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qemu-e2k/block
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Stefan Hajnoczi e8b6535533 block: add BDRV_REQ_REGISTERED_BUF request flag 
Block drivers may optimize I/O requests accessing buffers previously
registered with bdrv_register_buf(). Checking whether all elements of a
request's QEMUIOVector are within previously registered buffers is
expensive, so we need a hint from the user to avoid costly checks.

Add a BDRV_REQ_REGISTERED_BUF request flag to indicate that all
QEMUIOVector elements in an I/O request are known to be within
previously registered buffers.

Always pass the flag through to driver read/write functions. There is
little harm in passing the flag to a driver that does not use it.
Passing the flag to drivers avoids changes across many block drivers.
Filter drivers would need to explicitly support the flag and pass
through to their children when the children support it. That's a lot of
code changes and it's hard to remember to do that everywhere, leading to
silent reduced performance when the flag is accidentally dropped.

The only problematic scenario with the approach in this patch is when a
driver passes the flag through to internal I/O requests that don't use
the same I/O buffer. In that case the hint may be set when it should
actually be clear. This is a rare case though so the risk is low.

Some drivers have assert(!flags), which no longer works when
BDRV_REQ_REGISTERED_BUF is passed in. These assertions aren't very
useful anyway since the functions are called almost exclusively by
bdrv_driver_preadv/pwritev() so if we get flags handling right there
then the assertion is not needed.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20221013185908.1297568-7-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
 		2022-10-26 14:56:42 -04:00
..
export block: Change blk_{pread,pwrite}() param order 2022-07-12 12:14:56 +02:00
monitor monitor: expose monitor_puts to rest of code 2022-10-06 11:53:40 +01:00
accounting.c block: add missed block_acct_setup with new block device init procedure 2022-09-30 18:42:34 +02:00
aio_task.c block/aio_task: assert `max_busy_tasks` is greater than 0 2021-10-05 18:56:41 +02:00
amend.c block/amend: Keep strong reference to BDS 2022-03-04 18:18:26 +01:00
backup.c block: simplify handling of try to merge different sized bitmaps 2022-06-24 17:07:06 +02:00
blkdebug.c block: use int64_t instead of int in driver discard handlers 2021-09-29 13:46:32 -05:00
blkio.c blkio: add libblkio block driver 2022-10-26 14:56:42 -04:00
blklogwrites.c block: Change bdrv_{pread,pwrite,pwrite_sync}() param order 2022-07-12 12:14:55 +02:00
blkreplay.c block: use int64_t instead of int in driver discard handlers 2021-09-29 13:46:32 -05:00
blkverify.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
block-backend.c block: pass size to bdrv_unregister_buf() 2022-10-26 14:56:42 -04:00
block-copy.c block/block-copy: block_copy(): add timeout_ns parameter 2022-06-29 10:56:12 +03:00
block-gen.h scripts: add block-coroutine-wrapper.py 2020-10-05 10:59:06 +01:00
bochs.c block: Change bdrv_{pread,pwrite,pwrite_sync}() param order 2022-07-12 12:14:55 +02:00
cloop.c block: Make bdrv_{pread,pwrite}() return 0 on success 2022-07-12 12:14:55 +02:00
commit.c block: Change blk_{pread,pwrite}() param order 2022-07-12 12:14:56 +02:00
copy-before-write.c copy-before-write: add missing coroutine_fn annotations 2022-10-07 12:11:41 +02:00
copy-before-write.h block/copy-before-write.h: global state API + assertions 2022-03-04 18:18:25 +01:00
copy-on-read.c block: use int64_t instead of int in driver discard handlers 2021-09-29 13:46:32 -05:00
copy-on-read.h Clean up ill-advised or unusual header guards 2022-05-11 16:50:01 +02:00
coroutines.h block: Remove remaining unused symbols in coroutines.h 2022-07-12 12:14:56 +02:00
create.c block_int-common.h: assertions in the callers of BlockDriver function pointers 2022-03-04 18:18:25 +01:00
crypto.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
crypto.h nomaintainer: Fix Lesser GPL version number 2020-11-15 17:04:40 +01:00
curl.c curl: add missing coroutine_fn annotations 2022-10-07 12:11:41 +02:00
dirty-bitmap.c block: simplify handling of try to merge different sized bitmaps 2022-06-24 17:07:06 +02:00
dmg-bz2.c
…
dmg-lzfse.c block: Remove unused include 2020-11-09 15:44:21 +01:00
dmg.c block: Make bdrv_{pread,pwrite}() return 0 on success 2022-07-12 12:14:55 +02:00
dmg.h
…
file-posix.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
file-win32.c block: use int64_t instead of uint64_t in driver write handlers 2021-09-29 13:46:31 -05:00
