From bfdb6b585b6842362977b8c10fe7858fb96a1dd0 Mon Sep 17 00:00:00 2001 From: Pádraig Brady Date: Fri, 11 Feb 2011 08:55:22 +0000 Subject: copy: process empty extents more efficiently * src/copy.c (extent_copy): Treat an allocated but empty extent much like a hole. I.E. don't read data we know is going to be NUL. Also we convert the empty extent to a hole only when SPARSE_ALWAYS so that the source and dest have the same allocation. This will be improved soon, when we use fallocate() to do the allocation. * tests/cp/fiemap-empty: A new test for efficiency and correctness of copying empty extents. * tests/Makefile.am: Reference the new test. * NEWS: Mention the change in behavior. --- tests/Makefile.am | 5 +-- tests/cp/fiemap-empty | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 92 insertions(+), 2 deletions(-) create mode 100755 tests/cp/fiemap-empty (limited to 'tests') diff --git a/tests/Makefile.am b/tests/Makefile.am index e7f3fffb1..685eb52b9 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -321,8 +321,9 @@ TESTS = \ cp/dir-vs-file \ cp/existing-perm-race \ cp/fail-perm \ - cp/fiemap-perf \ - cp/fiemap-2 \ + cp/fiemap-empty \ + cp/fiemap-perf \ + cp/fiemap-2 \ cp/file-perm-race \ cp/into-self \ cp/link \ diff --git a/tests/cp/fiemap-empty b/tests/cp/fiemap-empty new file mode 100755 index 000000000..f1ed71c71 --- /dev/null +++ b/tests/cp/fiemap-empty @@ -0,0 +1,89 @@ +#!/bin/sh +# Test cp reads unwritten extents efficiently + +# Copyright (C) 2011 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 . + +. "${srcdir=.}/init.sh"; path_prepend_ ../src +print_ver_ cp + +touch fiemap_chk +fiemap_capable_ fiemap_chk || + skip_test_ 'this file system lacks FIEMAP support' +rm fiemap_chk + +# TODO: rather than requiring `fallocate`, possible add +# this functionality to truncate --alloc +fallocate --help >/dev/null || skip_test_ 'The fallocate utility is required' +fallocate -l 1 -n falloc.test || + skip_test_ 'this file system lacks FALLOCATE support' +rm falloc.test + +fallocate -l 600000000 space.test || + skip_test_ 'this test needs at least 600MB free space' + +# Disable this test on old BTRFS (e.g. Fedora 14) +# which reports ordinary extents for unwritten ones. +filefrag space.test || skip_test_ 'the `filefrag` utility is missing' +filefrag -v space.test | grep -F 'unwritten' > /dev/null || + skip_test_ 'this file system does not report empty extents as "unwritten"' + +rm space.test + +# Ensure we read a large empty file quickly +fallocate -l 300000000 empty.big || framework_failure +timeout 3 cp --sparse=always empty.big cp.test || fail=1 +test $(stat -c %s empty.big) = $(stat -c %s cp.test) || fail=1 +rm empty.big cp.test + +# Ensure we handle extents beyond file size correctly. +# Note until we support fallocate, we will not maintain +# the file allocation. Ammend this test when fallocate is supported +fallocate -l 10000000 -n unwritten.withdata || framework_failure +dd count=10 if=/dev/urandom conv=notrunc iflag=fullblock of=unwritten.withdata +cp unwritten.withdata cp.test || fail=1 +test $(stat -c %s unwritten.withdata) = $(stat -c %s cp.test) || fail=1 +cmp unwritten.withdata cp.test || fail=1 +rm unwritten.withdata cp.test + +# The following to generate unaccounted extents followed by a hole, is not +# supported by ext4 at least. The ftruncate discards all extents not +# accounted for in the size. +# fallocate -l 10000000 -n unacc.withholes +# dd count=10 if=/dev/urandom conv=notrunc iflag=fullblock of=unacc.withholes +# truncate -s20000000 unacc.withholes + +# Ensure we handle a hole after empty extents correctly. +# Since all extents are accounted for in the size, +# we can maintain the allocation independently from +# fallocate() support. +fallocate -l 10000000 empty.withholes +truncate -s 20000000 empty.withholes +sectors_per_block=$(expr $(stat -c %o .) / 512) +cp empty.withholes cp.test || fail=1 +test $(stat -c %s empty.withholes) = $(stat -c %s cp.test) || fail=1 +# These are usually equal but can vary by an IO block due to alignment +alloc_diff=$(expr $(stat -c %b empty.withholes) - $(stat -c %b cp.test)) +alloc_diff=$(echo $alloc_diff | tr -d -- -) # abs() +test $alloc_diff -le $sectors_per_block || fail=1 +# Again with SPARSE_ALWAYS +cp --sparse=always empty.withholes cp.test || fail=1 +test $(stat -c %s empty.withholes) = $(stat -c %s cp.test) || fail=1 +# cp.test should take 0 space, but allowing for some systems +# that store default extended attributes in data blocks +test $(stat -c %b cp.test) -le $sectors_per_block || fail=1 +rm empty.withholes cp.test + +Exit $fail -- cgit v1.2.3-54-g00ecf