+
+int blk_validate_limits(struct queue_limits *lim)
+{
+ unsigned int max_hw_sectors;
+
+ if (!lim->logical_block_size)
+ lim->logical_block_size = SECTOR_SIZE;
nit: This function is doing a bit more than validating, as the function
name suggests
+
+ if (!lim->physical_block_size)
+ lim->physical_block_size = SECTOR_SIZE;
+ if (lim->physical_block_size < lim->logical_block_size)
+ lim->physical_block_size = lim->physical_block_size;
+
+ if (!lim->io_min)
+ lim->io_min = SECTOR_SIZE;
+ if (lim->io_min < lim->physical_block_size)
+ lim->io_min = lim->physical_block_size;
+
+ if (!lim->max_hw_sectors)
+ lim->max_hw_sectors = BLK_SAFE_MAX_SECTORS;
+ if (WARN_ON_ONCE(lim->max_hw_sectors < PAGE_SIZE / SECTOR_SIZE))
+ return -EINVAL;
The WARN_ON_ONCE usage is odd, as it will only ever WARN once for a
specific q, while other queues associated with other drivers may have
the same limit issue. But I suppose if one issue is fixed, then the
other will make itself known...
+
+ lim->max_hw_sectors = round_down(lim->max_hw_sectors,
+ lim->logical_block_size >> SECTOR_SHIFT);
+
+ max_hw_sectors = min_not_zero(lim->max_hw_sectors,
+ lim->max_dev_sectors);
+ if (lim->max_user_sectors) {
+ if (lim->max_user_sectors > max_hw_sectors ||
+ lim->max_user_sectors < PAGE_SIZE / SECTOR_SIZE)
+ return -EINVAL;
+ lim->max_sectors = min(max_hw_sectors, lim->max_user_sectors);
+ } else {
+ lim->max_sectors = min(max_hw_sectors, BLK_DEF_MAX_SECTORS_CAP);
+ }
+
+/**
+ * queue_limits_commit_update - commit an atomic update of queue limits
+ * @q: queue to update
+ * @lim: limits to apply
+ *
+ * Apply the limits in @lim that were obtained from queue_limits_start_update()
+ * and updated by the caller to @q.
+ *
+ * Returns 0 if successful, else a negative error code.
+ */
+int queue_limits_commit_update(struct request_queue *q,
+ struct queue_limits *lim)
+ __releases(q->limits_lock)
+{
+ int error = blk_validate_limits(lim);
+
+ if (!error) {
+ q->limits = *lim;
this is duplicating what blk_alloc_queue() does
+ if (q->disk)
+ blk_apply_bdi_limits(q->disk->bdi, lim);
+ }
+ mutex_unlock(&q->limits_lock);
+ return error;
+}
+EXPORT_SYMBOL_GPL(queue_limits_commit_update);
+
/**
* blk_queue_bounce_limit - set bounce buffer limit for queue
* @q: the request queue for the device
diff --git a/block/blk.h b/block/blk.h
index 1ef920f72e0f87..58b5dbac2a487d 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -447,6 +447,7 @@ static inline void bio_release_page(struct bio *bio, struct
page *page)
unpin_user_page(page);
}
+int blk_validate_limits(struct queue_limits *lim);
struct request_queue *blk_alloc_queue(int node_id);
int disk_scan_partitions(struct gendisk *disk, blk_mode_t mode);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4a2e82c7971c86..5b5d3b238de1e7 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -473,6 +473,7 @@ struct request_queue {
struct mutex sysfs_lock;
struct mutex sysfs_dir_lock;
+ struct mutex limits_lock;
/*
* for reusing dead hctx instance in case of updating
@@ -861,6 +862,28 @@ static inline unsigned int blk_chunk_sectors_left(sector_t
offset,
return chunk_sectors - (offset & (chunk_sectors - 1));
}
+/**
+ * queue_limits_start_update - start an atomic update of queue limits
+ * @q: queue to update
+ *
+ * This functions starts an atomic update of the queue limits. It takes a lock
+ * to prevent other updates and returns a snapshot of the current limits that
+ * the caller can modify. The caller must call queue_limits_commit_update()
+ * to finish the update.
+ *
+ * Context: process context. The caller must have frozen the queue or ensured
+ * that there is outstanding I/O by other means.
+ */
+static inline struct queue_limits
+queue_limits_start_update(struct request_queue *q)
+ __acquires(q->limits_lock)
+{
+ mutex_lock(&q->limits_lock);
+ return q->limits;
+}
+int queue_limits_commit_update(struct request_queue *q,
+ struct queue_limits *lim);
It ain't so nice that the code for queue_limits_start_update() and
queue_limits_commit_update() pair are in separate files.
+
/*
* Access functions for manipulating queue properties
*/
