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2014-02-20Merge remote-tracking branch 'remotes/qmp-unstable/queue/qmp' into stagingPeter Maydell
* remotes/qmp-unstable/queue/qmp: monitor: Add object_add class argument completion. monitor: Add object_del id argument completion. monitor: Add device_add device argument completion. monitor: Add device_del id argument completion. qmp: expose list of supported character device backends Use error_is_set() only when necessary QMP: allow JSON dict arguments in qmp-shell hmp: migrate command (without -d) now blocks correctly Conflicts: blockdev.c [PMM: resolved trivial conflict in blockdev.c] Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-02-17Use error_is_set() only when necessaryMarkus Armbruster
error_is_set(&var) is the same as var != NULL, but it takes whole-program analysis to figure that out. Unnecessarily hard for optimizers, static checkers, and human readers. Dumb it down to obvious. Gets rid of several dozen Coverity false positives. Note that the obvious form is already used in many places. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Andreas Färber <afaerber@suse.de> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-02-14block: mirror - use local_err to avoid NULL errpJeff Cody
When starting a block job, commit_active_start() relies on whether *errp is set by mirror_start_job. This allows it to determine if the mirror job start failed, so that it can clean up any changes to open flags from the bdrv_reopen(). If errp is NULL, then it will not be able to determine if mirror_start_job failed or not. To avoid this, use a local Error variable, and then propagate the error (if any) to errp. Reported-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-02-14block: Don't throw away errno via error_setgJeff Cody
There are a handful of places in the block layer where a failure path has a valid -errno value, yet error_setg() is used. Those instances should instead use error_setg_errno(), to preserve as much error information as possible. This patch replaces those instances with error_setg_errno(), so that errno is passed up the stack in the error message. Reported-By: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-02-14block: Add notes to iSCSI's .bdrv_open and .bdrv_reopen_prepareJeff Cody
iSCSI currently does not need to do any actions to support the current usage of bdrv_reopen(). However, it is important to note a couple of things: 1.) A connection will not be re-established to an iSCSI target, and 2.) If iscsi_open() is changed to parse 'flags', then iscsi_reopen_prepare() may need to be more than a stub. In light of the above, this commit adds comments above both of the functions to bring attention to these facts. Signed-off-by: Jeff Cody <jcody@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-02-09blkdebug: Don't leak bs->file on failureKevin Wolf
Reported-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
2014-02-09raw: Fix BlockLimits passthroughKevin Wolf
raw copies over the BlockLimits of bs->file during bdrv_open(). However, since commit d34682cd it is immediately overwritten during bdrv_refresh_limits(). This caused all fields except for opt_transfer_length and opt_mem_alignment (which happen to be correctly inherited in generic code) to be zeroed. Move the BlockLimit assignment to a .bdrv_refresh_limits() callback to make it work again for all fields. Reported-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com>
2014-02-09qcow2: check for NULL l2metaHu Tao
In the case of a metadata preallocation with a large cluster size, qcow2_alloc_cluster_offset() can allocate nothing and returns a NULL l2meta. This patch checks for it and link2 l2 with only valid l2meta. Replace 9 and 512 with BDRV_SECTOR_BITS, BDRV_SECTOR_SIZE respectively while at the function. Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-09qcow2: fix offset overflow in qcow2_alloc_clusters_at()Hu Tao
When cluster size is big enough it can lead to an offset overflow in qcow2_alloc_clusters_at(). This patch fixes it. The allocation is stopped each time at L2 table boundary (see handle_alloc()), so the possible maximum bytes could be 2^(cluster_bits - 3 + cluster_bits) cluster_bits - 3 is used to compute the number of entry by L2 and the additional cluster_bits is to take into account each clusters referenced by the L2 entries. so int is safe for cluster_bits<=17, unsafe otherwise. Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-09qcow2: remove n_start and n_end of qcow2_alloc_cluster_offset()Hu Tao
n_start can be actually calculated from offset. The number of sectors to be allocated(n_end - n_start) can be passed in in num. By removing n_start and n_end, we can save two parameters. The side effect is there is a bug in qcow2.c:preallocate() that passes incorrect n_start to qcow2_alloc_cluster_offset() is fixed. The bug can be triggerred by a larger cluster size than the default value(65536), for example: ./qemu-img create -f qcow2 \ -o 'cluster_size=131072,preallocation=metadata' file.img 4G Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-09block/iscsi: always fill bs->bl.opt_transfer_lengthPeter Lieven
