From: NeilBrown If you try to assemble an array with too many missing devices, raid10 will now reject the attempt, instead of allowing it. Also check when hot-adding a drive and refuse the hot-add if the array is beyond hope. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton --- drivers/md/raid10.c | 30 +++++++++++++++++++++++++++--- 1 files changed, 27 insertions(+), 3 deletions(-) diff -puN drivers/md/raid10.c~md-fix-raid10-assembly-when-too-many-devices-are-missing drivers/md/raid10.c --- devel/drivers/md/raid10.c~md-fix-raid10-assembly-when-too-many-devices-are-missing 2005-09-06 17:10:29.000000000 -0700 +++ devel-akpm/drivers/md/raid10.c 2005-09-06 17:10:29.000000000 -0700 @@ -906,6 +906,27 @@ static void close_sync(conf_t *conf) conf->r10buf_pool = NULL; } +/* check if there are enough drives for + * every block to appear on atleast one + */ +static int enough(conf_t *conf) +{ + int first = 0; + + do { + int n = conf->copies; + int cnt = 0; + while (n--) { + if (conf->mirrors[first].rdev) + cnt++; + first = (first+1) % conf->raid_disks; + } + if (cnt == 0) + return 0; + } while (first != 0); + return 1; +} + static int raid10_spare_active(mddev_t *mddev) { int i; @@ -944,6 +965,8 @@ static int raid10_add_disk(mddev_t *mdde * very different from resync */ return 0; + if (!enough(conf)) + return 0; for (mirror=0; mirror < mddev->raid_disks; mirror++) if ( !(p=conf->mirrors+mirror)->rdev) { @@ -1684,9 +1707,10 @@ static int run(mddev_t *mddev) init_waitqueue_head(&conf->wait_idle); init_waitqueue_head(&conf->wait_resume); - if (!conf->working_disks) { - printk(KERN_ERR "raid10: no operational mirrors for %s\n", - mdname(mddev)); + /* need to check that every block has at least one working mirror */ + if (!enough(conf)) { + printk(KERN_ERR "raid10: not enough operational mirrors for %s\n", + mdname(mddev)); goto out_free_conf; } _