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path: root/block/qcow2.h
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2011-01-31qcow2: Add bdrv_discard supportKevin Wolf1-0/+2
This adds a bdrv_discard function to qcow2 that frees the discarded clusters. It does not yet pass the discard on to the underlying file system driver, but the space can be reused by future writes to the image. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-01-24qcow2: Batch flushes for COWKevin Wolf1-0/+1
qcow2 calls bdrv_flush() after performing COW in order to ensure that the L2 table change is never written before the copy is safe on disk. Now that the L2 table is cached, we can wait with flushing until we write out the next L2 table. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-01-24qcow2: Use QcowCacheKevin Wolf1-5/+7
Use the new functions of qcow2-cache.c for everything that works on refcount block and L2 tables. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-01-24qcow2: Add QcowCacheKevin Wolf1-0/+19
This adds some new cache functions to qcow2 which can be used for caching refcount blocks and L2 tables. When used with cache=writethrough they work like the old caching code which is spread all over qcow2, so for this case we have merely a cleanup. The interesting case is with writeback caching (this includes cache=none) where data isn't written to disk immediately but only kept in cache initially. This leads to some form of metadata write batching which avoids the current "write to refcount block, flush, write to L2 table" pattern for each single request when a lot of cluster allocations happen. Instead, cache entries are only written out if its required to maintain the right order. In the pure cluster allocation case this means that all metadata updates for requests are done in memory initially and on sync, first the refcount blocks are written to disk, then fsync, then L2 tables. This improves performance of scenarios with lots of cluster allocations noticably (e.g. installation or after taking a snapshot). Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-11-24block: Remove unused s->hd in various driversKevin Wolf1-1/+0
All drivers use bs->file instead of s->hd for quite a while now, so it's time to remove s->hd. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2010-10-22Copy snapshots out of QCOW2 diskedison1-0/+1
In order to backup snapshots, created from QCOW2 iamge, we want to copy snapshots out of QCOW2 disk to a seperate storage. The following patch adds a new option in "qemu-img": qemu-img convert -f qcow2 -O qcow2 -s snapshot_name src_img bck_img. Right now, it only supports to copy the full snapshot, delta snapshot is on the way. Changes from V1: all the comments from Kevin are addressed: Add read-only checking Fix coding style Change the name from bdrv_snapshot_load to bdrv_snapshot_load_tmp Signed-off-by: Disheng Su <edison@cloud.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-10-22qcow2: Support exact L1 table growthStefan Hajnoczi1-1/+1
The L1 table grow operation includes a size calculation that bumps up the new L1 table size in order to anticipate the size needs of vmstate data. This helps reduce the number of times that the L1 table has to be grown when vmstate data is appended. This size overhead is not necessary during image creation, bdrv_truncate(), or snapshot goto operations. In fact, existing qemu-iotests that exercise table growth are no longer able to trigger it because image creation preallocates an L1 table that is too large after changes to qcow_create2(). This patch keeps the size calculation but also adds exact growth for callers that do not want to inflate the L1 table size unnecessarily. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-09-21qcow2: Avoid bounce buffers for AIO read requestsKevin Wolf1-2/+2
qcow2 used to use bounce buffers for any AIO requests. This does not only imply unnecessary copying, but also unbounded allocations which should be avoided. This patch removes bounce buffers from the normal AIO read path, and constrains them to a constant size for encrypted images. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-07-06qcow2/vdi: Change check to distinguish error casesKevin Wolf1-1/+1
This distinguishes between harmless leaks and real corruption. Hopefully users better understand what qemu-img check wants to tell them. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-28qcow2: Allow qcow2_get_cluster_offset to return errorsKevin Wolf1-2/+2
qcow2_get_cluster_offset() looks up a given virtual disk offset and returns the offset of the corresponding cluster in the image file. Errors (e.g. L2 table can't be read) are currenctly indicated by a return value of 0, which is unfortuately the same as for any unallocated cluster. So in effect we can't check for errors. This makes the old return value a by-reference parameter and returns the usual 0/-errno error code. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-03qcow2: Implement bdrv_truncate() for growing imagesStefan Hajnoczi1-0/+6
This patch adds the ability to grow qcow2 images in-place using bdrv_truncate(). This enables qemu-img resize command support for qcow2. Snapshots are not supported and bdrv_truncate() will return -ENOTSUP. The notion of resizing an image with snapshots could lead to confusion: users may expect snapshots to remain unchanged, but this is not possible with the current qcow2 on-disk format where the header.size field is global instead of per-snapshot. Others may expect snapshots to change size along with the current image data. I think it is safest to not support snapshots and perhaps add behavior later if there is a consensus. Backing images continue to work. If the image is now larger than its backing image, zeroes are read when accessing beyond the end of the backing image. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-03block: Open the underlying image file in generic codeKevin Wolf1-1/+1
