This function iterates over all snapshots of a qcow2 file in order to
expand all zero clusters, but it does not validate the snapshots' L1
tables first.
We now have a function to take care of this, so let's use it.
We can also take the opportunity to replace the sector-based
bdrv_read() with bdrv_pread().
Cc: Eric Blake <eblake@redhat.com>
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
The align_offset() function is equivalent to the ROUND_UP() macro so
there's no need to use the former. The ROUND_UP() name is also a bit
more explicit.
This patch uses ROUND_UP() instead of the slower QEMU_ALIGN_UP()
because align_offset() already requires that the second parameter is a
power of two.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20180215131008.5153-1-berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function doesn't need any changes to support L2 slices, but since
it's now dealing with slices intead of full tables, the l2_table
variable is renamed for clarity.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 6107001fc79e6739242f1de7d191375e4f130aac.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function doesn't need any changes to support L2 slices, but since
it's now dealing with slices instead of full tables, the l2_table
variable is renamed for clarity.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 78bcc54bc632574dd0b900a77a00a1b6ffc359e6.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function doesn't need any changes to support L2 slices, but since
it's now dealing with slices intead of full tables, the l2_table
variable is renamed for clarity.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 812b0c3505bb1687e51285dccf1a94f0cecb1f74.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function doesn't need any changes to support L2 slices, but since
it's now dealing with slices instead of full tables, the l2_table
variable is renamed for clarity.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 0c5d4b9bf163aa3b49ec19cc512a50d83563f2ad.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
expand_zero_clusters_in_l1() expands zero clusters as a necessary step
to downgrade qcow2 images to a version that doesn't support metadata
zero clusters. This function takes an L1 table (which may or may not
be active) and iterates over all its L2 tables looking for zero
clusters.
Since we'll be loading L2 slices instead of full tables we need to add
an extra loop that iterates over all slices of each L2 table, and we
should also use the slice size when allocating the buffer used when
the L1 table is not active.
This function doesn't need any additional changes so apart from that
this patch simply updates the variable name from l2_table to l2_slice.
Finally, and since we have to touch the bdrv_read() / bdrv_write()
calls anyway, this patch takes the opportunity to replace them with
the byte-based bdrv_pread() / bdrv_pwrite().
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 43590976f730501688096cff103f2923b72b0f32.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Adding support for L2 slices to expand_zero_clusters_in_l1() needs
(among other things) an extra loop that iterates over all slices of
each L2 table.
Putting all changes in one patch would make it hard to read because
all semantic changes would be mixed with pure indentation changes.
To make things easier this patch simply creates a new block and
changes the indentation of all lines of code inside it. Thus, all
modifications in this patch are cosmetic. There are no semantic
changes and no variables are renamed yet. The next patch will take
care of that.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: c2ae9f31ed5b6e591477ad4654448badd1c89d73.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
At the moment it doesn't really make a difference whether we call
qcow2_get_refcount() before of after reading the L2 table, but if we
want to support L2 slices we'll need to read the refcount first.
This patch simply changes the order of those two operations to prepare
for that. The patch with the actual semantic changes will be easier to
read because of this.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 947a91d934053a2dbfef979aeb9568f57ef57c5d.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
zero_single_l2() limits the number of clusters to be zeroed to the
amount that fits inside an L2 table. Since we'll be loading L2 slices
instead of full tables we need to update that limit. The function is
renamed to zero_in_l2_slice() for clarity.
Apart from that, this function doesn't need any additional changes, so
this patch simply updates the variable name from l2_table to l2_slice.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: ebc16e7e79fa6969d8975ef487d679794de4fbcc.1517840877.git.berto@igalia.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
discard_single_l2() limits the number of clusters to be discarded
to the amount that fits inside an L2 table. Since we'll be loading
L2 slices instead of full tables we need to update that limit. The
function is renamed to discard_in_l2_slice() for clarity.
