From 9aeb7f99a134391e19ffad926cfb6a60d72139b4 Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Thu, 7 Apr 2022 10:57:11 -0600 Subject: [PATCH] md/raid5: Annotate rdev/replacement access when mddev_lock is held The mddev_lock should be held during raid5_remove_disk() which is when the rdev/replacement pointers are modified. So any access to these pointers marked __rcu should be safe whenever the mddev_lock is held. There are numerous such access that currently produce sparse warnings. Add a helper function, rdev_mdlock_deref() that wraps rcu_dereference_protected() in all these instances. This annotation fixes a number of sparse warnings. Signed-off-by: Logan Gunthorpe Reviewed-by: Christoph Hellwig Signed-off-by: Song Liu --- drivers/md/raid5.c | 65 ++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 43 insertions(+), 22 deletions(-) diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 6dc9d7cfa095..7c4f94c392ea 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -2658,6 +2658,18 @@ static struct md_rdev *rdev_pend_deref(struct md_rdev __rcu *rdev) atomic_read(&rcu_access_pointer(rdev)->nr_pending)); } +/* + * This helper wraps rcu_dereference_protected() and should be used + * when it is known that the mddev_lock() is held. This is safe + * seeing raid5_remove_disk() has the same lock held. + */ +static struct md_rdev *rdev_mdlock_deref(struct mddev *mddev, + struct md_rdev __rcu *rdev) +{ + return rcu_dereference_protected(rdev, + lockdep_is_held(&mddev->reconfig_mutex)); +} + static void raid5_end_read_request(struct bio * bi) { struct stripe_head *sh = bi->bi_private; @@ -7632,10 +7644,11 @@ static int raid5_run(struct mddev *mddev) for (i = 0; i < conf->raid_disks && conf->previous_raid_disks; i++) { - rdev = conf->disks[i].rdev; + rdev = rdev_mdlock_deref(mddev, conf->disks[i].rdev); if (!rdev && conf->disks[i].replacement) { /* The replacement is all we have yet */ - rdev = conf->disks[i].replacement; + rdev = rdev_mdlock_deref(mddev, + conf->disks[i].replacement); conf->disks[i].replacement = NULL; clear_bit(Replacement, &rdev->flags); rcu_assign_pointer(conf->disks[i].rdev, rdev); @@ -7867,36 +7880,38 @@ static int raid5_spare_active(struct mddev *mddev) { int i; struct r5conf *conf = mddev->private; - struct disk_info *tmp; + struct md_rdev *rdev, *replacement; int count = 0; unsigned long flags; for (i = 0; i < conf->raid_disks; i++) { - tmp = conf->disks + i; - if (tmp->replacement - && tmp->replacement->recovery_offset == MaxSector - && !test_bit(Faulty, &tmp->replacement->flags) - && !test_and_set_bit(In_sync, &tmp->replacement->flags)) { + rdev = rdev_mdlock_deref(mddev, conf->disks[i].rdev); + replacement = rdev_mdlock_deref(mddev, + conf->disks[i].replacement); + if (replacement + && replacement->recovery_offset == MaxSector + && !test_bit(Faulty, &replacement->flags) + && !test_and_set_bit(In_sync, &replacement->flags)) { /* Replacement has just become active. */ - if (!tmp->rdev - || !test_and_clear_bit(In_sync, &tmp->rdev->flags)) + if (!rdev + || !test_and_clear_bit(In_sync, &rdev->flags)) count++; - if (tmp->rdev) { + if (rdev) { /* Replaced device not technically faulty, * but we need to be sure it gets removed * and never re-added. */ - set_bit(Faulty, &tmp->rdev->flags); + set_bit(Faulty, &rdev->flags); sysfs_notify_dirent_safe( - tmp->rdev->sysfs_state); + rdev->sysfs_state); } - sysfs_notify_dirent_safe(tmp->replacement->sysfs_state); - } else if (tmp->rdev - && tmp->rdev->recovery_offset == MaxSector - && !test_bit(Faulty, &tmp->rdev->flags) - && !test_and_set_bit(In_sync, &tmp->rdev->flags)) { + sysfs_notify_dirent_safe(replacement->sysfs_state); + } else if (rdev + && rdev->recovery_offset == MaxSector + && !test_bit(Faulty, &rdev->flags) + && !test_and_set_bit(In_sync, &rdev->flags)) { count++; - sysfs_notify_dirent_safe(tmp->rdev->sysfs_state); + sysfs_notify_dirent_safe(rdev->sysfs_state); } } spin_lock_irqsave(&conf->device_lock, flags); @@ -7961,6 +7976,7 @@ static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev) } *rdevp = NULL; if (!test_bit(RemoveSynchronized, &rdev->flags)) { + lockdep_assert_held(&mddev->reconfig_mutex); synchronize_rcu(); if (atomic_read(&rdev->nr_pending)) { /* lost the race, try later */ @@ -8001,6 +8017,7 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev) int ret, err = -EEXIST; int disk; struct disk_info *p; + struct md_rdev *tmp; int first = 0; int last = conf->raid_disks - 1; @@ -8058,7 +8075,8 @@ static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev) } for (disk = first; disk <= last; disk++) { p = conf->disks + disk; - if (test_bit(WantReplacement, &p->rdev->flags) && + tmp = rdev_mdlock_deref(mddev, p->rdev); + if (test_bit(WantReplacement, &tmp->flags) && p->replacement == NULL) { clear_bit(In_sync, &rdev->flags); set_bit(Replacement, &rdev->flags); @@ -8349,6 +8367,7 @@ static void end_reshape(struct r5conf *conf) static void raid5_finish_reshape(struct mddev *mddev) { struct r5conf *conf = mddev->private; + struct md_rdev *rdev; if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) { @@ -8360,10 +8379,12 @@ static void raid5_finish_reshape(struct mddev *mddev) for (d = conf->raid_disks ; d < conf->raid_disks - mddev->delta_disks; d++) { - struct md_rdev *rdev = conf->disks[d].rdev; + rdev = rdev_mdlock_deref(mddev, + conf->disks[d].rdev); if (rdev) clear_bit(In_sync, &rdev->flags); - rdev = conf->disks[d].replacement; + rdev = rdev_mdlock_deref(mddev, + conf->disks[d].replacement); if (rdev) clear_bit(In_sync, &rdev->flags); } -- 2.11.0