5b15e2ecaf
Notable changes:
* The only big change is the switch to using a custom QIOChannel for
savevm-async, because the previously used QEMUFileOps was dropped.
Changes to the current implementation:
* Switch to vector based methods as required for an IO channel. For
short reads the passed-in IO vector is stuffed with zeroes at the
end, just to be sure.
* For reading: The documentation in include/io/channel.h states that
at least one byte should be read, so also error out when whe are
at the very end instead of returning 0.
* For reading: Fix off-by-one error when request goes beyond end.
The wrong code piece was:
if ((pos + size) > maxlen) {
size = maxlen - pos - 1;
}
Previously, the last byte would not be read. It's actually
possible to get a snapshot .raw file that has content all the way
up the final 512 byte (= BDRV_SECTOR_SIZE) boundary without any
trailing zero bytes (I wrote a script to do it).
Luckily, it didn't cause a real issue, because qemu_loadvm_state()
is not interested in the final (i.e. QEMU_VM_VMDESCRIPTION)
section. The buffer for reading it is simply freed up afterwards
and the function will assume that it read the whole section, even
if that's not the case.
* For writing: Make use of the generated blk_pwritev() wrapper
instead of manually wrapping the coroutine to simplify and save a
few lines.
* Adapt to changed interfaces for blk_{pread,pwrite}:
* a9262f551e ("block: Change blk_{pread,pwrite}() param order")
* 3b35d4542c ("block: Add a 'flags' param to blk_pread()")
* bf5b16fa40 ("block: Make blk_{pread,pwrite}() return 0 on success")
Those changes especially affected the qemu-img dd patches, because
the context also changed, but also some of our block drivers used
the functions.
* Drop qemu-common.h include: it got renamed after essentially
everything was moved to other headers. The only remaining user I
could find for things dropped from the header between 7.0 and 7.1
was qemu_get_vm_name() in the iscsi-initiatorname patch, but it
already includes the header to which the function was moved.
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
37 lines
1.5 KiB
Diff
37 lines
1.5 KiB
Diff
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Fabian Ebner <f.ebner@proxmox.com>
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Date: Wed, 22 Jun 2022 10:45:13 +0200
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Subject: [PATCH] block: alloc-track: avoid premature break
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While the bdrv_co_preadv() calls are expected to return 0 on success,
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qemu_iovec_memset() will return the number of bytes set (will be
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local_bytes, because the slice with that size was just initialized).
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Don't break out of the loop after the branch with qemu_iovec_memset(),
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because there might still be work to do. Additionally, ret is an int,
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which on 64-bit platforms is too small to hold the size_t returned by
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qemu_iovec_memset().
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The branch seems to be difficult to reach in practice, because the
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whole point of alloc-track is to be used with a backing device.
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Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
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---
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block/alloc-track.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/block/alloc-track.c b/block/alloc-track.c
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index 6b50fbe537..c1160af04b 100644
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--- a/block/alloc-track.c
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+++ b/block/alloc-track.c
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@@ -174,7 +174,8 @@ static int coroutine_fn track_co_preadv(BlockDriverState *bs,
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ret = bdrv_co_preadv(bs->backing, local_offset, local_bytes,
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&local_qiov, flags);
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} else {
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- ret = qemu_iovec_memset(&local_qiov, cur_offset, 0, local_bytes);
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+ qemu_iovec_memset(&local_qiov, cur_offset, 0, local_bytes);
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+ ret = 0;
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}
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if (ret != 0) {
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