the opt_transfer_length has nothing to do with logical block provisioning stuff so always copy it from the block limits VPD page. Reported-By: Benoit Canet <benoit@irqsave.net> Signed-off-by: Peter Lieven <pl@kamp.de> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-02-09block: add native support for NFSPeter Lieven
This patch adds native support for accessing images on NFS shares without the requirement to actually mount the entire NFS share on the host. NFS Images can simply be specified by an url of the form: nfs://<host>/<export>/<filename>[?param=value[&param2=value2[&...]]] For example: qemu-img create -f qcow2 nfs://10.0.0.1/qemu-images/test.qcow2 You need LibNFS from Ronnie Sahlberg available at: git://github.com/sahlberg/libnfs.git for this to work. During configure it is automatically probed for libnfs and support is enabled on-the-fly. You can forbid or enforce libnfs support with --disable-libnfs or --enable-libnfs respectively. Due to NFS restrictions you might need to execute your binaries as root, allow them to open priviledged ports (<1024) or specify insecure option on the NFS server. For additional information on ROOT vs. non-ROOT operation and URL format + parameters see: https://raw.github.com/sahlberg/libnfs/master/README Supported by qemu are the uid, gid and tcp-syncnt URL parameters. LibNFS currently support NFS version 3 only. Signed-off-by: Peter Lieven <pl@kamp.de> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-31block/vhdx: Error checking fixesMarkus Armbruster
Errors are inadvertently ignored in a few places. Has always been broken. Spotted by Coverity. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Jeff Cody <jcody@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-01-31block/vmdk: add basic .bdrv_check supportPeter Lieven
this adds a basic vmdk corruption check. it should detect severe table corruptions and file truncation. Signed-off-by: Peter Lieven <pl@kamp.de> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-01-31block: remove qcow2 .bdrv_make_empty implementationJeff Cody
The QCOW2 .bdrv_make_empty implementation always returns 0 for success, but does not actually do anything. The proper way to not support an optional driver function stub is to just not implement it, so let's remove the stub. Signed-off-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-01-31block: remove QED .bdrv_make_empty implementationJeff Cody
The QED .bdrv_make_empty() implementation does nothing but return -ENOTSUP, which causes problems in bdrv_commit(). Since the function stub exists for QED, it is called, which then always returns an error. The proper way to not support an optional driver function stub is to just not implement it, so let's remove the stub. Signed-off-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-01-24Merge remote-tracking branch 'bonzini/scsi-next' into stagingAnthony Liguori
* bonzini/scsi-next: scsi: Support TEST UNIT READY in the dummy LUN0 block: add .bdrv_reopen_prepare() stub for iscsi virtio-scsi: Prevent assertion on missed events virtio-scsi: Cleanup of I/Os that never started scsi: Assign cancel_io vector for scsi_disk_emulate_ops Conflicts: block/iscsi.c aliguori: resolve trivial merge conflict in block/iscsi.c Signed-off-by: Anthony Liguori <aliguori@amazon.com>
2014-01-24qemu-iotests: Test pwritev RMW logicKevin Wolf
Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2014-01-24blkdebug: Make required alignment configurableKevin Wolf
The new 'align' option of blkdebug can be used in order to emulate backends with a required 4k alignment on hosts which only really require 512 byte alignment. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24iscsi: Set bs->request_alignmentPaolo Bonzini
The iSCSI backend already gets the block size from the READ CAPACITY command it sends. Save it so that the generic block layer gets it too. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2014-01-24block: Switch BdrvTrackedRequest to byte granularityKevin Wolf
Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net>
2014-01-24raw: Probe required direct I/O alignmentPaolo Bonzini
Add a bs->request_alignment field that contains the required offset/length alignment for I/O requests and fill it in the raw block drivers. Use ioctls if possible, else see what alignment it takes for O_DIRECT to succeed. While at it, also expose the memory alignment requirements, which may be (and in practice are) different from the disk alignment requirements. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com>
2014-01-24block: Update BlockLimits when they might have changedKevin Wolf
When reopening with different flags, or when backing files disappear from the chain, the limits may change. Make sure they get updated in these cases. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Wenchao Xia <xiawenc@linux.vnet.ibm.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoît Canet <benoit@irqsave.net>
2014-01-24block: Move initialisation of BlockLimits to bdrv_refresh_limits()Kevin Wolf
