data loss in 2.6.9-rc1-mm1

[Gergely Tamas <dice@mfa.kfki.hu>]

Hi!

I've hit the following data loss problem under 2.6.9-rc1-mm1.

If I copy data from a file to another the target will be smaller then
the source file.

2.6.9-rc1 does not have this problem
2.6.8.1-mm4 does not have this problem
2.6.9-rc1-mm1 _does have_ this problem

I tried this with reiserfs and xfs and it happened with both of them.

See the testcase at the bottom of this mail.

Thanks in advance,
Gergely

--------------------------------------------------

$ uname -r
2.6.9-rc1

$ dd if=/dev/zero of=testfile bs=$((1024*1024)) count=10
10+0 records in
10+0 records out
10485760 bytes transferred in 0.028646 seconds (366045254 bytes/sec)

$ du -sb testfile
10485760        testfile

$ cat testfile > testfile.1

$ du -sb testfile.1
10485760        testfile.1

--------------------------------------------------

$ uname -r
2.6.8.1-mm4

$ dd if=/dev/zero of=testfile bs=$((1024*1024)) count=10
10+0 records in
10+0 records out
10485760 bytes transferred in 0.028632 seconds (366226397 bytes/sec)

$ du -sb testfile
10485760        testfile

$ cat testfile > testfile.1

$ du -sb testfile.1
10485760        testfile.1

--------------------------------------------------

$ uname -r
2.6.9-rc1-mm1

$ dd if=/dev/zero of=testfile bs=$((1024*1024)) count=10
10+0 records in
10+0 records out
10485760 bytes transferred in 0.028418 seconds (368981986 bytes/sec)

$ du -sb testfile
10485760        testfile

$ cat testfile > testfile.1

$ du -sb testfile.1
10481664        testfile.1