ext4: do not set posix acls on xattr inodes

We don't need acls on xattr inodes because they are not directly
accessible from user mode.

Besides lockdep complains about recursive locking of xattr_sem as seen
below.

=============================================
[ INFO: possible recursive locking detected ]
4.11.0-rc8+ #402 Not tainted
---------------------------------------------
python/1894 is trying to acquire lock:
(&ei->xattr_sem){++++..}, at: [<ffffffff804878a6>] ext4_xattr_get+0x66/0x270

but task is already holding lock:
(&ei->xattr_sem){++++..}, at: [<ffffffff80489500>] ext4_xattr_set_handle+0xa0/0x5d0

other info that might help us debug this:
Possible unsafe locking scenario:

CPU0
----
lock(&ei->xattr_sem);
lock(&ei->xattr_sem);

*** DEADLOCK ***

May be due to missing lock nesting notation

3 locks held by python/1894:
#0: (sb_writers#10){.+.+.+}, at: [<ffffffff803d829f>] mnt_want_write+0x1f/0x50
#1: (&sb->s_type->i_mutex_key#15){+.+...}, at: [<ffffffff803dda27>] vfs_setxattr+0x57/0xb0
#2: (&ei->xattr_sem){++++..}, at: [<ffffffff80489500>] ext4_xattr_set_handle+0xa0/0x5d0

stack backtrace:
CPU: 0 PID: 1894 Comm: python Not tainted 4.11.0-rc8+ #402
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
dump_stack+0x67/0x99
__lock_acquire+0x5f3/0x1830
lock_acquire+0xb5/0x1d0
down_read+0x2f/0x60
ext4_xattr_get+0x66/0x270
ext4_get_acl+0x43/0x1e0
get_acl+0x72/0xf0
posix_acl_create+0x5e/0x170
ext4_init_acl+0x21/0xc0
__ext4_new_inode+0xffd/0x16b0
ext4_xattr_set_entry+0x5ea/0xb70
ext4_xattr_block_set+0x1b5/0x970
ext4_xattr_set_handle+0x351/0x5d0
ext4_xattr_set+0x124/0x180
ext4_xattr_user_set+0x34/0x40
__vfs_setxattr+0x66/0x80
__vfs_setxattr_noperm+0x69/0x1c0
vfs_setxattr+0xa2/0xb0
setxattr+0x129/0x160
path_setxattr+0x87/0xb0
SyS_setxattr+0xf/0x20
entry_SYSCALL_64_fastpath+0x18/0xad

Signed-off-by: Tahsin Erdogan <[e-mail]>
Signed-off-by: Theodore Ts'o <[e-mail]>

fs/ext4/ext4.h

···
 /* ialloc.c */
 extern struct inode *__ext4_new_inode(handle_t *, struct inode *, umode_t,
 				      const struct qstr *qstr, __u32 goal,
-				      uid_t *owner, int handle_type,
-				      unsigned int line_no, int nblocks);
+				      uid_t *owner, __u32 i_flags,
+				      int handle_type, unsigned int line_no,
+				      int nblocks);
 
-#define ext4_new_inode(handle, dir, mode, qstr, goal, owner) \
+#define ext4_new_inode(handle, dir, mode, qstr, goal, owner, i_flags) \
 	__ext4_new_inode((handle), (dir), (mode), (qstr), (goal), (owner), \
-			 0, 0, 0)
+			 i_flags, 0, 0, 0)
 #define ext4_new_inode_start_handle(dir, mode, qstr, goal, owner, \
 				    type, nblocks)		    \
 	__ext4_new_inode(NULL, (dir), (mode), (qstr), (goal), (owner), \
-			 (type), __LINE__, (nblocks))
+			 0, (type), __LINE__, (nblocks))
 
 
 extern void ext4_free_inode(handle_t *, struct inode *);

fs/ext4/ialloc.c

···
  */
 struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 			       umode_t mode, const struct qstr *qstr,
-			       __u32 goal, uid_t *owner, int handle_type,
-			       unsigned int line_no, int nblocks)
+			       __u32 goal, uid_t *owner, __u32 i_flags,
+			       int handle_type, unsigned int line_no,
+			       int nblocks)
 {
 	struct super_block *sb;
 	struct buffer_head *inode_bitmap_bh = NULL;
···
 	/* Don't inherit extent flag from directory, amongst others. */
 	ei->i_flags =
 		ext4_mask_flags(mode, EXT4_I(dir)->i_flags & EXT4_FL_INHERITED);
+	ei->i_flags |= i_flags;
 	ei->i_file_acl = 0;
 	ei->i_dtime = 0;
 	ei->i_block_group = group;
···
 			goto fail_free_drop;
 	}
 
-	err = ext4_init_acl(handle, inode, dir);
-	if (err)
-		goto fail_free_drop;
+	if (!(ei->i_flags & EXT4_EA_INODE_FL)) {
+		err = ext4_init_acl(handle, inode, dir);
+		if (err)
+			goto fail_free_drop;
+	}
 
 	err = ext4_init_security(handle, inode, dir, qstr);
 	if (err)

fs/ext4/migrate.c

···
 	owner[0] = i_uid_read(inode);
 	owner[1] = i_gid_read(inode);
 	tmp_inode = ext4_new_inode(handle, d_inode(inode->i_sb->s_root),
-				   S_IFREG, NULL, goal, owner);
+				   S_IFREG, NULL, goal, owner, 0);
 	if (IS_ERR(tmp_inode)) {
 		retval = PTR_ERR(tmp_inode);
 		ext4_journal_stop(handle);

fs/ext4/xattr.c

···
 	 * in the same group, or nearby one.
 	 */
 	ea_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
-				  S_IFREG | 0600, NULL, inode->i_ino + 1, NULL);
+				  S_IFREG | 0600, NULL, inode->i_ino + 1, NULL,
+				  EXT4_EA_INODE_FL);
 	if (!IS_ERR(ea_inode)) {
 		ea_inode->i_op = &ext4_file_inode_operations;
 		ea_inode->i_fop = &ext4_file_operations;