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Subject[PATCH 051/118] drbd: _req_conflicts(): Get rid of the epoch_entries tree
Date
From: Andreas Gruenbacher <agruen@linbit.com>

Instead of keeping a separate tree for local and remote write requests
for finding requests and for conflict detection, use the same tree for
both purposes. Introduce a flag to allow distinguishing the two
possible types of entries in this tree.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
---
drivers/block/drbd/drbd_int.h | 3 ---
drivers/block/drbd/drbd_interval.h | 1 +
drivers/block/drbd/drbd_main.c | 1 -
drivers/block/drbd/drbd_receiver.c | 33 ++++++++++++++++-----------------
drivers/block/drbd/drbd_req.c | 28 ++++------------------------
drivers/block/drbd/drbd_worker.c | 2 +-
6 files changed, 22 insertions(+), 46 deletions(-)
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index e917859..faa7cbd 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1045,9 +1045,6 @@ struct drbd_conf {
struct list_head read_ee; /* IO in progress (any read) */
struct list_head net_ee; /* zero-copy network send in progress */

- /* Interval tree of pending remote write requests (struct drbd_epoch_entry) */
- struct rb_root epoch_entries;
-
/* this one is protected by ee_lock, single thread */
struct drbd_epoch_entry *last_write_w_barrier;

diff --git a/drivers/block/drbd/drbd_interval.h b/drivers/block/drbd/drbd_interval.h
index 9d1e5eb..4010ad9 100644
--- a/drivers/block/drbd/drbd_interval.h
+++ b/drivers/block/drbd/drbd_interval.h
@@ -9,6 +9,7 @@ struct drbd_interval {
sector_t sector; /* start sector of the interval */
unsigned int size; /* size in bytes */
sector_t end; /* highest interval end in subtree */
+ int local:1 /* local or remote request? */;
int waiting:1;
};

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index 13aadca..a2417e4 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -3450,7 +3450,6 @@ struct drbd_conf *drbd_new_device(unsigned int minor)
goto out_no_tl;
mdev->read_requests = RB_ROOT;
mdev->write_requests = RB_ROOT;
- mdev->epoch_entries = RB_ROOT;

mdev->current_epoch = kzalloc(sizeof(struct drbd_epoch), GFP_KERNEL);
if (!mdev->current_epoch)
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 558c630..cde48f3 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -336,6 +336,7 @@ struct drbd_epoch_entry *drbd_alloc_ee(struct drbd_conf *mdev,
drbd_clear_interval(&e->i);
e->i.size = data_size;
e->i.sector = sector;
+ e->i.local = false;
e->i.waiting = false;

e->epoch = NULL;
@@ -1512,7 +1513,7 @@ find_request(struct drbd_conf *mdev, struct rb_root *root, u64 id,

/* Request object according to our peer */
req = (struct drbd_request *)(unsigned long)id;
- if (drbd_contains_interval(root, sector, &req->i))
+ if (drbd_contains_interval(root, sector, &req->i) && req->i.local)
return req;
if (!missing_ok) {
dev_err(DEV, "%s: failed to find request %lu, sector %llus\n", func,
@@ -1792,17 +1793,12 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packet cmd,
/* conflict detection and handling:
* 1. wait on the sequence number,
* in case this data packet overtook ACK packets.
- * 2. check our interval trees for conflicting requests:
- * we only need to check the write_requests tree; the
- * epoch_entries tree cannot contain any overlaps because
- * they were already eliminated on the submitting node.
+ * 2. check for conflicting write requests.
*
* Note: for two_primaries, we are protocol C,
* so there cannot be any request that is DONE
* but still on the transfer log.
*
- * unconditionally add to the epoch_entries tree.
- *
* if no conflicting request is found:
* submit.
*
@@ -1827,12 +1823,9 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packet cmd,

spin_lock_irq(&mdev->tconn->req_lock);

