[Devel] [PATCH RHEL8 COMMIT] ploop: Become use top delta

[Konstantin Khorenko]

The commit is pushed to "branch-rh8-4.18.0-240.1.1.vz8.5.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh8-4.18.0-240.1.1.vz8.5.30
------>
commit d9dbafd09f920c78b5ed3a6d92df88df084839df
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date:   Mon May 17 19:04:40 2021 +0300

    ploop: Become use top delta
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
    
    =====================
    Patchset description:
    
    dm-ploop: Kill loop
    
    Intermediate patches can't be base for bisect.
    
    In scope of https://jira.sw.ru/browse/PSBM-123654
    
    Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 drivers/md/dm-ploop-map.c | 72 +++++++++++++++++++++++++++++++++++++++++++----
 drivers/md/dm-ploop.h     |  6 ++++
 2 files changed, 73 insertions(+), 5 deletions(-)

diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index b1fd15d5516d..518075645ed9 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -5,6 +5,7 @@
 #include <linux/init.h>
 #include <linux/vmalloc.h>
 #include <linux/uio.h>
+#include <uapi/linux/falloc.h>
 #include "dm-ploop.h"
 
 /*
@@ -49,6 +50,22 @@
 			read_unlock_irqrestore(&ploop->bat_rwlock, flags);	\
 	} while (0)
 
+static unsigned int bio_nr_segs(struct bio *bio)
+{
+	struct bvec_iter bi = {
+		.bi_size = bio->bi_iter.bi_size,
+		.bi_bvec_done = bio->bi_iter.bi_bvec_done,
+		.bi_idx = bio->bi_iter.bi_idx,
+	};
+        unsigned int nr_segs = 0;
+	struct bio_vec bv;
+
+	for_each_bvec(bv, bio->bi_io_vec, bi, bi)
+                nr_segs++;
+
+        return nr_segs;
+}
+
 static void ploop_index_wb_init(struct ploop_index_wb *piwb, struct ploop *ploop)
 {
 	piwb->ploop = ploop;
@@ -410,12 +427,19 @@ static bool bio_endio_if_all_zeros(struct bio *bio)
 	return true;
 }
 
+static int punch_hole(struct file *file, loff_t pos, loff_t len)
+{
+	return vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE,
+			     pos, len);
+}
+
 static void handle_discard_bio(struct ploop *ploop, struct bio *bio,
 		     unsigned int cluster, unsigned int dst_cluster)
 {
 	struct pio *h = bio_to_endio_hook(bio);
 	struct pio *inflight_h;
 	unsigned long flags;
+	loff_t pos;
 	int ret;
 
 	if (!cluster_is_in_top_delta(ploop, cluster) || ploop->nr_deltas != 1) {
@@ -463,9 +487,14 @@ static void handle_discard_bio(struct ploop *ploop, struct bio *bio,
 	read_unlock_irq(&ploop->bat_rwlock);
 	atomic_inc(&ploop->nr_discard_bios);
 
-	remap_to_cluster(ploop, bio, dst_cluster);
 	remap_to_origin(ploop, bio);
-	generic_make_request(bio);
+	remap_to_cluster(ploop, bio, dst_cluster);
+
+	pos = to_bytes(bio->bi_iter.bi_sector);
+	ret = punch_hole(top_delta(ploop)->file, pos, bio->bi_iter.bi_size);
+	if (ret)
+		bio->bi_status = errno_to_blk_status(ret);
+	bio_endio(bio);
 }
 
 static int ploop_discard_bio_end(struct ploop *ploop, struct bio *bio)
@@ -1279,6 +1308,41 @@ static bool locate_new_cluster_and_attach_bio(struct ploop *ploop,
 	return false;
 }
 
+static void data_rw_complete(struct pio *pio)
+{
+	struct bio *bio = pio->data;
+
+	if (pio->ret != bio->bi_iter.bi_size)
+                bio->bi_status = BLK_STS_IOERR;
+
+	bio_endio(bio);
+}
+
+static void submit_rw_mapped(struct ploop *ploop, loff_t clu_pos, struct bio *bio)
+{
+	struct pio *pio = bio_to_endio_hook(bio);
+	unsigned int rw, nr_segs;
+	struct bio_vec *bvec;
+	struct iov_iter iter;
+	loff_t pos;
+
+	pio->complete = data_rw_complete;
+	pio->data = bio;
+
+	rw = (op_is_write(bio->bi_opf) ? WRITE : READ);
+	nr_segs = bio_nr_segs(bio);
+	bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
+
+	iov_iter_bvec(&iter, rw, bvec, nr_segs, bio->bi_iter.bi_size);
+	iter.iov_offset = bio->bi_iter.bi_bvec_done;
+
+	remap_to_origin(ploop, bio);
+	remap_to_cluster(ploop, bio, clu_pos);
+	pos = to_bytes(bio->bi_iter.bi_sector);
+
+	call_rw_iter(top_delta(ploop)->file, pos, rw, &iter, bio);
+}
+
 static int process_one_deferred_bio(struct ploop *ploop, struct bio *bio,
 				    struct ploop_index_wb *piwb)
 {
@@ -1343,9 +1407,7 @@ static int process_one_deferred_bio(struct ploop *ploop, struct bio *bio,
 
 	maybe_link_submitting_bio(ploop, bio, cluster);
 
-	remap_to_cluster(ploop, bio, dst_cluster);
-	remap_to_origin(ploop, bio);
-	generic_make_request(bio);
+	submit_rw_mapped(ploop, dst_cluster, bio);
 out:
 	return 0;
 }
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index f8194e3869d7..55a30722b18b 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -105,6 +105,7 @@ struct ploop_cmd {
 
 #define PLOOP_BIOS_HTABLE_BITS	8
 #define PLOOP_BIOS_HTABLE_SIZE	(1 << PLOOP_BIOS_HTABLE_BITS)
+#define CLU_OFF(ploop, pos) (pos & (to_bytes(1 << ploop->cluster_log) - 1))
 
 enum piwb_type {
 	PIWB_TYPE_ALLOC = 0,	/* Allocation of new clusters */
@@ -322,6 +323,11 @@ static inline u8 top_level(struct ploop *ploop)
 	return ploop->nr_deltas - 1;
 }
 
+static inline struct ploop_delta *top_delta(struct ploop *ploop)
+{
+	return &ploop->deltas[top_level(ploop)];
+}
+
 static inline void ploop_hole_set_bit(unsigned long nr, struct ploop *ploop)
 {
 	if (!WARN_ON_ONCE(nr >= ploop->hb_nr))