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....@oracle.com>
>
> Reviewed-by: David Sterba <dste...@suse.com>
>
> > ---
> > 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?
Thanks,
-liubo
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