I want to make you aware of a possible bug in the reflink handling of btrfs: When I reflink a file larger 2GB (on the same subvol), the reflinking fails. But it works fine for files smaller 2GB in size. I was able to track this down to btrfs with great support of Martin Raiber who created a small demo code: Source: https://urbackup.atlassian.net/secure/attachment/10201/reflink.cpp Compile: g++ reflink.cpp -o reflink Usage: reflink source-file destination-file Works if source-file is smaller 2GB and errors otherwise. Environment: Debian Wheezy 7.2 i386 --> 32 bit Kernel: 3.10.11-1~bpo70+1 (most recent from wheezy backports rep) Anything missing? I´m happy to provide additional input! ====snip===demo program source======= #include <iostream> #include <errno.h> #include <stdio.h> #include <sys/types.h> #include <fcntl.h> #include <sys/ioctl.h> #include <unistd.h> bool os_create_reflink(const char* linkname, const char* fname) { int src_desc=open(fname, O_RDONLY); if( src_desc<0) return false; int dst_desc=open(linkname, O_WRONLY | O_CREAT | O_EXCL, S_IRWXU | S_IRWXG); if( dst_desc<0 ) { close(src_desc); return false; } #define BTRFS_IOCTL_MAGIC 0x94 #define BTRFS_IOC_CLONE _IOW (BTRFS_IOCTL_MAGIC, 9, int) int rc=ioctl(dst_desc, BTRFS_IOC_CLONE, src_desc); close(src_desc); close(dst_desc); return rc==0; } int main(int argc, char* argv[]) { if(argc<3) { std::cout << "not enough arguments: reflink [source file] [dest file]" << std::endl; return 1; } if(!os_create_reflink(argv[2], argv[1])) { perror("reflink"); return 2; } return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
