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>
58 lines
2.0 KiB
Diff
58 lines
2.0 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 10:45:11 +0200
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Subject: [PATCH] vma: create: support 64KiB-unaligned input images
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which fixes backing up templates with such disks in PVE, for example
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efitype=4m EFI disks on a file-based storage (size = 540672).
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If there is not enough left to read, blk_co_preadv will return -EIO,
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so limit the size in the last iteration.
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For writing, an unaligned end is already handled correctly.
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The call to memset is not strictly necessary, because writing also
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checks that it doesn't write data beyond the end of the image. But
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there are two reasons to do it:
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1. It's cleaner that way.
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2. It allows detecting when the final piece is all zeroes, which might
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not happen if the buffer still contains data from the previous
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iteration.
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Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
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---
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vma.c | 12 ++++++++++--
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1 file changed, 10 insertions(+), 2 deletions(-)
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diff --git a/vma.c b/vma.c
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index e6e9ffc7fe..304f02bc84 100644
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--- a/vma.c
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+++ b/vma.c
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@@ -548,7 +548,7 @@ static void coroutine_fn backup_run(void *opaque)
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struct iovec iov;
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QEMUIOVector qiov;
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- int64_t start, end;
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+ int64_t start, end, readlen;
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int ret = 0;
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unsigned char *buf = blk_blockalign(job->target, VMA_CLUSTER_SIZE);
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@@ -562,8 +562,16 @@ static void coroutine_fn backup_run(void *opaque)
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iov.iov_len = VMA_CLUSTER_SIZE;
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qemu_iovec_init_external(&qiov, &iov, 1);
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+ if (start + 1 == end) {
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+ memset(buf, 0, VMA_CLUSTER_SIZE);
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+ readlen = job->len - start * VMA_CLUSTER_SIZE;
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+ assert(readlen > 0 && readlen <= VMA_CLUSTER_SIZE);
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+ } else {
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+ readlen = VMA_CLUSTER_SIZE;
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+ }
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+
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ret = blk_co_preadv(job->target, start * VMA_CLUSTER_SIZE,
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- VMA_CLUSTER_SIZE, &qiov, 0);
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+ readlen, &qiov, 0);
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if (ret < 0) {
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vma_writer_set_error(job->vmaw, "read error", -1);
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goto out;
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