Hi Jim,
Thanks for your kind advise!
I'd like to adopt the timeout(1) approach for the test work.
My thought is:
1. Create and mount a file-backed ext4 partition rather than relying on the
HARD CODE path.
2. Create a 2gb sparse file without extent allocated for it.
3. It take nearly 30 seconds to transfer this file in normal copy, yet less
than 1 second through
FIEMAP-copy, is it a worst-case scenario that makes the difference as large as
possible?
4. run FIEMAP-copy, use timeout(1) to limit it will complete in 1 second, I
hope I understood your
opinion correctly ;).
The revised patches are shown as following:
>From b683f930c5e70481c2b6e000a626734f975b99ac Mon Sep 17 00:00:00 2001
From: Jie Liu <jeff....@oracle.com>
Date: Thu, 13 May 2010 22:09:30 +0800
Subject: [PATCH 1/1] cp: Add FIEMAP support for efficient sparse file copy
* src/fiemap.h: Add fiemap.h for fiemap ioctl(2) support.
Copied from linux's include/linux/fiemap.h, with minor formatting changes.
* src/copy.c (copy_reg): Now, when `cp' invoked with --sparse=[WHEN] option, we
will try to do FIEMAP-copy if the underlaying file system support it, fall back
to a normal copy if it fails.
Signed-off-by: Jie Liu <jeff....@oracle.com>
---
src/copy.c | 154 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
src/fiemap.h | 102 ++++++++++++++++++++++++++++++++++++++
2 files changed, 256 insertions(+), 0 deletions(-)
create mode 100644 src/fiemap.h
diff --git a/src/copy.c b/src/copy.c
index c16cef6..960e5fb 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -63,6 +63,10 @@
#include <sys/ioctl.h>
+#ifndef HAVE_FIEMAP
+# include "fiemap.h"
+#endif
+
#ifndef HAVE_FCHOWN
# define HAVE_FCHOWN false
# define fchown(fd, uid, gid) (-1)
@@ -149,6 +153,136 @@ clone_file (int dest_fd, int src_fd)
#endif
}
+#ifdef __linux__
+# ifndef FS_IOC_FIEMAP
+# define FS_IOC_FIEMAP _IOWR ('f', 11, struct fiemap)
+# endif
+/* Perform FIEMAP(available in mainline 2.6.27) copy if possible.
+ Call ioctl(2) with FS_IOC_FIEMAP to efficiently map file allocation
+ excepts holes. So the overhead to deal with holes with lseek(2) in
+ normal copy could be saved. This would result in much faster backups
+ for any kind of sparse file. */
+static bool
+fiemap_copy_ok (int src_fd, int dest_fd, size_t buf_size,
+ off_t src_total_size, char const *src_name,
+ char const *dst_name, bool *normal_copy_required)
+{
+ bool fail = false;
+ bool last = false;
+ char fiemap_buf[4096];
+ struct fiemap *fiemap = (struct fiemap *)fiemap_buf;
+ struct fiemap_extent *fm_ext = &fiemap->fm_extents[0];
+ uint32_t count = (sizeof (fiemap_buf) - sizeof (*fiemap)) /
+ sizeof (struct fiemap_extent);
+ off_t last_ext_logical = 0;
+ uint64_t last_ext_len = 0;
+ uint64_t last_read_size = 0;
+ unsigned int i = 0;
+
+ do
+ {
+ fiemap->fm_start = 0ULL;
+ fiemap->fm_length = FIEMAP_MAX_OFFSET;
+ fiemap->fm_extent_count = count;
+
+ /* When ioctl(2) fails, fall back to the normal copy only if it
+ is the first time we met. */
+ if (ioctl (src_fd, FS_IOC_FIEMAP, (unsigned long) fiemap) < 0)
+ {
+ /* If `i > 0', then at least one ioctl(2) has been performed before.
