Commit Graph

195 Commits

Author SHA1 Message Date
Max Reitz
a134d90f50 qcow2: Fix fail path in realloc_refcount_block()
If qcow2_alloc_clusters() fails, new_offset and ret will both be
negative after the fail label, thus passing the first if condition and
subsequently resulting in a call of qcow2_free_clusters() with an
invalid (negative) offset parameter. Fix this by introducing a new label
"fail_free_cluster" which is only invoked if new_offset is indeed
pointing to a newly allocated cluster that should be cleaned up by
freeing it.

While we're at it, clean up the whole fail path. qcow2_cache_put()
should (and actually can) never fail, hence the return value can safely
be ignored (aside from asserting that it indeed did not fail).

Furthermore, there is no reason to give QCOW2_DISCARD_ALWAYS to
qcow2_free_clusters(), a mere QCOW2_DISCARD_OTHER will suffice.

Ultimately, rename the "fail" label to "done", as it is invoked both on
failure and success.

Suggested-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-03-19 09:39:41 +01:00
Max Reitz
8a15b813e6 qcow2: Correct comment for realloc_refcount_block()
Contrary to the comment describing this function's behavior, it does not
return 0 on success, but rather the offset of the newly allocated
cluster. This patch adjusts the comment accordingly to reflect the
actual behavior.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2014-03-19 09:39:41 +01:00
Max Reitz
26d49c4675 qcow2-refcount: Sanitize refcount table entry
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>
2014-03-13 14:23:27 +01:00
Hu Tao
33304ec9fa qcow2: fix offset overflow in qcow2_alloc_clusters_at()
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>
2014-02-09 09:12:39 +01:00
Hu Tao
ac95acdb8e qcow2: use start_of_cluster() and offset_into_cluster() everywhere
Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-12-06 16:53:50 +01:00
Max Reitz
3e3553905c qcow2: Make overlap check mask variable
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>
2013-10-11 16:50:00 +02:00
Max Reitz
231bb26764 qcow2: Use negated overflow check mask
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>
2013-10-11 16:50:00 +02:00
Max Reitz
8f730dd24e qcow2: Free preallocated zero clusters
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>
2013-10-11 16:49:59 +02:00
Max Reitz
998b959c1e qcow2: Use pread for inactive L1 in overlap check
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>
2013-10-11 16:49:59 +02:00
Max Reitz
db0749012b qcow2: CHECK_OFLAG_COPIED is obsolete
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>
2013-10-02 11:40:41 +02:00
Max Reitz
1e242b5544 qcow2: Correct endianness in overlap check
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>
2013-10-02 11:06:35 +02:00
Max Reitz
7454d60045 qcow2: Don't shadow return value
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>
2013-09-25 10:08:56 +02:00
Max Reitz
32b6444d23 qcow2-cluster: Expand zero clusters
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>
2013-09-12 10:12:46 +02:00
Max Reitz
afa50193cd qcow2-refcount: Repair shared refcount blocks
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>
2013-09-02 10:06:59 +02:00
Max Reitz
e23e400ec6 qcow2-refcount: Repair OFLAG_COPIED errors
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>
2013-08-30 15:48:44 +02:00
Max Reitz
4f6ed88c03 qcow2-refcount: Move OFLAG_COPIED checks
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>
2013-08-30 15:48:44 +02:00
Max Reitz
a40f1c2add qcow2: Metadata overlap checks
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>
2013-08-30 15:48:43 +02:00
Max Reitz
8b81a7b6ba qcow2-refcount: Snapshot update for zero clusters
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>
2013-08-30 15:28:52 +02:00
Kevin Wolf
0b919fae31 qcow2: Batch discards
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>
2013-06-24 10:25:17 +02:00
Kevin Wolf
67af674e47 qcow2: Options to enable discard for freed clusters
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>
2013-06-24 10:25:17 +02:00
Kevin Wolf
6cfcb9b8b9 qcow2: Add refcount update reason to all callers
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>
2013-06-24 10:25:17 +02:00
Kevin Wolf
c2b6ff51e4 qcow2: Fix L1 write error handling in qcow2_update_snapshot_refcount
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>
2013-04-05 18:58:05 +02:00
Kevin Wolf
c2bc78b6a9 qcow2: Return real error in qcow2_update_snapshot_refcount
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>
2013-04-05 18:58:05 +02:00
