Rapid incremental backup of changed files in a file system

A method for use in rapid incremental backup of changed files in a file system, the method comprising:

• scanning a file system hierarchy of a file system in a top-down manner for determining a list of changed files for performing incremental backup of the file system;
• evaluating a directory tree modification attribute of each directory hierarchy of the file system hierarchy of the file system in the top-down manner, wherein the file system hierarchy includes a set of directory hierarchies, each directory hierarchy including a set of directories, each directory of the set of directories including a set of files, wherein the directory tree modification attribute of each directory hierarchy indicates whether at least one file in respective entire directory hierarchy has changed since a last backup, wherein the directory tree modification attribute is updated upon finding at least one changed file in the respective directory hierarchy since the last backup and without changing a modification time of a directory associated with the respective directory tree hierarchy;
• based on the evaluation, determining that a file of a directory hierarchy is being changed by a file system access operation for a first time since the last backup, and upon determining that the file is being changed by the file system access operation for the first time since the last backup, placing the file in a queue, and servicing the queue in background to update a directory tree modification attribute of the directory hierarchy;
• based on the determination, determining whether the directory hierarchy has been changed since the last backup;
• and
• based on the determination, determining whether to skip traversing the directory hierarchy during the scanning of the file system hierarchy for determining the list of changed files for performing incremental backup of the file system upon determining that the directory hierarchy has not been changed since the last backup.

A system for use in rapid incremental backup of changed files in a file system, the system comprising:

• a processor;
• first logic, for execution by the processor, to scanning a file system hierarchy of a file system in a top-down manner for determining a list of changed files for performing incremental backup of the file system;
• second logic, for execution by the processor, to evaluate a directory tree modification attribute of each directory hierarchy of the file system hierarchy of the file system in the top-down manner, wherein the file system hierarchy includes a set of directory hierarchies, each directory hierarchy including a set of directories, each directory of the set of directories including a set of files, wherein the directory tree modification attribute of each directory hierarchy indicates whether at least one file in respective entire directory hierarchy has changed since a last backup, wherein the directory tree modification attribute is updated upon finding at least one changed file in the respective directory hierarchy since the last backup and without changing a modification time of a directory associated with the respective directory tree hierarchy;
• third logic, for execution by the processor, to determine, based on the evaluation, whether a directory hierarchy of the file system hierarchy has been changed since the last backup;
• and
• fourth logic, for execution by the processor, to skip traversing, based on the determination, files included in a directory hierarchy during the scanning of the file system hierarchy upon determining that the directory tree modification attribute associated with the directory hierarchy has not been updated since the last backup.