On Sat, Feb 26, 2011 at 10:05:40AM +0800, Yan, Zheng  wrote:

On Sat, Feb 26, 2011 at 7:43 AM, Ilya Dryomov [off-list ref] wr=

ote:

quoted

In case of an ENOSPC error from btrfs_relocate_chunk() (line 2202) =

while

quoted

relocating a block group with offset 0 we end up endlessly looping.
This happens because key.offset -=3D 1 statement then unconditional=

ly

quoted

brings us back to the beginnig of the loop (key.offset =3D=3D (u64)=

-1).

quoted

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
=C2=A0fs/btrfs/volumes.c | =C2=A0 =C2=A03 ++-
=C2=A01 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index dd13eb8..0cb94ce 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c

@@ -2212,7 +2212,8 @@ again:

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=

 =C2=A0 =C2=A0goto done;

quoted

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0if (ret =3D=3D=

 -ENOSPC)

quoted

=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=

 =C2=A0 =C2=A0failed++;

quoted

- =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 key.offset -=3D =

1;

quoted

+ =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 if (--key.offset=

 =3D=3D -1)

quoted

+ =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=

=A0 =C2=A0 break;

quoted

=C2=A0 =C2=A0 =C2=A0 =C2=A0}

=20
it should be  if (--key.offset =3D=3D (u64) -1)
=20

quoted

=C2=A0 =C2=A0 =C2=A0 =C2=A0if (failed && !retried) {
--
1.7.2.3

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fs" in

quoted

the body of a message to majordomo@vger.kernel.org
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html

quoted

I wonder how I managed to screw that up, I got it right in the commit
description..  Sorry for the noise, here is an updated version.

---

=46rom: Ilya Dryomov [off-list ref]
Date: Sat, 26 Feb 2011 01:29:25 +0200
Subject: [PATCH] Btrfs: fix infinite loop in btrfs_shrink_device()

In case of an ENOSPC error from btrfs_relocate_chunk() (line 2202) whil=
e
relocating a block group with offset 0 we end up endlessly looping.
This happens because key.offset -=3D 1 statement then unconditionally
brings us back to the beginning of the loop (key.offset =3D=3D (u64)-1)=
=2E

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
---
 fs/btrfs/volumes.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index dd13eb8..cd334ae 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c

@@ -2212,7 +2212,8 @@ again:
 			goto done;
 		if (ret =3D=3D -ENOSPC)
 			failed++;
-		key.offset -=3D 1;
+		if (--key.offset =3D=3D (u64)-1)
+			break;
 	}

=20
 	if (failed && !retried) {
--=20
1.7.2.3

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