### Comments for ChangeSet
A partial block write over a block on a failed device
would need to pre-read that block, which means pre-read all
blocks in stripe and generate that block. But the generate-block
code never checked for this possibility, so it wouldn't happen.
----------- Diffstat output ------------
./drivers/md/raid5.c | 18 +++++++++++++++---
1 files changed, 15 insertions(+), 3 deletions(-)
--- ./drivers/md/raid5.c 2002/11/06 23:05:40 1.2
+++ ./drivers/md/raid5.c 2002/11/06 23:07:44 1.3
@@ -836,6 +836,7 @@ static void handle_stripe(struct stripe_
int i;
int syncing;
int locked=0, uptodate=0, to_read=0, to_write=0, failed=0, written=0;
+ int non_overwrite = 0;
int failed_num=0;
struct r5dev *dev;
@@ -883,7 +884,11 @@ static void handle_stripe(struct stripe_
if (dev->toread) to_read++;
- if (dev->towrite) to_write++;
+ if (dev->towrite) {
+ to_write++;
+ if (!test_bit(R5_OVERWRITE, &dev->flags))
+ non_overwrite++;
+ }
if (dev->written) written++;
rdev = conf->disks[i].rdev; /* FIXME, should I be looking rdev */
if (!rdev || !rdev->in_sync) {
@@ -975,12 +980,19 @@ static void handle_stripe(struct stripe_
/* Now we might consider reading some blocks, either to check/generate
* parity, or to satisfy requests
+ * or to load a block that is being partially written.
*/
- if (to_read || (syncing && (uptodate+failed < disks))) {
+ if (to_read || non_overwrite || (syncing && (uptodate+failed < disks))) {
for (i=disks; i--;) {
dev = &sh->dev[i];
if (!test_bit(R5_LOCKED, &dev->flags) && !test_bit(R5_UPTODATE, &dev->flags) &&
- (dev->toread || syncing || (failed && sh->dev[failed_num].toread))) {
+ (dev->toread ||
+ (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
+ syncing ||
+ (failed && (sh->dev[failed_num].toread ||
+ (sh->dev[failed_num].towrite && !test_bit(R5_OVERWRITE, &sh->dev[failed_num].flags))))
+ )
+ ) {
/* we would like to get this block, possibly
* by computing it, but we might not be able to
*/
-
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