From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Sun, 14 Oct 2018 10:19:27 -0700 From: Christoph Hellwig To: "Darrick J. Wong" Cc: david@fromorbit.com, sandeen@redhat.com, linux-nfs@vger.kernel.org, linux-cifs@vger.kernel.org, Amir Goldstein , linux-unionfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, ocfs2-devel@oss.oracle.com Subject: Re: [PATCH 07/25] vfs: combine the clone and dedupe into a single remap_file_range Message-ID: <20181014171927.GD30673@infradead.org> References: <153938912912.8361.13446310416406388958.stgit@magnolia> <153938919123.8361.13059492965161549195.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <153938919123.8361.13059492965161549195.stgit@magnolia> Sender: owner-linux-mm@kvack.org List-ID: > unsigned (*mmap_capabilities)(struct file *); > #endif > ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int); > - int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, u64); > - int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, u64); > + int (*remap_file_range)(struct file *file_in, loff_t pos_in, > + struct file *file_out, loff_t pos_out, > + u64 len, unsigned int remap_flags); None of the other methods in this file name their parameters. While I generally don't like people leaving them out, in the end consistency is even more important. > +int btrfs_remap_file_range(struct file *src_file, loff_t off, > + struct file *dst_file, loff_t destoff, u64 len, > + unsigned int remap_flags) > { > + if (!remap_check_flags(remap_flags, RFR_SAME_DATA)) > + return -EINVAL; > + > + if (remap_flags & RFR_SAME_DATA) { So at least for btrfs there seems to be no shared code at all below the function calls. This kinda speaks against the argument that they fundamentally are the same.. > +/* > + * These flags control the behavior of the remap_file_range function pointer. > + * > + * RFR_SAME_DATA: only remap if contents identical (i.e. deduplicate) > + */ > +#define RFR_SAME_DATA (1 << 0) > + > +#define RFR_VALID_FLAGS (RFR_SAME_DATA) RFR? Why not REMAP_FILE_* Also why not the well understood REMAP_FILE_DEDUP instead of the odd SAME_DATA? > + > +/* > + * Filesystem remapping implementations should call this helper on their > + * remap flags to filter out flags that the implementation doesn't support. > + * > + * Returns true if the flags are ok, false otherwise. > + */ > +static inline bool remap_check_flags(unsigned int remap_flags, > + unsigned int supported_flags) > +{ > + return (remap_flags & ~(supported_flags & RFR_VALID_FLAGS)) == 0; > +} Any reason to even bother with a helper for this? ->fallocate seems to be doing fine without the helper, and the resulting code seems a lot easier to understand to me. > @@ -1759,10 +1779,9 @@ struct file_operations { > #endif > ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, > loff_t, size_t, unsigned int); > - int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, > - u64); > - int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, > - u64); > + int (*remap_file_range)(struct file *file_in, loff_t pos_in, > + struct file *file_out, loff_t pos_out, > + u64 len, unsigned int remap_flags); Same comment here. Didn't we have some nice doc tools to avoid this duplication? :)