From: Sergei Trofimovich <slyfox@xxxxxxxxxx>
btrfs_print_leaf() is usually called in emergency situations.
Don't die on SIGSEGV in such situations. Skip gracefully instead:
> [ 18.680000] parent transid verify failed on 227736236032 wanted 132659 found 123593
> [ 22.410000] btrfs: btrfs_print_leaf got NULL extent buffer. Skip printing.
> [ 22.410000] ------------[ cut here ]------------
> [ 22.410000] WARNING: at linux-2.6/fs/btrfs/extent-tree.c:4482 __btrfs_free_extent+0x650/0x7e0()
> [ 22.410000] Call Trace:
> [ 22.410000] 6f569a98: [<600314a2>] warn_slowpath_common+0x62/0x90
...
> [ 22.410000] btrfs unable to find ref byte nr 39186432 parent 0 root 5 owner 0 offset 0
Instead of OOPsing in btrfs_print_leaf in get a little deeper and print useful info.
Signed-off-by: Sergei Trofimovich <slyfox@xxxxxxxxxx>
---
fs/btrfs/print-tree.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index fb2605d..7089603 100644
--- a/fs/btrfs/print-tree.c
+++ b/fs/btrfs/print-tree.c
@@ -159,7 +159,7 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
{
int i;
u32 type;
- u32 nr = btrfs_header_nritems(l);
+ u32 nr;
struct btrfs_item *item;
struct btrfs_root_item *ri;
struct btrfs_dir_item *di;
@@ -172,6 +172,13 @@ void btrfs_print_leaf(struct btrfs_root *root, struct extent_buffer *l)
struct btrfs_key key;
struct btrfs_key found_key;
+ if (!l) {
+ printk(KERN_ERR "btrfs: btrfs_print_leaf got NULL extent buffer. Skip printing.\n");
+ return;
+ }
+
+ nr = btrfs_header_nritems(l);
+
printk(KERN_INFO "leaf %llu total ptrs %d free space %d\n",
(unsigned long long)btrfs_header_bytenr(l), nr,
btrfs_leaf_free_space(root, l));
--
1.7.3.4
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