Re: [PATCH] Btrfs: fix unexpected -EEXIST when creating new inode

[Liu Bo <bo.li.liu@oracle.com>]

On Wed, Feb 28, 2018 at 04:06:40PM +0000, Filipe Manana wrote:
> On Thu, Jan 25, 2018 at 6:02 PM, Liu Bo <bo.li.liu@oracle.com> wrote:
> > The highest objectid, which is assigned to new inode, is decided at
> > the time of initializing fs roots.  However, in cases where log replay
> > gets processed, the btree which fs root owns might be changed, so we
> > have to search it again for the highest objectid, otherwise creating
> > new inode would end up with -EEXIST.
> >
> > cc: <stable@vger.kernel.org> v4.4-rc6+
> > Fixes: f32e48e92596 ("Btrfs: Initialize btrfs_root->highest_objectid when loading tree root and subvolume roots")
> > Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
> 
> Hi Bo,
> 
> Any reason to not have submitted a test case for fstests?
> Unless I missed something this should be easy to reproduce, deterministic issue.
>

It's on my todo list for a while until I forgot it...will do after I
fix the bugs I have now.

I found this originally from running generic/475.

Thanks,

-liubo
> thanks
> 
> > ---
> >  fs/btrfs/tree-log.c | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> >
> > diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
> > index a7e6235..646cdbf 100644
> > --- a/fs/btrfs/tree-log.c
> > +++ b/fs/btrfs/tree-log.c
> > @@ -28,6 +28,7 @@
> >  #include "hash.h"
> >  #include "compression.h"
> >  #include "qgroup.h"
> > +#include "inode-map.h"
> >
> >  /* magic values for the inode_only field in btrfs_log_inode:
> >   *
> > @@ -5715,6 +5716,24 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
> >                                                       path);
> >                 }
> >
> > +               if (!ret && wc.stage == LOG_WALK_REPLAY_ALL) {
> > +                       struct btrfs_root *root = wc.replay_dest;
> > +
> > +                       btrfs_release_path(path);
> > +
> > +                       /*
> > +                        * We have just replayed everything, and the highest
> > +                        * objectid of fs roots probably has changed in case
> > +                        * some inode_item's got replayed.
> > +                        */
> > +                       /*
> > +                        * root->objectid_mutex is not acquired as log replay
> > +                        * could only happen during mount.
> > +                        */
> > +                       ret = btrfs_find_highest_objectid(root,
> > +                                                 &root->highest_objectid);
> > +               }
> > +
> >                 key.offset = found_key.offset - 1;
> >                 wc.replay_dest->log_root = NULL;
> >                 free_extent_buffer(log->node);
> > --
> > 2.9.4
> >
> > --
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> 
> 
> 
> -- 
> Filipe David Manana,
> 
> “Whether you think you can, or you think you can't — you're right.”