Tao Ma wrote: > Hi Jim, > On 05/29/2010 12:44 AM, Jim Meyering wrote: >> Tao Ma wrote: >> >>> Hi Jim >>> >>> On 05/27/2010 06:30 PM, Jim Meyering wrote: >>>> jeff.liu wrote: >>>>> This is the revised version, it fixed the fiemap-start offset calculation >>>>> approach to remove it out >>>>> of the 'for (i = 0; i< fiemap->fm_mapped_extents; i++)' loop. >>>> >>>> Hi Jeff, >>>> >>>> I've included below the state of my local changes. >>>> Unfortunately, with that 5-patch series, there is always a test failure >>>> on F13/ext4. Maybe someone who knows more about extents can provide an >>>> explanation? >>> Just want to clarify why ocfs2 didn't work here. I guess the reason >>> also works for ext4 since both ext4 and ocfs2 use block group to >>> organize their blocks in the volume. >> >> Hi Tao, >> >> Thank you for the explanation. >> I'm glad to hear that there is no underlying problem. >> >>> I checked the perl test script to create sparse src file, it will >>> create contiguous bytes(around 20-24k) at an interval of around 40k.So >>> in general, these 20-24k should be contiguous. But that does exist >>> some scenario that they could be separately into 2 extents. Consider >>> one block group is used to allocate blocks to this file, when the >>> block group only has 10K left while you are requiring 20K, it will use >>> the left 10K in this group and allocate 10K from another block >>> group. That would become 2 extents since they can't be contiguous. >> >>> So I guess the right step is to check the holes by using filefrag if >>> you prefer this tool and want to make sure cp doesn't copy holes(I get >> >> Do you know of a tool other than filefrag that I could use? > nope. >> >> It looks like a small script could filter filefrag -v output, detect >> split extents and rewrite to make the output match what's expected. >> Probably not worth it, though, since this is already a very fragile test.
I went ahead and did it, after all. Here's the script, filefrag-extent-compare. With it, this test should pass when run on any of those four file system types. eval '(exit $?0)' && eval 'exec perl -wS "$0" ${1+"$@"}' & eval 'exec perl -wS "$0" $argv:q' if 0; # Determine whether two files have the same extents by comparing # the logical block numbers and lengths from filefrag -v for each. # Invoke like this: # This helper function, f, extracts logical block number and lengths. # f() { awk '/^ *[0-9]/ {printf "%d %d ",$2,NF<5?$NF:$5} END {print ""}'; } # { filefrag -v j1 | f; filefrag -v j2 | f; } | ./filefrag-extent-compare use warnings; use strict; (my $ME = $0) =~ s|.*/||; my @line = <>; my $n_lines = @line; $n_lines == 2 or die "$ME: expected exactly two input lines; got $n_lines\n"; my @A = split ' ', $line[0]; my @B = split ' ', $line[1]; @A % 2 || @B % 2 and die "$ME: unexpected input: odd number of numbers; expected even\n"; my @a; my @b; foreach my $i (0...@a/2-1) { $a[$i] = { L_BLK => $A[2*$i], LEN => $A[2*$i+1] } }; foreach my $i (0...@b/2-1) { $b[$i] = { L_BLK => $B[2*$i], LEN => $B[2*$i+1] } }; my $i = 0; my $j = 0; while (1) { !defined $a[$i] && !defined $b[$j] and exit 0; defined $a[$i] && defined $b[$j] or die "\...@a and \...@b have different lengths, even after adjustment\n"; ($a[$i]->{L_BLK} == $b[$j]->{L_BLK} && $a[$i]->{LEN} == $b[$j]->{LEN}) and next; ($a[$i]->{LEN} < $b[$j]->{LEN} && exists $a[$i+1] && $a[$i]->{LEN} + $a[$i+1]->{LEN} == $b[$j]->{LEN}) and ++$i, next; exists $b[$j+1] && $a[$i]->{LEN} == $b[$i]->{LEN} + $b[$i+1]->{LEN} and ++$j, next; die "differing extent:\n" . " [$i]=$a[$i]->{L_BLK} $a[$i]->{LEN}\n" . " [$j]=$b[$j]->{L_BLK} $b[$j]->{LEN}\n" } continue { ++$i; ++$j; }