Apart from that, this function doesn't need any additional changes, so
this patch simply updates the variable name from l2_table to l2_slice.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: 1cb44a5b68be5334cb01b97a3db3a3c5a43396e5.1517840877.git.berto@igalia.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
handle_alloc() loads an L2 table and limits the number of checked
clusters to the amount that fits inside that table. Since we'll be
loading L2 slices instead of full tables we need to update that limit.
Apart from that, this function doesn't need any additional changes, so
this patch simply updates the variable name from l2_table to l2_slice.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: b243299c7136f7014c5af51665431ddbf5e99afd.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
handle_copied() loads an L2 table and limits the number of checked
clusters to the amount that fits inside that table. Since we'll be
loading L2 slices instead of full tables we need to update that limit.
Apart from that, this function doesn't need any additional changes, so
this patch simply updates the variable name from l2_table to l2_slice.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 541ac001a7d6b86bab2392554bee53c2b312148c.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
There's a loop in this function that iterates over the L2 entries in a
table, so now we need to assert that it remains within the limits of
an L2 slice.
Apart from that, this function doesn't need any additional changes, so
this patch simply updates the variable name from l2_table to l2_slice.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: f9846a1c2efc51938e877e2a25852d9ab14797ff.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
qcow2_get_cluster_offset() checks how many contiguous bytes are
available at a given offset. The returned number of bytes is limited
by the amount that can be addressed without having to load more than
one L2 table.
Since we'll be loading L2 slices instead of full tables this patch
changes the limit accordingly using the size of the L2 slice for the
calculations instead of the full table size.
One consequence of this is that with small L2 slices operations such
as 'qemu-img map' will need to iterate in more steps because each
qcow2_get_cluster_offset() call will potentially return a smaller
number. However the code is already prepared for that so this doesn't
break semantics.
The l2_table variable is also renamed to l2_slice to reflect this, and
offset_to_l2_index() is replaced with offset_to_l2_slice_index().
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 6b602260acb33da56ed6af9611731cb7acd110eb.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This patch updates get_cluster_table() to return L2 slices instead of
full L2 tables.
The code itself needs almost no changes, it only needs to call
offset_to_l2_slice_index() instead of offset_to_l2_index(). This patch
also renames all the relevant variables and the documentation.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 64cf064c0021ba315d3f3032da0f95db1b615f33.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
After the previous patch we're now always using l2_load() in
get_cluster_table() regardless of whether a new L2 table has to be
allocated or not.
This patch refactors that part of the code to use one single l2_load()
call.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: ce31758c4a1fadccea7a6ccb93951eb01d95fd4c.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This patch updates l2_allocate() to support the qcow2 cache returning
L2 slices instead of full L2 tables.
The old code simply gets an L2 table from the cache and initializes it
with zeroes or with the contents of an existing table. With a cache
that returns slices instead of tables the idea remains the same, but
the code must now iterate over all the slices that are contained in an
L2 table.
Since now we're operating with slices the function can no longer
return the newly-allocated table, so it's up to the caller to retrieve
the appropriate L2 slice after calling l2_allocate() (note that with
this patch the caller is still loading full L2 tables, but we'll deal
with that in a separate patch).
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20fc0415bf0e011e29f6487ec86eb06a11f37445.1517840877.git.berto@igalia.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Adding support for L2 slices to l2_allocate() needs (among other
things) an extra loop that iterates over all slices of a new L2 table.
Putting all changes in one patch would make it hard to read because
all semantic changes would be mixed with pure indentation changes.
To make things easier this patch simply creates a new block and
changes the indentation of all lines of code inside it. Thus, all
modifications in this patch are cosmetic. There are no semantic
changes and no variables are renamed yet. The next patch will take
care of that.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: d0d7dca8520db304524f52f49d8157595a707a35.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Each entry in the qcow2 L2 cache stores a full L2 table (which uses a
complete cluster in the qcow2 image). A cluster is usually too large
to be used efficiently as the size for a cache entry, so we want to
decouple both values by allowing smaller cache entries. Therefore the
qcow2 L2 cache will no longer return full L2 tables but slices
instead.
