[PATCH] btrfs: fix uninitialized variable warning

[David Sterba]

From: David Sterba dste...@suse.cz

With Linus' tree, today's linux-next build (powercp ppc64_defconfig)
produced this warning:

fs/btrfs/delayed-inode.c: In function 'btrfs_delayed_update_inode':
fs/btrfs/delayed-inode.c:1598:6: warning: 'ret' may be used
uninitialized in this function

Introduced by commit 16cdcec736cd (btrfs: implement delayed inode items
operation).

This fixes a bug in btrfs_update_inode(): if the returned value from
btrfs_delayed_update_inode is a nonzero garbage, inode stat data are not
updated and several call paths may hit a BUG_ON or fail with strange
code.

Reported-by: Stephen Rothwell s...@canb.auug.org.au
Signed-off-by: David Sterba dste...@suse.cz
---

patch pushed to git://repo.or.cz/linux-2.6/btrfs-unstable.git #fixes

 fs/btrfs/delayed-inode.c |2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 01e2950..8cb012f 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -1595,7 +1595,7 @@ int btrfs_delayed_update_inode(struct btrfs_trans_handle 
*trans,
   struct btrfs_root *root, struct inode *inode)
 {
struct btrfs_delayed_node *delayed_node;
-   int ret;
+   int ret = 0;
 
delayed_node = btrfs_get_or_create_delayed_node(inode);
if (IS_ERR(delayed_node))
-- 
1.7.5.2.353.g5df3e

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Re: [PATCH] btrfs: fix uninitialized variable warning

[Chris Mason]

Excerpts from David Sterba's message of 2011-06-03 10:50:14 -0400:
 From: David Sterba dste...@suse.cz
 
 With Linus' tree, today's linux-next build (powercp ppc64_defconfig)
 produced this warning:
 
 fs/btrfs/delayed-inode.c: In function 'btrfs_delayed_update_inode':
 fs/btrfs/delayed-inode.c:1598:6: warning: 'ret' may be used
 uninitialized in this function
 
 Introduced by commit 16cdcec736cd (btrfs: implement delayed inode items
 operation).
 
 This fixes a bug in btrfs_update_inode(): if the returned value from
 btrfs_delayed_update_inode is a nonzero garbage, inode stat data are not
 updated and several call paths may hit a BUG_ON or fail with strange
 code.

Ugh, thanks!  It looks like the gcc uninit stuff isn't as verbose as it
used to be, but it does catch a bunch of allocated/set but not used
vars.

I have a nitems = 0 fix in my tree as well.

-chris
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