On 02/23/2011 09:30 AM, Josef Bacik wrote:
> On Wed, Feb 23, 2011 at 09:12:36AM +0800, liubo wrote:
>> On 02/22/2011 10:32 PM, David Sterba wrote:
>>> Hi,
>>>
>>> no deeper analysis done, but the double free error was obvious :)
>>>
>>> On Tue, Feb 22, 2011 at 07:42:25PM +0800, liubo wrote:
>>>> When we recover from crash via write-ahead log tree and process
>>>> the inode refs, for each btrfs_inode_ref item, we will
>>>> 1) check if we already have a perfect match in fs/file tree, if
>>>> we have, then we're done.
>>>> 2) search the corresponding back reference in fs/file tree, and
>>>> check all the names in this back reference to see if they are
>>>> also in the log to avoid conflict corners.
>>>> 3) recover the logged inode refs to fs/file tree.
>>>>
>>>> In current btrfs, however,
>>>> - for 2)'s check, once is enough, since the checked back references
>>>> will remain unchanged after processing all the inode refs belonged
>>>> to the key.
>>>> - it has no need to do another 1) between 2) and 3).
>>>>
>>>> This patch focus on the above problems and
>>>> I've made a small test to show how it improves,
>>>>
>>>> $dd if=/dev/zero of=foobar bs=4K count=1
>>>> $sync
>>>> $make 100 hard links continuously, like ln foobar link_i
>>>> $fsync foobar
>>>> $echo b > /proc/sysrq-trigger
>>>> after reboot
>>>> $time mount DEV PATH
>>>>
>>>> without patch:
>>>> real 0m0.285s
>>>> user 0m0.001s
>>>> sys 0m0.009s
>>>>
>>>> with patch:
>>>> real 0m0.123s
>>>> user 0m0.000s
>>>> sys 0m0.010s
>>>>
>>>> Signed-off-by: Liu Bo <liubo2...@cn.fujitsu.com>
>>>> ---
>>>> fs/btrfs/tree-log.c | 33 +++++++++++----------------------
>>>> 1 files changed, 11 insertions(+), 22 deletions(-)
>>>>
>>>> diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
>>>> index a4bbb85..8f2a9f3 100644
>>>> --- a/fs/btrfs/tree-log.c
>>>> +++ b/fs/btrfs/tree-log.c
>>>> @@ -799,12 +799,12 @@ static noinline int add_inode_ref(struct
>>>> btrfs_trans_handle *trans,
>>>> struct inode *dir;
>>>> int ret;
>>>> struct btrfs_inode_ref *ref;
>>>> - struct btrfs_dir_item *di;
>>>> struct inode *inode;
>>>> char *name;
>>>> int namelen;
>>>> unsigned long ref_ptr;
>>>> unsigned long ref_end;
>>>> + int search_done = 0;
>>>>
>>>> /*
>>>> * it is possible that we didn't log all the parent directories
>>>> @@ -845,7 +845,10 @@ again:
>>>> * existing back reference, and we don't want to create
>>>> * dangling pointers in the directory.
>>>> */
>>>> -conflict_again:
>>>> +
>>>> + if (search_done)
>>>> + goto insert;
>>>> +
>>>> ret = btrfs_search_slot(NULL, root, key, path, 0, 0);
>>>> if (ret == 0) {
>>>> char *victim_name;
>>>> @@ -888,35 +891,21 @@ conflict_again:
>>>> victim_name_len);
>>>> kfree(victim_name);
>>> ^^^^^^^^^^^^^^^^^^^
>>>> btrfs_release_path(root, path);
>>>> - goto conflict_again;
>>>> }
>>>> kfree(victim_name);
>>> ^^^^^^^^^^^^^^^^^^^
>>> double free
>> thanks for reviewing, but the first one is followed by a goto phrase, so IMO
>> it is ok.
>>
>
> Your patch removes that goto, so it's not ok. Thanks,
ahh, my fault.
I'll fix it, thanks a lot, :)
liubo
>
> Josef
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