
early in raw_open_common. If this fails, propagate the error up. The
signature of aio_get_linux_aio() was not modified, because it seems
preferable to return the actual errno from the possible failing
initialization calls.
Additionally, when the AioContext changes, we need to associate a
LinuxAioState with the new AioContext. Use the bdrv_attach_aio_context
callback and call the new aio_setup_linux_aio(), which will allocate a
new AioContext if needed, and return errors on failures. If it fails for
any reason, fallback to threaded AIO with an error message, as the
device is already in-use by the guest.
Add an assert that aio_get_linux_aio() cannot return NULL.
Signed-off-by: Nishanth Aravamudan <naravamudan@digitalocean.com>
Message-id: 20180622193700.6523-1-naravamudan@digitalocean.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
When creating a file, we should take the WRITE and RESIZE permissions.
We do not need either for the creation itself, but we do need them for
clearing and resizing it. So we can take the proper permissions by
replacing O_TRUNC with an explicit truncation to 0, and by taking the
appropriate file locks between those two steps.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20180509215336.31304-3-mreitz@redhat.com
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
raw_apply_lock_bytes() and raw_check_lock_bytes() currently take a
BDRVRawState *, but they only use the lock_fd field. During image
creation, we do not have a BDRVRawState, but we do have an FD; so if we
want to reuse the functions there, we should modify them to receive only
the FD.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 20180509215336.31304-2-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
With copy_file_range(2), we can implement the bdrv_co_copy_range
semantics.
Signed-off-by: Fam Zheng <famz@redhat.com>
Message-id: 20180601092648.24614-6-famz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