*/
+ if (i == 0)
+ *normal_copy_required = true;
+ return false;
+ }
+
+ /* If 0 extents are returned, then more ioctls are not needed. */
+ if (fiemap->fm_mapped_extents == 0)
+ break;
+
+ for (i = 0; i < fiemap->fm_mapped_extents; i++)
+ {
+ assert (fm_ext[i].fe_logical <= OFF_T_MAX);
+
+ off_t ext_logical = fm_ext[i].fe_logical;
+ uint64_t ext_len = fm_ext[i].fe_length;
+
+ if (lseek (src_fd, ext_logical, SEEK_SET) < 0LL)
+ {
+ error (0, errno, _("cannot lseek %s"), quote (src_name));
+ return fail;
+ }
+
+ if (lseek (dest_fd, ext_logical, SEEK_SET) < 0LL)
+ {
+ error (0, errno, _("cannot lseek %s"), quote (dst_name));
+ return fail;
+ }
+
+ if (fm_ext[i].fe_flags & FIEMAP_EXTENT_LAST)
+ {
+ last_ext_logical = ext_logical;
+ last_ext_len = ext_len;
+ last = true;
+ }
+
+ while (0 < ext_len)
+ {
+ char buf[buf_size];
+
+ /* Avoid reading into the holes if the left extent
+ length is shorter than the buffer size. */
+ if (ext_len < buf_size)
+ buf_size = ext_len;
+
+ ssize_t n_read = read (src_fd, buf, buf_size);
+ if (n_read < 0)
+ {
+#ifdef EINTR
+ if (errno == EINTR)
+ continue;
+#endif
+ error (0, errno, _("reading %s"), quote (src_name));
+ return fail;
+ }
+
+ if (n_read == 0)
+ {
+ /* Figure out how many bytes read from the last extent. */
+ last_read_size = last_ext_len - ext_len;
+ break;
+ }
+
+ if (full_write (dest_fd, buf, n_read) != n_read)
+ {
+ error (0, errno, _("writing %s"), quote (dst_name));
+ return fail;
+ }
+
+ ext_len -= n_read;
+ }
+
+ fiemap->fm_start = (fm_ext[i-1].fe_logical + fm_ext[i-1].fe_length);
+ }
+ } while (! last);
+
+ /* If a file ends up with holes, the sum of the last extent logical offset
+ and the read-returned size will be shorter than the actual size of the
+ file. Use ftruncate to extend the length of the destination file. */
+ if (last_ext_logical + last_read_size < src_total_size)
+ {
+ if (ftruncate (dest_fd, src_total_size) < 0)
+ {
+ error (0, errno, _("extending %s"), quote (dst_name));
+ return fail;
+ }
+ }
+
+ return ! fail;
+}
+#else
+static bool fiemap_copy_ok (ignored) { errno == ENOTSUP; return false; }
+#endif
+
/* FIXME: describe */
/* FIXME: rewrite this to use a hash table so we avoid the quadratic
performance hit that's probably noticeable only on trees deeper
@@ -679,6 +813,25 @@ copy_reg (char const *src_name, char const *dst_name,
#endif
}
+ if (make_holes)
+ {
+ bool require_normal_copy = false;
+ /* Perform efficient FIEMAP copy for sparse files, fall back to the
+ standard copy only if the ioctl(2) fails. */
+ if (fiemap_copy_ok (source_desc, dest_desc, buf_size,
+ src_open_sb.st_size, src_name,
+ dst_name, &require_normal_copy))
+ goto preserve_metadata;
+ else
+ {
+ if (! require_normal_copy)
+ {
+ return_val = false;
+ goto close_src_and_dst_desc;
+ }
+ }
+ }
+
/* If not making a sparse file, try to use a more-efficient
buffer size. */
if (! make_holes)
@@ -807,6 +960,7 @@ copy_reg (char const *src_name, char const *dst_name,
}
}
+preserve_metadata:
if (x->preserve_timestamps)
{
struct timespec timespec[2];
diff --git a/src/fiemap.h b/src/fiemap.h
new file mode 100644
index 0000000..d33293b
--- /dev/null
+++ b/src/fiemap.h
@@ -0,0 +1,102 @@
+/* FS_IOC_FIEMAP ioctl infrastructure.
