The code to overwrite/reread for addressing read errors
in raid1/raid10 currently assumes that the read will
not alter the buffer which could be used to write to
the next device.  This is not a safe assumption to make.

So we split the loops into a overwrite loop and a separate re-read
loop, so that the writing is complete before reading is attempted.

Cc: Paul Clements <[EMAIL PROTECTED]>
Signed-off-by: Neil Brown <[EMAIL PROTECTED]>

### Diffstat output
 ./drivers/md/raid1.c  |   38 ++++++++++++++++++++++++++++++--------
 ./drivers/md/raid10.c |   22 ++++++++++++++++++----
 2 files changed, 48 insertions(+), 12 deletions(-)

diff ./drivers/md/raid1.c~current~ ./drivers/md/raid1.c
--- ./drivers/md/raid1.c~current~       2005-12-01 14:03:25.000000000 +1100
+++ ./drivers/md/raid1.c        2005-12-01 14:03:40.000000000 +1100
@@ -1252,6 +1252,7 @@ static void sync_request_write(mddev_t *
                        } while (!success && d != r1_bio->read_disk);
 
                        if (success) {
+                               int start = d;
                                /* write it back and re-read */
                                set_bit(R1BIO_Uptodate, &r1_bio->state);
                                while (d != r1_bio->read_disk) {
@@ -1265,14 +1266,23 @@ static void sync_request_write(mddev_t *
                                                         sect + 
rdev->data_offset,
                                                         s<<9,
                                                         
bio->bi_io_vec[idx].bv_page,
-                                                        WRITE) == 0 ||
-                                           sync_page_io(rdev->bdev,
+                                                        WRITE) == 0)
+                                               md_error(mddev, rdev);
+                               }
+                               d = start;
+                               while (d != r1_bio->read_disk) {
+                                       if (d == 0)
+                                               d = conf->raid_disks;
+                                       d--;
+                                       if (r1_bio->bios[d]->bi_end_io != 
end_sync_read)
+                                               continue;
+                                       rdev = conf->mirrors[d].rdev;
+                                       if (sync_page_io(rdev->bdev,
                                                         sect + 
rdev->data_offset,
                                                         s<<9,
                                                         
bio->bi_io_vec[idx].bv_page,
-                                                        READ) == 0) {
+                                                        READ) == 0)
                                                md_error(mddev, rdev);
-                                       }
                                }
                        } else {
                                char b[BDEVNAME_SIZE];
@@ -1444,6 +1454,7 @@ static void raid1d(mddev_t *mddev)
 
                                if (success) {
                                        /* write it back and re-read */
+                                       int start = d;
                                        while (d != r1_bio->read_disk) {
                                                if (d==0)
                                                        d = conf->raid_disks;
@@ -1453,13 +1464,24 @@ static void raid1d(mddev_t *mddev)
                                                    test_bit(In_sync, 
&rdev->flags)) {
                                                        if 
(sync_page_io(rdev->bdev,
                                                                         sect + 
rdev->data_offset,
-                                                                        s<<9, 
conf->tmppage, WRITE) == 0 ||
-                                                           
sync_page_io(rdev->bdev,
+                                                                        s<<9, 
conf->tmppage, WRITE) == 0)
+                                                               /* Well, this 
device is dead */
+                                                               md_error(mddev, 
rdev);
+                                               }
+                                       }
+                                       d = start;
+                                       while (d != r1_bio->read_disk) {
+                                               if (d==0)
+                                                       d = conf->raid_disks;
+                                               d--;
+                                               rdev = conf->mirrors[d].rdev;
+                                               if (rdev &&
+                                                   test_bit(In_sync, 
&rdev->flags)) {
+                                                       if 
(sync_page_io(rdev->bdev,
                                                                         sect + 
rdev->data_offset,
-                                                                        s<<9, 
conf->tmppage, READ) == 0) {
+                                                                        s<<9, 
conf->tmppage, READ) == 0)
                                                                /* Well, this 
device is dead */
                                                                md_error(mddev, 
rdev);
-                                                       }
                                                }
                                        }
                                } else {

diff ./drivers/md/raid10.c~current~ ./drivers/md/raid10.c
--- ./drivers/md/raid10.c~current~      2005-12-01 14:03:25.000000000 +1100
+++ ./drivers/md/raid10.c       2005-12-01 14:03:41.000000000 +1100
@@ -1421,6 +1421,7 @@ static void raid10d(mddev_t *mddev)
                                } while (!success && sl != r10_bio->read_slot);
 
                                if (success) {
+                                       int start = sl;
                                        /* write it back and re-read */
                                        while (sl != r10_bio->read_slot) {
                                                int d;
@@ -1434,14 +1435,27 @@ static void raid10d(mddev_t *mddev)
                                                        if 
(sync_page_io(rdev->bdev,
                                                                         
r10_bio->devs[sl].addr +
                                                                         sect + 
rdev->data_offset,
-                                                                        s<<9, 
conf->tmppage, WRITE) == 0 ||
-                                                           
sync_page_io(rdev->bdev,
+                                                                        s<<9, 
conf->tmppage, WRITE) == 0)
+                                                               /* Well, this 
device is dead */
+                                                               md_error(mddev, 
rdev);
+                                               }
+                                       }
+                                       sl = start;
+                                       while (sl != r10_bio->read_slot) {
+                                               int d;
+                                               if (sl==0)
+                                                       sl = conf->copies;
+                                               sl--;
+                                               d = r10_bio->devs[sl].devnum;
+                                               rdev = conf->mirrors[d].rdev;
+                                               if (rdev &&
+                                                   test_bit(In_sync, 
&rdev->flags)) {
+                                                       if 
(sync_page_io(rdev->bdev,
                                                                         
r10_bio->devs[sl].addr +
                                                                         sect + 
rdev->data_offset,
-                                                                        s<<9, 
conf->tmppage, READ) == 0) {
+                                                                        s<<9, 
conf->tmppage, READ) == 0)
                                                                /* Well, this 
device is dead */
                                                                md_error(mddev, 
rdev);
-                                                       }
                                                }
                                        }
                                } else {
-
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