Return-Path: Received: from mx141.netapp.com ([216.240.21.12]:17103 "EHLO mx141.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751797AbbIOP6J (ORCPT ); Tue, 15 Sep 2015 11:58:09 -0400 Subject: Re: [PATCH v2 8/9] vfs: copy_file_range() can do a pagecache copy with splice To: "Darrick J. Wong" References: <1442003423-6884-1-git-send-email-Anna.Schumaker@Netapp.com> <1442003423-6884-9-git-send-email-Anna.Schumaker@Netapp.com> <20150915033217.GG10391@birch.djwong.org> CC: , , , , , , , , , From: Anna Schumaker Message-ID: <55F8400C.3000402@Netapp.com> Date: Tue, 15 Sep 2015 11:58:04 -0400 MIME-Version: 1.0 In-Reply-To: <20150915033217.GG10391@birch.djwong.org> Content-Type: text/plain; charset="utf-8" Sender: linux-nfs-owner@vger.kernel.org List-ID: On 09/14/2015 11:32 PM, Darrick J. Wong wrote: > 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. Sure, I'll add that. > >> >> 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). I guess I can, but only iff everybody has agreed on using copy for dedupes instead of somethink like fallocate. Anna > > --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