[PATCH -next 4/6] md/raid10: remove rcu protection to access rdev from conf

From: Yu Kuai
Date: Sun Oct 15 2023 - 21:28:59 EST

From: Yu Kuai <yukuai3@xxxxxxxxxx>

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 raid10.

This patch also cleanup the code to handle the case that replacement
replace rdev while IO is still inflight.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
drivers/md/raid10.c | 210 ++++++++++++--------------------------------
1 file changed, 57 insertions(+), 153 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 33ab00323cae..806a7fe2f74a 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -743,7 +743,6 @@ static struct md_rdev *read_balance(struct r10conf *conf,
struct geom *geo = &conf->geo;

raid10_find_phys(conf, r10_bio);
- rcu_read_lock();
best_dist_slot = -1;
min_pending = UINT_MAX;
best_dist_rdev = NULL;
@@ -775,18 +774,11 @@ static struct md_rdev *read_balance(struct r10conf *conf,
if (r10_bio->devs[slot].bio == IO_BLOCKED)
continue;
disk = r10_bio->devs[slot].devnum;
- rdev = rcu_dereference(conf->mirrors[disk].replacement);
+ rdev = conf->mirrors[disk].replacement;
if (rdev == NULL || test_bit(Faulty, &rdev->flags) ||
r10_bio->devs[slot].addr + sectors >
- rdev->recovery_offset) {
- /*
- * Read replacement first to prevent reading both rdev
- * and replacement as NULL during replacement replace
- * rdev.
- */
- smp_mb();
- rdev = rcu_dereference(conf->mirrors[disk].rdev);
- }
+ rdev->recovery_offset)
+ rdev = conf->mirrors[disk].rdev;
if (rdev == NULL ||
test_bit(Faulty, &rdev->flags))
continue;
@@ -876,7 +868,6 @@ static struct md_rdev *read_balance(struct r10conf *conf,
r10_bio->read_slot = slot;
} else
rdev = NULL;
- rcu_read_unlock();
*max_sectors = best_good_sectors;

return rdev;
@@ -1198,9 +1189,8 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
*/
gfp = GFP_NOIO | __GFP_HIGH;

- rcu_read_lock();
disk = r10_bio->devs[slot].devnum;
- err_rdev = rcu_dereference(conf->mirrors[disk].rdev);
+ err_rdev = conf->mirrors[disk].rdev;
if (err_rdev)
snprintf(b, sizeof(b), "%pg", err_rdev->bdev);
else {
@@ -1208,7 +1198,6 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
/* This never gets dereferenced */
err_rdev = r10_bio->devs[slot].rdev;
}
- rcu_read_unlock();
}

if (!regular_request_wait(mddev, conf, bio, r10_bio->sectors))
@@ -1279,15 +1268,8 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
int devnum = r10_bio->devs[n_copy].devnum;
struct bio *mbio;

- if (replacement) {
- rdev = conf->mirrors[devnum].replacement;
- if (rdev == NULL) {
- /* Replacement just got moved to main 'rdev' */
- smp_mb();
- rdev = conf->mirrors[devnum].rdev;
- }
- } else
- rdev = conf->mirrors[devnum].rdev;
+ rdev = replacement ? conf->mirrors[devnum].replacement :
+ conf->mirrors[devnum].rdev;

mbio = bio_alloc_clone(rdev->bdev, bio, GFP_NOIO, &mddev->bio_set);
if (replacement)
@@ -1321,25 +1303,6 @@ static void raid10_write_one_disk(struct mddev *mddev, struct r10bio *r10_bio,
}
}

-static struct md_rdev *dereference_rdev_and_rrdev(struct raid10_info *mirror,
- struct md_rdev **prrdev)
-{
- struct md_rdev *rdev, *rrdev;
-
- rrdev = rcu_dereference(mirror->replacement);
- /*
- * Read replacement first to prevent reading both rdev and
- * replacement as NULL during replacement replace rdev.
- */
- smp_mb();
- rdev = rcu_dereference(mirror->rdev);
- if (rdev == rrdev)
- rrdev = NULL;
-
- *prrdev = rrdev;
- return rdev;
-}
-
static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)
{
int i;
@@ -1348,11 +1311,11 @@ static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)

retry_wait:
blocked_rdev = NULL;
- rcu_read_lock();
for (i = 0; i < conf->copies; i++) {
struct md_rdev *rdev, *rrdev;

