2 # SPDX-License-Identifier: GPL-2.0
3 # Copyright (c) 2003-2004 Silicon Graphics, Inc. All Rights Reserved.
10 # Modify a filesystem's superblock and AGF metadata structures
11 # so that only a subset of the allocation groups will be used.
12 # Intended use is in testing large virtual devices (eg. loop)
13 # with extremely large filesystems, where we want to ensure
14 # high allocation groups are used as much as possible (where
15 # the block addresses are large).
19 getopts('cf:l:qr:v', \%opt);
21 die "Usage: $0 [-f AG] [-l AG] [-r bytes] [-cqv] device\n" unless (@ARGV == 1);
22 my $device = shift @ARGV;
23 die "$device: no such file\n" unless (-e $device);
25 my $clearall = defined($opt{'c'}) ? 1 : 0;
26 my $retain = defined($opt{'r'}) ? $opt{'r'} : -1;
27 my $quiet = defined($opt{'q'}) ? 1 : 0;
28 my $verbose = defined($opt{'v'}) ? 1 : 0;
29 my $nagfirst = defined($opt{'f'}) ? $opt{'f'} : 0;
30 my $naglast = defined($opt{'l'}) ? $opt{'l'} : 0;
33 # "clearall" means clear everything barring the final AG.
34 # "retain" means clearall and retain a specified amount in the
35 # second-from-last AG as well (value is the number of bytes).
36 # [NB: retain with a value of zero is now the same as clearall].
43 my $xfsdb = 'xfs_db -x';
47 $xfsdb .= ' -c ' . $_;
49 print $xfsdb, ' ', $device, "\n" if ($verbose);
51 die unless open(DB, "$xfsdb $device 2>/dev/null |");
53 if (/^(\S+) = (.*)$/) {
63 # Stage 1: Get control information from the superblock
66 my @sbprint = ( '"print fdblocks"', '"print agcount"', '"print blocksize"' );
67 my @agffree = ( '"print freeblks"' );
69 my %sb = xfs_db 'sb', @sbprint;
70 print "=== Initially ", $sb{'fdblocks'}, " blocks free across ",
71 $sb{'agcount'}, " AGs\n" unless $quiet;
72 if ($clearall && ($nagfirst || $naglast)) {
73 print STDERR " o Clearall/retain specified with first/last AG\n";
76 if ($nagfirst >= $sb{'agcount'}) {
77 print STDERR " o First AG number is too large\n";
80 if ($naglast >= $sb{'agcount'}) {
81 print STDERR " o Last AG number is too large\n";
84 if ($naglast - $nagfirst < 0) {
85 print STDERR " o No AGs to clear\n";
89 $naglast = $sb{'agcount'} - 2;
94 $retain /= $sb{'blocksize'}; # convert to fsblocks
95 %check = xfs_db "'agf $naglast'", @agffree;
96 if ($check{'freeblks'} < $retain) {
97 print STDERR " o Insufficient space to retain\n";
105 # Stage 2: Wipe out all completely masked allocation groups.
108 my @agfprint = ( '"print freeblks"', '"print flcount"' );
109 my @agfcommands = ( '"write freeblks 0"',
110 '"write longest 0"', '"write flcount 0"',
111 '"write bnolevel 1"', '"write cntlevel 1"',
112 '"write flfirst 0"', '"write fllast 0"' );
113 my @bnoprint = ( '"addr bnoroot"', '"print numrecs"' );
114 my @bnocommands = ( '"addr bnoroot"', '"write numrecs 0"',
115 '"write leftsib -1"', '"write rightsib -1"' );
116 my @cntprint = ( '"addr cntroot"', '"print numrecs"' );
117 my @cntcommands = ( '"addr cntroot"', '"write numrecs 0"',
118 '"write leftsib -1"', '"write rightsib -1"' );
120 print "=== Wiping ", $naglast - $nagfirst + 1,
121 " AGs starting from AG #", $nagfirst, "\n" unless $quiet;
124 while ($ag <= $naglast) {
125 print " o AG#", $ag, " AGF fields\n" unless $quiet;
127 my %agf = xfs_db "'agf $ag'", @agfprint;
128 xfs_db "'agf $ag'", @agfcommands;
130 my $blockcnt = $agf{'freeblks'} + $agf{'flcount'};
131 $sb{'fdblocks'} -= $blockcnt;
132 print " cleared ", $blockcnt, " blocks from AG#", $ag, "\n"
135 my %btree = xfs_db "'agf $ag'", @bnoprint;
136 xfs_db "'agf $ag'", @bnocommands, "'agf $ag'", @cntcommands;
137 print " cleared ", $btree{'numrecs'}, " BNO/CNT btree recs in AG#",
138 $ag, "\n" unless $quiet;
145 # Stage 3: Wipe out any partially masked allocation group.
149 print " o AG#", $ag, " AGF fields (partial)\n" unless $quiet;
151 my %ragf = xfs_db "'agf $ag'", '"print freeblks"',
152 '"addr bnoroot"', '"print recs[1].startblock"';
153 my $maskblks = $ragf{'freeblks'} - $retain;
154 my $newstart = $ragf{'recs[1].startblock'} + $maskblks;
156 "'write freeblks $retain'", "'write longest $retain'",
157 "'agf $ag'", '"addr bnoroot"',
158 "'write recs[1].startblock $newstart'",
159 "'write recs[1].blockcount $retain'",
160 "'agf $ag'", '"addr cntroot"',
161 "'write recs[1].startblock $newstart'",
162 "'write recs[1].blockcount $retain'";
164 $sb{'fdblocks'} -= $maskblks;
165 print " cleared ", $maskblks, " blocks from AG#", $ag, "\n"
169 print "=== Updating final freespace count, ", $sb{'fdblocks'}, " blocks\n"
171 xfs_db "'sb 0'", "'write fdblocks $sb{'fdblocks'}'"