On Sat, 2010-03-13 at 11:37 +0100, Matthias Rieber wrote:
> Hi,
>
> I tried the kernel 2.6.33 and I still have the data corruption problems.
> When I remount the partition with the sync option and repeat the test,
> all files seem to be intact. I'm using an ext3 filesystem on a lvm
> volume for my UMLs.
>
> matthias
>
I traced down the problem to the sector handling in ubd. There is a bug
in the ubd driver handling of multi sector requests. I added code to
restrict block requests to one sector (512 bytes) only. See attached
revised diff against 2.6.33.
-Janjaap
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index cf8a97f..a529c3f 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -305,10 +305,12 @@ int line_ioctl(struct tty_struct *tty, struct file * file,
for (i = 0; i < ARRAY_SIZE(tty_ioctls); i++)
if (cmd == tty_ioctls[i].cmd)
break;
+#ifdef DEBUG
if (i == ARRAY_SIZE(tty_ioctls)) {
printk(KERN_ERR "%s: %s: unknown ioctl: 0x%x\n",
__func__, tty->name, cmd);
}
+#endif
ret = -ENOIOCTLCMD;
break;
}
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 5ff5546..655ed9e 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -746,8 +746,12 @@ static int ubd_open_dev(struct ubd *ubd_dev)
}
ubd_dev->fd = fd;
+ /* A setting higher than 1 sector currently (v2.6.33) generates
+ data loss, both for raw and cow ubd. */
+ blk_queue_max_sectors(ubd_dev->queue, 1 * sizeof(long));
+ blk_queue_max_phys_segments(ubd_dev->queue, 1 * sizeof(long));
+
if(ubd_dev->cow.file != NULL){
- blk_queue_max_sectors(ubd_dev->queue, 8 * sizeof(long));
err = -ENOMEM;
ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
@@ -1223,7 +1227,7 @@ static void do_ubd_request(struct request_queue *q)
struct io_thread_req *io_req;
struct request *req;
sector_t sector;
- int n;
+ int n, last_sectors;
while(1){
struct ubd *dev = q->queuedata;
@@ -1239,9 +1243,12 @@ static void do_ubd_request(struct request_queue *q)
req = dev->request;
sector = blk_rq_pos(req);
+ last_sectors = 0;
while(dev->start_sg < dev->end_sg){
struct scatterlist *sg = &dev->sg[dev->start_sg];
+ sector += last_sectors;
+ last_sectors = 0;
io_req = kmalloc(sizeof(struct io_thread_req),
GFP_ATOMIC);
if(io_req == NULL){
@@ -1253,7 +1260,7 @@ static void do_ubd_request(struct request_queue *q)
(unsigned long long)sector << 9,
sg->offset, sg->length, sg_page(sg));
- sector += sg->length >> 9;
+ last_sectors = sg->length >> 9;
n = os_write_file(thread_fd, &io_req,
sizeof(struct io_thread_req *));
if(n != sizeof(struct io_thread_req *)){
diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S
index 7fcad58..0731311 100644
--- a/arch/um/kernel/dyn.lds.S
+++ b/arch/um/kernel/dyn.lds.S
@@ -50,8 +50,20 @@ SECTIONS
.rela.got : { *(.rela.got) }
.rel.bss : { *(.rel.bss .rel.bss.* .rel.gnu.linkonce.b.*) }
.rela.bss : { *(.rela.bss .rela.bss.* .rela.gnu.linkonce.b.*) }
- .rel.plt : { *(.rel.plt) }
- .rela.plt : { *(.rela.plt) }
+ .rel.plt :
+ {
+ *(.rel.plt)
+ PROVIDE_HIDDEN (__rel_iplt_start = .);
+ *(.rel.iplt)
+ PROVIDE_HIDDEN (__rel_iplt_end = .);
+ }
+ .rela.plt :
+ {
+ *(.rela.plt)
+ PROVIDE_HIDDEN (__rela_iplt_start = .);
+ *(.rela.iplt)
+ PROVIDE_HIDDEN (__rela_iplt_end = .);
+ }
.init : {
KEEP (*(.init))
} =0x90909090
diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S
index e7a6cca..a658604 100644
--- a/arch/um/kernel/uml.lds.S
+++ b/arch/um/kernel/uml.lds.S
@@ -36,6 +36,21 @@ SECTIONS
*(.gnu.linkonce.t*)
}
+ .rel.plt :
+ {
+ *(.rel.plt)
+ PROVIDE_HIDDEN (__rel_iplt_start = .);
+ *(.rel.iplt)
+ PROVIDE_HIDDEN (__rel_iplt_end = .);
+ }
+ .rela.plt :
+ {
+ *(.rela.plt)
+ PROVIDE_HIDDEN (__rela_iplt_start = .);
+ *(.rela.iplt)
+ PROVIDE_HIDDEN (__rela_iplt_end = .);
+ }
+
. = ALIGN(PAGE_SIZE);
.syscall_stub : {
__syscall_stub_start = .;
diff --git a/arch/um/sys-x86_64/ptrace.c b/arch/um/sys-x86_64/ptrace.c
index f3458d7..1c738c7 100644
--- a/arch/um/sys-x86_64/ptrace.c
+++ b/arch/um/sys-x86_64/ptrace.c
@@ -69,7 +69,7 @@ int poke_user(struct task_struct *child, long addr, long data)
else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
(addr <= offsetof(struct user, u_debugreg[7]))) {
addr -= offsetof(struct user, u_debugreg[0]);
- addr = addr >> 2;
+ addr = addr >> 3; // long is 8 bytes on x86_64
if ((addr == 4) || (addr == 5))
return -EIO;
child->thread.arch.debugregs[addr] = data;
@@ -114,7 +114,7 @@ int peek_user(struct task_struct *child, long addr, long data)
else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
(addr <= offsetof(struct user, u_debugreg[7]))) {
addr -= offsetof(struct user, u_debugreg[0]);
- addr = addr >> 2;
+ addr = addr >> 3; // long is 8 bytes on x86_64
tmp = child->thread.arch.debugregs[addr];
}
return put_user(tmp, (unsigned long *) data);
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