- rdev = dereference_rdev_and_rrdev(&conf->mirrors[i], &rrdev);
+ rdev = conf->mirrors[i].rdev;
+ rrdev = conf->mirrors[i].replacement;
if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
atomic_inc(&rdev->nr_pending);
blocked_rdev = rdev;
@@ -1391,7 +1354,6 @@ static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)
}
}
}
- rcu_read_unlock();

if (unlikely(blocked_rdev)) {
/* Have to wait for this device to get unblocked, then retry */
@@ -1474,14 +1436,14 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,

wait_blocked_dev(mddev, r10_bio);

- rcu_read_lock();
max_sectors = r10_bio->sectors;

for (i = 0; i < conf->copies; i++) {
int d = r10_bio->devs[i].devnum;
struct md_rdev *rdev, *rrdev;

- rdev = dereference_rdev_and_rrdev(&conf->mirrors[d], &rrdev);
+ rdev = conf->mirrors[d].rdev;
+ rrdev = conf->mirrors[d].replacement;
if (rdev && (test_bit(Faulty, &rdev->flags)))
rdev = NULL;
if (rrdev && (test_bit(Faulty, &rrdev->flags)))
@@ -1535,7 +1497,6 @@ static void raid10_write_request(struct mddev *mddev, struct bio *bio,
atomic_inc(&rrdev->nr_pending);
}
}
- rcu_read_unlock();

if (max_sectors < r10_bio->sectors)
r10_bio->sectors = max_sectors;
@@ -1625,17 +1586,8 @@ static void raid10_end_discard_request(struct bio *bio)
set_bit(R10BIO_Uptodate, &r10_bio->state);

dev = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
- if (repl)
- rdev = conf->mirrors[dev].replacement;
- if (!rdev) {
- /*
- * raid10_remove_disk uses smp_mb to make sure rdev is set to
- * replacement before setting replacement to NULL. It can read
- * rdev first without barrier protect even replacement is NULL
- */
- smp_rmb();
- rdev = conf->mirrors[dev].rdev;
- }
+ rdev = repl ? conf->mirrors[dev].replacement :
+ conf->mirrors[dev].rdev;

raid_end_discard_bio(r10_bio);
rdev_dec_pending(rdev, conf->mddev);
@@ -1785,11 +1737,11 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
* inc refcount on their rdev. Record them by setting
* bios[x] to bio
*/
- rcu_read_lock();
for (disk = 0; disk < geo->raid_disks; disk++) {
struct md_rdev *rdev, *rrdev;

- rdev = dereference_rdev_and_rrdev(&conf->mirrors[disk], &rrdev);
+ rdev = conf->mirrors[disk].rdev;
+ rrdev = conf->mirrors[disk].replacement;
r10_bio->devs[disk].bio = NULL;
r10_bio->devs[disk].repl_bio = NULL;

@@ -1809,7 +1761,6 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
atomic_inc(&rrdev->nr_pending);
}
}
- rcu_read_unlock();

atomic_set(&r10_bio->remaining, 1);
for (disk = 0; disk < geo->raid_disks; disk++) {
@@ -1939,6 +1890,8 @@ static void raid10_status(struct seq_file *seq, struct mddev *mddev)
struct r10conf *conf = mddev->private;
int i;

+ lockdep_assert_held(&mddev->lock);
+
if (conf->geo.near_copies < conf->geo.raid_disks)
seq_printf(seq, " %dK chunks", mddev->chunk_sectors / 2);
if (conf->geo.near_copies > 1)
@@ -1953,12 +1906,11 @@ static void raid10_status(struct seq_file *seq, struct mddev *mddev)
}
seq_printf(seq, " [%d/%d] [", conf->geo.raid_disks,
conf->geo.raid_disks - mddev->degraded);
- rcu_read_lock();
for (i = 0; i < conf->geo.raid_disks; i++) {
- struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
+ struct md_rdev *rdev = READ_ONCE(conf->mirrors[i].rdev);
+
seq_printf(seq, "%s", rdev && test_bit(In_sync, &rdev->flags) ? "U" : "_");
}
- rcu_read_unlock();
seq_printf(seq, "]");
}

