Re: BUG: warning at fs/ext3/inode.c:1016/ext3_getblk()

[Mingming Cao <cmm@us.ibm.com>]

Badari Pulavarty wrote:
> On Tue, 2006-09-05 at 17:47 -0400, Will Simoneau wrote:
>
> > On 14:06 Tue 05 Sep     , Badari Pulavarty wrote:
> >
> > > Will Simoneau wrote:
> > >
> > > > Has anyone seen this before? These three traces occured at different times
> > > > today when three new user accounts (and associated quotas) were created. 
> > > > This
> > > > machine is an NFS server which uses quotas on an ext3 fs (dir_index is on).
> > > > Kernel is 2.6.17.11 on an x86 smp w/64G highmem; 4G ram is installed. The
> > > > affected filesystem is on a software raid1 of two hardware raid0 volumes 
> > >
> > > > from a
> > >
> > > > megaraid card.
> > > >
> > > > BUG: warning at fs/ext3/inode.c:1016/ext3_getblk()
> > > > <c01c5140> ext3_getblk+0x98/0x2a6  <c03b2806> md_wakeup_thread+0x26/0x2a
> > > > <c01c536d> ext3_bread+0x1f/0x88  <c01cedf9> ext3_quota_read+0x136/0x1ae
> > > > <c018b683> v1_read_dqblk+0x61/0xac  <c0188f32> dquot_acquire+0xf6/0x107
> > > > <c01ceaba> ext3_acquire_dquot+0x46/0x68  <c01897d4> dqget+0x155/0x1e7
> > > > <c018a97b> dquot_transfer+0x3e0/0x3e9  <c016fe52> dput+0x23/0x13e
>
>
> I think, we found your problem.
>
> ext3_getblk() is not handling HOLE correctly. Does this patch help ?
> Mingming, what do you think ?

Looks correct to me, ext3_get_blocks_handle() returning 0 is a valid 
case when the block is not being mapped(hole).

It would be nice to add a WARN_ON() in the ext3_get_blocks_handle() code 
when we allocating more than requested (maxblocks) blocks...:)

Mingming


> Badari
>
> ext3_get_blocks_handle() returns number of blocks it mapped.
> It returns 0 in case of HOLE. ext3_getblk() should handle
> HOLE properly (currently its dumping warning stack and
> returning -EIO).
>
> Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
> ---
>  fs/ext3/inode.c |    9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> Index: linux-2.6.18-rc5/fs/ext3/inode.c
> ===================================================================
> --- linux-2.6.18-rc5.orig/fs/ext3/inode.c	2006-08-27 20:41:48.000000000 -0700
> +++ linux-2.6.18-rc5/fs/ext3/inode.c	2006-09-05 15:32:57.000000000 -0700
> @@ -1009,11 +1009,12 @@ struct buffer_head *ext3_getblk(handle_t
>  	buffer_trace_init(&dummy.b_history);
>  	err = ext3_get_blocks_handle(handle, inode, block, 1,
>  					&dummy, create, 1);
> -	if (err == 1) {
> +	/*
> +	 * ext3_get_blocks_handle() returns number of blocks
> +	 * mapped. 0 in case of a HOLE.
> +	 */
> +	if (err > 0) {
>  		err = 0;
> -	} else if (err >= 0) {
> -		WARN_ON(1);
> -		err = -EIO;
>  	}
>  	*errp = err;
>  	if (!err && buffer_mapped(&dummy)) {
>
>
> -
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