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path: root/block/qcow2.h
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2018-03-09qcow2: Generalize validate_table_offset() into qcow2_validate_table()Alberto Garcia
This function checks that the offset and size of a table are valid. While the offset checks are fine, the size check is too generic, since it only verifies that the total size in bytes fits in a 64-bit integer. In practice all tables used in qcow2 have much smaller size limits, so the size needs to be checked again for each table using its actual limit. This patch generalizes this function by allowing the caller to specify the maximum size for that table. In addition to that it allows passing an Error variable. The function is also renamed and made public since we're going to use it in other parts of the code. Signed-off-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-03-09qcow2: introduce qcow2_write_caches and qcow2_flush_cachesPaolo Bonzini
They will be used to avoid recursively taking s->lock during bdrv_open or bdrv_check. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <1516279431-30424-7-git-send-email-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2018-03-02qcow2: Replace align_offset() with ROUND_UP()Alberto Garcia
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>
2018-02-13qcow2: Allow configuring the L2 slice sizeAlberto Garcia
Now that the code is ready to handle L2 slices we can finally add an option to allow configuring their size. An L2 slice is the portion of an L2 table that is read by the qcow2 cache. Until now the cache was always reading full L2 tables, and since the L2 table size is equal to the cluster size this was not very efficient with large clusters. Here's a more detailed explanation of why it makes sense to have smaller cache entries in order to load L2 data: https://lists.gnu.org/archive/html/qemu-block/2017-09/msg00635.html This patch introduces a new command-line option to the qcow2 driver named l2-cache-entry-size (cf. l2-cache-size). The cache entry size has the same restrictions as the cluster size: it must be a power of two and it has the same range of allowed values, with the additional requirement that it must not be larger than the cluster size. The L2 cache entry size (L2 slice size) remains equal to the cluster size for now by default, so this feature must be explicitly enabled. Although my tests show that 4KB slices consistently improve performance and give the best results, let's wait and make more tests with different cluster sizes before deciding on an optimal default. Now that the cache entry size is not necessarily equal to the cluster size we need to reflect that in the MIN_L2_CACHE_SIZE documentation. That minimum value is a requirement of the COW algorithm: we need to read two L2 slices (and not two L2 tables) in order to do COW, see l2_allocate() for the actual code. Signed-off-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: c73e5611ff4a9ec5d20de68a6c289553a13d2354.1517840877.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-13qcow2: Add offset_to_l2_slice_index()Alberto Garcia
Similar to offset_to_l2_index(), this function takes a guest offset and returns the index in the L2 slice that contains its L2 entry. An L2 slice has currently the same size as an L2 table (one cluster), so both functions return the same value for now. Signed-off-by: Alberto Garcia <berto@igalia.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: a1c45c5c5a76146dd1712d8d1e7b409ad539c718.1517840877.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-13qcow2: Add l2_slice_size field to BDRVQcow2StateAlberto Garcia
The BDRVQcow2State structure contains an l2_size field, which stores the number of 64-bit entries in an L2 table. For efficiency reasons we want to be able to load slices instead of full L2 tables, so we need to know how many entries an L2 slice can hold. An L2 slice is the portion of an L2 table that is loaded by the qcow2 cache. At the moment that cache can only load complete tables, therefore an L2 slice has the same size as an L2 table (one cluster) and l2_size == l2_slice_size. Later we'll allow smaller slices, but until then we have to use this new l2_slice_size field to make the rest of the code ready for 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: adb048595f9fb5dfb110c802a8b3c3be3b937f37.1517840877.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-13qcow2: Add offset_to_l1_index()Alberto Garcia
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>
2018-02-13qcow2: Remove BDS parameter from qcow2_cache_is_table_offset()Alberto Garcia
This function was only using the BlockDriverState parameter to pass it to qcow2_cache_get_table_addr(). 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: eb0ed90affcf302e5a954bafb5931b5215483d3a.1517840877.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-13qcow2: Remove BDS parameter from qcow2_cache_discard()Alberto Garcia
