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path: root/block/qcow2-refcount.c
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2014-03-13qcow2-refcount: Sanitize refcount table entryMax Reitz1-1/+2
When reading the refcount table entry in get_refcount(), only bits which are actually significant for the refcount block offset should be taken into account. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Laszlo Ersek <lersek@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2014-02-09qcow2: fix offset overflow in qcow2_alloc_clusters_at()Hu Tao1-1/+7
When cluster size is big enough it can lead to an offset overflow in qcow2_alloc_clusters_at(). This patch fixes it. The allocation is stopped each time at L2 table boundary (see handle_alloc()), so the possible maximum bytes could be 2^(cluster_bits - 3 + cluster_bits) cluster_bits - 3 is used to compute the number of entry by L2 and the additional cluster_bits is to take into account each clusters referenced by the L2 entries. so int is safe for cluster_bits<=17, unsafe otherwise. Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Benoit Canet <benoit@irqsave.net> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-12-06qcow2: use start_of_cluster() and offset_into_cluster() everywhereHu Tao1-11/+11
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com> Reviewed-by: Fam Zheng <famz@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-10-11qcow2: Make overlap check mask variableMax Reitz1-1/+1
Replace the QCOW2_OL_DEFAULT macro by a variable overlap_check in BDRVQcowState. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-10-11qcow2: Use negated overflow check maskMax Reitz1-12/+10
In qcow2_check_metadata_overlap and qcow2_pre_write_overlap_check, change the parameter signifying the checks to perform from its current positive form to a negative one, i.e., it will no longer explicitly specify every check to perform but rather a mask of checks not to perform. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-10-11qcow2: Free preallocated zero clustersMax Reitz1-3/+5
In qcow2_free_any_clusters, preallocated zero clusters should be freed just as normal clusters are. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-10-11qcow2: Use pread for inactive L1 in overlap checkMax Reitz1-4/+3
Currently, qcow2_check_metadata_overlap uses bdrv_read to read inactive L1 tables from disk. The number of sectors to read is calculated through a truncating integer division, therefore, if the L1 table size is not a multiple of the sector size, the final entries will not be read and their entries in memory remain undefined (from the g_malloc). Using bdrv_pread fixes this. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-10-02qcow2: CHECK_OFLAG_COPIED is obsoleteMax Reitz1-3/+1
CHECK_OFLAG_COPIED as a parameter to check_refcounts_l1 and check_refcounts_l2 is obselete now, since the OFLAG_COPIED consistency check is actually no longer performed by these functions (but by check_oflag_copied). Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-10-02qcow2: Correct endianness in overlap checkMax Reitz1-2/+2
If an inactive L1 table is loaded from disk, its entries are in big endian and have to be converted to host byte order before using them. Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-09-25qcow2: Don't shadow return valueMax Reitz1-1/+0
When trying to update the refcounts for a snapshot, the return value of update_refcount on a compressed cluster was pretty much ignored, cancelling the update on error but returning 0. This is caused by an inner "ret" variable shadowing the outer one (the latter is used in the return statement). Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-09-12qcow2-cluster: Expand zero clustersMax Reitz1-14/+15
Add functionality for expanding zero clusters. This is necessary for downgrading the image version to one without zero cluster support. For non-backed images, this function may also just discard zero clusters instead of truly expanding them. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-09-02qcow2-refcount: Repair shared refcount blocksMax Reitz1-2/+146
If the refcount of a refcount block is greater than one, we can at least try to repair that problem by duplicating the affected block. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-08-30qcow2-refcount: Repair OFLAG_COPIED errorsMax Reitz1-6/+52
Since the OFLAG_COPIED checks are now executed after the refcounts have been repaired (if repairing), it is safe to assume that they are correct but the OFLAG_COPIED flag may be not. Therefore, if its value differs from what it should be (considering the according refcount), that discrepancy can be repaired by correctly setting (or clearing that flag. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-08-30qcow2-refcount: Move OFLAG_COPIED checksMax Reitz1-33/+82
Move the OFLAG_COPIED checks out of check_refcounts_l1 and check_refcounts_l2 and after the actual refcount checks/fixes (since the refcounts might actually change there). Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-08-30qcow2: Metadata overlap checksMax Reitz1-0/+172
Two new functions are added; the first one checks a given range in the image file for overlaps with metadata (main header, L1 tables, L2 tables, refcount table and blocks). The second one should be used immediately before writing to the image file as it calls the first function and, upon collision, marks the image as corrupt and makes the BDS unusable, thereby preventing further access. Both functions take a bitmask argument specifying the structures which should be checked for overlaps, making it possible to also check metadata writes against colliding with other structures. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-08-30qcow2-refcount: Snapshot update for zero clustersMax Reitz1-17/+35
