The null_blk configfs file 'features' provides a string that lists
available null_blk features for userspace programs to reference.
The string is defined as a long constant in the code, which tends to be
forgotten for updates. It also causes checkpatch.pl to report
"WARNING: quoted string split across lines".
To avoid these drawbacks, generate the feature string on the fly. Refer
to the ca_name field of each element in the nullb_device_attrs table and
concatenate them in the given buffer. Also, modify order of the
nullb_device_attrs table to not change the list order of the generated
string.
Of note is that the feature "index" was missing before this commit.
This commit adds it to the generated string.
Suggested-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@xxxxxxx>
---
drivers/block/null_blk/main.c | 93 ++++++++++++++++++++---------------
1 file changed, 54 insertions(+), 39 deletions(-)
diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
index 178e62cd9a9f..f720707b7cfb 100644
--- a/drivers/block/null_blk/main.c
+++ b/drivers/block/null_blk/main.c
@@ -591,42 +591,46 @@ static ssize_t nullb_device_zone_offline_store(struct config_item *item,
}
CONFIGFS_ATTR_WO(nullb_device_, zone_offline);
+/*
+ * Place the elements in alphabetical order to keep the confingfs
+ * 'features' string readable.
+ */
static struct configfs_attribute *nullb_device_attrs[] = {
- &nullb_device_attr_size,
- &nullb_device_attr_completion_nsec,
- &nullb_device_attr_submit_queues,
- &nullb_device_attr_poll_queues,
- &nullb_device_attr_home_node,
- &nullb_device_attr_queue_mode,
+ &nullb_device_attr_badblocks,
+ &nullb_device_attr_blocking,
&nullb_device_attr_blocksize,
- &nullb_device_attr_max_sectors,
- &nullb_device_attr_irqmode,
+ &nullb_device_attr_cache_size,
+ &nullb_device_attr_completion_nsec,
+ &nullb_device_attr_discard,
+ &nullb_device_attr_fua,
+ &nullb_device_attr_home_node,
&nullb_device_attr_hw_queue_depth,
&nullb_device_attr_index,
- &nullb_device_attr_blocking,
- &nullb_device_attr_use_per_node_hctx,
- &nullb_device_attr_power,
- &nullb_device_attr_memory_backed,
- &nullb_device_attr_discard,
+ &nullb_device_attr_irqmode,
+ &nullb_device_attr_max_sectors,
&nullb_device_attr_mbps,
- &nullb_device_attr_cache_size,
- &nullb_device_attr_badblocks,
- &nullb_device_attr_zoned,
- &nullb_device_attr_zone_size,
- &nullb_device_attr_zone_capacity,
- &nullb_device_attr_zone_nr_conv,
- &nullb_device_attr_zone_max_open,
- &nullb_device_attr_zone_max_active,
- &nullb_device_attr_zone_append_max_sectors,
- &nullb_device_attr_zone_readonly,
- &nullb_device_attr_zone_offline,
- &nullb_device_attr_zone_full,
- &nullb_device_attr_virt_boundary,
+ &nullb_device_attr_memory_backed,
&nullb_device_attr_no_sched,
- &nullb_device_attr_shared_tags,
- &nullb_device_attr_shared_tag_bitmap,
- &nullb_device_attr_fua,
+ &nullb_device_attr_poll_queues,
+ &nullb_device_attr_power,
+ &nullb_device_attr_queue_mode,
&nullb_device_attr_rotational,
+ &nullb_device_attr_shared_tag_bitmap,
+ &nullb_device_attr_shared_tags,
+ &nullb_device_attr_size,
+ &nullb_device_attr_submit_queues,
+ &nullb_device_attr_use_per_node_hctx,
+ &nullb_device_attr_virt_boundary,
+ &nullb_device_attr_zone_append_max_sectors,
+ &nullb_device_attr_zone_capacity,
+ &nullb_device_attr_zone_full,
+ &nullb_device_attr_zone_max_active,
+ &nullb_device_attr_zone_max_open,
+ &nullb_device_attr_zone_nr_conv,
+ &nullb_device_attr_zone_offline,
+ &nullb_device_attr_zone_readonly,
+ &nullb_device_attr_zone_size,
+ &nullb_device_attr_zoned,
NULL,
};
@@ -704,16 +708,27 @@ nullb_group_drop_item(struct config_group *group, struct config_item *item)
static ssize_t memb_group_features_show(struct config_item *item, char *page)
{
- return snprintf(page, PAGE_SIZE,
- "badblocks,blocking,blocksize,cache_size,fua,"
- "completion_nsec,discard,home_node,hw_queue_depth,"
- "irqmode,max_sectors,mbps,memory_backed,no_sched,"
- "poll_queues,power,queue_mode,shared_tag_bitmap,"
- "shared_tags,size,submit_queues,use_per_node_hctx,"
- "virt_boundary,zoned,zone_capacity,zone_max_active,"
- "zone_max_open,zone_nr_conv,zone_offline,zone_readonly,"
- "zone_size,zone_append_max_sectors,zone_full,"
- "rotational\n");
+
+ struct configfs_attribute **entry;
+ const char *fmt = "%s,";
+ size_t left = PAGE_SIZE;
+ size_t written = 0;
+ int ret;
+
+ for (entry = &nullb_device_attrs[0]; *entry && left > 0; entry++) {
+ if (!*(entry + 1))
+ fmt = "%s\n";
+ ret = snprintf(page + written, left, fmt, (*entry)->ca_name);
+ if (ret >= left) {
+ WARN_ONCE(1, "Too many null_blk features to print\n");
+ memzero_explicit(page, PAGE_SIZE);
+ return 0;
+ }
+ left -= ret;
+ written += ret;
+ }
+
+ return written;
}
CONFIGFS_ATTR_RO(memb_group_, features);
--
2.47.0