Kevin Wolf
c349ca4bb2 qcow2: Fix "total clusters" number in bdrv_check
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>
2013-03-28 11:52:42 +01:00
Stefan Hajnoczi
3647917919 qcow2: drop unnecessary flush in qcow2_update_snapshot_refcount()
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>
2013-03-15 16:07:50 +01:00
Stefan Hajnoczi
f9cb2860bd qcow2: drop flush in update_cluster_refcount()
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>
2013-03-15 16:07:50 +01:00
Stefan Hajnoczi
2154f24e4e qcow2: flush in qcow2_update_snapshot_refcount()
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>
2013-03-15 16:07:50 +01:00
Stefan Hajnoczi
c1f5bafd70 qcow2: set L2 cache dependency in qcow2_alloc_bytes()
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>
2013-03-15 16:07:50 +01:00
Stefan Hajnoczi
9991923b26 qcow2: flush refcount cache correctly in alloc_refcount_block()
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>
2013-03-15 16:07:49 +01:00
Stefan Hajnoczi
4db35162ea qcow2: support compressed clusters in BlockFragInfo
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2013-02-22 21:21:09 +01:00
Stefan Hajnoczi
fba31bae2d qcow2: record fragmentation statistics during check
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>
2013-02-22 21:21:09 +01:00
Stefan Hajnoczi
801f704452 qcow2: introduce check_refcounts_l1/l2() flags
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>
2013-02-22 21:21:09 +01:00
Federico Simoncelli
c6bb9ad198 qemu-img: find the image end offset during check
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>
2013-02-22 21:21:08 +01:00
Markus Armbruster
6528499fa4 g_malloc(0) and g_malloc0(0) return NULL; simplify
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>
2013-01-30 11:14:46 +01:00
Paolo Bonzini
737e150e89 block: move include files to include/block/
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2012-12-19 08:31:31 +01:00
Kevin Wolf
a354807706 qcow2: Fix refcount table size calculation
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>
2012-11-14 18:19:21 +01:00
Stefan Hajnoczi
206e6d8551 qcow2: preserve free_byte_offset when qcow2_alloc_bytes() fails
When qcow2_alloc_clusters() error handling code was introduced in commit
5d757b563d, 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>
2012-07-09 15:53:01 +02:00
Paolo Bonzini
6af4e9ead4 qcow2: always operate caches in writeback mode
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>
2012-06-15 14:03:43 +02:00
Kevin Wolf
166acf546f qcow2: Support for fixing refcount inconsistencies
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-06-15 14:03:42 +02:00
Zhi Yong Wu
87267753a3 qcow2: fix endianness conversion
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>
2012-06-15 14:03:42 +02:00
Kevin Wolf
6377af48b0 qcow2: Support reading zero clusters
This adds support for reading zero clusters in version 3 images.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20 15:57:29 +02:00
Kevin Wolf
afdf0abe77 qcow2: Ignore reserved bits in check_refcounts
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>
2012-04-20 15:57:29 +02:00
Kevin Wolf
76dc9e0c8f qcow2: Ignore reserved bits in refcount table entries
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2012-04-20 15:57:29 +02:00
Kevin Wolf
c7a4c37a0f qcow2: Refactor qcow2_free_any_clusters
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>
2012-04-20 15:57:28 +02:00
Kevin Wolf
8e37f681d5 qcow2: Ignore reserved bits in L1/L2 entries
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>
2012-04-20 15:57:28 +02:00
Kevin Wolf
f24423bd90 qcow2: Fix refcount block allocation during qcow2_alloc_cluster_at()
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>
2012-04-20 15:56:19 +02:00
Kevin Wolf
2795ecf681 qcow2: Fix return value of alloc_refcount_block
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>
2012-04-19 16:03:27 +02:00
Kevin Wolf
256900b16b qcow2: Add qcow2_alloc_clusters_at()
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>
2012-03-12 15:14:07 +01:00
Kevin Wolf
43a0cac465 qcow2: Fix order of refcount updates in qcow2_snapshot_goto
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>
2011-12-05 14:51:36 +01:00
Frediano Ziglio
2f4b759367 qcow2: remove unused qcow2_create_refcount_update function
Signed-off-by: Frediano Ziglio <freddy77@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-08-25 15:23:10 +02:00
Frediano Ziglio
35ee5e39c5 qcow2: use always stderr for debugging
let all DEBUG_ALLOC2 printf goes to stderr