This function separates filling the BlockLimits from bdrv_open(), which allows it to call it from other operations which may change the limits (e.g. modifications to the backing file chain or bdrv_reopen) Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net>
2014-01-24block: resize backing image during active layer commit, if neededJeff Cody
If the top image to commit is the active layer, and also larger than the base image, then an I/O error will likely be returned during block-commit. For instance, if we have a base image with a virtual size 10G, and a active layer image of size 20G, then committing the snapshot via 'block-commit' will likely fail. This will automatically attempt to resize the base image, if the active layer image to be committed is larger. Signed-off-by: Jeff Cody <jcody@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24block/curl: Implement the libcurl timer callback interfacePeter Maydell
libcurl versions 7.16.0 and later have a timer callback interface which must be implemented in order for libcurl to make forward progress (it will sometimes rely on being called back on the timeout if there are no file descriptors registered). Implement the callback, and use a QEMU AIO timer to ensure we prod libcurl again when it asks us to. Based on Peter's original patch plus my fix to add curl_multi_timeout_do. Should compile just fine even on older versions of libcurl. I also tried copy-on-read and streaming: $ ./qemu-img create -f qcow2 -o \ backing_file=http://download.fedoraproject.org/pub/fedora/linux/releases/20/Live/x86_64/Fedora-Live-Desktop-x86_64-20-1.iso \ foo.qcow2 1G $ x86_64-softmmu/qemu-system-x86_64 \ -drive if=none,file=foo.qcow2,copy-on-read=on,id=cd \ -device ide-cd,drive=cd --enable-kvm -m 1024 Direct http usage is probably too slow, but with copy-on-read ultimately the image does boot! After some time, streaming gets canceled by an EIO, which needs further investigation. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24block: Create authorizations mechanism for external snapshot and resize.Benoît Canet
Signed-off-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24qmp: Add QMP query-named-block-nodes to list the named BlockDriverState nodes.Benoît Canet
Signed-off-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24qapi: Add "backing" to BlockStatsFam Zheng
Currently there is no way to query BlockStats of the backing chain. This adds "backing" field into BlockStats to make it possible. The comment of "parent" is reworded. Signed-off-by: Fam Zheng <famz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24vmdk: Fix format specific information (create type) for streamOptimizedFam Zheng
Previously the field is wrong: $ ./qemu-img create -f vmdk -o subformat=streamOptimized /tmp/a.vmdk 1G $ ./qemu-img info /tmp/a.vmdk image: /tmp/a.vmdk file format: vmdk virtual size: 1.0G (1073741824 bytes) disk size: 12K Format specific information: cid: 1390460459 parent cid: 4294967295 >>> create type: monolithicSparse <snip> Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24drive mirror:fix memory leakZhang Min
In the function mirror_iteration() -> qemu_iovec_init(), it allocates memory for op->qiov.iov, when the write request calls back, but in the function mirror_iteration_done(), it only frees the op, not free the op->qiov.iov, so this causes memory leak. It should use qemu_iovec_destroy() to free op->qiov. Signed-off-by: Zhang Min <rudy.zhangmin@huawei.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24sheepdog: fix 'qemu-img map'Liu Yuan
It was muted in the previous commit 4bc74be9. Let's revive it since nothing prevents us to do it. With this patch, following command will work as other formats: $ qemu-img map sheepdog:image Cc: qemu-devel@nongnu.org Cc: Kevin Wolf <kwolf@redhat.com> Cc: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Liu Yuan <namei.unix@gmail.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24vmdk: Check for overhead when openingFam Zheng
Report an error if file size is even smaller than metadata. Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-24qcow2: fix wrong value of L1E_OFFSET_MASK, L2E_OFFSET_MASK and REFT_OFFSET_MASKHu Tao
Accoring to qcow spec, the offset fields in l1e, l2e and ref table entry start at bit 9. The offset is cluster offset, and the smallest possible cluster size is 512 bytes. Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22blkverify: Don't require protocol filenameMax Reitz
If the filename is not prefixed by "blkverify:" in blkverify_parse_filename(), the blkverify driver was not selected through that protocol prefix, but by an explicit command line (or QMP) option (like driver=blkverify). If blkverify_parse_filename() has been called, a filename has been given. If it is not prefixed, it is probably really just a plain filename. This is no problem, since we can use it as the test image filename and rely on the user to specify the raw image filename through the new corresponding option. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22blkverify: Allow command-line configurationMax Reitz
Introduce the "test" and "raw" options for specifying images. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22blkdebug: Allow command-line file configurationMax Reitz