This patch updates l2_load() so it can handle L2 slices correctly.
Apart from the offset of the L2 table (which we already had) we also
need the guest offset in order to calculate which one of the slices
we need.
An L2 slice has currently the same size as an L2 table (one cluster),
so for now this function will load exactly the same data as before.
This patch also removes a stale comment about the return value being
a pointer to the L2 table. This function returns an error code since
55c17e9821.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: b830aa1fc5b6f8e3cb331d006853fe22facca847.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Similar to offset_to_l2_index(), this function returns the index in
the L1 table for a given guest offset. This is only used in a couple
of places and it's not a particularly complex calculation, but it
makes the code a bit more readable.
Although in the qcow2_get_cluster_offset() case the old code was
taking advantage of the l1_bits variable, we're going to get rid of
the other uses of l1_bits in a later patch anyway, so it doesn't make
sense to keep it just for this.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: a5f626fed526b7459a0425fad06d823d18df8522.1517840877.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function was only using the BlockDriverState parameter to pass it
to qcow2_cache_get_table_idx(). This is no longer necessary so this
parameter can be removed.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 6f98155489054a457563da77cdad1a66ebb3e896.1517840876.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function was only using the BlockDriverState parameter to pass it
to qcow2_cache_get_table_idx(). This is no longer necessary so this
parameter can be removed.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 5c40516a91782b083c1428b7b6a41bb9e2679bfb.1517840876.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
This function has not been returning the offset of the L2 table since
commit 3948d1d487
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: b498733b6706a859a03678d74ecbd26aeba129aa.1517840876.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
g_realloc() aborts the program if it fails to allocate the required
amount of memory. We want to detect that scenario and return an error
instead, so let's use g_try_realloc().
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This cleanup makes the number of objects depending on qapi/error.h
drop from 1910 (out of 4743) to 1612 in my "build everything" tree.
While there, separate #include from file comment with a blank line,
and drop a useless comment on why qemu/osdep.h is included first.
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20180201111846.21846-5-armbru@redhat.com>
[Semantic conflict with commit 34e304e975 resolved, OSX breakage fixed]
We should check whether the cluster offset we are about to use is
actually valid; that is, whether it is aligned to cluster boundaries.
Reported-by: R. Nageswara Sastry <nasastry@in.ibm.com>
Buglink: https://bugs.launchpad.net/qemu/+bug/1728643
Buglink: https://bugs.launchpad.net/qemu/+bug/1728657
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20171110203111.7666-3-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
If the refcount data is corrupted then we can end up trying to
allocate a new L2 table at offset 0 in the image, triggering an
assertion in the qcow2 cache that would crash QEMU:
qcow2_cache_entry_mark_dirty: Assertion `c->entries[i].offset != 0' failed
This patch adds an explicit check for this scenario and a new test
case.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 92dac37191ae7844a2da22c122204eb493cc3133.1509718618.git.berto@igalia.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
We are gradually moving away from sector-based interfaces, towards
byte-based. In the common case, allocation is unlikely to ever use
values that are not naturally sector-aligned, but it is possible
that byte-based values will let us be more precise about allocation
at the end of an unaligned file that can do byte-based access.
Changing the name of the function from bdrv_get_block_status() to
bdrv_block_status() ensures that the compiler enforces that all
callers are updated. For now, the io.c layer still assert()s that
all callers are sector-aligned, but that can be relaxed when a later
patch implements byte-based block status in the drivers.
There was an inherent limitation in returning the offset via the
return value: we only have room for BDRV_BLOCK_OFFSET_MASK bits, which
means an offset can only be mapped for sector-aligned queries (or,
if we declare that non-aligned input is at the same relative position
modulo 512 of the answer), so the new interface also changes things to
return the offset via output through a parameter by reference rather
than mashed into the return value. We'll have some glue code that
munges between the two styles until we finish converting all uses.
