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Message-ID: <f7d3e39f5ced7832d451de172004172b59a994eb.camel@ibm.com>
Date: Mon, 24 Feb 2025 22:09:21 +0000
From: Viacheslav Dubeyko <Slava.Dubeyko@....com>
To: "neilb@...e.de" <neilb@...e.de>
CC: "brauner@...nel.org" <brauner@...nel.org>, Xiubo Li <xiubli@...hat.com>,
"idryomov@...il.com" <idryomov@...il.com>,
Olga Kornievskaia
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Subject: RE: [PATCH 3/6] ceph: return the correct dentry on mkdir
On Mon, 2025-02-24 at 13:15 +1100, NeilBrown wrote:
> On Fri, 21 Feb 2025, Viacheslav Dubeyko wrote:
> > On Fri, 2025-02-21 at 10:36 +1100, NeilBrown wrote:
> > > ceph already splices the correct dentry (in splice_dentry()) from the
> > > result of mkdir but does nothing more with it.
> > >
> > > Now that ->mkdir can return a dentry, return the correct dentry.
> > >
> > > Signed-off-by: NeilBrown <neilb@...e.de>
> > > ---
> > > fs/ceph/dir.c | 9 ++++++++-
> > > 1 file changed, 8 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> > > index 39e0f240de06..c1a1c168bb27 100644
> > > --- a/fs/ceph/dir.c
> > > +++ b/fs/ceph/dir.c
> > > @@ -1099,6 +1099,7 @@ static struct dentry *ceph_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> > > struct ceph_client *cl = mdsc->fsc->client;
> > > struct ceph_mds_request *req;
> > > struct ceph_acl_sec_ctx as_ctx = {};
> > > + struct dentry *ret = NULL;
> >
> > I believe that it makes sense to initialize pointer by error here and always
> > return ret as output. If something goes wrong in the logic, then we already have
> > error.
>
> I'm not certain that I understand, but I have made a change which seems
> to be consistent with the above and included it below. Please let me
> know if it is what you intended.
>
> >
> > > int err;
> > > int op;
> > >
> > > @@ -1166,14 +1167,20 @@ static struct dentry *ceph_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> > > !req->r_reply_info.head->is_dentry)
> > > err = ceph_handle_notrace_create(dir, dentry);
> > > out_req:
> > > + if (!err && req->r_dentry != dentry)
> > > + /* Some other dentry was spliced in */
> > > + ret = dget(req->r_dentry);
> > > ceph_mdsc_put_request(req);
> > > out:
> > > if (!err)
> > > + /* Should this use 'ret' ?? */
> >
> > Could we make a decision should or shouldn't? :)
> > It looks not good to leave this comment instead of proper implementation. Do we
> > have some obstacles to make this decision?
>
> I suspect we should use ret, but I didn't want to make a change which
> wasn't directly required by my needed. So I highlighted this which
> looks to me like a possible bug, hoping that someone more familiar with
> the code would give an opinion. Do you agree that 'ret' (i.e.
> ->r_dentry) should be used when ret is not NULL?
>
I think if we are going to return ret as a dentry, then it makes sense to call
the ceph_init_inode_acls() for d_inode(ret). I don't see the point to call
ceph_init_inode_acls() for d_inode(dentry) then.
> >
> > > ceph_init_inode_acls(d_inode(dentry), &as_ctx);
> > > else
> > > d_drop(dentry);
> > > ceph_release_acl_sec_ctx(&as_ctx);
> > > - return ERR_PTR(err);
> > > + if (err)
> > > + return ERR_PTR(err);
> > > + return ret;
> >
> > What's about this?
> >
> > return err ? ERR_PTR(err) : ret;
>
> We could do that, but you said above that you thought we should always
> return 'ret' - which does make some sense.
>
> What do you think of the following alternate patch?
>
Patch looks good to me. Thanks.
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@....com>
> Thanks,
> NeilBrown
>
> diff --git a/fs/ceph/dir.c b/fs/ceph/dir.c
> index 39e0f240de06..d2e5c557df83 100644
> --- a/fs/ceph/dir.c
> +++ b/fs/ceph/dir.c
> @@ -1099,6 +1099,7 @@ static struct dentry *ceph_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> struct ceph_client *cl = mdsc->fsc->client;
> struct ceph_mds_request *req;
> struct ceph_acl_sec_ctx as_ctx = {};
> + struct dentry *ret;
> int err;
> int op;
>
> @@ -1116,32 +1117,32 @@ static struct dentry *ceph_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> ceph_vinop(dir), dentry, dentry, mode);
> op = CEPH_MDS_OP_MKDIR;
> } else {
> - err = -EROFS;
> + ret = ERR_PTR(-EROFS);
> goto out;
> }
>
> if (op == CEPH_MDS_OP_MKDIR &&
> ceph_quota_is_max_files_exceeded(dir)) {
> - err = -EDQUOT;
> + ret = ERR_PTR(-EDQUOT);
> goto out;
> }
> if ((op == CEPH_MDS_OP_MKSNAP) && IS_ENCRYPTED(dir) &&
> !fscrypt_has_encryption_key(dir)) {
> - err = -ENOKEY;
> + ret = ERR_PTR(-ENOKEY);
> goto out;
> }
>
>
> req = ceph_mdsc_create_request(mdsc, op, USE_AUTH_MDS);
> if (IS_ERR(req)) {
> - err = PTR_ERR(req);
> + ret = ERR_CAST(req);
> goto out;
> }
>
> mode |= S_IFDIR;
> req->r_new_inode = ceph_new_inode(dir, dentry, &mode, &as_ctx);
> if (IS_ERR(req->r_new_inode)) {
> - err = PTR_ERR(req->r_new_inode);
> + ret = ERR_CAST(req->r_new_inode);
> req->r_new_inode = NULL;
> goto out_req;
> }
> @@ -1165,15 +1166,23 @@ static struct dentry *ceph_mkdir(struct mnt_idmap *idmap, struct inode *dir,
> !req->r_reply_info.head->is_target &&
> !req->r_reply_info.head->is_dentry)
> err = ceph_handle_notrace_create(dir, dentry);
> + ret = ERR_PTR(err);
> out_req:
> + if (!IS_ERR(ret) && req->r_dentry != dentry)
> + /* Some other dentry was spliced in */
> + ret = dget(req->r_dentry);
> ceph_mdsc_put_request(req);
> out:
> - if (!err)
> - ceph_init_inode_acls(d_inode(dentry), &as_ctx);
> - else
> + if (!IS_ERR(ret)) {
> + if (ret)
> + ceph_init_inode_acls(d_inode(ret), &as_ctx);
> + else
> + ceph_init_inode_acls(d_inode(dentry), &as_ctx);
> + } else {
> d_drop(dentry);
> + }
> ceph_release_acl_sec_ctx(&as_ctx);
> - return ERR_PTR(err);
> + return ret;
> }
>
> static int ceph_link(struct dentry *old_dentry, struct inode *dir,
>
Thanks,
Slava.
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