[Devel] [RFC PATCH vz9 v3 02/11] ploop: Use READ_ONCE/WRITE_ONCE to access md page data
Alexander Atanasov
alexander.atanasov at virtuozzo.com
Mon Oct 21 13:13:49 MSK 2024
Prepare to reduce locking by using atomic 32 bit access to the fields.
To ensure this we need to use the _ONCE macros.
https://virtuozzo.atlassian.net/browse/VSTOR-91659
Signed-off-by: Alexander Atanasov <alexander.atanasov at virtuozzo.com>
---
drivers/md/dm-ploop-bat.c | 20 ++++++++++----------
drivers/md/dm-ploop-cmd.c | 28 ++++++++++++++--------------
drivers/md/dm-ploop-map.c | 22 +++++++++++-----------
drivers/md/dm-ploop.h | 2 +-
4 files changed, 36 insertions(+), 36 deletions(-)
diff --git a/drivers/md/dm-ploop-bat.c b/drivers/md/dm-ploop-bat.c
index f28bd5d7b322..886a05cdd23a 100644
--- a/drivers/md/dm-ploop-bat.c
+++ b/drivers/md/dm-ploop-bat.c
@@ -143,9 +143,9 @@ bool ploop_try_update_bat_entry(struct ploop *ploop, u32 clu, u8 level, u32 dst_
clu = ploop_bat_clu_idx_in_page(clu); /* relative offset */
- if (md->bat_levels[clu] == level) {
+ if (READ_ONCE(md->bat_levels[clu]) == level) {
bat_entries = md->kmpage;
- bat_entries[clu] = dst_clu;
+ WRITE_ONCE(bat_entries[clu], dst_clu);
return true;
}
return false;
@@ -287,11 +287,11 @@ static int ploop_convert_bat_entries(struct ploop *ploop, struct rb_root *md_roo
page_id++;
for (; i <= end; i++) {
- if (bat_entries[i] > max_file_clu)
+ if (READ_ONCE(bat_entries[i]) > max_file_clu)
ret = -EPROTO;
- if (!bat_entries[i])
- bat_entries[i] = BAT_ENTRY_NONE;
- if (bat_entries[i] < bat_clusters)
+ if (!READ_ONCE(bat_entries[i]))
+ WRITE_ONCE(bat_entries[i], BAT_ENTRY_NONE);
+ if (READ_ONCE(bat_entries[i]) < bat_clusters)
ret = -EXDEV;
}
@@ -431,21 +431,21 @@ static void ploop_apply_delta_mappings(struct ploop *ploop,
if (clu == nr_be - 1)
stop = true;
- if (bat_entries[i] != BAT_ENTRY_NONE) {
+ if (READ_ONCE(bat_entries[i]) != BAT_ENTRY_NONE) {
/* md0 is already populated */
WARN_ON_ONCE(md->id && is_top_level);
goto set_not_hole;
}
if (!is_raw)
- dst_clu = d_bat_entries[i];
+ dst_clu = READ_ONCE(d_bat_entries[i]);
else
dst_clu = clu;
if (dst_clu == BAT_ENTRY_NONE)
continue;
- md->bat_levels[i] = level;
- bat_entries[i] = dst_clu;
+ WRITE_ONCE(md->bat_levels[i], level);
+ WRITE_ONCE(bat_entries[i], dst_clu);
set_not_hole:
if (is_top_level)
ploop_set_not_hole(ploop, bat_entries[i]);
diff --git a/drivers/md/dm-ploop-cmd.c b/drivers/md/dm-ploop-cmd.c
index b1b77e4546c4..13a56d702fc3 100644
--- a/drivers/md/dm-ploop-cmd.c
+++ b/drivers/md/dm-ploop-cmd.c
@@ -47,7 +47,7 @@ static void ploop_advance_holes_bitmap(struct ploop *ploop,
for (; i <= end; i++) {
if (!ploop_md_page_cluster_is_in_top_delta(ploop, md, i))
continue;
- dst_clu = bat_entries[i];
+ dst_clu = READ_ONCE(bat_entries[i]);
/* This may happen after grow->shrink->(now) grow */
if (dst_clu < ploop->hb_nr &&
test_bit(dst_clu, ploop->holes_bitmap)) {
@@ -162,7 +162,7 @@ static u32 ploop_find_bat_entry(struct ploop *ploop, u32 dst_clu, bool *is_locke
ploop_init_be_iter(ploop, md->id, &i, &end);
bat_entries = md->kmpage;
for (; i <= end; i++) {
- if (bat_entries[i] != dst_clu)
+ if (READ_ONCE(bat_entries[i]) != dst_clu)
continue;
if (ploop_md_page_cluster_is_in_top_delta(ploop, md, i)) {
clu = ploop_page_clu_idx_to_bat_clu(md->id, i);
@@ -734,17 +734,17 @@ static void notify_delta_merged(struct ploop *ploop, u8 level,
stop = true;
/* deltas above @level become renumbered */
- if (bat_entries[i] != BAT_ENTRY_NONE &&
- md->bat_levels[i] > level) {
+ if (READ_ONCE(bat_entries[i]) != BAT_ENTRY_NONE &&
+ READ_ONCE(md->bat_levels[i]) > level) {
md->bat_levels[i]--;
continue;
}
- if (bat_entries[i] != BAT_ENTRY_NONE &&
- md->bat_levels[i] < level)
+ if (READ_ONCE(bat_entries[i]) != BAT_ENTRY_NONE &&
+ READ_ONCE(md->bat_levels[i]) < level)
continue;
- if (d_bat_entries[i] == BAT_ENTRY_NONE) {
+ if (READ_ONCE(d_bat_entries[i]) == BAT_ENTRY_NONE) {