Introduce the "image" option as an alternative to specifying the image through the filename. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22block: Allow reference for bdrv_file_open()Max Reitz
Allow specifying a reference to an existing block device (by name) for bdrv_file_open() instead of a filename and/or options. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22blkdebug: Use command-line in read_config()Max Reitz
Use qemu_config_parse_qdict() to parse the command-line options in addition to the config file. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22blkdebug: Always call read_config()Max Reitz
Move the check whether there actually is a config file into the read_config() function. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22blkdebug: Don't require sophisticated filenameMax Reitz
If the filename is not prefixed by "blkdebug:" in blkdebug_parse_filename(), the blkdebug driver was not selected through that protocol prefix, but by an explicit command line option (file.driver=blkdebug or something similar). Contrary to the current reaction, this is not a problem at all; we just need to store the filename (in the x-image option) and can go on; the user just has to manually specify the config option. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22blkdebug: Use errp for read_config()Max Reitz
Use an Error variable in the read_config() function. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22vmdk: Fix big flat extent IOFam Zheng
Local variable "n" as int64_t avoids overflow with large sector number calculation. See test case change for failure case. Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22sheepdog: fix clone operation by 'qemu-img create -b'Liu Yuan
We should pass base_inode->vdi_id to base_vdi_id of SheepdogVdiReq so that sheep can create a clone instead a fresh volume. This fixes following command: qemu-create -b sheepdog:base sheepdog:clone so users can boot sheepdog:clone as a normal volume. Cc: qemu-devel@nongnu.org Cc: Kevin Wolf <kwolf@redhat.com> Cc: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Liu Yuan <namei.unix@gmail.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22gluster: Add support for creating zero-filled imageBharata B Rao
GlusterFS supports creation of zero-filled file on GlusterFS volume by means of an API called glfs_zerofill(). Use this API from QEMU to create an image that is filled with zeroes by using the preallocation option of qemu-img. qemu-img create gluster://server/volume/image -o preallocation=full 10G The allowed values for preallocation are 'full' and 'off'. By default preallocation is off and image is not zero-filled. glfs_zerofill() offloads the writing of zeroes to the server and if the storage supports SCSI WRITESAME, GlusterFS server can issue BLKZEROOUT ioctl to achieve the zeroing. Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22gluster: Implement .bdrv_co_write_zeroes for glusterBharata B Rao
Support .bdrv_co_write_zeroes() from gluster driver by using GlusterFS API glfs_zerofill() that off-loads the writing of zeroes to GlusterFS server. Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22gluster: Convert aio routines into coroutinesBharata B Rao
Convert the read, write, flush and discard implementations from aio-based ones to coroutine based ones. Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22block/iscsi: return -ENOMEM if an async call fails immediatelyPeter Lieven
if an async libiscsi call fails directly it can only be due to an out of memory condition. All other errors are returned through the callback. Signed-off-by: Peter Lieven <pl@kamp.de> Reviewed-by: Ronnie Sahlberg <ronniesahlberg@gmail.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-22rbd: switch from pipe to QEMUBH completion notificationStefan Hajnoczi
rbd callbacks are called from non-QEMU threads. Up until now a pipe was used to signal completion back to the QEMU iothread. The pipe writer code handles EAGAIN using select(2). The select(2) API is not scalable since fd_set size is static. FD_SET() can write beyond the end of fd_set if the file descriptor number is too high. (QEMU's main loop uses poll(2) to avoid this issue with select(2).) Since the pipe itself is quite clumsy to use and QEMUBH is now thread-safe, just schedule a BH from the rbd callback function. This way we can simplify I/O completion in addition to eliminating the potential FD_SET() crash when file descriptor numbers become too high. Crash scenario: QEMU already has 1024 file descriptors open. Hotplug an rbd drive and get the pipe writer to take the select(2) code path. Reviewed-by: Josh Durgin <josh.durgin@inktank.com> Tested-by: Josh Durgin <josh.durgin@inktank.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-01-15block: add .bdrv_reopen_prepare() stub for iscsiJeff Cody
To suppport reopen(), the .bdrv_reopen_prepare() stub must exist. iSCSI does not have anything that needs to be done to support reopen, so we can just implement the _prepare() stub. Signed-off-by: Jeff Cody <jcody@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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