filter-compress.c block: use int64_t instead of int in driver discard handlers 2021-09-29 13:46:32 -05:00
gluster.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
io.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
io_uring.c block/io_uring: add missing include file 2022-08-02 11:01:24 +02:00
iscsi-opts.c modules: add block module annotations 2021-07-09 18:20:27 +02:00
iscsi.c iscsi: add missing coroutine_fn annotations 2022-10-07 12:11:40 +02:00
linux-aio.c misc: fix commonly doubled up words 2022-08-01 11:58:02 +02:00
meson.build blkio: add libblkio block driver 2022-10-26 14:56:42 -04:00
mirror.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
nbd.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
nfs.c nfs: add missing coroutine_fn annotations 2022-10-07 12:11:40 +02:00
null.c block: use int64_t instead of uint64_t in driver write handlers 2021-09-29 13:46:31 -05:00
nvme.c block: pass size to bdrv_unregister_buf() 2022-10-26 14:56:42 -04:00
parallels-ext.c block: Change bdrv_{pread,pwrite,pwrite_sync}() param order 2022-07-12 12:14:55 +02:00
parallels.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
parallels.h parallels: support bitmap extension for read-only mode 2021-03-08 14:56:55 +01:00
preallocate.c block: fix preallocate filter: don't do unaligned preallocate requests 2022-03-07 09:19:20 +01:00
progress_meter.c progressmeter: protect with a mutex 2021-06-25 14:24:24 +03:00
qapi-sysemu.c block: add 'force' parameter to 'blockdev-change-medium' command 2022-04-25 12:02:36 +02:00
qapi.c block: use GDateTime for formatting timestamp when dumping snapshot info 2021-06-14 13:28:50 +01:00
qcow.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
qcow2-bitmap.c block/qcow2-bitmap: Add missing cast to silent GCC error 2022-09-30 18:02:30 +02:00
qcow2-cache.c block: Change bdrv_{pread,pwrite,pwrite_sync}() param order 2022-07-12 12:14:55 +02:00
qcow2-cluster.c qcow2: add missing coroutine_fn annotations 2022-10-07 12:11:40 +02:00
qcow2-refcount.c qcow2: add missing coroutine_fn annotations 2022-10-07 12:11:40 +02:00
qcow2-snapshot.c block: Use bdrv_co_pwrite_sync() when caller is coroutine_fn 2022-07-12 12:14:56 +02:00
qcow2-threads.c
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qcow2.c qcow2: add missing coroutine_fn annotations 2022-10-07 12:11:40 +02:00
qcow2.h qcow2: add missing coroutine_fn annotations 2022-10-07 12:11:40 +02:00
qed-check.c
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qed-cluster.c
…
qed-l2-cache.c osdep: Move memalign-related functions to their own header 2022-03-07 13:16:49 +00:00
qed-table.c osdep: Move memalign-related functions to their own header 2022-03-07 13:16:49 +00:00
qed.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
qed.h
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quorum.c quorum: Remove unnecessary forward declaration 2022-10-07 12:11:41 +02:00
raw-format.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
rbd.c block/rbd: report a better error when namespace does not exist 2022-06-24 17:07:06 +02:00
replication.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
reqlist.c block/reqlist: add reqlist_wait_all() 2022-03-07 09:33:30 +01:00
snapshot-access.c block: introduce snapshot-access block driver 2022-03-07 09:33:31 +01:00
snapshot.c include/block/snapshot: global state API + assertions 2022-03-04 18:18:25 +01:00
ssh.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
stream.c block/stream: Drain subtree around graph change 2022-03-29 16:30:55 +02:00
throttle-groups.c block/throttle-groups: throttle_group_co_io_limits_intercept(): 64bit bytes 2021-02-03 08:14:00 -06:00
throttle.c throttle: add missing coroutine_fn annotations 2022-10-07 12:11:41 +02:00
trace-events nbd: trace long NBD operations 2022-06-29 10:57:02 +03:00
trace.h
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vdi.c block: Change blk_{pread,pwrite}() param order 2022-07-12 12:14:56 +02:00
vhdx-endian.c
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vhdx-log.c block: Change bdrv_{pread,pwrite,pwrite_sync}() param order 2022-07-12 12:14:55 +02:00
vhdx.c block: add BDRV_REQ_REGISTERED_BUF request flag 2022-10-26 14:56:42 -04:00
vhdx.h
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vmdk.c vmdk: add missing coroutine_fn annotations 2022-10-07 12:11:41 +02:00
vpc.c block: Change blk_{pread,pwrite}() param order 2022-07-12 12:14:56 +02:00
vvfat.c block: Change bdrv_{pread,pwrite,pwrite_sync}() param order 2022-07-12 12:14:55 +02:00
win32-aio.c osdep: Move memalign-related functions to their own header 2022-03-07 13:16:49 +00:00
write-threshold.c write-threshold: deal with includes 2021-05-14 16:14:10 +02:00