+ Some portions copyright (C) 2007 Cluster File Systems, Inc
+ Authors: Mark Fasheh <mfas...@suse.com>
+ Kalpak Shah <kalpak.s...@sun.com>
+ Andreas Dilger <adil...@sun.com>. */
+
+/* Copy from kernel, modified to respect GNU code style by Jie Liu. */
+
+#ifndef _LINUX_FIEMAP_H
+# define _LINUX_FIEMAP_H
+
+# include <linux/types.h>
+
+struct fiemap_extent
+{
+ /* Logical offset in bytes for the start of the extent
+ from the beginning of the file. */
+ uint64_t fe_logical;
+
+ /* Physical offset in bytes for the start of the extent
+ from the beginning of the disk. */
+ uint64_t fe_physical;
+
+ /* Length in bytes for this extent. */
+ uint64_t fe_length;
+
+ uint64_t fe_reserved64[2];
+
+ /* FIEMAP_EXTENT_* flags for this extent. */
+ uint32_t fe_flags;
+
+ uint32_t fe_reserved[3];
+};
+
+struct fiemap
+{
+ /* Logical offset(inclusive) at which to start mapping(in). */
+ uint64_t fm_start;
+
+ /* Logical length of mapping which userspace wants(in). */
+ uint64_t fm_length;
+
+ /* FIEMAP_FLAG_* flags for request(in/out). */
+ uint32_t fm_flags;
+
+ /* Number of extents that were mapped(out). */
+ uint32_t fm_mapped_extents;
+
+ /* Size of fm_extents array(in). */
+ uint32_t fm_extent_count;
+
+ uint32_t fm_reserved;
+
+ /* Array of mapped extents(out). */
+ struct fiemap_extent fm_extents[0];
+};
+
+/* The maximum offset can be mapped for a file. */
+# define FIEMAP_MAX_OFFSET (~0ULL)
+
+/* Sync file data before map. */
+# define FIEMAP_FLAG_SYNC 0x00000001
+
+/* Map extented attribute tree. */
+# define FIEMAP_FLAG_XATTR 0x00000002
+
+# define FIEMAP_FLAGS_COMPAT (FIEMAP_FLAG_SYNC | FIEMAP_FLAG_XATTR)
+
+/* Last extent in file. */
+# define FIEMAP_EXTENT_LAST 0x00000001
+
+/* Data location unknown. */
+# define FIEMAP_EXTENT_UNKNOWN 0x00000002
+
+/* Location still pending, Sets EXTENT_UNKNOWN. */
+# define FIEMAP_EXTENT_DELALLOC 0x00000004
+
+/* Data can not be read while fs is unmounted. */
+# define FIEMAP_EXTENT_ENCODED 0x00000008
+
+/* Data is encrypted by fs. Sets EXTENT_NO_BYPASS. */
+# define FIEMAP_EXTENT_DATA_ENCRYPTED 0x00000080
+
+/* Extent offsets may not be block aligned. */
+# define FIEMAP_EXTENT_NOT_ALIGNED 0x00000100
+
+/* Data mixed with metadata. Sets EXTENT_NOT_ALIGNED. */
+# define FIEMAP_EXTENT_DATA_INLINE 0x00000200
+
+/* Multiple files in block. Set EXTENT_NOT_ALIGNED. */
+# define FIEMAP_EXTENT_DATA_TAIL 0x00000400
+
+/* Space allocated, but not data (i.e. zero). */
+# define FIEMAP_EXTENT_UNWRITTEN 0x00000800
+
+/* File does not natively support extents. Result merged for efficiency. */
+# define FIEMAP_EXTENT_MERGED 0x00001000
+
+/* Space shared with other files. */
+# define FIEMAP_EXTENT_SHARED 0x00002000
+
+#endif
--
1.5.4.3
>From f18e1801d1dfca9fa278572b8172a5f97da2adc1 Mon Sep 17 00:00:00 2001
From: Jie Liu <jeff....@oracle.com>
Date: Thu, 13 May 2010 22:17:53 +0800
Subject: [PATCH 1/1] tests: add a new test for FIEMAP-copy
* tests/cp/sparse-fiemap: Add a new test for FIEMAP-copy against a
loopbacked ext4 partition.