For the most part this patch is just the addition of scaling at the
callers followed by inverse scaling at bdrv_block_status(), coupled
with the tweak in calling convention. But some code, particularly
bdrv_is_allocated(), gets a lot simpler because it no longer has to
mess with sectors.
For ease of review, bdrv_get_block_status_above() will be tackled
separately.
Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Instead of sector offset, take the bytes offset when encrypting
or decrypting data.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170927125340.12360-6-berrange@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This patch add shrinking of the image file for qcow2. As a result, this allows
us to reduce the virtual image size and free up space on the disk without
copying the image. Image can be fragmented and shrink is done by punching holes
in the image file.
Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20170918124230.8152-4-pbutsykin@virtuozzo.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
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-----END PGP SIGNATURE-----
Merge remote-tracking branch 'remotes/elmarco/tags/tidy-pull-request' into staging
# gpg: Signature made Thu 31 Aug 2017 11:29:33 BST
# gpg: using RSA key 0xDAE8E10975969CE5
# gpg: Good signature from "Marc-André Lureau <marcandre.lureau@redhat.com>"
# gpg: aka "Marc-André Lureau <marcandre.lureau@gmail.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg: It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 87A9 BD93 3F87 C606 D276 F62D DAE8 E109 7596 9CE5
* remotes/elmarco/tags/tidy-pull-request: (29 commits)
eepro100: replace g_malloc()+memcpy() with g_memdup()
test-iov: replace g_malloc()+memcpy() with g_memdup()
i386: replace g_malloc()+memcpy() with g_memdup()
i386: introduce ELF_NOTE_SIZE macro
decnumber: use DIV_ROUND_UP
kvm: use DIV_ROUND_UP
i386/dump: use DIV_ROUND_UP
ppc: use DIV_ROUND_UP
msix: use DIV_ROUND_UP
usb-hub: use DIV_ROUND_UP
q35: use DIV_ROUND_UP
piix: use DIV_ROUND_UP
virtio-serial: use DIV_ROUND_UP
console: use DIV_ROUND_UP
monitor: use DIV_ROUND_UP
virtio-gpu: use DIV_ROUND_UP
vga: use DIV_ROUND_UP
ui: use DIV_ROUND_UP
vnc: use DIV_ROUND_UP
vvfat: use DIV_ROUND_UP
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
I used the clang-tidy qemu-round check to generate the fix:
https://github.com/elmarco/clang-tools-extra
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Most qcow2 files are uncompressed so it is wasteful to allocate (32 + 1)
* cluster_size + 512 bytes upfront. Allocate s->cluster_cache and
s->cluster_data when the first read operation is performance on a
compressed cluster.
The buffers are freed in .bdrv_close(). .bdrv_open() no longer has any
code paths that can allocate these buffers, so remove the free functions
in the error code path.
This patch can result in significant memory savings when many qcow2
disks are attached or backing file chains are long:
Before 12.81% (1,023,193,088B)
After 5.36% (393,893,888B)
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20170821135530.32344-1-stefanha@redhat.com
Cc: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This adds support for using LUKS as an encryption format
with the qcow2 file, using the new encrypt.format parameter
to request "luks" format. e.g.
# qemu-img create --object secret,data=123456,id=sec0 \
-f qcow2 -o encrypt.format=luks,encrypt.key-secret=sec0 \
test.qcow2 10G
The legacy "encryption=on" parameter still results in
creation of the old qcow2 AES format (and is equivalent
to the new 'encryption-format=aes'). e.g. the following are
equivalent:
# qemu-img create --object secret,data=123456,id=sec0 \
-f qcow2 -o encryption=on,encrypt.key-secret=sec0 \
test.qcow2 10G
# qemu-img create --object secret,data=123456,id=sec0 \
-f qcow2 -o encryption-format=aes,encrypt.key-secret=sec0 \
test.qcow2 10G
With the LUKS format it is necessary to store the LUKS
partition header and key material in the QCow2 file. This
data can be many MB in size, so cannot go into the QCow2
header region directly. Thus the spec defines a FDE
(Full Disk Encryption) header extension that specifies
the offset of a set of clusters to hold the FDE headers,
as well as the length of that region. The LUKS header is
thus stored in these extra allocated clusters before the
main image payload.
