[PATCH] erofs: mark inodes without acls in erofs_read_inode()

[Gao Xiang <hsiangkao@linux.alibaba.com>]

Similar to commit 91ef18b567da ("ext4: mark inodes without acls in
__ext4_iget()"), the ACL state won't be read when the file owner
performs a lookup, and the RCU fast path for lookups won't work
because the ACL state remains unknown.

If there are no extended attributes, or if the xattr filter
indicates that no ACL xattr is present, call cache_no_acl() directly.

Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
---
 fs/erofs/inode.c |  5 +++++
 fs/erofs/xattr.c | 20 ++++++++++++++++++++
 fs/erofs/xattr.h |  1 +
 3 files changed, 26 insertions(+)

diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index bce98c845a18..2e02d4b466ce 100644
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -137,6 +137,11 @@ static int erofs_read_inode(struct inode *inode)
 		err = -EFSCORRUPTED;
 		goto err_out;
 	}
+
+	if (IS_ENABLED(CONFIG_EROFS_FS_POSIX_ACL) &&
+	    erofs_inode_has_noacl(inode, ptr, ofs))
+		cache_no_acl(inode);
+
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFDIR:
 		vi->dot_omitted = (ifmt >> EROFS_I_DOT_OMITTED_BIT) & 1;
diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
index 512b998bdfff..14d22adc1476 100644
--- a/fs/erofs/xattr.c
+++ b/fs/erofs/xattr.c
@@ -574,4 +574,24 @@ struct posix_acl *erofs_get_acl(struct inode *inode, int type, bool rcu)
 	kfree(value);
 	return acl;
 }
+
+bool erofs_inode_has_noacl(struct inode *inode, void *kaddr, unsigned int ofs)
+{
+	static const unsigned int bitmask =
+		BIT(21) |	/* system.posix_acl_default */
+		BIT(30);	/* system.posix_acl_access */
+	struct erofs_sb_info *sbi = EROFS_I_SB(inode);
+	const struct erofs_xattr_ibody_header *ih = kaddr + ofs;
+
+	if (EROFS_I(inode)->xattr_isize < sizeof(*ih))
+		return true;
+
+	if (erofs_sb_has_xattr_filter(sbi) && !sbi->xattr_filter_reserved &&
+	    !check_add_overflow(ofs, sizeof(*ih), &ofs) &&
+	    ofs <= i_blocksize(inode)) {
+		if ((ih->h_name_filter & bitmask) == bitmask)
+			return true;
+	}
+	return false;
+}
 #endif
diff --git a/fs/erofs/xattr.h b/fs/erofs/xattr.h
index 36f2667afc2d..a3ceefa1554d 100644
--- a/fs/erofs/xattr.h
+++ b/fs/erofs/xattr.h
@@ -30,4 +30,5 @@ struct posix_acl *erofs_get_acl(struct inode *inode, int type, bool rcu);
 #define erofs_get_acl	(NULL)
 #endif
 
+bool erofs_inode_has_noacl(struct inode *inode, void *kaddr, unsigned int ofs);
 #endif
-- 
2.43.5