Patch "Btrfs: fix inode eviction infinite loop after extent_same ioctl" has been added to the 4.0-stable tree

Patch "Btrfs: fix inode eviction infinite loop after extent_same ioctl" has been added to the 4.0-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    Btrfs: fix inode eviction infinite loop after extent_same ioctl

to the 4.0-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     btrfs-fix-inode-eviction-infinite-loop-after-extent_same-ioctl.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 113e8283869b9855c8b999796aadd506bbac155f Mon Sep 17 00:00:00 2001
From: Filipe Manana <fdmanana@suse.com>
Date: Mon, 30 Mar 2015 18:26:47 +0100
Subject: Btrfs: fix inode eviction infinite loop after extent_same ioctl

From: Filipe Manana <fdmanana@suse.com>

commit 113e8283869b9855c8b999796aadd506bbac155f upstream.

If we pass a length of 0 to the extent_same ioctl, we end up locking an
extent range with a start offset greater then its end offset (if the
destination file's offset is greater than zero). This results in a warning
from extent_io.c:insert_state through the following call chain:

  btrfs_extent_same()
    btrfs_double_lock()
      lock_extent_range()
        lock_extent(inode->io_tree, offset, offset + len - 1)
          lock_extent_bits()
            __set_extent_bit()
              insert_state()
                --> WARN_ON(end < start)

This leads to an infinite loop when evicting the inode. This is the same
problem that my previous patch titled
"Btrfs: fix inode eviction infinite loop after cloning into it" addressed
but for the extent_same ioctl instead of the clone ioctl.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/btrfs/ioctl.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2897,6 +2897,9 @@ static int btrfs_extent_same(struct inod
 	if (src == dst)
 		return -EINVAL;
 
+	if (len == 0)
+		return 0;
+
 	btrfs_double_lock(src, loff, dst, dst_loff, len);
 
 	ret = extent_same_check_offsets(src, loff, len);


Patches currently in stable-queue which might be from fdmanana@suse.com are

queue-4.0/btrfs-fix-log-tree-corruption-when-fs-mounted-with-o-discard.patch
queue-4.0/btrfs-fix-inode-eviction-infinite-loop-after-extent_same-ioctl.patch
queue-4.0/btrfs-fix-inode-eviction-infinite-loop-after-cloning-into-it.patch