This function was only using the BlockDriverState parameter to pass it to qcow2_cache_get_table_idx() and qcow2_cache_table_release(). 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: 9724f7e38e763ad3be32627c6b7fe8df9edb1476.1517840877.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-13qcow2: Remove BDS parameter from qcow2_cache_clean_unused()Alberto Garcia
This function was only using the BlockDriverState parameter to pass it to qcow2_cache_table_release(). 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: b74f17591af52f201de0ea3a3b2dd0a81932334d.1517840876.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-13qcow2: Remove BDS parameter from qcow2_cache_destroy()Alberto Garcia
This function was never using the BlockDriverState parameter so it can be safely 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: 49c74fe8b3aead9056e61a85b145ce787d06262b.1517840876.git.berto@igalia.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2018-02-13qcow2: Remove BDS parameter from qcow2_cache_put()Alberto Garcia
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>
2018-02-13qcow2: Remove BDS parameter from qcow2_cache_entry_mark_dirty()Alberto Garcia
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>
2018-02-13block: maintain persistent disabled bitmapsVladimir Sementsov-Ogievskiy
To maintain load/store disabled bitmap there is new approach: - deprecate @autoload flag of block-dirty-bitmap-add, make it ignored - store enabled bitmaps as "auto" to qcow2 - store disabled bitmaps without "auto" flag to qcow2 - on qcow2 open load "auto" bitmaps as enabled and others as disabled (except in_use bitmaps) Also, adjust iotests 165 and 176 appropriately. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-id: 20180202160752.143796-1-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-12-22qcow2: get rid of qcow2_backing_read1 routineEdgar Kaziakhmedov
Since bdrv_co_preadv does all neccessary checks including reading after the end of the backing file, avoid duplication of verification before bdrv_co_preadv call. Signed-off-by: Edgar Kaziakhmedov <edgar.kaziakhmedov@virtuozzo.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-11-17qcow2: Add bounds check to get_refblock_offset()Max Reitz
Reported-by: R. Nageswara Sastry <nasastry@in.ibm.com> Buglink: https://bugs.launchpad.net/qemu/+bug/1728661 Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20171110203111.7666-5-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>
2017-10-06qcow2: truncate the tail of the image file after shrinking the imagePavel Butsykin
Now after shrinking the image, at the end of the image file, there might be a tail that probably will never be used. So we can find the last used cluster and cut the tail. Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 20170929121613.25997-3-pbutsykin@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-09-26qcow2: add shrink image supportPavel Butsykin
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>
2017-09-26qcow2: add qcow2_cache_discardPavel Butsykin
Whenever l2/refcount table clusters are discarded from the file we can automatically drop unnecessary content of the cache tables. This reduces the chance of eviction useful cache data and eliminates inconsistent data in the cache with the data in the 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: 20170918124230.8152-3-pbutsykin@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11block/qcow2: falloc/full preallocating growthMax Reitz
Implement the preallocation modes falloc and full for growing qcow2 images. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20170613202107.10125-15-mreitz@redhat.com Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11block/qcow2: Add qcow2_refcount_area()Max Reitz
This function creates a collection of self-describing refcount structures (including a new refcount table) at the end of a qcow2 image file. Optionally, these structures can also describe a number of additional clusters beyond themselves; this will be important for preallocated truncation, which will place the data clusters and L2 tables there. For now, we can use this function to replace the part of alloc_refcount_block() that grows the refcount table (from which it is actually derived). Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-id: 20170613202107.10125-13-mreitz@redhat.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2: add .bdrv_remove_persistent_dirty_bitmapVladimir Sementsov-Ogievskiy
Realize .bdrv_remove_persistent_dirty_bitmap interface. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 20170628120530.31251-29-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2: add .bdrv_can_store_new_dirty_bitmapVladimir Sementsov-Ogievskiy
Realize .bdrv_can_store_new_dirty_bitmap interface. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: John Snow <jsnow@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: 20170628120530.31251-23-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2: store bitmaps on reopening image as read-onlyVladimir Sementsov-Ogievskiy
