bcachefs: Make bch2_setattr_nonsize() fully atomic

updating i_mode may also require an update to the acl - the inode update
and acl xattr updates are now atomic.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

3 files changed, 123 insertions, 27 deletions

diff --git a/fs/bcachefs/acl.c b/fs/bcachefs/acl.c
index 3f03fed2947f..de4a96f4d7d8 100644
--- a/fs/bcachefs/acl.c
+++ b/fs/bcachefs/acl.c
@@ -355,4 +355,47 @@ err:
 	return ret;
 }
 
+int bch2_acl_chmod(struct btree_trans *trans,
+		   struct bch_inode_info *inode,
+		   umode_t mode,
+		   struct posix_acl **new_acl)
+{
+	struct btree_iter *iter;
+	struct bkey_s_c_xattr xattr;
+	struct bkey_i_xattr *new;
+	struct posix_acl *acl;
+	int ret = 0;
+
+	iter = bch2_hash_lookup(trans, bch2_xattr_hash_desc,
+			&inode->ei_str_hash, inode->v.i_ino,
+			&X_SEARCH(BCH_XATTR_INDEX_POSIX_ACL_ACCESS, "", 0),
+			BTREE_ITER_INTENT);
+	if (IS_ERR(iter))
+		return PTR_ERR(iter) != -ENOENT ? PTR_ERR(iter) : 0;
+
+	xattr = bkey_s_c_to_xattr(bch2_btree_iter_peek_slot(iter));
+
+	acl = bch2_acl_from_disk(xattr_val(xattr.v),
+			le16_to_cpu(xattr.v->x_val_len));
+	if (IS_ERR_OR_NULL(acl))
+		return PTR_ERR(acl);
+
+	ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
+	if (ret)
+		goto err;
+
+	new = bch2_acl_to_xattr(trans, acl, ACL_TYPE_ACCESS);
+	if (IS_ERR(new)) {
+		ret = PTR_ERR(new);
+		goto err;
+	}
+
+	bch2_trans_update(trans, iter, &new->k_i, 0);
+	*new_acl = acl;
+	acl = NULL;
+err:
+	kfree(acl);
+	return ret;
+}
+
 #endif /* CONFIG_BCACHEFS_POSIX_ACL */
diff --git a/fs/bcachefs/acl.h b/fs/bcachefs/acl.h
index 2e5ab78c779a..1e15245e8040 100644
--- a/fs/bcachefs/acl.h
+++ b/fs/bcachefs/acl.h
@@ -3,6 +3,7 @@
 
 struct bch_inode_unpacked;
 struct bch_hash_info;
+struct bch_inode_info;
 struct posix_acl;
 
 #ifdef CONFIG_BCACHEFS_POSIX_ACL
@@ -32,6 +33,8 @@ int bch2_set_acl_trans(struct btree_trans *,
 		       struct posix_acl *, int);
 int __bch2_set_acl(struct inode *, struct posix_acl *, int);
 int bch2_set_acl(struct inode *, struct posix_acl *, int);
+int bch2_acl_chmod(struct btree_trans *, struct bch_inode_info *,
+		   umode_t, struct posix_acl **);
 
 #else
 
@@ -48,6 +51,14 @@ static inline int __bch2_set_acl(struct inode *inode, struct posix_acl *acl, int
 	return 0;
 }
 
+static inline int bch2_acl_chmod(struct btree_trans *trans,
+				 struct bch_inode_info *inode,
+				 umode_t mode,
+				 struct posix_acl **new_acl)
+{
+	return 0;
+}
+
 #endif /* CONFIG_BCACHEFS_POSIX_ACL */
 
 #endif /* _BCACHEFS_ACL_H */
diff --git a/fs/bcachefs/fs.c b/fs/bcachefs/fs.c
index c255e3892e11..de7f44062d45 100644
--- a/fs/bcachefs/fs.c
+++ b/fs/bcachefs/fs.c
@@ -83,6 +83,9 @@ void bch2_inode_update_after_write(struct bch_fs *c,
 	set_nlink(&inode->v, bi->bi_flags & BCH_INODE_UNLINKED
 		  ? 0
 		  : bi->bi_nlink + nlink_bias(inode->v.i_mode));
+	i_uid_write(&inode->v, bi->bi_uid);
+	i_gid_write(&inode->v, bi->bi_gid);
+	inode->v.i_mode	= bi->bi_mode;
 
 	if (fields & ATTR_ATIME)
 		inode->v.i_atime = bch2_time_to_timespec(c, bi->bi_atime);
@@ -101,7 +104,6 @@ int __must_check bch2_write_inode_trans(struct btree_trans *trans,
 				inode_set_fn set,
 				void *p)
 {
-	struct bch_fs *c = trans->c;
 	struct btree_iter *iter;
 	struct bkey_inode_buf *inode_p;
 	struct bkey_s_c k;
@@ -134,15 +136,6 @@ int __must_check bch2_write_inode_trans(struct btree_trans *trans,
 	       !(inode_u->bi_flags & BCH_INODE_I_SIZE_DIRTY) &&
 	       inode_u->bi_size > i_size_read(&inode->v));
 
