mirror of https://github.com/ceph/go-ceph
137 lines
4.2 KiB
Go
137 lines
4.2 KiB
Go
package rbd
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/*
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#cgo LDFLAGS: -lrbd
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#undef _GNU_SOURCE
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#include <errno.h>
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#include <stdlib.h>
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#include <rbd/librbd.h>
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extern int callDiffIterateCallback(uint64_t ofs, size_t len, int exists, int index);
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// cgo is having trouble converting the callback from the librbd header
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// to a unsafe.Pointer. This shim exists solely to help it along.
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static inline int wrap_rbd_diff_iterate2(
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rbd_image_t image,
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const char *fromsnapname,
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uint64_t ofs, uint64_t len,
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uint8_t include_parent, uint8_t whole_object,
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void *cb,
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void *arg) {
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return rbd_diff_iterate2(image, fromsnapname, ofs, len, include_parent, whole_object, cb, arg);
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}
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*/
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import "C"
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import (
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"unsafe"
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"github.com/ceph/go-ceph/internal/callbacks"
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)
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var diffIterateCallbacks = callbacks.New()
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// DiffIncludeParent values control if the difference should include the parent
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// image.
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type DiffIncludeParent uint8
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// DiffWholeObject values control if the diff extents should cover the whole
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// object.
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type DiffWholeObject uint8
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// DiffIterateCallback defines the function signature needed for the
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// DiffIterate callback.
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//
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// The function will be called with the arguments: offset, length, exists, and
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// data. The offset and length correspond to the changed region of the image.
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// The exists value is set to zero if the region is known to be zeros,
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// otherwise it is set to 1. The data value is the extra data parameter that
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// was set on the DiffIterateConfig and is meant to be used for passing
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// arbitrary user-defined items to the callback function.
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//
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// The callback can trigger the iteration to terminate early by returning
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// a non-zero error code.
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type DiffIterateCallback func(uint64, uint64, int, interface{}) int
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// DiffIterateConfig is used to define the parameters of a DiffIterate call.
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// Callback, Offset, and Length should always be specified when passed to
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// DiffIterate. The other values are optional.
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type DiffIterateConfig struct {
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SnapName string
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Offset uint64
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Length uint64
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IncludeParent DiffIncludeParent
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WholeObject DiffWholeObject
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Callback DiffIterateCallback
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Data interface{}
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}
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const (
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// ExcludeParent will exclude the parent from the diff.
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ExcludeParent = DiffIncludeParent(0)
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// IncludeParent will include the parent in the diff.
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IncludeParent = DiffIncludeParent(1)
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// DisableWholeObject will not use the whole object in the diff.
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DisableWholeObject = DiffWholeObject(0)
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// EnableWholeObject will use the whole object in the diff.
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EnableWholeObject = DiffWholeObject(1)
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)
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// DiffIterate calls a callback on changed extents of an image.
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//
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// Calling DiffIterate will cause the callback specified in the
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// DiffIterateConfig to be called as many times as there are changed
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// regions in the image (controlled by the parameters as passed to librbd).
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//
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// See the documentation of DiffIterateCallback for a description of the
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// arguments to the callback and the return behavior.
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//
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// Implements:
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// int rbd_diff_iterate2(rbd_image_t image,
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// const char *fromsnapname,
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// uint64_t ofs, uint64_t len,
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// uint8_t include_parent, uint8_t whole_object,
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// int (*cb)(uint64_t, size_t, int, void *),
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// void *arg);
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func (image *Image) DiffIterate(config DiffIterateConfig) error {
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if err := image.validate(imageIsOpen); err != nil {
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return err
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}
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if config.Callback == nil {
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return RBDError(C.EINVAL)
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}
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var cSnapName *C.char
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if config.SnapName != NoSnapshot {
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cSnapName = C.CString(config.SnapName)
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defer C.free(unsafe.Pointer(cSnapName))
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}
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cbIndex := diffIterateCallbacks.Add(config)
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defer diffIterateCallbacks.Remove(cbIndex)
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ret := C.wrap_rbd_diff_iterate2(
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image.image,
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cSnapName,
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C.uint64_t(config.Offset),
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C.uint64_t(config.Length),
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C.uint8_t(config.IncludeParent),
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C.uint8_t(config.WholeObject),
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C.callDiffIterateCallback,
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unsafe.Pointer(uintptr(cbIndex)))
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return getError(ret)
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}
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//export diffIterateCallback
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func diffIterateCallback(
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offset C.uint64_t, length C.size_t, exists, index C.int) C.int {
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v := diffIterateCallbacks.Lookup(int(index))
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config := v.(DiffIterateConfig)
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return C.int(config.Callback(
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uint64(offset), uint64(length), int(exists), config.Data))
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}
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