Just like label change, use sb_want_write() to do a correct protection.
Signed-off-by: Qu Wenruo <[email protected]>
---
v4:
Newly introduced.
v5:
Change to sb_want_write().
v6:
Move sb_want_write() to the beginning of the function.
v7:
None
v8:
Move sb_want_write() after get fs_info.
v9:
Fix a unpaired sb_drop_write() in error handler.
---
fs/btrfs/sysfs.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 7e548f7..19876ba 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -121,10 +121,14 @@ static ssize_t btrfs_feature_attr_store(struct kobject
*kobj,
if (!fs_info)
return -EPERM;
- ret = kstrtoul(skip_spaces(buf), 0, &val);
+ ret = sb_want_write(fs_info->sb);
if (ret)
return ret;
+ ret = kstrtoul(skip_spaces(buf), 0, &val);
+ if (ret)
+ goto out;
+
if (fa->feature_set == FEAT_COMPAT) {
set = BTRFS_FEATURE_COMPAT_SAFE_SET;
clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
@@ -141,22 +145,25 @@ static ssize_t btrfs_feature_attr_store(struct kobject
*kobj,
/* Nothing to do */
if ((val && (features & fa->feature_bit)) ||
(!val && !(features & fa->feature_bit)))
- return count;
+ goto out;
if ((val && !(set & fa->feature_bit)) ||
(!val && !(clear & fa->feature_bit))) {
btrfs_info(fs_info,
"%sabling feature %s on mounted fs is not supported.",
val ? "En" : "Dis", fa->kobj_attr.attr.name);
- return -EPERM;
+ ret = -EPERM;
+ goto out;
}
btrfs_info(fs_info, "%s %s feature flag",
val ? "Setting" : "Clearing", fa->kobj_attr.attr.name);
trans = btrfs_start_transaction(fs_info->fs_root, 0);
- if (IS_ERR(trans))
- return PTR_ERR(trans);
+ if (IS_ERR(trans)) {
+ ret = PTR_ERR(trans);
+ goto out;
+ }
spin_lock(&fs_info->super_lock);
features = get_features(fs_info, fa->feature_set);
@@ -168,10 +175,12 @@ static ssize_t btrfs_feature_attr_store(struct kobject
*kobj,
spin_unlock(&fs_info->super_lock);
ret = btrfs_commit_transaction(trans, fs_info->fs_root);
- if (ret)
- return ret;
- return count;
+out:
+ sb_drop_write(fs_info->sb);
+ if (!ret)
+ return count;
+ return ret;
}
static umode_t btrfs_feature_visible(struct kobject *kobj,
--
2.3.0
--
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