Hi, We are planning to add a new FOP to GlusterFS to exploit the WRITE SAME capability of the underlying block device in case of BD xlator. Linux has recently added support for WRITE SAME by means of a new ioctl (BLKZEROOUT) that can be used to zero-out a range of blocks. We are proposing the following FOP to support BLKZEROOUT ioctl in GlusterFS: int zerofill(struct glfs_fd *glfd, off_t offset, size_t len) This will zero-out the range of the file represented by @glfd, starting from @offset for @len bytes. Posix backend can implement the zerofill() in whatever way that is convenient/efficient, all it has do is to write zeroes to the file in the specified range. BD backend will issue ioctl(fd, BLKZEROOUT, params[2]) in response to zerofill(glfd, offset, len). param[0] is the starting sector number which should be derived from offset. param[1] is the nr_sectors which should be derived from len. Regards, Bharata. -- http://raobharata.wordpress.com/