Aside from all the cryptographic differences implied by
use of the LUKS format, there is one further key difference
between the use of legacy AES and LUKS encryption in qcow2.
For LUKS, the initialiazation vectors are generated using
the host physical sector as the input, rather than the
guest virtual sector. This guarantees unique initialization
vectors for all sectors when qcow2 internal snapshots are
used, thus giving stronger protection against watermarking
attacks.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170623162419.26068-14-berrange@redhat.com
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This converts the qcow2 driver to make use of the QCryptoBlock
APIs for encrypting image content, using the legacy QCow2 AES
scheme.
With this change it is now required to use the QCryptoSecret
object for providing passwords, instead of the current block
password APIs / interactive prompting.
$QEMU \
-object secret,id=sec0,file=/home/berrange/encrypted.pw \
-drive file=/home/berrange/encrypted.qcow2,encrypt.key-secret=sec0
The test 087 could be simplified since there is no longer a
difference in behaviour when using blockdev_add with encrypted
images for the running vs stopped CPU state.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170623162419.26068-12-berrange@redhat.com
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Instead of requiring separate input/output buffers for
encrypting data, change qcow2_encrypt_sectors() to assume
use of a single buffer, encrypting in place. The current
callers all used the same buffer for input/output already.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170623162419.26068-11-berrange@redhat.com
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
We already have functions for doing these calculations, so let's use
them instead of doing everything by hand. This makes the code a bit
more readable.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
If the guest tries to write data that results on the allocation of a
new cluster, instead of writing the guest data first and then the data
from the COW regions, write everything together using one single I/O
operation.
This can improve the write performance by 25% or more, depending on
several factors such as the media type, the cluster size and the I/O
request size.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Instead of passing a single buffer pointer to do_perform_cow_write(),
pass a QEMUIOVector. This will allow us to merge the write requests
for the COW regions and the actual data into a single one.
Although do_perform_cow_read() does not strictly need to change its
API, we're doing it here as well for consistency.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reading both COW regions requires two separate requests, but it's
perfectly possible to merge them and perform only one. This generally
improves performance, particularly on rotating disk drives. The
downside is that the data in the middle region is read but discarded.
This patch takes a conservative approach and only merges reads when
the size of the middle region is <= 16KB.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This patch splits do_perform_cow() into three separate functions to
read, encrypt and write the COW regions.
perform_cow() can now read both regions first, then encrypt them and
finally write them to disk. The memory allocation is also done in
this function now, using one single buffer large enough to hold both
regions.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Instead of calling perform_cow() twice with a different COW region
each time, call it just once and make perform_cow() handle both
regions.
This patch simply moves code around. The next one will do the actual
reordering of the COW operations.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Qcow2COWRegion has two attributes:
- The offset of the COW region from the start of the first cluster
touched by the I/O request. Since it's always going to be positive
and the maximum request size is at most INT_MAX, we can use a
regular unsigned int to store this offset.
- The size of the COW region in bytes. This is guaranteed to be >= 0,
so we should use an unsigned type instead.
In x86_64 this reduces the size of Qcow2COWRegion from 16 to 8 bytes.
It will also help keep some assertions simpler now that we know that
there are no negative numbers.
The prototype of do_perform_cow() is also updated to reflect these
changes.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
We are using the return value of qcow2_encrypt_sectors() to detect
problems but we are throwing away the returned Error since we have no
way to report it to the user. Therefore we can simply get rid of the
local Error variable and pass NULL instead.
Alternatively we could try to figure out a way to pass the original
error instead of simply returning -EIO, but that would be more
invasive, so let's keep the current approach.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
When converting a 1.1 image down to 0.10, qemu-iotests 060 forces
a contrived failure where allocating a cluster used to replace a
zero cluster reads unaligned data. Since it is a zero cluster
rather than a data cluster being converted, changing the error
message to match our earlier change in 'qcow2: Make distinction
between zero cluster types obvious' is worthwhile.
