On Sat, Mar 23, 2019 at 08:03:20PM +0100, Bernd Petrovitsch wrote: > Hi all! > > On 23/03/2019 17:59, Bharath Vedartham wrote: > [..] > > I was wondering how we can overwrite the copy functionality while > > writing our own filesystem in linux. > > VFS does not offer any sort of API for copy. I think it calls create and > > Yes. > > > write when we execute the copy the file/dir. > > I am interested in overwriting the way copy happens in my > > filesystem(which I am writing for fun :p). > > Any ideas? > > strace a "cp" and see which system calls are used. > Look into the source code and see how it's implemented. > > There is actually more than one method but the usual (while simplest, > most versatile and probably fastest) method used is: open source and > destination files, read from the source, write into the destination > until EOF. > I have observed that it is a mixture of system calls. I am interested in implementing copy-on-write in my filesystem(for fun). I feel that, it would require my creat vfs api to be aware of the fact that "cp" is calling it. I want to keep things as generic as possible. I ll proceed by reading the source of union filesystems (overlayfs) to see how they implement copy-on-write. > MfG, > Bernd > -- > Bernd Petrovitsch Email : bernd@xxxxxxxxxxxxxxxxxxx > LUGA : http://www.luga.at _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