@@ -1980,7 +1932,6 @@ static int _enough(struct r10conf *conf, int previous, int ignore)
ncopies = conf->geo.near_copies;
}

- rcu_read_lock();
do {
int n = conf->copies;
int cnt = 0;
@@ -1988,7 +1939,7 @@ static int _enough(struct r10conf *conf, int previous, int ignore)
while (n--) {
struct md_rdev *rdev;
if (this != ignore &&
- (rdev = rcu_dereference(conf->mirrors[this].rdev)) &&
+ (rdev = conf->mirrors[this].rdev) &&
test_bit(In_sync, &rdev->flags))
cnt++;
this = (this+1) % disks;
@@ -1999,7 +1950,6 @@ static int _enough(struct r10conf *conf, int previous, int ignore)
} while (first != 0);
has_enough = 1;
out:
- rcu_read_unlock();
return has_enough;
}

@@ -2164,7 +2114,7 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
err = 0;
if (rdev->saved_raid_disk != mirror)
conf->fullsync = 1;
- rcu_assign_pointer(p->rdev, rdev);
+ WRITE_ONCE(p->rdev, rdev);
break;
}

@@ -2178,7 +2128,7 @@ static int raid10_add_disk(struct mddev *mddev, struct md_rdev *rdev)
disk_stack_limits(mddev->gendisk, rdev->bdev,
rdev->data_offset << 9);
conf->fullsync = 1;
- rcu_assign_pointer(p->replacement, rdev);
+ WRITE_ONCE(p->replacement, rdev);
}

return err;
@@ -2218,15 +2168,12 @@ static int raid10_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
err = -EBUSY;
goto abort;
}
- *rdevp = NULL;
+ WRITE_ONCE(*rdevp, NULL);
if (p->replacement) {
/* We must have just cleared 'rdev' */
- p->rdev = p->replacement;
+ WRITE_ONCE(p->rdev, p->replacement);
clear_bit(Replacement, &p->replacement->flags);
- smp_mb(); /* Make sure other CPUs may see both as identical
- * but will never see neither -- if they are careful.
- */
- p->replacement = NULL;
+ WRITE_ONCE(p->replacement, NULL);
}

clear_bit(WantReplacement, &rdev->flags);
@@ -2725,20 +2672,18 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
if (s > (PAGE_SIZE>>9))
s = PAGE_SIZE >> 9;

- rcu_read_lock();
do {
sector_t first_bad;
int bad_sectors;

d = r10_bio->devs[sl].devnum;
- rdev = rcu_dereference(conf->mirrors[d].rdev);
+ rdev = conf->mirrors[d].rdev;
if (rdev &&
test_bit(In_sync, &rdev->flags) &&
!test_bit(Faulty, &rdev->flags) &&
is_badblock(rdev, r10_bio->devs[sl].addr + sect, s,
&first_bad, &bad_sectors) == 0) {
atomic_inc(&rdev->nr_pending);
- rcu_read_unlock();
success = sync_page_io(rdev,
r10_bio->devs[sl].addr +
sect,
@@ -2746,7 +2691,6 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
conf->tmppage,
REQ_OP_READ, false);
rdev_dec_pending(rdev, mddev);
- rcu_read_lock();
if (success)
break;
}
@@ -2754,7 +2698,6 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
if (sl == conf->copies)
sl = 0;
} while (sl != slot);
- rcu_read_unlock();

if (!success) {
/* Cannot read from anywhere, just mark the block
@@ -2778,20 +2721,18 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10

start = sl;
/* write it back and re-read */
- rcu_read_lock();
while (sl != slot) {
if (sl==0)
sl = conf->copies;
sl--;
d = r10_bio->devs[sl].devnum;
- rdev = rcu_dereference(conf->mirrors[d].rdev);
+ rdev = conf->mirrors[d].rdev;
if (!rdev ||
test_bit(Faulty, &rdev->flags) ||
!test_bit(In_sync, &rdev->flags))
continue;

