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2023-02-01block: Convert bdrv_get_info() to co_wrapper_mixedEmanuele Giuseppe Esposito
bdrv_get_info() is categorized as an I/O function, and it currently doesn't run in a coroutine. We should let it take a graph rdlock since it traverses the block nodes graph, which however is only possible in a coroutine. Therefore turn it into a co_wrapper to move the actual function into a coroutine where the lock can be taken. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20230113204212.359076-11-kwolf@redhat.com> Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-02-01block: Convert bdrv_refresh_total_sectors() to co_wrapper_mixedEmanuele Giuseppe Esposito
BlockDriver->bdrv_getlength is categorized as IO callback, and it currently doesn't run in a coroutine. We should let it take a graph rdlock since the callback traverses the block nodes graph, which however is only possible in a coroutine. Therefore turn it into a co_wrapper to move the actual function into a coroutine where the lock can be taken. Because now this function creates a new coroutine and polls, we need to take the AioContext lock where it is missing, for the only reason that internally co_wrapper calls AIO_WAIT_WHILE and it expects to release the AioContext lock. This is especially messy when a co_wrapper creates a coroutine and polls in bdrv_open_driver, because this function has so many callers in so many context that it can easily lead to deadlocks. Therefore the new rule for bdrv_open_driver is that the caller must always hold the AioContext lock of the given bs (except if it is a coroutine), because the function calls bdrv_refresh_total_sectors() which is now a co_wrapper. Once the rwlock is ultimated and placed in every place it needs to be, we will poll using AIO_WAIT_WHILE_UNLOCKED and remove the AioContext lock. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20230113204212.359076-7-kwolf@redhat.com> Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-02-01block: Convert bdrv_io_unplug() to co_wrapperEmanuele Giuseppe Esposito
BlockDriver->bdrv_io_unplug is categorized as IO callback, and it currently doesn't run in a coroutine. We should let it take a graph rdlock since the callback traverses the block nodes graph, which however is only possible in a coroutine. The only caller of this function is blk_io_unplug(), therefore make blk_io_unplug() a co_wrapper, so that we're always running in a coroutine where the lock can be taken. Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-Id: <20230113204212.359076-4-kwolf@redhat.com> Reviewed-by: Emanuele Giuseppe Esposito <eesposit@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2023-01-23block/blkio: Fix inclusion of required headersPeter Krempa
After recent header file inclusion rework the build fails when the blkio module is enabled: ../block/blkio.c: In function ‘blkio_detach_aio_context’: ../block/blkio.c:321:24: error: implicit declaration of function ‘bdrv_get_aio_context’; did you mean ‘qemu_get_aio_context’? [-Werror=implicit-function-declaration] 321 | aio_set_fd_handler(bdrv_get_aio_context(bs), | ^~~~~~~~~~~~~~~~~~~~ | qemu_get_aio_context ../block/blkio.c:321:24: error: nested extern declaration of ‘bdrv_get_aio_context’ [-Werror=nested-externs] ../block/blkio.c:321:24: error: passing argument 1 of ‘aio_set_fd_handler’ makes pointer from integer without a cast [-Werror=int-conversion] 321 | aio_set_fd_handler(bdrv_get_aio_context(bs), | ^~~~~~~~~~~~~~~~~~~~~~~~ | | | int In file included from /home/pipo/git/qemu.git/include/qemu/job.h:33, from /home/pipo/git/qemu.git/include/block/blockjob.h:30, from /home/pipo/git/qemu.git/include/block/block_int-global-state.h:28, from /home/pipo/git/qemu.git/include/block/block_int.h:27, from ../block/blkio.c:13: /home/pipo/git/qemu.git/include/block/aio.h:476:37: note: expected ‘AioContext *’ but argument is of type ‘int’ 476 | void aio_set_fd_handler(AioContext *ctx, | ~~~~~~~~~~~~^~~ ../block/blkio.c: In function ‘blkio_file_open’: ../block/blkio.c:821:34: error: passing argument 2 of ‘blkio_attach_aio_context’ makes pointer from integer without a cast [-Werror=int-conversion] 821 | blkio_attach_aio_context(bs, bdrv_get_aio_context(bs)); | ^~~~~~~~~~~~~~~~~~~~~~~~ | | | int Fix it by including 'block/block-io.h' which contains the required declarations. Fixes: e2c1c34f139f49ef909bb4322607fb8b39002312 Signed-off-by: Peter Krempa <pkrempa@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Message-id: 2bc956011404a1ab03342aefde0087b5b4762562.1674477350.git.pkrempa@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-11-10block/blkio: Set BlockDriver::has_variable_length to falseAlberto Faria
