From: NeilBrown Two refinements to the 'attempt-overwrite-on-read-error' mechanism. 1/ If the array is read-only, don't attempt an over-write. 2/ If there are more than max_nr_stripes read errors on a device with no success, fail the drive. This will make sure a dead drive will be eventually kicked even when we aren't trying to rewrite (which would normally kick a dead drive more quickly. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton --- drivers/md/md.c | 1 + drivers/md/raid5.c | 25 +++++++++++++++++-------- include/linux/raid/md_k.h | 3 +++ 3 files changed, 21 insertions(+), 8 deletions(-) diff -puN drivers/md/md.c~md-improvements-to-raid5-handling-of-read-errors drivers/md/md.c --- 25/drivers/md/md.c~md-improvements-to-raid5-handling-of-read-errors Fri Oct 14 14:15:55 2005 +++ 25-akpm/drivers/md/md.c Fri Oct 14 14:15:55 2005 @@ -1582,6 +1582,7 @@ static mdk_rdev_t *md_import_device(dev_ rdev->in_sync = 0; rdev->data_offset = 0; atomic_set(&rdev->nr_pending, 0); + atomic_set(&rdev->read_errors, 0); size = rdev->bdev->bd_inode->i_size >> BLOCK_SIZE_BITS; if (!size) { diff -puN drivers/md/raid5.c~md-improvements-to-raid5-handling-of-read-errors drivers/md/raid5.c --- 25/drivers/md/raid5.c~md-improvements-to-raid5-handling-of-read-errors Fri Oct 14 14:15:55 2005 +++ 25-akpm/drivers/md/raid5.c Fri Oct 14 14:15:55 2005 @@ -420,21 +420,29 @@ static int raid5_end_read_request(struct clear_bit(R5_ReadError, &sh->dev[i].flags); clear_bit(R5_ReWrite, &sh->dev[i].flags); } + if (atomic_read(&conf->disks[i].rdev->read_errors)) + atomic_set(&conf->disks[i].rdev->read_errors, 0); } else { + int retry = 0; clear_bit(R5_UPTODATE, &sh->dev[i].flags); - if (conf->mddev->degraded) { + atomic_inc(&conf->disks[i].rdev->read_errors); + if (conf->mddev->degraded) printk("R5: read error not correctable.\n"); - clear_bit(R5_ReadError, &sh->dev[i].flags); - clear_bit(R5_ReWrite, &sh->dev[i].flags); - md_error(conf->mddev, conf->disks[i].rdev); - } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) { + else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) /* Oh, no!!! */ printk("R5: read error NOT corrected!!\n"); + else if (atomic_read(&conf->disks[i].rdev->read_errors) + > conf->max_nr_stripes) + printk("raid5: Too many read errors, failing device.\n"); + else + retry = 1; + if (retry) + set_bit(R5_ReadError, &sh->dev[i].flags); + else { clear_bit(R5_ReadError, &sh->dev[i].flags); clear_bit(R5_ReWrite, &sh->dev[i].flags); md_error(conf->mddev, conf->disks[i].rdev); - } else - set_bit(R5_ReadError, &sh->dev[i].flags); + } } rdev_dec_pending(conf->disks[i].rdev, conf->mddev); #if 0 @@ -1328,7 +1336,8 @@ static void handle_stripe(struct stripe_ /* If the failed drive is just a ReadError, then we might need to progress * the repair/check process */ - if (failed == 1 && test_bit(R5_ReadError, &sh->dev[failed_num].flags) + if (failed == 1 && ! conf->mddev->ro && + test_bit(R5_ReadError, &sh->dev[failed_num].flags) && !test_bit(R5_LOCKED, &sh->dev[failed_num].flags) && test_bit(R5_UPTODATE, &sh->dev[failed_num].flags) ) { diff -puN include/linux/raid/md_k.h~md-improvements-to-raid5-handling-of-read-errors include/linux/raid/md_k.h --- 25/include/linux/raid/md_k.h~md-improvements-to-raid5-handling-of-read-errors Fri Oct 14 14:15:55 2005 +++ 25-akpm/include/linux/raid/md_k.h Fri Oct 14 14:15:55 2005 @@ -134,6 +134,9 @@ struct mdk_rdev_s * only maintained for arrays that * support hot removal */ + atomic_t read_errors; /* number of consecutive read errors that + * we have tried to ignore. + */ }; typedef struct mdk_personality_s mdk_personality_t; _