Account for all cluster types in qcow2_update_snapshot_refcounts; this prevents this function from updating the refcount of unallocated zero clusters which effectively led to wrong adjustments of the refcount of cluster 0 (the main qcow2 header). This in turn resulted in images with (unallocated) zero clusters having a cluster 0 refcount greater than one after creating a snapshot. Signed-off-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-06-24qcow2: Batch discardsKevin Wolf1-3/+79
This optimises the discard operation for freed clusters by batching discard requests (both snapshot deletion and bdrv_discard end up updating the refcounts cluster by cluster). Note that we don't discard asynchronously, but keep s->lock held. This is to avoid that a freed cluster is reallocated and written to while the discard is still in flight. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-06-24qcow2: Options to enable discard for freed clustersKevin Wolf1-0/+5
Deleted snapshots are discarded in the image file by default, discard requests take their default from the -drive discard=... option and other places that free clusters must always be enabled explicitly. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-06-24qcow2: Add refcount update reason to all callersKevin Wolf1-21/+34
This adds a refcount update reason to all callers of update_refcounts(), so that a follow-up patch can use this information to decide whether clusters that reach a refcount of 0 should be discarded in the image file. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-04-05qcow2: Fix L1 write error handling in qcow2_update_snapshot_refcountKevin Wolf1-6/+8
It ignored the error code, and at least the 'goto fail' is obvious nonsense as it creates an endless loop (if the next attempt doesn't magically succeed) and leaves the in-memory L1 table in big-endian instead of converting it back. In error cases, there's no point in writing an updated L1 table, so skip this part for them. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-04-05qcow2: Return real error in qcow2_update_snapshot_refcountKevin Wolf1-6/+5
This fixes the error message triggered by the following script: cat > /tmp/blkdebug.cfg <<EOF [inject-error] event = "cluster_free" errno = "28" immediately = "off" EOF $qemu_img create -f qcow2 test.qcow2 10G $qemu_img snapshot -c snap test.qcow2 $qemu_img snapshot -d snap blkdebug:/tmp/blkdebug.cfg:test.qcow2 Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-03-28qcow2: Fix "total clusters" number in bdrv_checkKevin Wolf1-1/+3
This should be based on the virtual disk size, not on the size of the image. Interesting observation: With some VM state stored in the image file, percentages higher than 100% are possible, even though snapshots themselves are ignored. This is a qcow2 bug to be fixed another day: The VM state should be discarded in the active L2 tables after completing the snapshot creation. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-03-15qcow2: drop unnecessary flush in qcow2_update_snapshot_refcount()Stefan Hajnoczi1-4/+0
We already flush when the function completes. There is no need to flush after every compressed cluster. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-03-15qcow2: drop flush in update_cluster_refcount()Stefan Hajnoczi1-2/+0
The update_cluster_refcount() function increments/decrements a cluster's refcount and then returns the new refcount value. There is no need to flush since both update_cluster_refcount() callers already take care of this: 1. qcow2_alloc_bytes() calls update_cluster_refcount() when compressed sectors will be appended to an existing cluster with enough free space. qcow2_alloc_bytes() already flushes so there is no need to do so in update_cluster_refcount(). 2. qcow2_update_snapshot_refcount() sets a cache dependency on refcounts if it needs to update L2 entries. It also flushes before completing. Removing this flush significantly speeds up qcow2 snapshot creation: $ qemu-img create -f qcow2 test.qcow2 -o size=50G,preallocation=metadata $ time qemu-img snapshot -c new test.qcow2 Time drops from more than 3 minutes to under 1 second. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-03-15qcow2: flush in qcow2_update_snapshot_refcount()Stefan Hajnoczi1-1/+1
Users of qcow2_update_snapshot_refcount() do not flush consistently. qcow2_snapshot_create() flushes but qcow2_snapshot_goto() and qcow2_snapshot_delete() do not. Solve this by moving the bdrv_flush() into qcow2_update_snapshot_refcount(). Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-03-15qcow2: set L2 cache dependency in qcow2_alloc_bytes()Stefan Hajnoczi1-1/+5
Compressed writes use qcow2_alloc_bytes() to allocate space with byte granularity. The affected clusters' refcounts will be incremented but we do not need to flush yet. Set a L2 cache dependency on the refcount block cache, so that the refcounts get written out before the L2 updates. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-03-15qcow2: flush refcount cache correctly in alloc_refcount_block()Stefan Hajnoczi1-2/+8
update_refcount() affects the refcount cache, it does not write to disk. Therefore bdrv_flush(bs->file) does nothing. We need to flush the refcount cache in order to write out the refcount updates! While we're here also add error returns when qcow2_cache_flush() fails. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-02-22qcow2: support compressed clusters in BlockFragInfoStefan Hajnoczi1-0/+1
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-02-22qcow2: record fragmentation statistics during checkStefan Hajnoczi1-1/+24
The qemu-img check command can display fragmentation statistics: * Total number of clusters in virtual disk * Number of allocated clusters * Number of fragmented clusters This patch adds fragmentation statistics support to qcow2. Compressed and normal clusters count as allocated. Zero clusters are not counted as allocated unless their L2 entry has a non-zero offset (e.g. preallocation). Only the current L1 table counts towards the statistics - snapshots are ignored. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-02-22qcow2: introduce check_refcounts_l1/l2() flagsStefan Hajnoczi1-6/+12
