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??
> - 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 reworked it like this:
--- a/fs/ext3/inode.c~ext3_getblk-should-handle-hole-correctly
+++ a/fs/ext3/inode.c
@@ -1010,11 +1010,14 @@ 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) {
+ if (err > 1)
+ WARN_ON(1);
err = 0;
- } else if (err >= 0) {
- WARN_ON(1);
- err = -EIO;
}
*errp = err;
if (!err && buffer_mapped(&dummy)) {
_
ie:
/*
* ext3_get_blocks_handle() returns number of blocks
* mapped. 0 in case of a HOLE.
*/
if (err > 0) {
if (err > 1)
WARN_ON(1);
err = 0;
}
*errp = err;
-
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