From: NeilBrown Date: Fri, 1 Sep 2006 04:27:36 +0000 (-0700) Subject: [PATCH] md: Fix issues with referencing rdev in md/raid1 X-Git-Tag: v2.6.18-rc6~24 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ddac7c7e3a0fe9cfdcef0de24476b8d69f8cf3e7;p=linux-2.6 [PATCH] md: Fix issues with referencing rdev in md/raid1 We need to be careful when referencing mirrors[i].rdev. It can disappear under us at various times. So: fix a couple of problem places. comment a couple of non-problem places move an 'atomic_add' which deferences rdev down a little way to some where where it is sure to not be NULL. Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c index 87bfe9e7d8..3b4d69c056 100644 --- a/drivers/md/raid1.c +++ b/drivers/md/raid1.c @@ -930,10 +930,13 @@ static void status(struct seq_file *seq, mddev_t *mddev) seq_printf(seq, " [%d/%d] [", conf->raid_disks, conf->working_disks); - for (i = 0; i < conf->raid_disks; i++) + rcu_read_lock(); + for (i = 0; i < conf->raid_disks; i++) { + mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev); seq_printf(seq, "%s", - conf->mirrors[i].rdev && - test_bit(In_sync, &conf->mirrors[i].rdev->flags) ? "U" : "_"); + rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_"); + } + rcu_read_unlock(); seq_printf(seq, "]"); } @@ -975,7 +978,6 @@ static void error(mddev_t *mddev, mdk_rdev_t *rdev) static void print_conf(conf_t *conf) { int i; - mirror_info_t *tmp; printk("RAID1 conf printout:\n"); if (!conf) { @@ -985,14 +987,17 @@ static void print_conf(conf_t *conf) printk(" --- wd:%d rd:%d\n", conf->working_disks, conf->raid_disks); + rcu_read_lock(); for (i = 0; i < conf->raid_disks; i++) { char b[BDEVNAME_SIZE]; - tmp = conf->mirrors + i; - if (tmp->rdev) + mdk_rdev_t *rdev = rcu_dereference(conf->mirrors[i].rdev); + if (rdev) printk(" disk %d, wo:%d, o:%d, dev:%s\n", - i, !test_bit(In_sync, &tmp->rdev->flags), !test_bit(Faulty, &tmp->rdev->flags), - bdevname(tmp->rdev->bdev,b)); + i, !test_bit(In_sync, &rdev->flags), + !test_bit(Faulty, &rdev->flags), + bdevname(rdev->bdev,b)); } + rcu_read_unlock(); } static void close_sync(conf_t *conf) @@ -1008,20 +1013,20 @@ static int raid1_spare_active(mddev_t *mddev) { int i; conf_t *conf = mddev->private; - mirror_info_t *tmp; /* * Find all failed disks within the RAID1 configuration - * and mark them readable + * and mark them readable. + * Called under mddev lock, so rcu protection not needed. */ for (i = 0; i < conf->raid_disks; i++) { - tmp = conf->mirrors + i; - if (tmp->rdev - && !test_bit(Faulty, &tmp->rdev->flags) - && !test_bit(In_sync, &tmp->rdev->flags)) { + mdk_rdev_t *rdev = conf->mirrors[i].rdev; + if (rdev + && !test_bit(Faulty, &rdev->flags) + && !test_bit(In_sync, &rdev->flags)) { conf->working_disks++; mddev->degraded--; - set_bit(In_sync, &tmp->rdev->flags); + set_bit(In_sync, &rdev->flags); } } @@ -1237,7 +1242,7 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio) /* ouch - failed to read all of that. * Try some synchronous reads of other devices to get * good data, much like with normal read errors. Only - * read into the pages we already have so they we don't + * read into the pages we already have so we don't * need to re-issue the read request. * We don't need to freeze the array, because being in an * active sync request, there is no normal IO, and @@ -1257,6 +1262,10 @@ static void sync_request_write(mddev_t *mddev, r1bio_t *r1_bio) s = PAGE_SIZE >> 9; do { if (r1_bio->bios[d]->bi_end_io == end_sync_read) { + /* No rcu protection needed here devices + * can only be removed when no resync is + * active, and resync is currently active + */ rdev = conf->mirrors[d].rdev; if (sync_page_io(rdev->bdev, sect + rdev->data_offset, @@ -1463,6 +1472,11 @@ static void raid1d(mddev_t *mddev) s = PAGE_SIZE >> 9; do { + /* Note: no rcu protection needed here + * as this is synchronous in the raid1d thread + * which is the thread that might remove + * a device. If raid1d ever becomes multi-threaded.... + */ rdev = conf->mirrors[d].rdev; if (rdev && test_bit(In_sync, &rdev->flags) && @@ -1486,7 +1500,6 @@ static void raid1d(mddev_t *mddev) d = conf->raid_disks; d--; rdev = conf->mirrors[d].rdev; - atomic_add(s, &rdev->corrected_errors); if (rdev && test_bit(In_sync, &rdev->flags)) { if (sync_page_io(rdev->bdev, @@ -1509,9 +1522,11 @@ static void raid1d(mddev_t *mddev) s<<9, conf->tmppage, READ) == 0) /* Well, this device is dead */ md_error(mddev, rdev); - else + else { + atomic_add(s, &rdev->corrected_errors); printk(KERN_INFO "raid1:%s: read error corrected (%d sectors at %llu on %s)\n", mdname(mddev), s, (unsigned long long)(sect + rdev->data_offset), bdevname(rdev->bdev, b)); + } } } } else { @@ -1787,19 +1802,17 @@ static sector_t sync_request(mddev_t *mddev, sector_t sector_nr, int *skipped, i for (i=0; iraid_disks; i++) { bio = r1_bio->bios[i]; if (bio->bi_end_io == end_sync_read) { - md_sync_acct(conf->mirrors[i].rdev->bdev, nr_sectors); + md_sync_acct(bio->bi_bdev, nr_sectors); generic_make_request(bio); } } } else { atomic_set(&r1_bio->remaining, 1); bio = r1_bio->bios[r1_bio->read_disk]; - md_sync_acct(conf->mirrors[r1_bio->read_disk].rdev->bdev, - nr_sectors); + md_sync_acct(bio->bi_bdev, nr_sectors); generic_make_request(bio); } - return nr_sectors; }