* tests/Makefile.am (sparse-fiemap): Reference the new test.
Signed-off-by: Jie Liu <jeff....@oracle.com>
---
tests/Makefile.am | 2 +
tests/cp/sparse-fiemap | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 63 insertions(+), 0 deletions(-)
create mode 100644 tests/cp/sparse-fiemap
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 46d388a..a76c6a7 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -25,6 +25,7 @@ root_tests = \
cp/special-bits \
cp/cp-mv-enotsup-xattr \
cp/capability \
+ cp/sparse-fiemap \
dd/skip-seek-past-dev \
install/install-C-root \
ls/capability \
@@ -319,6 +320,7 @@ TESTS = \
cp/same-file \
cp/slink-2-slink \
cp/sparse \
+ cp/sparse-fiemap \
cp/special-f \
cp/src-base-dot \
cp/symlink-slash \
diff --git a/tests/cp/sparse-fiemap b/tests/cp/sparse-fiemap
new file mode 100644
index 0000000..f9d3a94
--- /dev/null
+++ b/tests/cp/sparse-fiemap
@@ -0,0 +1,61 @@
+#!/bin/sh
+# Test cp --sparse=always through fiemap copy
+
+# Copyright (C) 2006-2010 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+if test "$VERBOSE" = yes; then
+ set -x
+ cp --version
+fi
+
+. $srcdir/test-lib.sh
+require_root_
+
+cwd=`pwd`
+cleanup_() { cd /; umount "$cwd/mnt"; }
+
+# Create an ext4 loopback file system
+dd if=/dev/zero of=blob bs=8192 count=1000 > /dev/null 2>&1 \
+ || skip=1
+mkdir mnt
+mkfs -t ext4 -F blob ||
+ skip_test_ "failed to create ext4 file system"
+mount -oloop blob mnt || skip=1
+echo test > mnt/f || skip=1
+test -s mnt/f || skip=1
+
+test $skip = 1 &&
+ skip_test_ "insufficient mount/ext4 support"
+
+rm -f mnt/f
+
+# Create a 2gb sparse file
+dd if=/dev/zero of=mnt/sparse bs=1k count=1 seek=2096128 > /dev/null 2>&1 ||
framework_failure
+
+# It take more than 20 seconds to transfer the created sparse file
+# through normal copy, by contrast, it take even less than 1 second
+# through FIEMAP-copy.
+timeout 1 cp --sparse=always mnt/sparse mnt/sparse_fiemap || fail=1
+test $? = 124 && fail=1
+
+# Ensure that the sparse file copied through fiemap has the same size
+# in bytes as the original.
+test `stat --printf %s $sparse` = `stat --printf %s $fiemap` || fail=1
+
+rm -f mnt/sparse
+rm -f mnt/sparse_fiemap
+
+Exit $fail
--
1.5.4.3
Thanks,
-Jeff
>
> Then I remembered that here we have timeout(1), so:
> you may ignore the above and consider this a suggestion
> to use timeout:
>
> But that was in Parted, where we can't guarantee that the timeout
> program is available. Here in coreutils, you're guaranteed to
> have timeout(1) (just built), so you might want to use it, too:
> Contrive a test that takes a very long time without FIEMAP support
> yet that runs in a couple seconds with it. Then run cp via timeout
> with a 10-second limit. If timeout's exit status is not 0,
> then make the test fail.
>
> That has the advantage of letting you use an example that would take
> far longer that we typically want to wait for a non-FIEMAP test.
> I.e., perform only the FIEMAP-copy and ensure that it's "quick enough".
> You don't have to perform a non-FIEMAP one.
>
> Another advantage: if you don't do the old/slow sparse copy,
> there's no need for comparison (and bc or awk) at all.
>
>
>
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