Re: [PATCH 6/7] fsx: support FIEXCHANGE_RANGE

["Darrick J. Wong" <djwong@kernel.org>]

On Tue, Feb 28, 2023 at 09:55:28AM +0800, Zorro Lang wrote:
> On Fri, Dec 30, 2022 at 02:19:49PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > Upgrade fsx to support exchanging file contents.
> > 
> > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > ---
> 
> Hi Darrick,
> 
> I've merged most of patches of [NYE DELUGE 2/4], now I'm trying to merge
> the rest of it this time.
> 
> This patch will get build warning [1] from autoconf, can you rebase this patch
> to current for-next branch, and use autoupdate to update the configure.ac
> and lib/autoconf/general.m4 ?

Will do.  Thanks for merging this all, I really appreciate it!

--D

> Thanks,
> Zorro
> 
> [1]
> autoconf
> configure.ac:73: warning: The macro `AC_TRY_LINK' is obsolete.
> configure.ac:73: You should run autoupdate.
> ./lib/autoconf/general.m4:2920: AC_TRY_LINK is expanded from...
> m4/package_libcdev.m4:161: AC_HAVE_FIEXCHANGE is expanded from...
> configure.ac:73: the top level
> ./configure \   
>                 --libexecdir=/usr/lib \
>                 --exec_prefix=/var/lib
> 
> >  configure.ac          |    1 
> >  include/builddefs.in  |    1 
> >  ltp/Makefile          |    4 +
> >  ltp/fsx.c             |  160 ++++++++++++++++++++++++++++++++++++++++++++++++-
> >  m4/package_libcdev.m4 |   21 ++++++
> >  src/fiexchange.h      |  101 +++++++++++++++++++++++++++++++
> >  src/global.h          |    6 ++
> >  7 files changed, 292 insertions(+), 2 deletions(-)
> >  create mode 100644 src/fiexchange.h
> > 
> > 
> > diff --git a/configure.ac b/configure.ac
> > index e92bd6b26d..4687d8a3c0 100644
> > --- a/configure.ac
> > +++ b/configure.ac
> > @@ -70,6 +70,7 @@ AC_HAVE_SEEK_DATA
> >  AC_HAVE_BMV_OF_SHARED
> >  AC_HAVE_NFTW
> >  AC_HAVE_RLIMIT_NOFILE
> > +AC_HAVE_FIEXCHANGE
> 
> [snip]
> 
> >  	setvbuf(stdout, (char *)0, _IOLBF, 0); /* line buffered stdout */
> >  
> >  	while ((ch = getopt_long(argc, argv,
> > -				 "b:c:dfg:i:j:kl:m:no:p:qr:s:t:w:xyABD:EFJKHzCILN:OP:RS:UWXZ",
> > +				 "0b:c:dfg:i:j:kl:m:no:p:qr:s:t:w:xyABD:EFJKHzCILN:OP:RS:UWXZ",
> 
> Looks like we nearly used up most of letters for fsx, to avoid some operations.
> 
> Maybe we can use a single option (e.g. -a means avoid) and suboptions to
> help that. For example "-a xchg_range,clone_range,dedupe_range" to avoid
> these 3 operations. Or use long option, e.g. --no-xchg-range, --no-clone-range
> to replace short ones.
> 
> What do you think? (Anyway, that's not the problem of this patch)
> 
> Thanks,
> Zorro
> 
> >  				 longopts, NULL)) != EOF)
> >  		switch (ch) {
> >  		case 'b':
> > @@ -2747,6 +2898,9 @@ main(int argc, char **argv)
> >  		case 'I':
> >  			insert_range_calls = 0;
> >  			break;
> > +		case '0':
> > +			xchg_range_calls = 0;
> > +			break;
> >  		case 'J':
> >  			clone_range_calls = 0;
> >  			break;
> > @@ -2988,6 +3142,8 @@ main(int argc, char **argv)
> >  		dedupe_range_calls = test_dedupe_range();
> >  	if (copy_range_calls)
> >  		copy_range_calls = test_copy_range();
> > +	if (xchg_range_calls)
> > +		xchg_range_calls = test_xchg_range();
> >  
> >  	while (numops == -1 || numops--)
> >  		if (!test())
> > diff --git a/m4/package_libcdev.m4 b/m4/package_libcdev.m4
> > index e1b381c16f..db663970c2 100644
> > --- a/m4/package_libcdev.m4
> > +++ b/m4/package_libcdev.m4
> > @@ -157,3 +157,24 @@ AC_DEFUN([AC_HAVE_RLIMIT_NOFILE],
> >         AC_MSG_RESULT(no))
> >      AC_SUBST(have_rlimit_nofile)
> >    ])
> > +
> > +#
> > +# Check if we have a FIEXCHANGE_RANGE ioctl (Linux)
> > +#
> > +AC_DEFUN([AC_HAVE_FIEXCHANGE],
> > +  [ AC_MSG_CHECKING([for FIEXCHANGE_RANGE])
> > +    AC_TRY_LINK([
> > +#define _GNU_SOURCE
> > +#include <sys/syscall.h>
> > +#include <sys/ioctl.h>
> > +#include <unistd.h>
> > +#include <linux/fs.h>
> > +#include <linux/fiexchange.h>
> > +    ], [
> > +         struct file_xchg_range fxr;
> > +         ioctl(-1, FIEXCHANGE_RANGE, &fxr);
> > +    ], have_fiexchange=yes
> > +       AC_MSG_RESULT(yes),
> > +       AC_MSG_RESULT(no))
> > +    AC_SUBST(have_fiexchange)
> > +  ])
> > diff --git a/src/fiexchange.h b/src/fiexchange.h
> > new file mode 100644
> > index 0000000000..29b3ac0ff5
> > --- /dev/null
> > +++ b/src/fiexchange.h
> > @@ -0,0 +1,101 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later WITH Linux-syscall-note */
