On Tue, Jul 14, 2009 at 10:52 PM, Aneesh Kumar
K.V<aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote:
> On Tue, Jul 14, 2009 at 01:58:29PM -0700, Curt Wohlgemuth wrote:
>> After the patch I posted last week regarding buffer head ref leaks in
>> no-journal mode, I looked at all the code that uses buffer heads and
>> searched for more potential leaks.
>>
>> The patch below fixes the issues I found; these can occur even when a
>> journal is present.
>>
>> The change to inode.c fixes a double release if
>> ext4_journal_get_create_access() fails.
>>
>> The changes to namei.c are more complicated. add_dirent_to_buf() will
>> release the input buffer head EXCEPT when it returns -ENOSPC. There are
>> some callers of this routine that don't always do the brelse() in the event
>> that -ENOSPC is returned. Unfortunately, to put this fix into ext4_add_entry()
>> required capturing the return value of make_indexed_dir() and
>> add_dirent_to_buf().
>>
>> I'd appreciate comments on these changes, in particular if I'm just missing
>> something obvious here.
>>
>> Signed-off-by: Curt Wohlgemuth <curtw@xxxxxxxxxx>
>>
>> ---
>> diff -Naur orig/fs/ext4/inode.c new/fs/ext4/inode.c
>> --- orig/fs/ext4/inode.c 2009-07-14 11:19:01.000000000 -0700
>> +++ new/fs/ext4/inode.c 2009-07-14 11:51:42.000000000 -0700
>> @@ -758,8 +758,9 @@
>> BUFFER_TRACE(bh, "call get_create_access");
>> err = ext4_journal_get_create_access(handle, bh);
>> if (err) {
>> + /* Don't brelse(bh) here; it's done in journal_forget()
>> + * below */
>> unlock_buffer(bh);
>> - brelse(bh);
>> goto failed;
>> }
>>
>
> I am not able to find the journal_foget call in the path. brelse is
> dropping the buffer_head reference got from sb_getblk right ? Can you
> tell me what is that i am missing ?
Look at the code at the "failed" label. For each of the allocated BHs
thus far, there's a call to ext4_journal_forget().
Oops, I should have put "ext4_journal_forget()" in the comment; my apologies.
I'll resend this out, along with a change to ext4_add_entry() to
remove the gotos.
Thanks,
Curt
>
>
>> diff -Naur orig/fs/ext4/namei.c new/fs/ext4/namei.c
>> --- orig/fs/ext4/namei.c 2009-07-14 11:19:46.000000000 -0700
>> +++ new/fs/ext4/namei.c 2009-07-14 11:19:28.000000000 -0700
>> @@ -1498,12 +1498,14 @@
>
> .. snip..
>
> -aneesh
>
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