atomic_inc(&rdev->nr_pending);
- rcu_read_unlock();
if (r10_sync_page_io(rdev,
r10_bio->devs[sl].addr +
sect,
@@ -2810,7 +2751,6 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
rdev->bdev);
}
rdev_dec_pending(rdev, mddev);
- rcu_read_lock();
}
sl = start;
while (sl != slot) {
@@ -2818,14 +2758,13 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
sl = conf->copies;
sl--;
d = r10_bio->devs[sl].devnum;
- rdev = rcu_dereference(conf->mirrors[d].rdev);
+ rdev = conf->mirrors[d].rdev;
if (!rdev ||
test_bit(Faulty, &rdev->flags) ||
!test_bit(In_sync, &rdev->flags))
continue;

atomic_inc(&rdev->nr_pending);
- rcu_read_unlock();
switch (r10_sync_page_io(rdev,
r10_bio->devs[sl].addr +
sect,
@@ -2853,9 +2792,7 @@ static void fix_read_error(struct r10conf *conf, struct mddev *mddev, struct r10
}

rdev_dec_pending(rdev, mddev);
- rcu_read_lock();
}
- rcu_read_unlock();

sectors -= s;
sect += s;
@@ -3329,14 +3266,13 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
/* Completed a full sync so the replacements
* are now fully recovered.
*/
- rcu_read_lock();
for (i = 0; i < conf->geo.raid_disks; i++) {
struct md_rdev *rdev =
- rcu_dereference(conf->mirrors[i].replacement);
+ conf->mirrors[i].replacement;
+
if (rdev)
rdev->recovery_offset = MaxSector;
}
- rcu_read_unlock();
}
conf->fullsync = 0;
}
@@ -3417,9 +3353,8 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
struct raid10_info *mirror = &conf->mirrors[i];
struct md_rdev *mrdev, *mreplace;

- rcu_read_lock();
- mrdev = rcu_dereference(mirror->rdev);
- mreplace = rcu_dereference(mirror->replacement);
+ mrdev = mirror->rdev;
+ mreplace = mirror->replacement;

if (mrdev && (test_bit(Faulty, &mrdev->flags) ||
test_bit(In_sync, &mrdev->flags)))
@@ -3427,22 +3362,18 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
if (mreplace && test_bit(Faulty, &mreplace->flags))
mreplace = NULL;

- if (!mrdev && !mreplace) {
- rcu_read_unlock();
+ if (!mrdev && !mreplace)
continue;
- }

still_degraded = 0;
/* want to reconstruct this device */
rb2 = r10_bio;
sect = raid10_find_virt(conf, sector_nr, i);
- if (sect >= mddev->resync_max_sectors) {
+ if (sect >= mddev->resync_max_sectors)
/* last stripe is not complete - don't
* try to recover this sector.
*/
- rcu_read_unlock();
continue;
- }
/* Unless we are doing a full sync, or a replacement
* we only need to recover the block if it is set in
* the bitmap
@@ -3458,14 +3389,12 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
* that there will never be anything to do here
*/
chunks_skipped = -1;
- rcu_read_unlock();
continue;
}
if (mrdev)
atomic_inc(&mrdev->nr_pending);
if (mreplace)
atomic_inc(&mreplace->nr_pending);
- rcu_read_unlock();

r10_bio = raid10_alloc_init_r10buf(conf);
r10_bio->state = 0;
@@ -3484,10 +3413,9 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
/* Need to check if the array will still be
* degraded
*/
- rcu_read_lock();
for (j = 0; j < conf->geo.raid_disks; j++) {
- struct md_rdev *rdev = rcu_dereference(
- conf->mirrors[j].rdev);
+ struct md_rdev *rdev = conf->mirrors[j].rdev;
+
if (rdev == NULL || test_bit(Faulty, &rdev->flags)) {
still_degraded = 1;
break;
@@ -3502,8 +3430,7 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
int k;
int d = r10_bio->devs[j].devnum;
sector_t from_addr, to_addr;
- struct md_rdev *rdev =
- rcu_dereference(conf->mirrors[d].rdev);
+ struct md_rdev *rdev = conf->mirrors[d].rdev;
sector_t sector, first_bad;
int bad_sectors;
if (!rdev ||
@@ -3582,7 +3509,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
atomic_inc(&r10_bio->remaining);
break;
}
- rcu_read_unlock();
if (j == conf->copies) {
/* Cannot recover, so abort the recovery or
* record a bad block */
@@ -3709,12 +3635,10 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,

