block: Use g_new() & friends to avoid multiplying sizes

g_new(T, n) is safer than g_malloc(sizeof(*v) * n) for two reasons.
One, it catches multiplication overflowing size_t. Two, it returns
T * ra

block: Use g_new() & friends to avoid multiplying sizes

g_new(T, n) is safer than g_malloc(sizeof(*v) * n) for two reasons.
One, it catches multiplication overflowing size_t. Two, it returns
T * rather than void *, which lets the compiler catch more type
errors.

Perhaps a conversion to g_malloc_n() would be neater in places, but
that's merely four years old, and we can't use such newfangled stuff.

This commit only touches allocations with size arguments of the form
sizeof(T), plus two that use 4 instead of sizeof(uint32_t). We can
make the others safe by converting to g_malloc_n() when it becomes
available to us in a couple of years.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

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qcow2: Handle failure for potentially large allocations

Some code in the block layer makes potentially huge allocations. Failure
is not completely unexpected there, so avoid aborting qemu and handle

qcow2: Handle failure for potentially large allocations

Some code in the block layer makes potentially huge allocations. Failure
is not completely unexpected there, so avoid aborting qemu and handle
out-of-memory situations gracefully.

This patch addresses the allocations in the qcow2 block driver.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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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 ne

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>

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qcow2-cache: Empty cache

Add a function for emptying a cache, i.e., flushing it and marking all
elements invalid.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redha

qcow2-cache: Empty cache

Add a function for emptying a cache, i.e., flushing it and marking all
elements invalid.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

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qcow2: Employ metadata overlap checks

The pre-write overlap check function is now called before most of the
qcow2 writes (aborting it on collision or other error).

Signed-off-by: Max Reitz <mreitz@

qcow2: Employ metadata overlap checks

The pre-write overlap check function is now called before most of the
qcow2 writes (aborting it on collision or other error).

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

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block: move include files to include/block/

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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 w

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>

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qcow2: Add some tracing

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

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>

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

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>

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Reorganize struct Qcow2Cache for better struct packing

Move size after the two pointers in struct Qcow2Cache to get better
packing of struct elements on 64 bit architectures.

Signed-off-by: Jes Sor

Reorganize struct Qcow2Cache for better struct packing

Move size after the two pointers in struct Qcow2Cache to get better
packing of struct elements on 64 bit architectures.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

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qcow2: Batch flushes for COW

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 cach

qcow2: Batch flushes for COW

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>

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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>

qcow2: Add QcowCache

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 wh

qcow2: Add QcowCache

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>

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