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| author | Max Reitz <mreitz@redhat.com> | 2015-02-10 15:28:46 -0500 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2015-03-10 14:02:21 +0100 |
| commit | 7324c10f96c821b00d691e2c8ced67d8536bf1d6 (patch) | |
| tree | 9f42bbfb21f1d40261aabcc18d4918610750b390 /block/qcow2.h | |
| parent | c6e9d8ae6629aaf3c6d483032d219b988d78583f (diff) | |
| download | qemu-7324c10f96c821b00d691e2c8ced67d8536bf1d6.tar.gz | |
qcow2: Only return status from qcow2_get_refcount
Refcounts can theoretically be of type uint64_t; in order to be able to
represent the full range, qcow2_get_refcount() cannot use a single
variable to represent both all refcount values and also keep some values
reserved for errors.
One solution would be to add an Error pointer parameter to
qcow2_get_refcount(); however, no caller could (currently) pass that
error message, so it would have to be emitted immediately and be
passed to the next caller by returning -EIO or something similar.
Therefore, an Error parameter does not offer any advantages here.
The solution applied by this patch is simpler to use. Because no caller
would be able to pass the error message, they would have to print it and
free it, whereas with this patch the caller only needs to pass the
returned integer (which is often a no-op from the code perspective,
because that integer will be stored in a variable "ret" which will be
returned by the fail path of many callers).
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block/qcow2.h')
| -rw-r--r-- | block/qcow2.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/block/qcow2.h b/block/qcow2.h index 55138c9d92..a33431f05a 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -478,7 +478,8 @@ void qcow2_signal_corruption(BlockDriverState *bs, bool fatal, int64_t offset, int qcow2_refcount_init(BlockDriverState *bs); void qcow2_refcount_close(BlockDriverState *bs); -int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index); +int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index, + uint16_t *refcount); int qcow2_update_cluster_refcount(BlockDriverState *bs, int64_t cluster_index, int addend, enum qcow2_discard_type type); |