Return-Path: Received: from mx141.netapp.com ([216.240.21.12]:56128 "EHLO mx141.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935305AbbI2SFf (ORCPT ); Tue, 29 Sep 2015 14:05:35 -0400 From: Anna Schumaker To: , , , , , , , , , , Subject: [PATCH v4 8/9] vfs: Add vfs_copy_file_range() support for pagecache copies Date: Tue, 29 Sep 2015 14:05:11 -0400 Message-ID: <1443549913-8091-9-git-send-email-Anna.Schumaker@Netapp.com> In-Reply-To: <1443549913-8091-1-git-send-email-Anna.Schumaker@Netapp.com> References: <1443549913-8091-1-git-send-email-Anna.Schumaker@Netapp.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-nfs-owner@vger.kernel.org List-ID: This allows us to have an in-kernel copy mechanism that avoids frequent switches between kernel and user space. This is especially useful so NFSD can support server-side copies. I make pagecache copies configurable by adding three new (exclusive) flags: - COPY_FR_REFLINK tells vfs_copy_file_range() to only create a reflink. - COPY_FR_COPY does a full data copy, but may be filesystem accelerated. - COPY_FR_DEDUP creates a reflink, but only if the contents of both ranges are identical. 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 Reviewed-by: Darrick J. Wong --- v4: - Reword commit message - Rename COPY_FR_DEDUPE -> COPY_FR_DEDUP --- fs/read_write.c | 61 +++++++++++++++++++++++++++++++---------------- include/linux/copy.h | 6 +++++ include/uapi/linux/Kbuild | 1 + include/uapi/linux/copy.h | 8 +++++++ 4 files changed, 56 insertions(+), 20 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 ee9fa37..4fb9b8e 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 +1362,26 @@ 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, unsigned int flags) { - struct inode *inode_in; - struct inode *inode_out; ssize_t ret; - if (flags) + /* Flags should only be used exclusively. */ + if ((flags & COPY_FR_COPY) && (flags & ~COPY_FR_COPY)) + return -EINVAL; + if ((flags & COPY_FR_REFLINK) && (flags & ~COPY_FR_REFLINK)) + return -EINVAL; + if ((flags & COPY_FR_DEDUP) && (flags & ~COPY_FR_DEDUP)) 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; + /* Default behavior is to try both. */ + if (flags == 0) + flags = COPY_FR_COPY | COPY_FR_REFLINK; 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_out->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 +1389,13 @@ 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 && (file_in->f_op == file_out->f_op)) + 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 f7b2db4..faafd67 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..b807dcd --- /dev/null +++ b/include/uapi/linux/copy.h @@ -0,0 +1,8 @@ +#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. */ +#define COPY_FR_DEDUP (1 << 2) /* Deduplicate file data. */ + +#endif /* _UAPI_LINUX_COPY_H */ -- 2.5.3