Store bitmaps and mark them read-only on reopening image as read-only. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: 20170628120530.31251-21-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2: add persistent dirty bitmaps supportVladimir Sementsov-Ogievskiy
Store persistent dirty bitmaps in qcow2 image. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: 20170628120530.31251-20-vsementsov@virtuozzo.com [mreitz: Always assign ret in store_bitmap() in case of an error] Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2: support .bdrv_reopen_bitmaps_rwVladimir Sementsov-Ogievskiy
Realize bdrv_reopen_bitmaps_rw interface. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: John Snow <jsnow@redhat.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-id: 20170628120530.31251-15-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2: autoloading dirty bitmapsVladimir Sementsov-Ogievskiy
Auto loading bitmaps are bitmaps in Qcow2, with the AUTO flag set. They are loaded when the image is opened and become BdrvDirtyBitmaps for the corresponding drive. Extra data in bitmaps is not supported for now. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 20170628120530.31251-12-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2: add bitmaps extensionVladimir Sementsov-Ogievskiy
Add bitmap extension as specified in docs/specs/qcow2.txt. For now, just mirror extension header into Qcow2 state and check constraints. Also, calculate refcounts for qcow2 bitmaps, to not break qemu-img check. For now, disable image resize if it has bitmaps. It will be fixed later. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 20170628120530.31251-9-vsementsov@virtuozzo.com Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2-refcount: rename inc_refcounts() and make it publicVladimir Sementsov-Ogievskiy
This is needed for the following patch, which will introduce refcounts checking for qcow2 bitmaps. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com> Message-id: 20170628120530.31251-8-vsementsov@virtuozzo.com [mreitz: s/inc_refcounts/qcow2_inc_refcounts_imrt/ in one more (new) place] Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-07-11qcow2: add support for LUKS encryption formatDaniel P. Berrange
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>
2017-07-11qcow2: convert QCow2 to use QCryptoBlock for encryptionDaniel P. Berrange
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>
2017-07-11qcow2: make qcow2_encrypt_sectors encrypt in placeDaniel P. Berrange
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>
2017-06-26qcow2: Merge the writing of the COW regions with the guest dataAlberto Garcia
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>
2017-06-26qcow2: Use unsigned int for both members of Qcow2COWRegionAlberto Garcia
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>
2017-05-11qcow2: Discard/zero clusters by byte countEric Blake
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>
2017-05-11qcow2: Make distinction between zero cluster types obviousEric Blake
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>
2017-05-11qcow2: Name typedef for cluster typeEric Blake
Although it doesn't add all that much type safety (this is C, after all), it does add a bit of legibility to use the name QCow2ClusterType instead of a plain int. In particular, qcow2_get_cluster_offset() has an overloaded return type; a QCow2ClusterType on success, and -errno on failure; keeping the cluster type in a separate variable makes it slightly easier for the next patch to make further computations based on the type. Suggested-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Eric Blake <eblake@redhat.com> Message-id: 20170507000552.20847-6-eblake@redhat.com [mreitz: Use the new type in two more places (one of them pulled from the next patch)] Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-05-11qcow2: Reuse preallocated zero clustersMax Reitz
Instead of just freeing preallocated zero clusters and completely allocating them from scratch, reuse them. We cannot do this in handle_copied(), however, since this is a COW operation. Therefore, we have to add the new logic to handle_alloc() and simply return the existing offset if it exists. The only catch is that we have to convince qcow2_alloc_cluster_link_l2() not to free the old clusters (because we have reused them). Reported-by: Eric Blake <eblake@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2017-02-12qcow2: Optimize the refcount-block overlap checkAlberto Garcia
