On Mon, May 25, 2009 at 05:08:12PM -0400, Alan Stern wrote:
> On Mon, 25 May 2009, Michael S. Tsirkin wrote:
>
> > > So apparently this is a bug in the device; it doesn't respond correctly
> > > to the first READ command. But since it does respond correctly to
> > > later commands, everything works okay thereafter. You ought to be able
> > > to recover from the error by running
> > >
> > > blockdev --rereadpt /dev/sdb
> > >
> > > manually.
> >
> > Yes, this helps.
> > Would it make sense for kernel to retry automatically?
> > Why doesn't it?
>
> I don't know the details in this case. Most likely the error code
> (Logical Block Address Out of Range) is interpreted as a fatal
> non-retryable error. For other sorts of errors, the kernel does retry.
>
> > > As far as I can tell, this has nothing to do with any user programs in
> > > the distribution. It appears to be entirely the device's fault.
> > >
> > > Alan Stern
> >
> > BTW, any idea how come I later get errors apparently from amiga fs?
>
> Not a clue. Unless it was some odd side effect of the partition code
> trying to interpret an uninitialized buffer.
>
> Alan Stern
So, the following works for me as a work-around. But it's probably not
the appropriate way to solve the problem. Or is it? Can someone who
understands partitions and filesystems tell?
block: retry on I/O error when reading partition table
Retry once on an I/O error when reading the partition table:
there's no much to loose, and this helps with some disk on
key devices I have.
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
---
diff --git a/fs/partitions/check.c b/fs/partitions/check.c
index 99e33ef..28b857a 100644
--- a/fs/partitions/check.c
+++ b/fs/partitions/check.c
@@ -510,25 +510,34 @@ int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
struct hd_struct *part;
struct parsed_partitions *state;
int p, highest, res;
+ int i;
if (bdev->bd_part_count)
return -EBUSY;
- res = invalidate_partition(disk, 0);
- if (res)
- return res;
-
- disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
- while ((part = disk_part_iter_next(&piter)))
- delete_partition(disk, part->partno);
- disk_part_iter_exit(&piter);
- if (disk->fops->revalidate_disk)
- disk->fops->revalidate_disk(disk);
- check_disk_size_change(disk, bdev);
- bdev->bd_invalidated = 0;
- if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
- return 0;
- if (IS_ERR(state)) /* I/O error reading the partition table */
+ /* Michael S. Tsirkin has a disk on key where rescanning helps. */
+#define RESCAN_RETRY_CNT 2
+ for (i = 0; i < RESCAN_RETRY_CNT; ++i) {
+ res = invalidate_partition(disk, 0);
+ if (res)
+ return res;
+
+ disk_part_iter_init(&piter, disk, DISK_PITER_INCL_EMPTY);
+ while ((part = disk_part_iter_next(&piter)))
+ delete_partition(disk, part->partno);
+ disk_part_iter_exit(&piter);
+
+ if (disk->fops->revalidate_disk)
+ disk->fops->revalidate_disk(disk);
+ check_disk_size_change(disk, bdev);
+ bdev->bd_invalidated = 0;
+ if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
+ return 0;
+ if (!IS_ERR(state))
+ break;
+ /* I/O error reading the partition table. Retry. */
+ }
+ if (IS_ERR(state)) /* I/O error reading the partition table */
return -EIO;
/* tell userspace that the media / partition table may have changed */
--
MST
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