- drbd_insert_interval(&mdev->epoch_entries, &e->i);
-
first = 1;
for (;;) {
struct drbd_interval *i;
- struct drbd_request *req2;
int have_unacked = 0;
int have_conflict = 0;
prepare_to_wait(&mdev->misc_wait, &wait,
@@ -1840,18 +1833,23 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packet cmd,

i = drbd_find_overlap(&mdev->write_requests, sector, size);
if (i) {
- req2 = container_of(i, struct drbd_request, i);
-
/* only ALERT on first iteration,
* we may be woken up early... */
if (first)
- dev_alert(DEV, "%s[%u] Concurrent local write detected!"
+ dev_alert(DEV, "%s[%u] Concurrent %s write detected!"
" new: %llus +%u; pending: %llus +%u\n",
current->comm, current->pid,
+ i->local ? "local" : "remote",
(unsigned long long)sector, size,
- (unsigned long long)req2->i.sector, req2->i.size);
- if (req2->rq_state & RQ_NET_PENDING)
- ++have_unacked;
+ (unsigned long long)i->sector, i->size);
+
+ if (i->local) {
+ struct drbd_request *req2;
+
+ req2 = container_of(i, struct drbd_request, i);
+ if (req2->rq_state & RQ_NET_PENDING)
+ ++have_unacked;
+ }
++have_conflict;
}
if (!have_conflict)
@@ -1877,7 +1875,6 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packet cmd,
}

if (signal_pending(current)) {
- drbd_remove_epoch_entry_interval(mdev, e);
spin_unlock_irq(&mdev->tconn->req_lock);
finish_wait(&mdev->misc_wait, &wait);
goto out_interrupted;
@@ -1900,6 +1897,8 @@ static int receive_Data(struct drbd_conf *mdev, enum drbd_packet cmd,
spin_lock_irq(&mdev->tconn->req_lock);
}
finish_wait(&mdev->misc_wait, &wait);
+
+ drbd_insert_interval(&mdev->write_requests, &e->i);
}

list_add(&e->w.list, &mdev->active_ee);
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 078f77b..df5f106 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -74,6 +74,7 @@ static struct drbd_request *drbd_req_new(struct drbd_conf *mdev,
drbd_clear_interval(&req->i);
req->i.sector = bio_src->bi_sector;
req->i.size = bio_src->bi_size;
+ req->i.local = true;
req->i.waiting = false;

INIT_LIST_HEAD(&req->tl_requests);
@@ -317,8 +318,6 @@ static void _req_may_be_done_not_susp(struct drbd_request *req, struct bio_and_e
* to happen, but this is the rationale why we also have to check for
* conflicting requests with local origin, and why we have to do so regardless
* of whether we allowed multiple primaries.
- *
- * In case we only have one primary, the epoch_entries tree is empty.
*/
static int _req_conflicts(struct drbd_request *req)
{
@@ -334,35 +333,16 @@ static int _req_conflicts(struct drbd_request *req)

i = drbd_find_overlap(&mdev->write_requests, sector, size);
if (i) {
- struct drbd_request *req2 =
- container_of(i, struct drbd_request, i);
-
- dev_alert(DEV, "%s[%u] Concurrent local write detected! "
+ dev_alert(DEV, "%s[%u] Concurrent %s write detected! "
"[DISCARD L] new: %llus +%u; "
"pending: %llus +%u\n",
current->comm, current->pid,
+ i->local ? "local" : "remote",
(unsigned long long)sector, size,
- (unsigned long long)req2->i.sector, req2->i.size);
+ (unsigned long long)i->sector, i->size);
goto out_conflict;
}

- if (!RB_EMPTY_ROOT(&mdev->epoch_entries)) {
- /* check for overlapping requests with remote origin */
- i = drbd_find_overlap(&mdev->epoch_entries, sector, size);
- if (i) {
- struct drbd_epoch_entry *e =
- container_of(i, struct drbd_epoch_entry, i);
-
- dev_alert(DEV, "%s[%u] Concurrent remote write detected!"
- " [DISCARD L] new: %llus +%u; "
- "pending: %llus +%u\n",
- current->comm, current->pid,
- (unsigned long long)sector, size,
- (unsigned long long)e->i.sector, e->i.size);
- goto out_conflict;
- }
- }
-
/* this is like it should be, and what we expected.
* our users do behave after all... */
put_net_conf(mdev->tconn);
diff --git a/drivers/block/drbd/drbd_worker.c b/drivers/block/drbd/drbd_worker.c
index afad8ea..0359600 100644
--- a/drivers/block/drbd/drbd_worker.c
+++ b/drivers/block/drbd/drbd_worker.c
@@ -123,7 +123,7 @@ static void drbd_endio_write_sec_final(struct drbd_epoch_entry *e) __releases(lo
list_add_tail(&e->w.list, &mdev->done_ee);

/*
- * Do not remove from the epoch_entries tree here: we did not send the
+ * Do not remove from the write_requests tree here: we did not send the
* Ack yet and did not wake possibly waiting conflicting requests.
* Removed from the tree from "drbd_process_done_ee" within the
* appropriate w.cb (e_end_block/e_end_resync_block) or from
--
1.7.4.1


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