On the lseek man page (http://man7.org/linux/man-pages/man2/lseek.2.html), in its description of SEEK_DATA and SEEK_HOLE it says that: The SEEK_HOLE and SEEK_DATA operations are supported for the following filesystems: * Btrfs (since Linux 3.1) * OCFS (since Linux 3.2) * XFS (since Linux 3.5) * ext4 (since Linux 3.8) * tmpfs(5) (since Linux 3.8) * NFS (since Linux 3.18) * FUSE (since Linux 4.5) I think that the reference to OCFS on the manpage should actually be to the OCFS2 file system. I think the 'OCFS (since Linux 3.2)' manpage reference is referring to this commit to OCFS2: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/fs?id=93862d5e1ab875664c6cc95254fc365028a48bb1 This OCFS2 commit was included as part of the Linux 3.2-rc4 drop (https://lwn.net/Articles/470337/). Can someone with more experience with OCFS and OCFS2 confirm that the manpage should be changed to OCFS2 instead of OCFS? Bill commit 93862d5e1ab875664c6cc95254fc365028a48bb1 Author: Sunil Mushran <sunil.mushran@xxxxxxxxxx> Date: Mon Jul 25 14:58:15 2011 -0700 ocfs2: Implement llseek() SEEK_HOLE sets the file pointer to the start of either a hole or an unwritten (preallocated) extent, that is greater than or equal to the supplied offset. SEEK_DATA sets the file pointer to the start of an allocated extent (not unwritten) that is greater than or equal to the supplied offset. If the supplied offset is on a desired region, then the file pointer is set to it. Offsets greater than or equal to the file size return -ENXIO. Unwritten (preallocated) extents are considered holes because the file system treats reads to such regions in the same way as it does to holes. Signed-off-by: Sunil Mushran <sunil.mushran@xxxxxxxxxx>
