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| author | Yu Kuai <yukuai3@huawei.com> | 2023-11-25 16:16:03 +0800 |
|---|---|---|
| committer | Song Liu <song@kernel.org> | 2023-11-27 15:49:05 -0800 |
| commit | ad8606702f268903b26795e6b93605646fd1a6a8 (patch) | |
| tree | 2bfd1c6af1b58d618bcd5841ae5ee84bc9649a71 /drivers/md/raid5-ppl.c | |
| parent | 2d32777d60de81aa020a2431567020af26564c71 (diff) | |
| download | lwn-ad8606702f268903b26795e6b93605646fd1a6a8.tar.gz lwn-ad8606702f268903b26795e6b93605646fd1a6a8.zip | |
md/raid5: remove rcu protection to access rdev from conf
Because it's safe to accees rdev from conf:
- If any spinlock is held, because synchronize_rcu() from
md_kick_rdev_from_array() will prevent 'rdev' to be freed until
spinlock is released;
- If 'reconfig_lock' is held, because rdev can't be added or removed from
array;
- If there is normal IO inflight, because mddev_suspend() will prevent
rdev to be added or removed from array;
- If there is sync IO inflight, because 'MD_RECOVERY_RUNNING' is
checked in remove_and_add_spares().
And these will cover all the scenarios in raid456.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231125081604.3939938-5-yukuai1@huaweicloud.com
Diffstat (limited to 'drivers/md/raid5-ppl.c')
| -rw-r--r-- | drivers/md/raid5-ppl.c | 16 |
1 files changed, 4 insertions, 12 deletions
diff --git a/drivers/md/raid5-ppl.c b/drivers/md/raid5-ppl.c index eaea57aee602..da4ba736c4f0 100644 --- a/drivers/md/raid5-ppl.c +++ b/drivers/md/raid5-ppl.c @@ -620,11 +620,9 @@ static void ppl_do_flush(struct ppl_io_unit *io) struct md_rdev *rdev; struct block_device *bdev = NULL; - rcu_read_lock(); - rdev = rcu_dereference(conf->disks[i].rdev); + rdev = conf->disks[i].rdev; if (rdev && !test_bit(Faulty, &rdev->flags)) bdev = rdev->bdev; - rcu_read_unlock(); if (bdev) { struct bio *bio; @@ -882,9 +880,7 @@ static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e, (unsigned long long)r_sector, dd_idx, (unsigned long long)sector); - /* Array has not started so rcu dereference is safe */ - rdev = rcu_dereference_protected( - conf->disks[dd_idx].rdev, 1); + rdev = conf->disks[dd_idx].rdev; if (!rdev || (!test_bit(In_sync, &rdev->flags) && sector >= rdev->recovery_offset)) { pr_debug("%s:%*s data member disk %d missing\n", @@ -936,9 +932,7 @@ static int ppl_recover_entry(struct ppl_log *log, struct ppl_header_entry *e, 0, &disk, &sh); BUG_ON(sh.pd_idx != le32_to_cpu(e->parity_disk)); - /* Array has not started so rcu dereference is safe */ - parity_rdev = rcu_dereference_protected( - conf->disks[sh.pd_idx].rdev, 1); + parity_rdev = conf->disks[sh.pd_idx].rdev; BUG_ON(parity_rdev->bdev->bd_dev != log->rdev->bdev->bd_dev); pr_debug("%s:%*s write parity at sector %llu, disk %pg\n", @@ -1404,9 +1398,7 @@ int ppl_init_log(struct r5conf *conf) for (i = 0; i < ppl_conf->count; i++) { struct ppl_log *log = &ppl_conf->child_logs[i]; - /* Array has not started so rcu dereference is safe */ - struct md_rdev *rdev = - rcu_dereference_protected(conf->disks[i].rdev, 1); + struct md_rdev *rdev = conf->disks[i].rdev; mutex_init(&log->io_mutex); spin_lock_init(&log->io_list_lock); |