On Wed, May 18, 2016 at 10:52:25AM -0700, Liu Bo wrote:
> On Wed, May 18, 2016 at 11:41:05AM +0200, David Sterba wrote:
> > On Tue, May 17, 2016 at 05:21:48PM -0700, Liu Bo wrote:
> > > btrfs's fiemap is supposed to return 0 on success and
> > > return < 0 on error, however, ret becomes 1 after looking
> > > up the last file extent, and if the offset is beyond EOF,
> > > we can return 1.
> > >
> > > This may confuse applications using ioctl(FIEL_IOC_FIEMAP).
> > >
> > > Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
> >
> > Reviewed-by: David Sterba <dsterba@xxxxxxxx>
> >
> > > ---
> > > fs/btrfs/extent_io.c | 6 +++++-
> > > 1 file changed, 5 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> > > index d247fc0..16ece52 100644
> > > --- a/fs/btrfs/extent_io.c
> > > +++ b/fs/btrfs/extent_io.c
> > > @@ -4379,8 +4379,12 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
> > > if (ret < 0) {
> > > btrfs_free_path(path);
> > > return ret;
> > > + } else {
> > > + WARN_ON(!ret);
> > > + if (ret == 1)
> > > + ret = 0;
> > > }
> >
> > So, ret == 1 can end up here from btrfs_lookup_file_extent ->
> > btrfs_search_slot(..., ins_len=0, cow=0) and the offset does not exist,
> > we'll get path pointed to the slot where it would be inserted and ret is 1.
>
> Sounds better than the commit log, would you like me to update it?
Done.
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