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Sun, 21 May 2023 19:13:02 -0700 (PDT) X-Received: by 2002:a05:6a20:5483:b0:10b:e90d:13a2 with SMTP id i3-20020a056a20548300b0010be90d13a2mr590790pzk.36.1684721582215; Sun, 21 May 2023 19:13:02 -0700 (PDT) Received: from [10.72.12.68] ([43.228.180.230]) by smtp.gmail.com with ESMTPSA id i9-20020aa79089000000b0064559b58eb8sm3081025pfa.154.2023.05.21.19.12.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 21 May 2023 19:13:01 -0700 (PDT) Message-ID: Date: Mon, 22 May 2023 10:12:49 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH v21 16/30] ceph: Provide a splice-read stub Content-Language: en-US To: David Howells , Jens Axboe , Al Viro , Christoph Hellwig Cc: Matthew Wilcox , Jan Kara , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , Hillf Danton , Christian Brauner , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , Ilya Dryomov , ceph-devel@vger.kernel.org References: <20230520000049.2226926-1-dhowells@redhat.com> <20230520000049.2226926-17-dhowells@redhat.com> From: Xiubo Li In-Reply-To: <20230520000049.2226926-17-dhowells@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A, RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/20/23 08:00, David Howells wrote: > Provide a splice_read stub for Ceph. This does the inode shutdown check > before proceeding and jumps to copy_splice_read() if the file has inline > data or is a synchronous file. > > We try and get FILE_RD and either FILE_CACHE and/or FILE_LAZYIO caps and > hold them across filemap_splice_read(). If we fail to get FILE_CACHE or > FILE_LAZYIO capabilities, we use copy_splice_read() instead. > > Signed-off-by: David Howells > cc: Christoph Hellwig > cc: Al Viro > cc: Jens Axboe > cc: Xiubo Li > cc: Ilya Dryomov > cc: Jeff Layton > cc: ceph-devel@vger.kernel.org > cc: linux-fsdevel@vger.kernel.org > cc: linux-block@vger.kernel.org > cc: linux-mm@kvack.org > --- > > Notes: > ver #21) > - Need to drop the caps ref. > - O_DIRECT is handled by the caller. > > fs/ceph/file.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 64 insertions(+), 1 deletion(-) > > diff --git a/fs/ceph/file.c b/fs/ceph/file.c > index f4d8bf7dec88..4285f6cb5d3b 100644 > --- a/fs/ceph/file.c > +++ b/fs/ceph/file.c > @@ -1745,6 +1745,69 @@ static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to) > return ret; > } > > +/* > + * Wrap filemap_splice_read with checks for cap bits on the inode. > + * Atomically grab references, so that those bits are not released > + * back to the MDS mid-read. > + */ > +static ssize_t ceph_splice_read(struct file *in, loff_t *ppos, > + struct pipe_inode_info *pipe, > + size_t len, unsigned int flags) > +{ > + struct ceph_file_info *fi = in->private_data; > + struct inode *inode = file_inode(in); > + struct ceph_inode_info *ci = ceph_inode(inode); > + ssize_t ret; > + int want = 0, got = 0; > + CEPH_DEFINE_RW_CONTEXT(rw_ctx, 0); > + > + dout("splice_read %p %llx.%llx %llu~%zu trying to get caps on %p\n", > + inode, ceph_vinop(inode), *ppos, len, inode); > + > + if (ceph_inode_is_shutdown(inode)) > + return -ESTALE; > + > + if (ceph_has_inline_data(ci) || > + (fi->flags & CEPH_F_SYNC)) > + return copy_splice_read(in, ppos, pipe, len, flags); > + > + ceph_start_io_read(inode); > + > + want = CEPH_CAP_FILE_CACHE; > + if (fi->fmode & CEPH_FILE_MODE_LAZY) > + want |= CEPH_CAP_FILE_LAZYIO; > + > + ret = ceph_get_caps(in, CEPH_CAP_FILE_RD, want, -1, &got); > + if (ret < 0) > + goto out_end; > + > + if ((got & (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO)) == 0) { > + dout("splice_read/sync %p %llx.%llx %llu~%zu got cap refs on %s\n", > + inode, ceph_vinop(inode), *ppos, len, > + ceph_cap_string(got)); > + > + ceph_put_cap_refs(ci, got); > + ceph_end_io_read(inode); > + return copy_splice_read(in, ppos, pipe, len, flags); > + } > + > + dout("splice_read %p %llx.%llx %llu~%zu got cap refs on %s\n", > + inode, ceph_vinop(inode), *ppos, len, ceph_cap_string(got)); > + > + rw_ctx.caps = got; > + ceph_add_rw_context(fi, &rw_ctx); > + ret = filemap_splice_read(in, ppos, pipe, len, flags); > + ceph_del_rw_context(fi, &rw_ctx); > + > + dout("splice_read %p %llx.%llx dropping cap refs on %s = %zd\n", > + inode, ceph_vinop(inode), ceph_cap_string(got), ret); > + > + ceph_put_cap_refs(ci, got); > +out_end: > + ceph_end_io_read(inode); > + return ret; > +} > + > /* > * Take cap references to avoid releasing caps to MDS mid-write. > * > @@ -2593,7 +2656,7 @@ const struct file_operations ceph_file_fops = { > .lock = ceph_lock, > .setlease = simple_nosetlease, > .flock = ceph_flock, > - .splice_read = generic_file_splice_read, > + .splice_read = ceph_splice_read, > .splice_write = iter_file_splice_write, > .unlocked_ioctl = ceph_ioctl, > .compat_ioctl = compat_ptr_ioctl, > LGTM. Reviewed-by: Xiubo Li Thanks - Xiubo