bio = r10_bio->devs[i].bio;
bio->bi_status = BLK_STS_IOERR;
- rcu_read_lock();
- rdev = rcu_dereference(conf->mirrors[d].rdev);
- if (rdev == NULL || test_bit(Faulty, &rdev->flags)) {
- rcu_read_unlock();
+ rdev = conf->mirrors[d].rdev;
+ if (rdev == NULL || test_bit(Faulty, &rdev->flags))
continue;
- }
+
sector = r10_bio->devs[i].addr;
if (is_badblock(rdev, sector, max_sync,
&first_bad, &bad_sectors)) {
@@ -3724,7 +3648,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
bad_sectors -= (sector - first_bad);
if (max_sync > bad_sectors)
max_sync = bad_sectors;
- rcu_read_unlock();
continue;
}
}
@@ -3740,11 +3663,10 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
bio_set_dev(bio, rdev->bdev);
count++;

- rdev = rcu_dereference(conf->mirrors[d].replacement);
- if (rdev == NULL || test_bit(Faulty, &rdev->flags)) {
- rcu_read_unlock();
+ rdev = conf->mirrors[d].replacement;
+ if (rdev == NULL || test_bit(Faulty, &rdev->flags))
continue;
- }
+
atomic_inc(&rdev->nr_pending);

/* Need to set up for writing to the replacement */
@@ -3761,7 +3683,6 @@ static sector_t raid10_sync_request(struct mddev *mddev, sector_t sector_nr,
bio->bi_iter.bi_sector = sector + rdev->data_offset;
bio_set_dev(bio, rdev->bdev);
count++;
- rcu_read_unlock();
}

if (count < 2) {
@@ -4471,11 +4392,11 @@ static int calc_degraded(struct r10conf *conf)
int degraded, degraded2;
int i;

- rcu_read_lock();
degraded = 0;
/* 'prev' section first */
for (i = 0; i < conf->prev.raid_disks; i++) {
- struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
+ struct md_rdev *rdev = conf->mirrors[i].rdev;
+
if (!rdev || test_bit(Faulty, &rdev->flags))
degraded++;
else if (!test_bit(In_sync, &rdev->flags))
@@ -4485,13 +4406,12 @@ static int calc_degraded(struct r10conf *conf)
*/
degraded++;
}
- rcu_read_unlock();
if (conf->geo.raid_disks == conf->prev.raid_disks)
return degraded;
- rcu_read_lock();
degraded2 = 0;
for (i = 0; i < conf->geo.raid_disks; i++) {
- struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
+ struct md_rdev *rdev = conf->mirrors[i].rdev;
+
if (!rdev || test_bit(Faulty, &rdev->flags))
degraded2++;
else if (!test_bit(In_sync, &rdev->flags)) {
@@ -4504,7 +4424,6 @@ static int calc_degraded(struct r10conf *conf)
degraded2++;
}
}
- rcu_read_unlock();
if (degraded2 > degraded)
return degraded2;
return degraded;
@@ -4936,16 +4855,15 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
blist = read_bio;
read_bio->bi_next = NULL;

- rcu_read_lock();
for (s = 0; s < conf->copies*2; s++) {
struct bio *b;
int d = r10_bio->devs[s/2].devnum;
struct md_rdev *rdev2;
if (s&1) {
- rdev2 = rcu_dereference(conf->mirrors[d].replacement);
+ rdev2 = conf->mirrors[d].replacement;
b = r10_bio->devs[s/2].repl_bio;
} else {
- rdev2 = rcu_dereference(conf->mirrors[d].rdev);
+ rdev2 = conf->mirrors[d].rdev;
b = r10_bio->devs[s/2].bio;
}
if (!rdev2 || test_bit(Faulty, &rdev2->flags))
@@ -4979,7 +4897,6 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr,
sector_nr += len >> 9;
nr_sectors += len >> 9;
}
- rcu_read_unlock();
r10_bio->sectors = nr_sectors;

