Copy-offload on a device stack

Patent metadata

Field	Value
Publication number	US-9715351-B2
Application number	US-201514622754-A
Country	US
Kind code	B2
Filing date	Feb 13, 2015
Priority date	Feb 13, 2015
Publication date	Jul 25, 2017
Grant date	Jul 25, 2017

Abstract

A read request, a write request, and copy descriptor are constructed and sent to logical volumes of a device stack to complete a copy-offload operation between a source logical volume and a destination logical volume. The read request is forwarded to a source physical volume of a device stack and a write request is forwarded to a destination physical volume of the device stack. Responsive to detecting that the read request has been received by the source physical volume of the device stack and the write request has been received by a destination physical volume of the device stack, the driver of the source physical volume or the driver of the destination physical volume construct a copy-offload request to be sent to a storage device, the copy-offload request comprising the read request, the write request, and the copy descriptor. The copy-offload request is subsequently sent to the storage device.

First claim

What is claimed is:

1. A method comprising:
receiving, by a processing device, a request to copy data from a source logical volume of a device stack to a destination logical volume of the device stack, wherein the device stack comprises a source intermediate volume that associates the source logical volume with a source physical volume, and a destination intermediate volume that associates the destination logical volume with a destination physical volume;
constructing, by the processing device, a read request to be sent to the source logical volume to read the data and a write request to be sent to the destination logical volume to write the data;
constructing, by the processing device, a copy descriptor to be associated with the read request and the write request;
associating, by the processing device, the copy descriptor with the read request and the write request;
sending, by the processing device, the read request to the source logical volume and the write request to the destination logical volume;
causing, by the processing device, the read request to be forwarded to the source physical volume of the device stack and the write request to be forwarded to the destination physical volume of the device stack;
responsive to determining that the read request has failed at the source intermediate volume of the device stack, causing a driver of the source intermediate volume to terminate the write request;
responsive to determining that the write request has failed at the destination intermediate volume of the device stack, causing a driver of the destination intermediate volume to terminate the read request;
responsive to detecting that the read request has been received by the source physical volume of the device stack and the write request has been received by a destination physical volume of the device stack, causing one of a driver of the source physical volume or a driver of the destination physical volume to construct a copy-offload request to be sent to a storage device, the copy-offload request comprising the read request, the write request, and the copy descriptor; and
sending the copy-offload request to the storage device.

2. The method of claim 1 further comprising:
responsive to execution of the copy-offload request by the storage device, receiving a sense code from the storage device;
translating the sense code to an error code;
updating the descriptor with the error code; and
returning the error code to the source logical volume and the destination logical volume.

3. The method of claim 1 wherein causing the read request to be forwarded to the source physical volume comprises:
responsive to detecting that the device stack comprises one or more intermediate volumes that associate the source logical volume with the source physical volume, constructing an intermediate read request to be sent to each of the one or more intermediate volumes;
sending the intermediate read request to each of the one or more intermediate volumes.

4. The method of claim 3 wherein causing the write request to be forwarded to the destination physical volume comprises:
responsive to detecting that the device stack comprises one or more intermediate volumes that associate the destination logical volume with the destination physical volume, constructing an intermediate write request to be sent to each of the one or more intermediate volumes; and
sending the intermediate write request to each of the one or more intermediate volumes.

5. The method of claim 2 further comprising:
responsive to determining that the copy-offload request has failed, causing one of the driver of the source physical volume or the driver of the destination physical volume to reject additional copy requests from the source physical volume to the destination physical volume for a predetermined period of time.

6. A computing apparatus comprising:
a memory; and
a processing device, operatively coupled to the memory to:
cause, by the processing device, a read request to be forwarded to a source physical volume of a device stack and a write request to be forwarded to a destination physical volume of the device stack, wherein the device stack comprises a source intermediate volume that associates a source logical volume with the source physical volume, and a destination intermediate volume that associates a destination logical volume with the destination physical volume;
construct a copy descriptor to be associated with the read request and the write request;
associate the copy descriptor with the read request and the write request;
responsive to determining that the read request has failed at the source intermediate volume of the device stack, cause the driver of the source intermediate volume to terminate the write request;
responsive to determining that the write request has failed at the destination intermediate volume of the device stack, cause the driver of the destination intermediate volume to terminate the read request;
responsive to detecting that the read request has been received by the source physical volume of the device stack and the write request has been received by a destination physical volume of the device stack, cause one of a driver of the source physical volume or a driver of the destination physical volume to construct a copy-offload request to be sent to a storage device, the copy-offload request comprising the read request, the write request, and the copy descriptor; and
send the copy-offload request to the storage device.

7. The apparatus of claim 6 , wherein the processing device is further to:
construct the read request to be sent to the source logical volume and the write request to be sent to the destination logical volume; and
send the read request to the source logical volume and the write request to the destination logical volume.

8. The apparatus of claim 7 , wherein the processing device is further to:
responsive to execution of the copy-offload request by the storage device, receive a sense code from the storage device;
translate the sense code to an error code;
update the descriptor with the error code; and
return the error code to the source logical volume and the destination logical volume.

9. The apparatus of claim 7 wherein to cause the read request to be forwarded to the source physical volume, the processing device is to:
responsive to detecting that the device stack comprises one or more intermediate volumes that associate the source logical volume with the source physical volume, construct an intermediate read request to be sent to each of the one or more intermediate volumes;
send the intermediate read request to each of the one or more intermediate volumes.

10. The apparatus of claim 9 wherein to cause the write request to be forwarded to the destination physical volume, the processing device is to:
responsive to detecting that the device stack comprises one or more intermediate volumes that associate the destination logical volume with the destination physical volume, construct an intermediate write request to be sent to each of the one or more intermediate volumes; and
send the intermediate write request to each of the one or more intermediate volumes.

11. The apparatus of claim 8 , wherein the processing device is further to:
responsive to determining that the copy-offload request has failed, cause one of the driver of the source physical volume or the driver of the destination physical volume to reject additional copy requests from the source physical volume to the destination physical volume for a predetermined period of time.

12. A non-transitory computer readable storage medium, having instructions stored therein,

Assignees

• Red Hat Inc

Inventors

• Pato{Hacek Over (C)}Ka Mikulá{Hacek Over (S)}

Classifications

• G06F3/0683

  Plurality of storage devices · CPC title

• G06F11/0787

  Storage of error reports, e.g. persistent data storage, storage using memory protection · CPC title

• G06F11/0727

  in a storage system, e.g. in a DASD or network based storage system (drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097) · CPC title

• G06F3/0619

  in relation to data integrity, e.g. data losses, bit errors · CPC title

• G06F3/065 Primary

  Replication mechanisms · CPC title