Hello Lucian, On Fri, Jan 14, 2011 at 1:35 AM, Lucian Adrian Grijincu <lucian.grijincu@xxxxxxxxx> wrote: > This functionality landed in Linux 2.6.38 since: > > commit 79124f18b335172e1916075c633745e12dae1dac > Author: Josef Bacik <josef@xxxxxxxxxx> > Date: Wed Nov 17 20:46:15 2010 -0500 > > fs: add hole punching to fallocate > > Hole punching has already been implemented by XFS and OCFS2, and has the > potential to be implemented on both BTRFS and EXT4 so we need a > generic way to > get to this feature. The simplest way in my mind is to add > FALLOC_FL_PUNCH_HOLE > to fallocate() since it already looks like the normal fallocate() operation. > I've tested this patch with XFS and BTRFS to make sure XFS did what it's > supposed to do and that BTRFS failed like it was supposed to. Thank you, > > CC: Josef Bacik <josef@xxxxxxxxxx> > CC: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Lucian Adrian Grijincu <lucian.grijincu@xxxxxxxxx> > --- > man2/fallocate.2 | 22 +++++++++++++++++++++- > 1 files changed, 21 insertions(+), 1 deletions(-) Pasting your patch back in line (which is preferred): ==== diff --git a/man2/fallocate.2 b/man2/fallocate.2 index 42eefbd..1279130 100644 --- a/man2/fallocate.2 +++ b/man2/fallocate.2 @@ -32,7 +32,7 @@ bytes. The .I mode argument determines the operation to be performed on the given range. -Currently only one flag is supported for +There are two flag values supported for .IR mode : .TP .B FALLOC_FL_KEEP_SIZE @@ -59,6 +59,26 @@ even if it is less than .\" All of the above flags were debated upon and we can not say .\" if any/which one of these flags will make it to the later kernels. .PP +.TP +.BR FALLOC_FL_PUNCH_HOLE " (since Linux 2.6.38) +Deallocate space inside a file in the byte range starting at +.I offset +and continuing for +.I len +bytes. +Partial filesystem blocks are zeroed, and +whole filesystem blocks are removed from the file. +Currently you can only have +.BR FALLOC_FL_PUNCH_HOLE +with +.BR FALLOC_FL_KEEP_SIZE +set, +so the file size (as reported by +.BR stat (2)) +does not change +when hole punching, even when puching the end of +a file off. +.PP If .B FALLOC_FL_KEEP_SIZE flag is not specified in ===== Josef actually sent me a patch describing FALLOC_FL_PUNCH_HOLE a while back which I never applied yet, but in some ways your patch is better (nice work!), so I'll apply your patch, and add some fixes from Josef's patch afterwards. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Author of "The Linux Programming Interface"; http://man7.org/tlpi/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
