[PATCH 3/6] zloop: simplify checks for writes to sequential zones

[Damien Le Moal <dlemoal@kernel.org>]

The function zloop_rw() already checks early that a request is fully
contained within the target zone. So this check does not need to be done
again for regular writes to sequential zones. Furthermore, since zone
append operations are always directed to the zone write pointer
location, we do not need to check for their alignment to that value
after setting it. So turn the "if" checking the write pointer alignment
into an "else if".

While at it, improve the comment describing the write pointer
modification and how this value is corrected in case of error.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
 drivers/block/zloop.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/drivers/block/zloop.c b/drivers/block/zloop.c
index 266d233776ad..0526277f6cd1 100644
--- a/drivers/block/zloop.c
+++ b/drivers/block/zloop.c
@@ -406,6 +406,11 @@ static void zloop_rw(struct zloop_cmd *cmd)
 	if (!test_bit(ZLOOP_ZONE_CONV, &zone->flags) && is_write) {
 		mutex_lock(&zone->lock);
 
+		/*
+		 * Zone append operations always go at the current write
+		 * pointer, but regular write operations must already be
+		 * aligned to the write pointer when submitted.
+		 */
 		if (is_append) {
 			if (zone->cond == BLK_ZONE_COND_FULL) {
 				ret = -EIO;
@@ -413,13 +418,7 @@ static void zloop_rw(struct zloop_cmd *cmd)
 			}
 			sector = zone->wp;
 			cmd->sector = sector;
-		}
-
-		/*
-		 * Write operations must be aligned to the write pointer and
-		 * fully contained within the zone capacity.
-		 */
-		if (sector != zone->wp || zone->wp + nr_sectors > zone_end) {
+		} else if (sector != zone->wp) {
 			pr_err("Zone %u: unaligned write: sect %llu, wp %llu\n",
 			       zone_no, sector, zone->wp);
 			ret = -EIO;
@@ -432,9 +431,9 @@ static void zloop_rw(struct zloop_cmd *cmd)
 			zone->cond = BLK_ZONE_COND_IMP_OPEN;
 
 		/*
-		 * Advance the write pointer of sequential zones. If the write
-		 * fails, the wp position will be corrected when the next I/O
-		 * copmpletes.
+		 * Advance the write pointer. If the write fails, the write
+		 * pointer position will be corrected when the next I/O starts
+		 * execution.
 		 */
 		zone->wp += nr_sectors;
 		if (zone->wp == zone_end) {
-- 
2.51.1