Setting it to true can cause the device size to be queried from libblkio in otherwise fast paths, degrading performance. Set it to false and require users to refresh the device size explicitly instead. Fixes: 4c8f4fda0504 ("block/blkio: Tolerate device size changes") Suggested-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Alberto Faria <afaria@redhat.com> Message-Id: <20221108144433.1334074-1-afaria@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2022-10-31block/blkio: Make driver nvme-io_uring take a "path" instead of a "filename"Alberto Faria
The nvme-io_uring driver expects a character special file such as /dev/ng0n1. Follow the convention of having a "filename" option when a regular file is expected, and a "path" option otherwise. This makes io_uring the only libblkio-based driver with a "filename" option, as it accepts a regular file (even though it can also take a block special file). Signed-off-by: Alberto Faria <afaria@redhat.com> Message-id: 20221028233854.839933-1-afaria@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-10-31block/blkio: Tolerate device size changesAlberto Faria
Some libblkio drivers may be able to work with regular files (e.g., io_uring) or otherwise resizable devices. Conservatively set BlockDriver::has_variable_length to true to ensure bdrv_nb_sectors() always gives up-to-date results. Also implement BlockDriver::bdrv_co_truncate for the case where no preallocation is needed and the device already has a size compatible with what was requested. Signed-off-by: Alberto Faria <afaria@redhat.com> Message-id: 20221029122031.975273-1-afaria@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-10-31block/blkio: Add virtio-blk-vfio-pci BlockDriverAlberto Faria
libblkio 1.1.0 [1] introduces a virtio-blk-vfio-pci driver, which accesses a virtio-blk PCI device using VFIO. Add a corresponding BlockDriver. [1] https://gitlab.com/libblkio/libblkio/-/tree/v1.1.0 Signed-off-by: Alberto Faria <afaria@redhat.com> Message-id: 20221028131635.710267-1-afaria@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-10-26blkio: implement BDRV_REQ_REGISTERED_BUF optimizationStefan Hajnoczi
Avoid bounce buffers when QEMUIOVector elements are within previously registered bdrv_register_buf() buffers. The idea is that emulated storage controllers will register guest RAM using bdrv_register_buf() and set the BDRV_REQ_REGISTERED_BUF on I/O requests. Therefore no blkio_map_mem_region() calls are necessary in the performance-critical I/O code path. This optimization doesn't apply if the I/O buffer is internally allocated by QEMU (e.g. qcow2 metadata). There we still take the slow path because BDRV_REQ_REGISTERED_BUF is not set. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Message-id: 20221013185908.1297568-13-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2022-10-26blkio: add libblkio block driverStefan Hajnoczi
libblkio (https://gitlab.com/libblkio/libblkio/) is a library for high-performance disk I/O. It currently supports io_uring, virtio-blk-vhost-user, and virtio-blk-vhost-vdpa with additional drivers under development. One of the reasons for developing libblkio is that other applications besides QEMU can use it. This will be particularly useful for virtio-blk-vhost-user which applications may wish to use for connecting to qemu-storage-daemon. libblkio also gives us an opportunity to develop in Rust behind a C API that is easy to consume from QEMU. This commit adds io_uring, nvme-io_uring, virtio-blk-vhost-user, and virtio-blk-vhost-vdpa BlockDrivers to QEMU using libblkio. It will be easy to add other libblkio drivers since they will share the majority of code. For now I/O buffers are copied through bounce buffers if the libblkio driver requires it. Later commits add an optimization for pre-registering guest RAM to avoid bounce buffers. The syntax is: --blockdev io_uring,node-name=drive0,filename=test.img,readonly=on|off,cache.direct=on|off --blockdev nvme-io_uring,node-name=drive0,filename=/dev/ng0n1,readonly=on|off,cache.direct=on --blockdev virtio-blk-vhost-vdpa,node-name=drive0,path=/dev/vdpa...,readonly=on|off,cache.direct=on --blockdev virtio-blk-vhost-user,node-name=drive0,path=vhost-user-blk.sock,readonly=on|off,cache.direct=on Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Acked-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Message-id: 20221013185908.1297568-3-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>