[lkml]   [2011]   [Sep]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] fallocate.2: add FALLOC_FL_PUNCH_HOLE flag definition
Hello Andreas,

On Wed, Sep 21, 2011 at 7:25 AM, Andreas Dilger <> wrote:
> On 2011-09-20, at 10:11 PM, Michael Kerrisk wrote:
>> Thanks for this patch. As noted in another mail, Lucian also sent a
>> patch for FALLOC_FL_PUNCH_HOLE, and I applied his patch first, and
>> then added some pieces from yours, as well as some of my own edits.
>> However, the addition of a second class of operation to the man page
>> made it clear that some significant restructuring of the page is
>> required. So I substantially reworked the page, including the
>> preexisting material on the default "file allocation" operation (Dave
>> C please note).
>>  .TP
>> .I offset
>> was less than 0, or
>> .I len
>> was less than or equal to 0.
> I wasn't sure if this is a bug in the manpage or actually how it is done
> in the kernel, but it seems this is a kernel implementation issue...
> Does it make sense to return an error if len == 0?  That just adds extra
> complexity on the part of the application, and doesn't reduce complexity
> in the kernel (whether the kernel checks for len == 0 and returns 0 or
> -EINVAL is not any different).  read() and write() and malloc() all allow
> a length of zero to succeed, since applications may compute this length
> and sometimes it is zero.

Good point. I agree: for comfort of userspace application writers and
for consistency with related interfaces, len == 0 shouldn't be an



Michael Kerrisk
Linux man-pages maintainer;
Author of "The Linux Programming Interface";
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2011-09-21 07:53    [W:0.040 / U:4.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site