From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Date: Tue, 10 May 2022 00:13:30 -0700 Subject: [Cluster-devel] [PATCH] gfs2: Use container_of() for gfs2_glock(aspace) In-Reply-To: <20220508100630.2642320-1-keescook@chromium.org> References: <20220508100630.2642320-1-keescook@chromium.org> Message-ID: List-Id: To: cluster-devel.redhat.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit > +/* gfs2_glock_get(), "glock" must be first. */ > +struct glock_aspace { > + struct gfs2_glock glock; > + struct address_space mapping; > +}; Why does glock need to be first? The whole point of using container_of is that we don't have to make that assumption. > static inline struct address_space *gfs2_glock2aspace(struct gfs2_glock *gl) > { > if (gl->gl_ops->go_flags & GLOF_ASPACE) > - return (struct address_space *)(gl + 1); > + return &(container_of(gl, struct glock_aspace, glock)->mapping); Do we even need the braces here? > struct inode *inode = mapping->host; > if (mapping->a_ops == &gfs2_meta_aops) > - return (((struct gfs2_glock *)mapping) - 1)->gl_name.ln_sbd; > + return container_of(mapping, struct glock_aspace, mapping)->glock.gl_name.ln_sbd; A local variable would be really nice for the reader here to decompose this a bit: struct glock_aspace *a = container_of(mapping, struct glock_aspace, mapping); return a->glock.gl_name.ln_sbd;