Hi Marcelo, Dave, Linus, Al
This definately falls under the "Don't do that" category, but my
box oopsed when i tried to mount a cd as UFS (You don't really wanna hear
the details). It happened to me initially on my main box (2.4.18-pre3), so
i reproduced the oops on my 2.5.2-pre3 test box. This, gentlemen, is the
tale of a wandering hobo called sb->s_blocksize and his short-lived foray
into the linux kernel
fs/ufs/super.c
ufs_read_super()
{
again:
sb_set_blocksize(sb, block_size); <== [1]
ubh = ubh_bread_uspi (uspi, sb,...
[...]
[1] We should have checked the return value!
fs/ufs/util.c
ubh_bread_uspi ()
{
<snip>
if (!(USPI_UBH->bh[i] = sb_bread(sb, fragment + i)));
<snip>
include/linux/fs.h
sb_bread(struct super_block *sb, int block)
{
return __bread(sb->s_bdev, block, sb->s_blocksize);
}
fs/buffer.c
struct buffer_head * __bread(struct block_device *bdev, int block, int
size)
{
struct buffer_head * bh = __getblk(bdev, block, size);
<snip>
struct buffer_head * __getblk(struct block_device *bdev, sector_t block,
int size)
{
<snip>
if (!grow_buffers(bdev, block, size)) <==
<snip>
static int grow_buffers(struct block_device *bdev, unsigned long block,
int size)
{
<snip>
/* Size must be within 512 bytes and PAGE_SIZE */
if (size < 512 || size > PAGE_SIZE)
BUG(); <== *Tadow* size is 0, hobo dude dies here
<snip>
Patch for 2.5.3-pre5
--- linux-2.5.3-pre5/fs/ufs/super.c.orig Sat Jan 26 08:41:33 2002
+++ linux-2.5.3-pre5/fs/ufs/super.c Sat Jan 26 08:42:51 2002
@@ -597,7 +597,10 @@
}
again:
- sb_set_blocksize(sb, block_size);
+ if (!sb_set_blocksize(sb, block_size)) {
+ printk(KERN_ERR "UFS: failed to set blocksize\n");
+ goto failed;
+ }
/*
* read ufs super block from device
Patch for 2.4.18-pre7
--- linux-2.4.18-pre7/fs/ufs/super.c.orig Sat Jan 26 08:52:35 2002
+++ linux-2.4.18-pre7/fs/ufs/super.c Sat Jan 26 08:53:18 2002
@@ -597,7 +597,11 @@
}
again:
- set_blocksize (sb->s_dev, block_size);
+ if (!set_blocksize (sb->s_dev, block_size)) {
+ printk(KERN_ERR "UFS: failed to set blocksize\n");
+ goto failed;
+ }
+
sb->s_blocksize = block_size;
/*
The Oops..
invalid operand: 0000
CPU: 0
EIP: 0010:[<c014e51e>] Not tainted
EFLAGS: 00010282
eax: 0000001d ebx: 00001640 ecx: c031eea4 edx: 00001c31
esi: 00000008 edi: 00000000 ebp: c156df18 esp: c87b1d98
ds: 0018 es: 0018 ss: 0018
Process mount (pid: 970, stackpage=c87b1000)
Stack: c02eaf0f 00000894 00000000 c9a6d0c4 00000000 00003634 00000000
00000008
c156df18 00000002 c014c4f7 c156df18 00000008 00000000 00000000
00000000
c8c37a00 c014c807 c156df18 00000008 00000000 cc8d48ee c87b1dfc
c037bca0
Call Trace: [<c014c4f7>] [<c014c807>] [<cc8d48ee>] [<c0209584>]
[<cc8d726d>]
[<c011a44b>] [<cc8d50ee>] [<c01ea216>] [<c01ea234>] [<c01529be>]
[<c015119b>]
[<cc8da24c>] [<c015146b>] [<cc8da24c>] [<c0167f96>] [<c01185a0>]
[<c01091dc>]
[<c016825b>] [<c01680ac>] [<c01688bf>] [<c01090eb>]
Code: 0f 0b 59 5b b9 ff ff ff ff 89 f6 8d bc 27 00 00 00 00 41 89
>>EIP; c014e51e <grow_buffers+6e/e0> <=====
Trace; c014c4f7 <__getblk+27/40>
Trace; c014c807 <__bread+17/80>
Trace; cc8d48ee <[ufs]ufs_parse_options+29e/2c0>
Trace; c0209584 <blk_get_queue+24/30>
Trace; cc8d726d <[ufs]ubh_bread_uspi+5d/c0>
Trace; c011a44b <__wake_up+7b/e0>
Trace; cc8d50ee <[ufs]ufs_read_super+39e/e80>
Trace; c01ea216 <vsprintf+16/20>
Trace; c01ea234 <sprintf+14/20>
Trace; c01529be <bdevname+2e/40>
Trace; c015119b <get_sb_bdev+29b/360>
Trace; cc8da24c <[ufs]ufs_fs_type+0/34>
Trace; c015146b <do_kern_mount+5b/110>
Trace; cc8da24c <[ufs]ufs_fs_type+0/34>
Trace; c0167f96 <do_add_mount+76/140>
Trace; c01185a0 <do_page_fault+0/5e0>
Trace; c01091dc <error_code+34/3c>
Trace; c016825b <do_mount+15b/180>
Trace; c01680ac <copy_mount_options+4c/a0>
Trace; c01688bf <sys_mount+df/180>
Trace; c01090eb <system_call+33/38>
Code; c014e51e <grow_buffers+6e/e0>
00000000 <_EIP>:
Code; c014e51e <grow_buffers+6e/e0> <=====
0: 0f 0b ud2a <=====
Code; c014e520 <grow_buffers+70/e0>
2: 59 pop %ecx
Code; c014e521 <grow_buffers+71/e0>
3: 5b pop %ebx
Code; c014e522 <grow_buffers+72/e0>
4: b9 ff ff ff ff mov $0xffffffff,%ecx
Code; c014e527 <grow_buffers+77/e0>
9: 89 f6 mov %esi,%esi
Code; c014e529 <grow_buffers+79/e0>
b: 8d bc 27 00 00 00 00 lea 0x0(%edi,1),%edi
Code; c014e530 <grow_buffers+80/e0>
12: 41 inc %ecx
Code; c014e531 <grow_buffers+81/e0>
13: 89 00 mov %eax,(%eax)