Signed-off-by: Frediano Ziglio <freddy77@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-08-25 15:22:25 +02:00
Anthony Liguori
7267c0947d Use glib memory allocation and free functions
qemu_malloc/qemu_free no longer exist after this commit.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2011-08-20 23:01:08 -05:00
Kevin Wolf
93913dfd8a qcow2: Use Qcow2Cache in writeback mode during loadvm/savevm
In snapshotting there is no guest involved, so we can safely use a writeback
mode and do the flushes in the right place (i.e. at the very end). This
improves the time that creating/restoring an internal snapshot takes with an
image in writethrough mode.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-07-19 15:39:22 +02:00
Kevin Wolf
80fa3341a7 qcow2: Fix memory leaks in error cases
This fixes memory leaks that may be caused by I/O errors during L1 table growth
(can happen during save_vm) and in qemu-img check.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-06-08 11:56:40 +02:00
Stefan Weil
a1c7273b82 Fix typos in comments and code (occured -> occurred and related)
The code changed here is an unused data type name (evt_flush_occurred).

Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2011-05-08 10:02:18 +01:00
Blue Swirl
1869a65385 qcow2-refcount: remove write-only variables
Variables l2_modified and l2_size are not really used, remove them.
Spotted by GCC 4.6.0:
  CC    block/qcow2-refcount.o
/src/qemu/block/qcow2-refcount.c: In function 'qcow2_update_snapshot_refcount':
/src/qemu/block/qcow2-refcount.c:708:37: error: variable 'l2_modified' set but not used [-Werror=unused-but-set-variable]
/src/qemu/block/qcow2-refcount.c:708:9: error: variable 'l2_size' set but not used [-Werror=unused-but-set-variable]

CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2011-01-31 10:05:34 +01:00
Kevin Wolf
29c1a7301a qcow2: Use QcowCache
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>
2011-01-24 16:41:49 +01:00
Kevin Wolf
1c02e2a171 qcow2: Invalidate cache after failed read
The cache content may be destroyed after a failed read, better not use it any
more.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
2010-11-04 13:54:37 +01:00
Blue Swirl
83e3f76c25 block: avoid a write only variable
Compiling with GCC 4.6.0 20100925 produced a warning:
/src/qemu/block/qcow2-refcount.c: In function 'update_refcount':
/src/qemu/block/qcow2-refcount.c:552:13: error: variable 'dummy' set but not used [-Werror=unused-but-set-variable]

Fix by adding a dummy cast so that the result is not unused.

Acked-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2010-10-13 18:38:07 +00:00
Kevin Wolf
29216ed14f qcow2: Move sync out of qcow2_alloc_clusters
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-09-21 15:39:42 +02:00
Kevin Wolf
1c4c28149f qcow2: Move sync out of update_refcount
Note that the flush is omitted intentionally in qcow2_free_clusters. If
anything, we can leak clusters here if we lose the writes.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-09-21 15:39:42 +02:00
Kevin Wolf
c01828fb51 qcow2: Move sync out of write_refcount_block_entries
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-09-21 15:39:42 +02:00
Kevin Wolf
9ac228e02c qcow2/vdi: Change check to distinguish error cases
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>
2010-07-06 17:05:49 +02:00
Kevin Wolf
f74550fd53 qcow2: Don't try to check tables that couldn't be loaded
Trying to check them leads to a second error message which is more confusing
than helpful:

    Can't get refcount for cluster 0: Invalid argument
    ERROR cluster 0 refcount=-22 reference=1