The check_refcounts_l1/l2() functions have a check_copied argument to check that the QCOW_O_COPIED flag is consistent with refcount == 1. This should be a bool, not an int. However, the next patch introduces qcow2 fragmentation statistics and also needs to pass an option to check_refcounts_l1/l2(). This is a good opportunity to use an int flags field. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-02-22qemu-img: find the image end offset during checkFederico Simoncelli1-2/+8
This patch adds the support for reporting the image end offset (in bytes). This is particularly useful after a conversion (or a rebase) where the destination is a block device in order to find the first unused byte at the end of the image. Signed-off-by: Federico Simoncelli <fsimonce@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2013-01-30g_malloc(0) and g_malloc0(0) return NULL; simplifyMarkus Armbruster1-5/+1
Once upon a time, it was decided that qemu_malloc(0) should abort. Switching to glib retired that bright idea. Some code that was added to cope with it (e.g. in commits 702ef63, b76b6e9) is still around. Bury it. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2012-12-19block: move include files to include/block/Paolo Bonzini1-1/+1
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-11-14qcow2: Fix refcount table size calculationKevin Wolf1-1/+2
A missing factor for the refcount table entry size in the calculation could mean that too little memory was allocated for the in-memory representation of the table, resulting in a buffer overflow. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Michael Tokarev <mjt@tls.msk.ru> Tested-by: Michael Tokarev <mjt@tls.msk.ru>
2012-07-09qcow2: preserve free_byte_offset when qcow2_alloc_bytes() failsStefan Hajnoczi1-3/+4
When qcow2_alloc_clusters() error handling code was introduced in commit 5d757b563d59142ca81e1073a8e8396750a0ad1a, the value of free_byte_offset was clobbered in the error case. This patch keeps free_byte_offset at 0 so we will try to allocate clusters again next time this function is called. Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15qcow2: always operate caches in writeback modePaolo Bonzini1-12/+0
Writethrough does not need special-casing anymore in the qcow2 caches. The block layer adds flushes after every guest-initiated data write, and these will also flush the qcow2 caches to the OS. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15qcow2: Support for fixing refcount inconsistenciesKevin Wolf1-9/+34
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15qcow2: fix endianness conversionZhi Yong Wu1-1/+1
Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20qcow2: Support reading zero clustersKevin Wolf1-0/+7
This adds support for reading zero clusters in version 3 images. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20qcow2: Ignore reserved bits in check_refcountsKevin Wolf1-44/+54
Also don't infer the cluster type directly from the L2 entries, but use qcow2_get_cluster_type() to keep everything in a single place. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20qcow2: Ignore reserved bits in refcount table entriesKevin Wolf1-1/+1
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20qcow2: Refactor qcow2_free_any_clustersKevin Wolf1-19/+22
Zero clusters will add another cluster type. Refactor the open-coded cluster type detection into a switch of QCOW2_CLUSTER_* options so that the detection is in a single place. This makes it easier to add new cluster types. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20qcow2: Ignore reserved bits in L1/L2 entriesKevin Wolf1-6/+6
This changes the still existing places that assume that the only flags are QCOW_OFLAG_COPIED and QCOW_OFLAG_COMPRESSED to properly mask out reserved bits. It does not convert bdrv_check yet. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20qcow2: Fix refcount block allocation during qcow2_alloc_cluster_at()Kevin Wolf1-0/+6
Refcount block allocation and refcount table growth rely on s->free_cluster_index pointing to somewhere after the current allocation. Change qcow2_alloc_cluster_at() to fulfill this assumption. Without this change it could happen that a newly allocated refcount block and the allocated data block point to the same area in the image file, causing data corruption in the long run. This fixes a bug that became first visible after commit 250196f1. Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-19qcow2: Fix return value of alloc_refcount_blockKevin Wolf1-1/+1
Someone forgot something in commit 29c1a730... Documenting the right return value is not enough, you also need to actually return it in the code. This bug sometimes causes error return values even when everything has succeeded: The new offset of the refcount block is truncated to 32 bits and interpreted as signed. At least with small cluster sizes it's easy to get a negative return value this way. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
2012-03-12qcow2: Add qcow2_alloc_clusters_at()Kevin Wolf1-0/+28
This function allows to allocate clusters at a given offset in the image file. This is useful if you want to allocate the second part of an area that must be contiguous. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-12-05qcow2: Fix order of refcount updates in qcow2_snapshot_gotoKevin Wolf1-1/+6
The refcount updates must be moved so that in the worst case we can get cluster leaks, but refcounts may never be too low. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-08-25qcow2: remove unused qcow2_create_refcount_update functionFrediano Ziglio1-18/+0
Signed-off-by: Frediano Ziglio <freddy77@gmail.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-08-25qcow2: use always stderr for debuggingFrediano Ziglio1-2/+2
let all DEBUG_ALLOC2 printf goes to stderr Signed-off-by: Frediano Ziglio <freddy77@gmail.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-08-20Use glib memory allocation and free functionsAnthony Liguori1-17/+17
qemu_malloc/qemu_free no longer exist after this commit. Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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