WARN_ON_ONCE(bat_entries[i] != BAT_ENTRY_NONE);
continue;
}
@@ -756,9 +756,9 @@ static void notify_delta_merged(struct ploop *ploop, u8 level,
*/
WRITE_ONCE(bat_entries[i], READ_ONCE(d_bat_entries[i]));
if (!forward)
- md->bat_levels[i] = level - 1;
+ WRITE_ONCE(md->bat_levels[i], level - 1);
else
- md->bat_levels[i] = level;
+ WRITE_ONCE(md->bat_levels[i], level);
}
if (stop)
break;
@@ -984,13 +984,13 @@ static int process_flip_upper_deltas(struct ploop *ploop)
ploop_init_be_iter(ploop, md->id, &i, &end);
bat_entries = md->kmpage;
for (; i <= end; i++) {
- if (bat_entries[i] == BAT_ENTRY_NONE)
+ if (READ_ONCE(bat_entries[i]) == BAT_ENTRY_NONE)
continue;
- if (md->bat_levels[i] == level) {
- md->bat_levels[i] = ploop_top_level(ploop);
+ if (READ_ONCE(md->bat_levels[i]) == level) {
+ WRITE_ONCE(md->bat_levels[i], ploop_top_level(ploop));
clear_bit(bat_entries[i], holes_bitmap);
- } else if (md->bat_levels[i] == ploop_top_level(ploop)) {
- md->bat_levels[i] = level;
+ } else if (READ_ONCE(md->bat_levels[i]) == ploop_top_level(ploop)) {
+ WRITE_ONCE(md->bat_levels[i], level);
}
}
}
diff --git a/drivers/md/dm-ploop-map.c b/drivers/md/dm-ploop-map.c
index ca2659ba30f5..edfa44b7214a 100644
--- a/drivers/md/dm-ploop-map.c
+++ b/drivers/md/dm-ploop-map.c
@@ -724,9 +724,9 @@ static void ploop_release_cluster(struct ploop *ploop, u32 clu)
clu = ploop_bat_clu_idx_in_page(clu); /* relative to page */
bat_entries = md->kmpage;
- dst_clu = bat_entries[clu];
- bat_entries[clu] = BAT_ENTRY_NONE;
- md->bat_levels[clu] = 0;
+ dst_clu = READ_ONCE(bat_entries[clu]);
+ WRITE_ONCE(bat_entries[clu], BAT_ENTRY_NONE);
+ WRITE_ONCE(md->bat_levels[clu], 0);
ploop_hole_set_bit(dst_clu, ploop);
}
@@ -794,8 +794,8 @@ static void ploop_advance_local_after_bat_wb(struct ploop *ploop,
}
if (success) {
- bat_entries[i] = dst_clu[i];
- md->bat_levels[i] = ploop_top_level(ploop);
+ bat_entries[i] = READ_ONCE(dst_clu[i]);
+ WRITE_ONCE(md->bat_levels[i], ploop_top_level(ploop));
} else {
ploop_hole_set_bit(i + off, ploop);
}
@@ -978,7 +978,7 @@ static void ploop_bat_page_zero_cluster(struct ploop *ploop,
clu = ploop_bat_clu_idx_in_page(clu);
to = piwb->kmpage;
- to[clu] = 0;
+ WRITE_ONCE(to[clu], 0);
}
static int ploop_find_dst_clu_bit(struct ploop *ploop, u32 *ret_dst_clu)
@@ -1090,9 +1090,9 @@ static int ploop_alloc_cluster(struct ploop *ploop, struct ploop_index_wb *piwb,
clu -= piwb->page_id * PAGE_SIZE / sizeof(map_index_t) - PLOOP_MAP_OFFSET;
to = piwb->kmpage;
- if (to[clu]) {
+ if (READ_ONCE(to[clu])) {
/* Already mapped by one of previous bios */
- *dst_clu = to[clu];
+ *dst_clu = READ_ONCE(to[clu]);
already_alloced = true;
}
@@ -1104,7 +1104,7 @@ static int ploop_alloc_cluster(struct ploop *ploop, struct ploop_index_wb *piwb,
goto out;
to = piwb->kmpage;
- to[clu] = *dst_clu;
+ WRITE_ONCE(to[clu], *dst_clu);
out:
return ret;
}
@@ -1386,7 +1386,7 @@ static void ploop_submit_cow_index_wb(struct ploop_cow *cow)
to = piwb->kmpage;
WARN_ON(to[clu]);
- to[clu] = cow->dst_clu;
+ WRITE_ONCE(to[clu], cow->dst_clu);
/* Prevent double clearing of holes_bitmap bit on complete_cow() */
cow->dst_clu = BAT_ENTRY_NONE;
@@ -1722,7 +1722,7 @@ static void ploop_process_one_discard_pio(struct ploop *ploop, struct pio *pio)
pio->bi_status = BLK_STS_IOERR;
goto err;
} else {
- to[clu] = 0;
+ WRITE_ONCE(to[clu], 0);
list_add_tail(&pio->list, &piwb->ready_data_pios);
}
diff --git a/drivers/md/dm-ploop.h b/drivers/md/dm-ploop.h
index 85291d3cbbe7..90c80954c198 100644
--- a/drivers/md/dm-ploop.h
+++ b/drivers/md/dm-ploop.h
@@ -428,7 +428,7 @@ static inline u32 ploop_bat_entries(struct ploop *ploop, u32 clu,
clu = ploop_bat_clu_idx_in_page(clu);
if (bat_level)
- *bat_level = md->bat_levels[clu];
+ *bat_level = READ_ONCE(md->bat_levels[clu]);
if (md_ret)
*md_ret = md;
--
2.43.0
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