Apple Inc.

Other

Owen Strain

Wenguang Wang

Deric S Horn

David Alexander Majnemer

Joseph Sokol, Jr

Methods and apparatuses that maintain birth time for a file system to optimize file update operations are described. The file system can include a plurality of snapshots or clones of data stored in one or more extents of blocks allocated in a storage device. Each extent may be associated with a time stamp according to the birth time. A request may be received from an executable using the file system to update data in a particular extent associated with a particular time stamp. In response, the current birth time in the file system and the particular time stamp may be compared to determine if the particular extent is not shared by more than one of the snapshots. If the particular time stamp is equal to the current birth time, the particular extent may be updated directly without performing an expensive operation to check whether a reference count of the particular extent is equal to one.

Methods and apparatuses to optimize updates in a file system based on birth time

The present technology includes an optimized b-tree. To improve concurrent access, a read lock can be applied to traversed nodes of a b-tree in a lock coupling. A read locked node can be promoted to a write locked node upon a determination that the node is likely to be modified, wherein the locked node first restricts access to further functions and then applies a write lock to the node when all existing functions accessing the node end. If one of the other functions attempts to promote the later function can be canceled and removed from the tree. A node can be promoted if the node is likely to be modified when considering multiple factors such as type of function, whether it is a leaf node, the number of keys in the node, or the number of keys in a child node.

Optimized b-tree

Disclosed herein are systems, methods, and non-transitory computer-readable storage media for performing in-place encryption. A system configured to practice the method receives a request from a user to encrypt an unencrypted volume of a computing device and identifies, generates, and/or randomly selects a volume key. Then the system converts the unencrypted volume to an encryptable format divided into portions. The system then encrypts, based on the volume key, the encryptable volume, portion by portion, to enable the user to use the computing device while encrypting. The system can maintain an encryption progress status and display the encryption progress status. The system can monitor disk accesses to the encryptable volume, and, when the disk accesses exceed a first threshold, apply a back-off algorithm to stop encrypting until the disk accesses fall below a second threshold. Thus, the computing device can be used while the encryption occurs in the background.

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Owen Strain