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-22 14:38:02 +02:00
Kevin Wolf
6882c8fa78 qcow2: Fix qemu-img check segfault on corrupted images
With corrupted images, we can easily get an cluster index that exceeds the
array size of the temporary refcount table.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-22 14:38:02 +02:00
Kevin Wolf
8b3b720620 qcow2: Use bdrv_(p)write_sync for metadata writes
Use bdrv_(p)write_sync to ensure metadata integrity in case of a crash.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-22 14:38:02 +02:00
Kevin Wolf
e14e8ba5d0 qcow2: Return real error code in load_refcount_block
This fixes load_refcount_block which completely ignored the return value of
write_refcount_block and always returned -EIO for bdrv_pwrite failure.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-15 09:41:58 +02:00
Kevin Wolf
2eaa8f6338 qcow2: Allow alloc_clusters_noref to return errors
Currently it would consider blocks for which get_refcount fails used. However,
it's unlikely that get_refcount would succeed for the next cluster, so it's not
really helpful. Return an error instead.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-15 09:41:58 +02:00
Kevin Wolf
018faafdbd qcow2: Allow get_refcount to return errors
get_refcount might need to load a refcount block from disk, so errors may
happen. Return the error code instead of assuming a refcount of 1 and change
the callers to respect error return values.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-06-15 09:41:58 +02:00
Kevin Wolf
86fa8da837 qcow2: Fix corruption after error in update_refcount
After it is done with updating refcounts in the cache, update_refcount writes
all changed entries to disk. If a refcount block allocation fails, however,
there was no change yet and therefore first_index = last_index = -1. Don't
treat -1 as a normal sector index (resulting in a 512 byte write!) but return
without updating anything in this case.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-28 13:29:16 +02:00
Kevin Wolf
25408c0950 qcow2: Fix corruption after refblock allocation
Refblock allocation code needs to take into consideration that update_refcount
will load a different refcount block into the cache, so it must initialize the
cache for a new refcount block only afterwards. Not doing this means that not
only the refcount in the wrong block is updated, but also that the caller will
work on the wrong block.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-28 13:29:15 +02:00
Kevin Wolf
ed0df867d9 qcow2: Return right error code in write_refcount_block_entries
write_refcount_block_entries used to return -EIO for any errors. Change this to
return the real error code.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-28 13:29:13 +02:00
Kevin Wolf
003fad6e2c qcow2: Remove abort on free_clusters failure
While it's true that during regular operation free_clusters failure would be a
bug, an I/O error can always happen. There's no need to kill the VM, the worst
thing that can happen (and it will) is that we leak some clusters.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-03 10:07:32 +02:00
Stefan Hajnoczi
508e089368 qcow2: Avoid shadowing variable in alloc_clusters_noref()
The i loop iterator is shadowed by the next free cluster index.  Both
using the variable name 'i' makes the code harder to read.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-03 10:07:31 +02:00
Kevin Wolf
66f82ceed6 block: Open the underlying image file in generic code
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>
2010-05-03 10:07:30 +02:00
Kevin Wolf
8252278afb qcow2: Trigger blkdebug events
This adds blkdebug events to qcow2 to allow injecting I/O errors in specific
places.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-04-23 16:08:46 +02:00
Kevin Wolf
746c3cb5d5 qcow2: More checks for qemu-img check
Implement some more refcount block related checks

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-02-23 13:23:29 -06:00
Kevin Wolf
92dcb59fd4 qcow2: Rewrite alloc_refcount_block/grow_refcount_table
The current implementation of alloc_refcount_block and grow_refcount_table has
fundamental problems regarding error handling. There are some places where an
I/O error means that the image is going to be corrupted. I have found that the
only way to fix this is to completely rewrite the thing.

In detail, the problem is that the refcount blocks itself are allocated using
alloc_refcount_noref (to avoid endless recursion when updating the refcount of
the new refcount block, which migh access just the same refcount block but its
allocation is not yet completed...). Only at the end of the refcount allocation
the refcount of the refcount block is increased. If an error happens in
between, the refcount block is in use, but has a refcount of zero and will
likely be overwritten later.