Format drivers shouldn't need to bother with things like file names, but rather just get an open BlockDriverState for the underlying protocol. This patch introduces this behaviour for bdrv_open implementation. For protocols which need to access the filename to open their file/device/connection/... a new callback bdrv_file_open is introduced which doesn't get an underlying file opened. For now, also some of the more obscure formats use bdrv_file_open because they open() the file themselves instead of using the block.c functions. They need to be fixed in later patches. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-02-10qcow2: Fix signedness bugsKevin Wolf1-4/+2
Checking for return codes < 0 isn't really going to work with unsigned types. Use signed types instead. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-26qcow2: Return 0/-errno in qcow2_alloc_cluster_offsetKevin Wolf1-2/+2
Returning 0/-errno allows it to distingush different errors classes. The cluster offset of newly allocated clusters is now returned in the QCowL2Meta struct. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-10-27Revert "qcow2: Bring synchronous read/write back to life"Kevin Wolf1-3/+0
It was merely a workaround and the real fix is done now. This reverts commit ef845c3bf421290153154635dc18eaa677cecb43. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-10-15qcow2: Bring synchronous read/write back to lifeKevin Wolf1-0/+3
When the synchronous read and write functions were dropped, they were replaced by generic emulation functions. Unfortunately, these emulation functions don't provide the same semantics as the original functions did. The original bdrv_read would mean that we read some data synchronously and that we won't be interrupted during this read. The latter assumption is no longer true with the emulation function which needs to use qemu_aio_poll and therefore allows the callback of any other concurrent AIO request to be run during the read. Which in turn means that (meta)data read earlier could have changed and be invalid now. qcow2 is not prepared to work in this way and it's just scary how many places there are where other requests could run. I'm not sure yet where exactly it breaks, but you'll see breakage with virtio on qcow2 with a backing file. Providing synchronous functions again fixes the problem for me. Patchworks-ID: 35437 Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-10-05qcow2: Increase maximum cluster size to 2 MBKevin Wolf1-1/+1
This patch increases the maximum qcow2 cluster size to 2 MB. Starting with 128k clusters, L2 tables span 2 GB or more of virtual disk space, causing 32 bit truncation and wraparound of signed integers. Therefore some variables need to use a larger data type. While being at reviewing data types, change some integers that are used for array indices to unsigned. In some places they were checked against some upper limit but not for negative values. This could avoid potential segfaults with corrupted qcow2 images. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-09-12Fix sys-queue.h conflict for goodBlue Swirl1-3/+3
Problem: Our file sys-queue.h is a copy of the BSD file, but there are some additions and it's not entirely compatible. Because of that, there have been conflicts with system headers on BSD systems. Some hacks have been introduced in the commits 15cc9235840a22c289edbe064a9b3c19c5f49896, f40d753718c72693c5f520f0d9899f6e50395e94, 96555a96d724016e13190b28cffa3bc929ac60dc and 3990d09adf4463eca200ad964cc55643c33feb50 but the fixes were fragile. Solution: Avoid the conflict entirely by renaming the functions and the file. Revert the previous hacks. Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2009-09-09qcow2: Order concurrent AIO requests on the same unallocated clusterKevin Wolf1-0/+7
When two AIO requests write to the same cluster, and this cluster is unallocated, currently both requests allocate a new cluster and the second one merges the first one when it is completed. This means an cluster allocation, a read and a cluster deallocation which cause some overhead. If we simply let the second request wait until the first one is done, we improve overall performance with AIO requests (specifially, qcow2/virtio combinations). This patch maintains a list of in-flight requests that have allocated new clusters. A second request touching the same cluster is limited so that it either doesn't touch the allocation of the first request (so it can have a non-overlapping allocation) or it waits for the first request to complete. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-29Fix QCOW2 debugging code to compile againFilip Navara1-0/+4
Updated to use C99 comments. Signed-off-by: Filip Navara <filip.navara@gmail.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-16qcow2: Rename global functionsKevin Wolf1-27/+27
The qcow2 source is now split into several more manageable files. During the conversion quite some functions that were static before needed to be changed to be global to make the source compile again. We were lucky enough not to get name conflicts with these additional global names, but they are not nice. This patch adds a qcow2_ prefix to all of the global functions in qcow2. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-16qcow2: Split out snapshot functionsKevin Wolf1-0/+16
qcow2-snapshot.c contains the code related to snapshotting. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-16qcow2: Split out guest cluster functionsKevin Wolf1-2/+35
qcow2-cluster.c contains all functions related to the management of guest clusters, i.e. what the guest sees on its virtual disk. This code is about mapping these guest clusters to host clusters in the image file using the two-level lookup tables. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-16qcow2: Split out refcount handlingKevin Wolf1-0/+154
qcow2-refcount.c contains all functions which are related to cluster allocation and management in the image file. A large part of this is the reference counting of these clusters. Also a header file qcow2.h is introduced which will contain the interface of the split qcow2 modules. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>