Preventing cross-volume file moves in an overlay optimizer

A method, performed by an overlay optimizer that includes an overlay-managing write filter, for preventing a cross-volume move from being performed when a file is moved from a folder that exists on a protected volume to a folder that exists on an overlay cache implemented on a separate volume, the method comprising:

• receiving a first I/O operation that attempts to open a file stored in a first folder;
• obtaining a process ID associated with the first I/O operation;
• determining a source volume where the file is stored and storing an association between the process ID and the source volume;
• receiving a second I/O operation that attempts to create a file in a second folder;
• obtaining a process ID associated with the second I/O operation;
• determining that the process ID associated with the second I/O operation matches the process ID associated with the first I/O operation;
• determining that the source volume is a protected volume;
• determining whether the second folder exists on the protected volume such that:
• when the second folder exists on the protected volume, the overlay optimizer allows the second I/O operation to create the file in the second folder on the protected volume;
• whereas
• when the second folder does not exist on the protected volume, the overlay optimizer redirects the second I/O operation to cause the file to be created in an overlay cache implemented on a separate volume.

A method, performed by an overlay optimizer that includes an overlay-managing write filter, for preventing a cross-volume move from being performed when a file is moved to a folder that exists on a protected volume from a folder that exists on an overlay cache implemented on a separate volume, the method comprising:

• receiving a first I/O operation that attempts to open a file stored in a first folder;
• obtaining a process ID associated with the first I/O operation;
• determining a source volume where the file is stored and storing an association between the process ID and the source volume;
• receiving a second I/O operation that attempts to create a file in a second folder;
• determining that the second I/O operation is associated with the separate volume on which the overlay cache is implemented;
• obtaining a process ID associated with the second I/O operation;
• determining that the process ID associated with the second I/O operation matches the process ID associated with the first I/O operation;
• determining that the source volume is the protected volume;
• determining that the second folder exists on the protected volume;
• creating the second folder on the separate volume;
• and
• modifying the second I/O operation to cause the file to be created in the second folder on the separate volume rather than in the second folder on the protected volume.