-	inode_u->bi_mode	= inode->v.i_mode;
-	inode_u->bi_uid		= i_uid_read(&inode->v);
-	inode_u->bi_gid		= i_gid_read(&inode->v);
-	inode_u->bi_project	= inode->ei_qid.q[QTYP_PRJ];
-	inode_u->bi_dev		= inode->v.i_rdev;
-	inode_u->bi_atime	= timespec_to_bch2_time(c, inode->v.i_atime);
-	inode_u->bi_mtime	= timespec_to_bch2_time(c, inode->v.i_mtime);
-	inode_u->bi_ctime	= timespec_to_bch2_time(c, inode->v.i_ctime);
-
 	if (set) {
 		ret = set(inode, inode_u, p);
 		if (ret)
@@ -191,12 +184,6 @@ retry:
 	return ret < 0 ? ret : 0;
 }
 
-int __must_check bch2_write_inode(struct bch_fs *c,
-				  struct bch_inode_info *inode)
-{
-	return __bch2_write_inode(c, inode, NULL, NULL, 0);
-}
-
 static struct inode *bch2_vfs_inode_get(struct bch_fs *c, u64 inum)
 {
 	struct bch_inode_unpacked inode_u;
@@ -848,10 +835,48 @@ err:
 	return ret;
 }
 
+static int inode_update_for_setattr_fn(struct bch_inode_info *inode,
+				       struct bch_inode_unpacked *bi,
+				       void *p)
+{
+	struct bch_fs *c = inode->v.i_sb->s_fs_info;
+	struct iattr *attr = p;
+	unsigned int ia_valid = attr->ia_valid;
+
+	if (ia_valid & ATTR_UID)
+		bi->bi_uid = from_kuid(inode->v.i_sb->s_user_ns, attr->ia_uid);
+	if (ia_valid & ATTR_GID)
+		bi->bi_gid = from_kgid(inode->v.i_sb->s_user_ns, attr->ia_gid);
+
+	if (ia_valid & ATTR_ATIME)
+		bi->bi_atime = timespec_to_bch2_time(c, attr->ia_atime);
+	if (ia_valid & ATTR_MTIME)
+		bi->bi_mtime = timespec_to_bch2_time(c, attr->ia_mtime);
+	if (ia_valid & ATTR_CTIME)
+		bi->bi_ctime = timespec_to_bch2_time(c, attr->ia_ctime);
+
+	if (ia_valid & ATTR_MODE) {
+		umode_t mode = attr->ia_mode;
+		kgid_t gid = ia_valid & ATTR_GID
+			? attr->ia_gid
+			: inode->v.i_gid;
+
+		if (!in_group_p(gid) &&
+		    !capable_wrt_inode_uidgid(&inode->v, CAP_FSETID))
+			mode &= ~S_ISGID;
+		bi->bi_mode = mode;
+	}
+
+	return 0;
+}
+
 static int bch2_setattr_nonsize(struct bch_inode_info *inode, struct iattr *iattr)
 {
 	struct bch_fs *c = inode->v.i_sb->s_fs_info;
 	struct bch_qid qid = inode->ei_qid;
+	struct btree_trans trans;
+	struct bch_inode_unpacked inode_u;
+	struct posix_acl *acl = NULL;
 	unsigned qtypes = 0;
 	int ret;
 
@@ -876,18 +901,38 @@ static int bch2_setattr_nonsize(struct bch_inode_info *inode, struct iattr *iatt
 					  inode->v.i_blocks +
 					  inode->ei_quota_reserved);
 		if (ret)
-			goto out_unlock;
+			goto err;
 	}
 
-	setattr_copy(&inode->v, iattr);
+	bch2_trans_init(&trans, c);
+retry:
+	bch2_trans_begin(&trans);
+	kfree(acl);
+	acl = NULL;
 
-	ret = bch2_write_inode(c, inode);
-out_unlock:
-	mutex_unlock(&inode->ei_update_lock);
+	ret = bch2_write_inode_trans(&trans, inode, &inode_u,
+				inode_update_for_setattr_fn, iattr) ?:
+		(iattr->ia_valid & ATTR_MODE
+		 ? bch2_acl_chmod(&trans, inode, iattr->ia_mode, &acl)
+		 : 0) ?:
+		bch2_trans_commit(&trans, NULL, NULL,
+				  &inode->ei_journal_seq,
+				  BTREE_INSERT_ATOMIC|
+				  BTREE_INSERT_NOUNLOCK|
+				  BTREE_INSERT_NOFAIL);
+	if (ret == -EINTR)
+		goto retry;
+	if (unlikely(ret))
+		goto err_trans;
 
-	if (!ret &&
-	    iattr->ia_valid & ATTR_MODE)
-		ret = posix_acl_chmod(&inode->v, inode->v.i_mode);
+	bch2_inode_update_after_write(c, inode, &inode_u, iattr->ia_valid);
+
+	if (acl)
+		set_cached_acl(&inode->v, ACL_TYPE_ACCESS, acl);
+err_trans:
+	bch2_trans_exit(&trans);
+err:
+	mutex_unlock(&inode->ei_update_lock);
 
 	return ret;
 }
@@ -1201,9 +1246,6 @@ static void bch2_vfs_inode_init(struct bch_fs *c,
 {
 	bch2_inode_update_after_write(c, inode, bi, ~0);
 
-	inode->v.i_mode		= bi->bi_mode;
-	i_uid_write(&inode->v, bi->bi_uid);
-	i_gid_write(&inode->v, bi->bi_gid);
 	inode->v.i_blocks	= bi->bi_sectors;
 	inode->v.i_ino		= bi->bi_inum;
 	inode->v.i_rdev		= bi->bi_dev;