On Thu, 2006-09-07 at 11:45 -0700, Andrew Morton wrote:
> On Wed, 06 Sep 2006 10:39:06 -0700
> Badari Pulavarty <pbadari@xxxxxxxxxx> wrote:
>
> > Hi Andrew,
> >
> > Its been reported that ext3_getblk() is not doing the right thing
> > and triggering following WARN():
> >
> > 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
> > <c01c7986> ext3_setattr+0xc3/0x240 <c0120f66> current_fs_time
> > +0x52/0x6a
> > <c017320e> notify_change+0x2bd/0x30d <c0159246> chown_common+0x9c/0xc5
> > <c02a222c> strncpy_from_user+0x3b/0x68 <c0167fe6> do_path_lookup
> > +0xdf/0x266
> > <c016841b> __user_walk_fd+0x44/0x5a <c01592b9> sys_chown+0x4a/0x55
> > <c015a43c> vfs_write+0xe7/0x13c <c01695d4> sys_mkdir+0x1f/0x23
> > <c0102a97> syscall_call+0x7/0xb
> >
> > Looking at the code, it looks like its not handle HOLE correctly.
> > It ends up returning -EIO.
>
> Strange. The fs should be spewing these warnings all over the place. For
> some reason this code is hard to trigger. Why??
I guess - ext3_getblk() mostly used by ext3_bread() and most callers
to it would be reading already allocated block.
>
> > - 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;
> > }
>
> That removes the warning if ext3_get_blocks_handle() returned a positive
> number greater than one. And it looks like we still need debugging support
> in this area.
I am not sure why we need it ? All we care about is one block. If
ext3_get_blocks_handle() returns more than one (which it shouldn't) -
it still be okay. Whats wrong with that ? Just curious ..
May be we should add a WARN() in ext3_get_blocks_handle() when it
returns more than asked for.
Thanks,
Badari
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