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Subject[03/98] md/raid5: allow for more than 2^31 chunks.
2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------
From: NeilBrown <neilb@suse.de>

commit 35f2a591192d0a5d9f7fc696869c76f0b8e49c3d upstream.

With many large drives and small chunk sizes it is possible
to create a RAID5 with more than 2^31 chunks. Make sure this
works.

Reported-by: Brett King <king.br@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/raid5.c | 19 +++++++------------
1 file changed, 7 insertions(+), 12 deletions(-)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -1649,8 +1649,8 @@ static sector_t raid5_compute_sector(rai
int previous, int *dd_idx,
struct stripe_head *sh)
{
- long stripe;
- unsigned long chunk_number;
+ sector_t stripe;
+ sector_t chunk_number;
unsigned int chunk_offset;
int pd_idx, qd_idx;
int ddf_layout = 0;
@@ -1670,17 +1670,12 @@ static sector_t raid5_compute_sector(rai
*/
chunk_offset = sector_div(r_sector, sectors_per_chunk);
chunk_number = r_sector;
- BUG_ON(r_sector != chunk_number);

/*
* Compute the stripe number
*/
- stripe = chunk_number / data_disks;
-
- /*
- * Compute the data disk and parity disk indexes inside the stripe
- */
- *dd_idx = chunk_number % data_disks;
+ stripe = chunk_number;
+ *dd_idx = sector_div(stripe, data_disks);

/*
* Select the parity disk based on the user selected algorithm.
@@ -1869,14 +1864,14 @@ static sector_t compute_blocknr(struct s
: conf->algorithm;
sector_t stripe;
int chunk_offset;
- int chunk_number, dummy1, dd_idx = i;
+ sector_t chunk_number;
+ int dummy1, dd_idx = i;
sector_t r_sector;
struct stripe_head sh2;


chunk_offset = sector_div(new_sector, sectors_per_chunk);
stripe = new_sector;
- BUG_ON(new_sector != stripe);

if (i == sh->pd_idx)
return 0;
@@ -1969,7 +1964,7 @@ static sector_t compute_blocknr(struct s
}

chunk_number = stripe * data_disks + i;
- r_sector = (sector_t)chunk_number * sectors_per_chunk + chunk_offset;
+ r_sector = chunk_number * sectors_per_chunk + chunk_offset;

check = raid5_compute_sector(conf, r_sector,
previous, &dummy1, &sh2);



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