For cases where a file lookup can look in different filesystems (like in
overlayfs), both super blocks must have the same encoding and the same
flags. To help with that, create a sb_same_encoding() function.
Signed-off-by: André Almeida <andrealmeid@xxxxxxxxxx>
Reviewed-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
Changes from v4:
- Move it to the begin of the series
Changes from v3:
- Improve wording
Changes from v2:
- Simplify the code. Instead of `if (cond) return true`, just do `return
cond`;
---
include/linux/fs.h | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 43b3a7cf6750d3db3e5350908c95bc8a729db41a..ec867f112fd5fce7c1cceeb8598979972688d220 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3754,6 +3754,24 @@ static inline bool sb_has_encoding(const struct super_block *sb)
return !!sb_encoding(sb);
}
+/*
+ * Compare if two super blocks have the same encoding and flags
+ */
+static inline bool sb_same_encoding(const struct super_block *sb1,
+ const struct super_block *sb2)
+{
+#if IS_ENABLED(CONFIG_UNICODE)
+ if (sb1->s_encoding == sb2->s_encoding)
+ return true;
+
+ return (sb1->s_encoding && sb2->s_encoding &&
+ (sb1->s_encoding->version == sb2->s_encoding->version) &&
+ (sb1->s_encoding_flags == sb2->s_encoding_flags));
+#else
+ return true;
+#endif
+}
+
int may_setattr(struct mnt_idmap *idmap, struct inode *inode,
unsigned int ia_valid);
int setattr_prepare(struct mnt_idmap *, struct dentry *, struct iattr *);
--
2.50.1
