[PATCH] pnfs-block: may be return NULL when find a extent

[PATCH] pnfs-block: may be return NULL when find a extent

[fanchaoting]

maybe return NULL when find a extent, if we use it later,
it will cause oops.

 Signed-off-by: fanchaoting<fanchaoting@cn.fujitsu.com>
---
 fs/nfs/blocklayout/extents.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/fs/nfs/blocklayout/extents.c b/fs/nfs/blocklayout/extents.c
index 9c3e117..131ea59 100644
--- a/fs/nfs/blocklayout/extents.c
+++ b/fs/nfs/blocklayout/extents.c
@@ -762,6 +762,11 @@ set_to_rw(struct pnfs_block_layout *bl, u64 offset, u64 length)

        spin_lock(&bl->bl_ext_lock);
        be = bl_find_get_extent_locked(bl, offset);
+       if (!be) {
+               spin_unlock(&bl->bl_ext_lock);
+               goto out_nosplit;
+       }
+
        rv = be->be_f_offset + be->be_length;
        if (be->be_state != PNFS_BLOCK_INVALID_DATA) {
                spin_unlock(&bl->bl_ext_lock);
--
1.7.1

RE: [PATCH] pnfs-block: may be return NULL when find a extent

[Peng, Tao]
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Re: [PATCH] pnfs-block: may be return NULL when find a extent

[fanchaoting]

Peng, Tao 写道:
>> -----Original Message-----
>> From: linux-nfs-owner@vger.kernel.org [mailto:linux-nfs-owner@vger.kernel.org] On Behalf Of
>> fanchaoting
>> Sent: Tuesday, March 12, 2013 2:09 PM
>> To: Myklebust, Trond
>> Cc: linux-nfs@vger.kernel.org
>> Subject: [PATCH] pnfs-block: may be return NULL when find a extent
>>
>> maybe return NULL when find a extent, if we use it later,
>> it will cause oops.
>>
> ah, I would say it is intentional because the lookup cannot fail here. If we are committing an extent but cannot find it in client's extent cache, it certainly is a bug somewhere else. I remember there are other places like this in block layout code as well and we used to put a BUG_ON() there. But since we are using the pointer right away and crash on NULL pointer dereference anyway, it was suggested to remove these BUG_ON()s during code review.
> 

Get it , thanks for telling me it.

> Are you fixing this because you saw a crash or because some static code analyzer complains?
> 
> Thanks,
> Tao
> 
>>  Signed-off-by: fanchaoting<fanchaoting@cn.fujitsu.com>
>> ---
>>  fs/nfs/blocklayout/extents.c |    5 +++++
>>  1 files changed, 5 insertions(+), 0 deletions(-)
>>
>> diff --git a/fs/nfs/blocklayout/extents.c b/fs/nfs/blocklayout/extents.c
>> index 9c3e117..131ea59 100644
>> --- a/fs/nfs/blocklayout/extents.c
>> +++ b/fs/nfs/blocklayout/extents.c
>> @@ -762,6 +762,11 @@ set_to_rw(struct pnfs_block_layout *bl, u64 offset, u64 length)
>>
>>         spin_lock(&bl->bl_ext_lock);
>>         be = bl_find_get_extent_locked(bl, offset);
>> +       if (!be) {
>> +               spin_unlock(&bl->bl_ext_lock);
>> +               goto out_nosplit;
>> +       }
>> +
>>         rv = be->be_f_offset + be->be_length;
>>         if (be->be_state != PNFS_BLOCK_INVALID_DATA) {
>>                 spin_unlock(&bl->bl_ext_lock);
>> --
>> 1.7.1
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>