> > +/*
> > + * FIEXCHANGE ioctl definitions, to facilitate exchanging parts of files.
> > + *
> > + * Copyright (C) 2022 Oracle.  All Rights Reserved.
> > + *
> > + * Author: Darrick J. Wong <djwong@kernel.org>
> > + */
> > +#ifndef _LINUX_FIEXCHANGE_H
> > +#define _LINUX_FIEXCHANGE_H
> > +
> > +#include <linux/types.h>
> > +
> > +/*
> > + * Exchange part of file1 with part of the file that this ioctl that is being
> > + * called against (which we'll call file2).  Filesystems must be able to
> > + * restart and complete the operation even after the system goes down.
> > + */
> > +struct file_xchg_range {
> > +	__s64		file1_fd;
> > +	__s64		file1_offset;	/* file1 offset, bytes */
> > +	__s64		file2_offset;	/* file2 offset, bytes */
> > +	__s64		length;		/* bytes to exchange */
> > +
> > +	__u64		flags;		/* see FILE_XCHG_RANGE_* below */
> > +
> > +	/* file2 metadata for optional freshness checks */
> > +	__s64		file2_ino;	/* inode number */
> > +	__s64		file2_mtime;	/* modification time */
> > +	__s64		file2_ctime;	/* change time */
> > +	__s32		file2_mtime_nsec; /* mod time, nsec */
> > +	__s32		file2_ctime_nsec; /* change time, nsec */
> > +
> > +	__u64		pad[6];		/* must be zeroes */
> > +};
> > +
> > +/*
> > + * Atomic exchange operations are not required.  This relaxes the requirement
> > + * that the filesystem must be able to complete the operation after a crash.
> > + */
> > +#define FILE_XCHG_RANGE_NONATOMIC	(1 << 0)
> > +
> > +/*
> > + * Check that file2's inode number, mtime, and ctime against the values
> > + * provided, and return -EBUSY if there isn't an exact match.
> > + */
> > +#define FILE_XCHG_RANGE_FILE2_FRESH	(1 << 1)
> > +
> > +/*
> > + * Check that the file1's length is equal to file1_offset + length, and that
> > + * file2's length is equal to file2_offset + length.  Returns -EDOM if there
> > + * isn't an exact match.
> > + */
> > +#define FILE_XCHG_RANGE_FULL_FILES	(1 << 2)
> > +
> > +/*
> > + * Exchange file data all the way to the ends of both files, and then exchange
> > + * the file sizes.  This flag can be used to replace a file's contents with a
> > + * different amount of data.  length will be ignored.
> > + */
> > +#define FILE_XCHG_RANGE_TO_EOF		(1 << 3)
> > +
> > +/* Flush all changes in file data and file metadata to disk before returning. */
> > +#define FILE_XCHG_RANGE_FSYNC		(1 << 4)
> > +
> > +/* Dry run; do all the parameter verification but do not change anything. */
> > +#define FILE_XCHG_RANGE_DRY_RUN		(1 << 5)
> > +
> > +/*
> > + * Do not exchange any part of the range where file1's mapping is a hole.  This
> > + * can be used to emulate scatter-gather atomic writes with a temp file.
> > + */
> > +#define FILE_XCHG_RANGE_SKIP_FILE1_HOLES (1 << 6)
> > +
> > +/*
> > + * Commit the contents of file1 into file2 if file2 has the same inode number,
> > + * mtime, and ctime as the arguments provided to the call.  The old contents of
> > + * file2 will be moved to file1.
> > + *
> > + * With this flag, all committed information can be retrieved even if the
> > + * system crashes or is rebooted.  This includes writing through or flushing a
> > + * disk cache if present.  The call blocks until the device reports that the
> > + * commit is complete.
> > + *
> > + * This flag should not be combined with NONATOMIC.  It can be combined with
> > + * SKIP_FILE1_HOLES.
> > + */
> > +#define FILE_XCHG_RANGE_COMMIT		(FILE_XCHG_RANGE_FILE2_FRESH | \
> > +					 FILE_XCHG_RANGE_FSYNC)
> > +
> > +#define FILE_XCHG_RANGE_ALL_FLAGS	(FILE_XCHG_RANGE_NONATOMIC | \
> > +					 FILE_XCHG_RANGE_FILE2_FRESH | \
> > +					 FILE_XCHG_RANGE_FULL_FILES | \
> > +					 FILE_XCHG_RANGE_TO_EOF | \
> > +					 FILE_XCHG_RANGE_FSYNC | \
> > +					 FILE_XCHG_RANGE_DRY_RUN | \
> > +					 FILE_XCHG_RANGE_SKIP_FILE1_HOLES)
> > +
> > +#define FIEXCHANGE_RANGE	_IOWR('X', 129, struct file_xchg_range)
> > +
> > +#endif /* _LINUX_FIEXCHANGE_H */
> > diff --git a/src/global.h b/src/global.h
> > index b44070993c..49570ef117 100644
> > --- a/src/global.h
> > +++ b/src/global.h
> > @@ -171,6 +171,12 @@
> >  #include <sys/mman.h>
> >  #endif
> >  
> > +#ifdef HAVE_FIEXCHANGE
> > +# include <linux/fiexchange.h>
> > +#else
> > +# include "fiexchange.h"
> > +#endif
> > +
> >  static inline unsigned long long
> >  rounddown_64(unsigned long long x, unsigned int y)
> >  {
> > 
>