Btrfs: revert checksum error statistic which can cause a BUG()

Commit 442a4f6308e694e0fa6025708bd5e4e424bbf51c added btrfs device
statistic counters for detected IO and checksum errors to Linux 3.5.
The statistic part that counts checksum errors in
end_bio_extent_readpage() can cause a BUG() in a subfunction:
"kernel BUG at fs/btrfs/volumes.c:3762!"
That part is reverted with the current patch.
However, the counting of checksum errors in the scrub context remains
active, and the counting of detected IO errors (read, write or flush
errors) in all contexts remains active.

Cc: stable <stable@vger.kernel.org> # 3.5
Signed-off-by: Stefan Behrens <sbehrens@giantdisaster.de>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 15 deletions

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 3e7c9ed6505b..49085f2336d2 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2329,23 +2329,10 @@ static void end_bio_extent_readpage(struct bio *bio, int err)
                 if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
                         ret = tree->ops->readpage_end_io_hook(page, start, end,
                                                               state, mirror);
-                        if (ret) {
-                                /* no IO indicated but software detected errors
-                                 * in the block, either checksum errors or
-                                 * issues with the contents */
-                                struct btrfs_root *root =
-                                        BTRFS_I(page->mapping->host)->root;
-                                struct btrfs_device *device;
-
+                        if (ret)
                                 uptodate = 0;
-                                device = btrfs_find_device_for_logical(
-                                                root, start, mirror);
-                                if (device)
-                                        btrfs_dev_stat_inc_and_print(device,
-                                                BTRFS_DEV_STAT_CORRUPTION_ERRS);
-                        } else {
+                        else
                                 clean_io_failure(start, page);
-                        }
                 }
 
                 if (!uptodate && tree->ops && tree->ops->readpage_io_failed_hook) {