Am 14.02.2017 um 20:25 hat Eric Blake geschrieben: > Passing a byte offset, but sector count, when we ultimately > want to operate on cluster granularity, is madness. Clean up > the external interfaces to take both offset and count as bytes, > while still keeping the assertion added previously that the > caller must align the values to a cluster. Then rename things > to make sure backports don't get confused by changed units: > instead of qcow2_discard_clusters() and qcow2_zero_clusters(), > we now have qcow2_cluster_discard() and qcow2_cluster_zeroize(). > > The internal functions still operate on clusters at a time, and > return an int for number of cleared clusters; but on an image > with 2M clusters, a single L2 table holds 256k entries that each > represent a 2M cluster, totalling well over INT_MAX bytes if we > ever had a request for that many bytes at once. All our callers > currently limit themselves to 32-bit bytes (and therefore fewer > clusters), but by making this function 64-bit clean, we have one > less place to clean up if we later improve the block layer to > support 64-bit bytes through all operations (with the block layer > auto-fragmenting on behalf of more-limited drivers), rather than > the current state where some interfaces are artificially limited > to INT_MAX at a time. > > Signed-off-by: Eric Blake <ebl...@redhat.com>
Reviewed-by: Kevin Wolf <kw...@redhat.com>
