Re: [PATCH v3 01/13] btrfs: add sysfs interface for supported sectorsize

[Anand Jain]

On 25/03/2021 15:14, Qu Wenruo wrote:

Add extra sysfs interface features/supported_ro_sectorsize and
features/supported_rw_sectorsize to indicate subpage support.

Currently for supported_rw_sectorsize all architectures only have their
PAGE_SIZE listed.

While for supported_ro_sectorsize, for systems with 64K page size, 4K
sectorsize is also supported.

 Change-log does match with the changes below.

This new sysfs interface would help mkfs.btrfs to do more accurate
warning.

Signed-off-by: Qu Wenruo <w...@suse.com>
---
  fs/btrfs/sysfs.c | 15 +++++++++++++++
  1 file changed, 15 insertions(+)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 6eb1c50fa98c..2f9c2639707c 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -360,11 +360,26 @@ static ssize_t supported_rescue_options_show(struct 
kobject *kobj,
  BTRFS_ATTR(static_feature, supported_rescue_options,
           supported_rescue_options_show);

+static ssize_t supported_sectorsizes_show(struct kobject *kobj,

+                                         struct kobj_attribute *a,
+                                         char *buf)
+{
+       ssize_t ret = 0;
+
+       /* Only support sectorsize == PAGE_SIZE yet */
+       ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%lu\n",
+                        PAGE_SIZE);
+       return ret;
+}

  ret can be removed completely here.

Thanks, Anand

+BTRFS_ATTR(static_feature, supported_sectorsizes,
+          supported_sectorsizes_show);
+
  static struct attribute *btrfs_supported_static_feature_attrs[] = {
        BTRFS_ATTR_PTR(static_feature, rmdir_subvol),
        BTRFS_ATTR_PTR(static_feature, supported_checksums),
        BTRFS_ATTR_PTR(static_feature, send_stream_version),
        BTRFS_ATTR_PTR(static_feature, supported_rescue_options),
+       BTRFS_ATTR_PTR(static_feature, supported_sectorsizes),
        NULL
  };