From: Evan Felix <evan.felix@pnl.gov> Here is a patch that fixes a major issue in the raid5/6 code. It seems that the code: logical_sector = bi->bi_sector & ~(STRIPE_SECTORS-1); (sector_t) = (sector_t) & (constant) that the right side of the & does not get extended correctly when the constant is promoted to the sector_t type. I have CONFIG_LBD turned on so sector_t should be 64bits wide. This fails to properly mask the value of 4294967296 (2TB/512) to 4294967296. in my case it was coming out 0. this cause the loop following this code to read from 0 to 4294967296 blocks so it could write one character. As you might imagine this makes a format of a 3.5TB filesystem take a very long time. --- 25-power4-akpm/drivers/md/raid5.c | 3 +-- 25-power4-akpm/drivers/md/raid6main.c | 2 +- 2 files changed, 2 insertions(+), 3 deletions(-) diff -puN drivers/md/raid5.c~raid56-masking-fix drivers/md/raid5.c --- 25-power4/drivers/md/raid5.c~raid56-masking-fix 2004-04-07 15:10:39.037782032 -0700 +++ 25-power4-akpm/drivers/md/raid5.c 2004-04-07 15:11:39.510588768 -0700 @@ -1358,9 +1358,8 @@ static int make_request (request_queue_t disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bi)); } - logical_sector = bi->bi_sector & ~(STRIPE_SECTORS-1); + logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1); last_sector = bi->bi_sector + (bi->bi_size>>9); - bi->bi_next = NULL; bi->bi_phys_segments = 1; /* over-loaded to count active stripes */ if ( bio_data_dir(bi) == WRITE ) diff -puN drivers/md/raid6main.c~raid56-masking-fix drivers/md/raid6main.c --- 25-power4/drivers/md/raid6main.c~raid56-masking-fix 2004-04-07 15:10:39.039781728 -0700 +++ 25-power4-akpm/drivers/md/raid6main.c 2004-04-07 15:10:39.044780968 -0700 @@ -1521,7 +1521,7 @@ static int make_request (request_queue_t disk_stat_add(mddev->gendisk, read_sectors, bio_sectors(bi)); } - logical_sector = bi->bi_sector & ~(STRIPE_SECTORS-1); + logical_sector = bi->bi_sector & ~((sector_t)STRIPE_SECTORS-1); last_sector = bi->bi_sector + (bi->bi_size>>9); bi->bi_next = NULL; _