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Providing multiple concurrent access to a file system

  • US 7,849,098 B1
  • Filed: 02/06/2004
  • Issued: 12/07/2010
  • Est. Priority Date: 02/06/2004
  • Status: Active Grant
First Claim
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1. A method for attempting to access a first data entity in a file system, the method being performed by a first computing entity, the file system also including one or more additional data entities that are concurrently accessible to at least one other computing entity, the method comprising:

  • the first computing entity attempting to obtain a lease for itself on the first data entity without needing another computing entity acting on its behalf, by reading, using a processor, an owner field included in the file system that can be used to determine whether the first data entity is leased by a computing entity and a time field included in the file system that can be used to determine whether a lease for the first data entity has expired and;

    if the owner field indicates that the first data entity is not currently leased, the first computing entity writing to the owner field in the file system to indicate an assumption of a lease of the first data entity and writing to the time field in the file system to indicate when the lease expires;

    elseif the owner field indicates that the first data entity has been leased, the first computing entity reading the time field in the file system and;

    if the time field indicates that the lease has expired, the first computing entity writing to the owner field in the file system to break the existing lease and to indicate an assumption of a new lease and the first computing entity writing to the time field in the file system to indicate when the new lease expires;

    elseif the time field indicates that the lease is still active, concluding that the first data entity is currently unavailable; and

    if a lease is obtained, the first computing entity accessing the first data entity while the lease is in effect.

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