Efficient, robust file handle invalidation

A method for efficiently generating and validating external file handles at a storage operating system of a storage system, the method comprising:

• associating a unique internal file handle with each file or directory stored on the storage system, the unique internal file handle used by the storage operating system when transferring the unique internal file handle's associated file or directory between a disk and memory of the storage system;
• generating an external file handle for the file or directory at the storage operating system;
• and
• in response to receiving the external file handle at the storage system, determining whether the external file handle is valid based on the result of one or more validity tests performed by the storage operating system, wherein the one or more validity tests determine that the external file handle is valid if at least one of the following criteria is satisfied:
• (a) the external file handle is formatted according to a stateful protocol;
• (b) no storage volumes loaded by the storage operating system were in use when an NVRAM memory in the storage system failed;
• and
• (c) a storage volume containing the file or directory was not in use when an NVRAM memory in the storage system failed.

A method for efficiently validating external file handles at a storage operating system of a storage system having an NVRAM memory, the method comprising:

• receiving an external file handle at the storage system;
• and
• determining that the external file handle is valid if at least one of the following criteria is satisfied:
• (a) the external file handle is formatted according to a stateful protocol;
• (b) a global nvfail count equals zero, the global nvfail count indicating the total number of times storage volumes loaded in the storage system were in use when the NVRAM memory failed;
• and
• (c) an nvfail count value equals zero, the nvfail count value indicating the number of times a storage volume containing a file or directory referenced by the external file handle was in use when the NVRAM memory failed;
• and
• if none of the criteria (a)–(c) is satisfied, then determining whether the external file handle is valid by comparing the external file handle to a unique internal file handle in the storage operating system.

A method for efficiently generating and validating external file handles at a storage operating system of a storage system, the method comprising:

• associating a unique internal file handle with each file or directory stored on the storage system, the unique internal file handle used by the storage operating system when transferring the unique internal file handle's associated file or directory between a disk and memory of the storage system;
• generating an external file handle for the file or directory at the storage operating system;
• in response to receiving the external file handle at the storage system, determining whether the external file handle is valid based on the result of one or more validity tests performed by the storage operating system;
• and
• determining that the external file handle is valid if the external file handle is formatted according to a stateful protocol.

A method for efficiently generating and validating external file handles at a storage operating system of a storage system, the method comprising:

• associating a unique internal file handle with each file or directory stored on the storage system, the unique internal file handle used by the storage operating system when transferring the unique internal file handle's associated file or directory between a disk and memory of the storage system;
• generating an external file handle for the file or directory at the storage operating system;
• in response to receiving the external file handle at the storage system, determining whether the external file handle is valid based on the result of one or more validity tests performed by the storage operating system;
• and
• determining that the external file handle is valid if no storage volumes loaded by the storage operating system were in use when a non-volatile memory in the storage system failed.

A method for efficiently generating and validating external file handles at a storage operating system of a storage system, the method comprising:

• associating a unique internal file handle with each file or directory stored on the storage system, the unique internal file handle used by the storage operating system when transferring the unique internal file handle's associated file or directory between a disk and memory of the storage system;
• generating an external file handle for the file or directory at the storage operating system;
• in response to receiving the external file handle at the storage system, determining whether the external file handle is valid based on the result of one or more validity tests performed by the storage operating system;
• and
• determining that the external file handle is valid if a storage volume containing the file or directory was not in use when a non-volatile memory in the storage system failed.

A method for efficiently generating and validating external file handles at a storage operating system of a storage system, the method comprising:

• associating a unique internal file handle with each file or directory stored on the storage system, the unique internal file handle used by the storage operating system when transferring the unique internal file handle's associated file or directory between a disk and memory of the storage system;
• generating an external file handle for the file or directory at the storage operating system using a file-access protocol engine;
• adjusting the value of a generation number contained in the unique internal file handle using non-volatile memory failure information;
• and
• in response to receiving the external file handle at the storage system, determining whether the external file handle is valid based on the result of one or more validity tests performed by the storage operating system.

A method for using an external file handle at a storage system, the method comprising:

• maintaining a backup copy of client requests in a non-volatile memory in the storage system;
• calculating, in response to a client-access request, an internal generation number for the requested file or directory;
• calculating a non-volatile memory failure (nvfail) count indicating a number of failures of the non-volatile memory;
• calculating, in response to the internal generation number and the nvfail count, an external generation number;
• and
• calculating, in response to the external generation number, a current external file handle.

A computer system, comprising:

• a non-volatile memory;
• means for associating a unique internal file handle with a file or directory stored by the computer system, the unique internal file handle used for transferring the file or directory between a disk and memory in the computer system;
• and
• means for generating an external file handle for the file or directory by combining non-volatile memory failure (“nvfail”) information with the unique internal file handle.

A system for efficiently generating external file handles, comprising:

• a memory configured to store instructions for execution by a processor, at least a portion of the instructions embodying a storage operating system configured to perform the steps of:
• associating a unique internal file handle with each file or directory stored on a storage system, the unique internal file handle used by the storage operating system when transferring the unique internal file handle's associated file or directory between a disk and memory of the storage system;
• and
• generating an external file handle for the file or directory at the storage operating system by combining NVRAM-failure (“nvfail”) information with the unique internal file handle.

A computer readable media, comprising:

• said computer readable media having instructions written thereon for execution on a processor for the practice of efficiently generating external file handles at a storage operating system of a storage system having an NVRAM memory comprising the steps of:
• associating a unique internal file handle with each file or directory stored on the storage system, the unique internal file handle used by the storage operating system when transferring the unique internal file handle's associated file or directory between a disk and memory of the storage system;
• and
• generating an external file handle for the file or directory at the storage operating system by combining NVRAM-failure (“nvfail”) information with the unique internal file handle.