/* Now submit the read */
@@ -5032,20 +4949,17 @@ static void reshape_request_write(struct mddev *mddev, struct r10bio *r10_bio)
struct bio *b;
int d = r10_bio->devs[s/2].devnum;
struct md_rdev *rdev;
- rcu_read_lock();
if (s&1) {
- rdev = rcu_dereference(conf->mirrors[d].replacement);
+ rdev = conf->mirrors[d].replacement;
b = r10_bio->devs[s/2].repl_bio;
} else {
- rdev = rcu_dereference(conf->mirrors[d].rdev);
+ rdev = conf->mirrors[d].rdev;
b = r10_bio->devs[s/2].bio;
}
- if (!rdev || test_bit(Faulty, &rdev->flags)) {
- rcu_read_unlock();
+ if (!rdev || test_bit(Faulty, &rdev->flags))
continue;
- }
+
atomic_inc(&rdev->nr_pending);
- rcu_read_unlock();
md_sync_acct_bio(b, r10_bio->sectors);
atomic_inc(&r10_bio->remaining);
b->bi_next = NULL;
@@ -5116,10 +5030,9 @@ static int handle_reshape_read_error(struct mddev *mddev,
if (s > (PAGE_SIZE >> 9))
s = PAGE_SIZE >> 9;

- rcu_read_lock();
while (!success) {
int d = r10b->devs[slot].devnum;
- struct md_rdev *rdev = rcu_dereference(conf->mirrors[d].rdev);
+ struct md_rdev *rdev = conf->mirrors[d].rdev;
sector_t addr;
if (rdev == NULL ||
test_bit(Faulty, &rdev->flags) ||
@@ -5128,14 +5041,12 @@ static int handle_reshape_read_error(struct mddev *mddev,

addr = r10b->devs[slot].addr + idx * PAGE_SIZE;
atomic_inc(&rdev->nr_pending);
- rcu_read_unlock();
success = sync_page_io(rdev,
addr,
s << 9,
pages[idx],
REQ_OP_READ, false);
rdev_dec_pending(rdev, mddev);
- rcu_read_lock();
if (success)
break;
failed:
@@ -5145,7 +5056,6 @@ static int handle_reshape_read_error(struct mddev *mddev,
if (slot == first_slot)
break;
}
- rcu_read_unlock();
if (!success) {
/* couldn't read this block, must give up */
set_bit(MD_RECOVERY_INTR,
@@ -5171,12 +5081,8 @@ static void end_reshape_write(struct bio *bio)
struct md_rdev *rdev = NULL;

d = find_bio_disk(conf, r10_bio, bio, &slot, &repl);
- if (repl)
- rdev = conf->mirrors[d].replacement;
- if (!rdev) {
- smp_mb();
- rdev = conf->mirrors[d].rdev;
- }
+ rdev = repl ? conf->mirrors[d].replacement :
+ conf->mirrors[d].rdev;

if (bio->bi_status) {
/* FIXME should record badblock */
@@ -5211,18 +5117,16 @@ static void raid10_finish_reshape(struct mddev *mddev)
mddev->resync_max_sectors = mddev->array_sectors;
} else {
int d;
- rcu_read_lock();
for (d = conf->geo.raid_disks ;
d < conf->geo.raid_disks - mddev->delta_disks;
d++) {
- struct md_rdev *rdev = rcu_dereference(conf->mirrors[d].rdev);
+ struct md_rdev *rdev = conf->mirrors[d].rdev;
if (rdev)
clear_bit(In_sync, &rdev->flags);
- rdev = rcu_dereference(conf->mirrors[d].replacement);
+ rdev = conf->mirrors[d].replacement;
if (rdev)
clear_bit(In_sync, &rdev->flags);
}
- rcu_read_unlock();
}
mddev->layout = mddev->new_layout;
mddev->chunk_sectors = 1 << conf->geo.chunk_shift;
--
2.39.2