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 Reviewed-by: Amir Goldstein --- 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