The metadata overlap checks introduced in a40f1c2add help detect corruption in the qcow2 image by verifying that data writes don't overlap with existing metadata sections. The 'refcount-block' check in particular iterates over the refcount table in order to get the addresses of all refcount blocks and check that none of them overlap with the region where we want to write. The problem with the refcount table is that since it always occupies complete clusters its size is usually very big. With the default values of cluster_size=64KB and refcount_bits=16 this table holds 8192 entries, each one of them enough to map 2GB worth of host clusters. So unless we're using images with several TB of allocated data this table is going to be mostly empty, and iterating over it is a waste of CPU. If the storage backend is fast enough this can have an effect on I/O performance. This patch keeps the index of the last used (i.e. non-zero) entry in the refcount table and updates it every time the table changes. The refcount-block overlap check then uses that index instead of reading the whole table. In my tests with a 4GB qcow2 file stored in RAM this doubles the amount of write IOPS. Signed-off-by: Alberto Garcia <berto@igalia.com> Message-id: 20170201123828.4815-1-berto@igalia.com Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
2016-11-11qcow2: Remove stale FIXME commentAlberto Garcia
It was from the time when none of the global functions had a qcow2_ prefix. Signed-off-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-10-24qcow2: Support BDRV_REQ_MAY_UNMAPFam Zheng
Handling this is similar to what is done to the L2 entry in the case of compressed clusters. Signed-off-by: Fam Zheng <famz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2016-09-15Remove unused function declarationsLadi Prosek
Unused function declarations were found using a simple gcc plugin and manually verified by grepping the sources. Signed-off-by: Ladi Prosek <lprosek@redhat.com> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
2016-06-16qcow2: Implement .bdrv_co_pwritev()Kevin Wolf
This changes qcow2 to implement the byte-based .bdrv_co_pwritev interface rather than the sector-based old one. As preallocation uses the same allocation function as normal writes, and the interface of that function needs to be changed, it is converted in the same patch. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2016-06-16qcow2: Use bytes instead of sectors for QCowL2MetaKevin Wolf
In preparation for implementing .bdrv_co_pwritev in qcow2. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2016-06-16qcow2: Implement .bdrv_co_preadv()Kevin Wolf
Reading from qcow2 images is now byte granularity. Most of the affected code in qcow2 actually gets simpler with this change. The only exception is encryption, which is fixed on 512 bytes blocks; in order to keep this working, bs->request_alignment is set for encrypted images. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2016-06-08qcow2: avoid extra flushes in qcow2Denis V. Lunev
The problem with excessive flushing was found by a couple of performance tests: - parallel directory tree creation (from 2 processes) - 32 cached writes + fsync at the end in a loop For the first one results improved from 2.6 loops/sec to 3.5 loops/sec. Each loop creates 10^3 directories with 10 files in each. For the second one results improved from ~600 fsync/sec to ~1100 fsync/sec. Though, it was run on SSD so it probably won't show such performance gain on rotational media. qcow2_cache_flush() calls bdrv_flush() unconditionally after writing cache entries of a particular cache. This can lead to as many as 2 additional fdatasyncs inside bdrv_flush. We can simply skip all fdatasync calls inside qcow2_co_flush_to_os as bdrv_flush for sure will do the job. These flushes are necessary to keep the right order of writes to the different caches. Though this is not necessary in the current code base as this ordering is ensured through the flush in qcow2_cache_flush_dependency(). Signed-off-by: Denis V. Lunev <den@openvz.org> CC: Pavel Borzenkov <pborzenkov@virtuozzo.com> CC: Kevin Wolf <kwolf@redhat.com> CC: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-12-18qcow2: Add function for refcount order amendmentMax Reitz
Add a function qcow2_change_refcount_order() which allows changing the refcount order of a qcow2 image. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-12-18block: Add opaque value to the amend CBMax Reitz
Add an opaque value which is to be passed to the bdrv_amend_options() status callback. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Alberto Garcia <berto@igalia.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2015-10-20coroutine: move into libqemuutil.a libraryDaniel P. Berrange
The coroutine files are currently referenced by the block-obj-y variable. The coroutine functionality though is already used by more than just the block code. eg migration code uses coroutine yield. In the future the I/O channel code will also use the coroutine yield functionality. Since the coroutine code is nicely self-contained it can be easily built as part of the libqemuutil.a library, making it widely available. The headers are also moved into include/qemu, instead of the include/block directory, since they are now part of the util codebase, and the impl was never in the block/ directory either. Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
2015-10-16qcow2: Remove forward declaration of QCowAIOCBKevin Wolf
This struct doesn't exist any more since commit 3fc48d09 in August 2011, it's about time to remove its forward declaration. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
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