Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:40452 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751728AbbIODcs (ORCPT ); Mon, 14 Sep 2015 23:32:48 -0400 Date: Mon, 14 Sep 2015 20:32:17 -0700 From: "Darrick J. Wong" To: Anna Schumaker Cc: linux-nfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, zab@zabbo.net, viro@zeniv.linux.org.uk, clm@fb.com, mtk.manpages@gmail.com, andros@netapp.com, hch@infradead.org Subject: Re: [PATCH v2 8/9] vfs: copy_file_range() can do a pagecache copy with splice Message-ID: <20150915033217.GG10391@birch.djwong.org> References: <1442003423-6884-1-git-send-email-Anna.Schumaker@Netapp.com> <1442003423-6884-9-git-send-email-Anna.Schumaker@Netapp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1442003423-6884-9-git-send-email-Anna.Schumaker@Netapp.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, Sep 11, 2015 at 04:30:21PM -0400, Anna Schumaker wrote: > The NFS server will need some kind offallback for filesystems that don't > have any kind of copy acceleration, and it should be generally useful to > have an in-kernel copy to avoid lots of switches between kernel and user > space. > > I make this configurable by adding two new flags. Users who only want a > reflink can pass COPY_FR_REFLINK, and users who want a full data copy can > pass COPY_FR_COPY. The default (flags=0) means to first attempt a > reflink, but use the pagecache if that fails. > > I moved the rw_verify_area() calls into the fallback code since some > filesystems can handle reflinking a large range. > > Signed-off-by: Anna Schumaker > --- > v2: > - Rename COPY_REFLINK -> COPY_FR_REFLINK > - Introduce COPY_FR_COPY flag > - Flags == 0 is really COPY_FR_COPY|COPY_FR_REFLINK > - Drop check for invalid flags > - Move call to do_splice_direct() into a new function > - Move rw_verify_area() checks into the new fallback function > --- > fs/read_write.c | 56 ++++++++++++++++++++++++++++------------------- > include/linux/copy.h | 6 +++++ > include/uapi/linux/Kbuild | 1 + > include/uapi/linux/copy.h | 7 ++++++ > 4 files changed, 48 insertions(+), 22 deletions(-) > create mode 100644 include/linux/copy.h > create mode 100644 include/uapi/linux/copy.h > > diff --git a/fs/read_write.c b/fs/read_write.c > index 363bd3e..ba24884 100644 > --- a/fs/read_write.c > +++ b/fs/read_write.c > @@ -7,6 +7,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -1329,6 +1330,29 @@ COMPAT_SYSCALL_DEFINE4(sendfile64, int, out_fd, int, in_fd, > } > #endif > > +static ssize_t vfs_copy_file_pagecache(struct file *file_in, loff_t pos_in, > + struct file *file_out, loff_t pos_out, > + size_t len) > +{ > + ssize_t ret; > + > + ret = rw_verify_area(READ, file_in, &pos_in, len); > + if (ret >= 0) { > + len = ret; > + ret = rw_verify_area(WRITE, file_out, &pos_out, len); > + if (ret >= 0) > + len = ret; > + } > + if (ret < 0) > + return ret; > + > + file_start_write(file_out); > + ret = do_splice_direct(file_in, &pos_in, file_out, &pos_out, len, 0); > + file_end_write(file_out); > + > + return ret; > +} > + > /* > * copy_file_range() differs from regular file read and write in that it > * specifically allows return partial success. When it does so is up to > @@ -1338,34 +1362,17 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, > struct file *file_out, loff_t pos_out, > size_t len, int flags) > { > - struct inode *inode_in; > - struct inode *inode_out; > ssize_t ret; > > - if (flags) > - return -EINVAL; > - > - /* copy_file_range allows full ssize_t len, ignoring MAX_RW_COUNT */ > - ret = rw_verify_area(READ, file_in, &pos_in, len); > - if (ret >= 0) > - ret = rw_verify_area(WRITE, file_out, &pos_out, len); > - if (ret < 0) > - return ret; > + if (flags == 0) > + flags = COPY_FR_COPY | COPY_FR_REFLINK; This function must return -EINVAL if any of the undefined flags bits are set. > > if (!(file_in->f_mode & FMODE_READ) || > !(file_out->f_mode & FMODE_WRITE) || > (file_out->f_flags & O_APPEND) || > - !file_out->f_op || !file_out->f_op->copy_file_range) > + !file_in->f_op) > return -EBADF; > > - inode_in = file_inode(file_in); > - inode_out = file_inode(file_out); > - > - /* make sure offsets don't wrap and the input is inside i_size */ > - if (pos_in + len < pos_in || pos_out + len < pos_out || > - pos_in + len > i_size_read(inode_in)) > - return -EINVAL; > - > if (len == 0) > return 0; > > @@ -1373,8 +1380,13 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in, > if (ret) > return ret; > > - ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, pos_out, > - len, flags); > + ret = -EOPNOTSUPP; > + if (file_out->f_op->copy_file_range) > + ret = file_out->f_op->copy_file_range(file_in, pos_in, file_out, > + pos_out, len, flags); > + if ((ret < 0) && (flags & COPY_FR_COPY)) > + ret = vfs_copy_file_pagecache(file_in, pos_in, file_out, > + pos_out, len); > if (ret > 0) { > fsnotify_access(file_in); > add_rchar(current, ret); > diff --git a/include/linux/copy.h b/include/linux/copy.h > new file mode 100644 > index 0000000..fd54543 > --- /dev/null > +++ b/include/linux/copy.h > @@ -0,0 +1,6 @@ > +#ifndef _LINUX_COPY_H > +#define _LINUX_COPY_H > + > +#include > + > +#endif /* _LINUX_COPY_H */ > diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild > index 70ff1d9..d46830a 100644 > --- a/include/uapi/linux/Kbuild > +++ b/include/uapi/linux/Kbuild > @@ -90,6 +90,7 @@ header-y += coda_psdev.h > header-y += coff.h > header-y += connector.h > header-y += const.h > +header-y += copy.h > header-y += cramfs_fs.h > header-y += cuda.h > header-y += cyclades.h > diff --git a/include/uapi/linux/copy.h b/include/uapi/linux/copy.h > new file mode 100644 > index 0000000..2da59a8 > --- /dev/null > +++ b/include/uapi/linux/copy.h > @@ -0,0 +1,7 @@ > +#ifndef _UAPI_LINUX_COPY_H > +#define _UAPI_LINUX_COPY_H > + > +#define COPY_FR_COPY (1 << 0) /* Only do a pagecache copy. */ > +#define COPY_FR_REFLINK (1 << 1) /* Only make a reflink. */ Could I have a COPY_FR_DEDUPE flag too, please? (I don't mind adding it myself when I get around to hooking up XFS, but I was hoping to get it in during the first round). --D > + > +#endif /* _UAPI_LINUX_COPY_H */ > -- > 2.5.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html