1. A file-sharing system comprising: a first file server ( 200 , 1800 ) including a first scan processing section ( 290 , 1810 ) configured to scan data included in a file to generate predetermined information, the first file server ( 200 , 1800 ) being configured to provide a file to a client terminal ( 100 ) based on a virtual file system ( 360 ) that is generated by virtually merging a first file system ( 370 , 380 ) and a second file system ( 490 ); and a second file server ( 400 , 1900 ) including a second scan processing section ( 460 , 1910 ) and the second file system ( 490 ), the second scan processing section ( 460 , 1910 ) being configured to scan data included in a file to generate predetermined information, wherein: the first scan processing section ( 290 , 1810 ), in response to a first scan processing request for files included in the first and second file systems ( 370 , 380 , 490 ) issued by a management terminal ( 110 ), executes scan processing to the files included in the first file system ( 370 , 380 ) based on the virtual file system ( 360 ), and sends a second scan processing request to the second file server ( 400 , 1900 ) to execute scan processing to the files included in the second file system ( 490 ), the second scan processing section ( 400 , 1910 ), in response to the second scan processing request received, executes scan processing to the target files and sends the scan processing result to the first file server ( 200 , 1800 ), and the first file server ( 200 , 1800 ) merges the scan processing result obtained with the first scan processing section ( 290 , 1810 ) and the scan processing result obtained with the second scan processing section ( 460 , 1910 ), and provides the merged result to the management terminal ( 110 ).