Suggested-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20170508171302.17805-1-eblake@redhat.com
[mreitz: Commit message fixes]
Signed-off-by: Max Reitz <mreitz@redhat.com>
Passing a byte offset, but sector count, when we ultimately
want to operate on cluster granularity, is madness. Clean up
the external interfaces to take both offset and count as bytes,
while still keeping the assertion added previously that the
caller must align the values to a cluster. Then rename things
to make sure backports don't get confused by changed units:
instead of qcow2_discard_clusters() and qcow2_zero_clusters(),
we now have qcow2_cluster_discard() and qcow2_cluster_zeroize().
The internal functions still operate on clusters at a time, and
return an int for number of cleared clusters; but on an image
with 2M clusters, a single L2 table holds 256k entries that each
represent a 2M cluster, totalling well over INT_MAX bytes if we
ever had a request for that many bytes at once. All our callers
currently limit themselves to 32-bit bytes (and therefore fewer
clusters), but by making this function 64-bit clean, we have one
less place to clean up if we later improve the block layer to
support 64-bit bytes through all operations (with the block layer
auto-fragmenting on behalf of more-limited drivers), rather than
the current state where some interfaces are artificially limited
to INT_MAX at a time.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170507000552.20847-13-eblake@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
We already audited (in commit 0c1bd469) that qcow2_discard_clusters()
is only passed cluster-aligned start values; but we can further
tighten the assertion that the only unaligned end value is at EOF.
Recent commits have taken advantage of an unaligned tail cluster,
for both discard and write zeroes.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170507000552.20847-12-eblake@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Similar to discard_single_l2(), we should try to avoid dirtying
the L2 cache when the cluster we are changing already has the
right characteristics.
Note that by the time we get to zero_single_l2(), BDRV_REQ_MAY_UNMAP
is a requirement to unallocate a cluster (this is because the block
layer clears that flag if discard.* flags during open requested that
we never punch holes - see the conversation around commit 170f4b2e,
https://lists.gnu.org/archive/html/qemu-devel/2016-09/msg07306.html).
Therefore, this patch can only reuse a zero cluster as-is if either
unmapping is not requested, or if the zero cluster was not associated
with an allocation.
Technically, there are some cases where an unallocated cluster
already reads as all zeroes (namely, when there is no backing file
[easy: check bs->backing], or when the backing file also reads as
zeroes [harder: we can't check bdrv_get_block_status since we are
already holding the lock]), where the guest would not immediately see
a difference if we left that cluster unallocated. But if the user
did not request unmapping, leaving an unallocated cluster is wrong;
and even if the user DID request unmapping, keeping a cluster
unallocated risks a subtle semantic change of guest-visible contents
if a backing file is later added, and it is not worth auditing
whether all internal uses such as mirror properly avoid an unmap
request. Thus, this patch is intentionally limited to just clusters
that are already marked as zero.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 20170507000552.20847-8-eblake@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Treat plain zero clusters differently from allocated ones, so that
we can simplify the logic of checking whether an offset is present.
Do this by splitting QCOW2_CLUSTER_ZERO into two new enums,
QCOW2_CLUSTER_ZERO_PLAIN and QCOW2_CLUSTER_ZERO_ALLOC.
I tried to arrange the enum so that we could use
'ret <= QCOW2_CLUSTER_ZERO_PLAIN' for all unallocated types, and
'ret >= QCOW2_CLUSTER_ZERO_ALLOC' for allocated types, although
I didn't actually end up taking advantage of the layout.
In many cases, this leads to simpler code, by properly combining
cases (sometimes, both zero types pair together, other times,
plain zero is more like unallocated while allocated zero is more
like normal).
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-id: 20170507000552.20847-7-eblake@redhat.com
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