The new approach is explained in comments in the code. The trick is basically
to let new refcount blocks describe their own refcount, so their refcount will
be automatically changed when they are hooked up in the refcount table.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-02-23 13:23:29 -06:00
Kevin Wolf
05121aedc4 qcow2: Factor next_refcount_table_size out
When the refcount table grows, it doesn't only grow by one entry but reserves
some space for future refcount blocks. The algorithm to calculate the number of
entries stays the same with the fixes, so factor it out before replacing the
rest.

As Juan suggested take the opportunity to simplify the code a bit.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-02-23 13:23:29 -06:00
Kevin Wolf
5d757b563d qcow2: Don't ignore qcow2_alloc_clusters return value
Now that qcow2_alloc_clusters can return error codes, we must handle them in
the callers of qcow2_alloc_clusters.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-26 14:59:19 -06:00
Kevin Wolf
db3a964fb6 qcow2: Don't ignore update_refcount return value
update_refcount can return errors that need to be handled by the callers.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-26 14:59:19 -06:00
Kevin Wolf
7322afe7ea qcow2: Allow updating no refcounts
There's absolutely no problem with updating the refcounts of 0 clusters.
At least snapshot code is doing this and would fail once the result of
update_refcount isn't ignored any more.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-26 14:59:19 -06:00
Kevin Wolf
09508d13f3 qcow2: Improve error handling in update_refcount
If update_refcount fails, try to undo any changes made so far to avoid
inconsistencies in the image file.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-26 14:59:19 -06:00
Kevin Wolf
f2b7c8b370 qcow2: Fix error handling in grow_refcount_table
Return the appropriate error code instead of -EIO.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-26 14:59:19 -06:00
Amit Shah
f7dcfac024 qcow2-refcount: remove dead assignment
clang-analyzer points out a redundant assignment.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2010-01-13 17:14:15 -06:00
Kevin Wolf
702ef63f3e qcow2: Fix some more qemu_malloc fallout
Oh joy...

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-12-03 11:45:50 -06:00
Kevin Wolf
c5baaa489f qcow2: Fix grow_refcount_table error handling
In case of failure, we haven't increased the refcount for the newly allocated
cluster yet. Therefore we must not free the cluster or its refcount will become
negative (and endless recursion is possible).

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-10-27 12:28:35 -05:00
Kevin Wolf
80ee15a6b2 qcow2: Increase maximum cluster size to 2 MB
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>
2009-10-05 09:32:52 -05:00
Blue Swirl
0bf9e31af1 Fix most warnings (errors with -Werror) when debugging is enabled
I used the following command to enable debugging:
perl -p -i -e 's/^\/\/#define DEBUG/#define DEBUG/g' * */* */*/*

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
2009-07-20 17:19:25 +00:00
Kevin Wolf
3f6a3ee51e qcow2: Fix L1 table memory allocation
Contrary to what one could expect, the size of L1 tables is not cluster
aligned. So as we're writing whole sectors now instead of single entries,
we need to ensure that the L1 table in memory is large enough; otherwise
write would access memory after the end of the L1 table.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-07-10 13:44:29 -05:00
Kevin Wolf
3b88e52b41 qcow2: Cache refcount blocks during snapshot creation
The really time consuming part of snapshotting is to adjust the reference count
of all clusters. Currently after each adjusted cluster the refcount block is
written to disk.

Don't write each single byte immediately to disk but cache all writes to the
refcount block and write them out once we're done with the block.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-29 14:18:07 -05:00
Kevin Wolf
9923e05e1a update_refcount: Write complete sectors
When updating the refcount blocks in update_refcount(), write complete sectors
instead of updating single entries.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-06-16 15:18:37 -05:00
Kevin Wolf
ed6ccf0f51 qcow2: Rename global functions
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>
2009-06-16 15:18:36 -05:00
Kevin Wolf
45aba42fba qcow2: Split out guest cluster functions
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>
2009-06-16 15:18:36 -05:00
Kevin Wolf
f7d0fe0239 qcow2: Split out refcount handling
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>
2009-06-16 15:18:36 -05:00