[PATCH 04/28] ext4: do not set posix acls on xattr inodes

[Tahsin Erdogan]

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 <tahsin@xxxxxxxxxx>
---
 fs/ext4/ext4.h    | 11 ++++++-----
 fs/ext4/ialloc.c  | 14 +++++++++-----
 fs/ext4/migrate.c |  2 +-
 fs/ext4/xattr.c   |  3 ++-
 4 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 24ef56b4572f..5d5fc0d0e2bc 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2400,16 +2400,17 @@ extern int ext4fs_dirhash(const char *name, int len, struct
 /* 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 *);
diff --git a/fs/ext4/ialloc.c b/fs/ext4/ialloc.c
index e2eb3cc06820..fb1b3df17f6e 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -742,8 +742,9 @@ static int recently_deleted(struct super_block *sb, ext4_group_t group, int ino)
  */
 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;
@@ -1052,6 +1053,7 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 	/* 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;
@@ -1108,9 +1110,11 @@ struct inode *__ext4_new_inode(handle_t *handle, struct inode *dir,
 			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)
diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 364ea4d4a943..cf5181b62df1 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -475,7 +475,7 @@ int ext4_ext_migrate(struct inode *inode)
 	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);
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 09ba0137d529..12210fe87ea3 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -832,7 +832,8 @@ static struct inode *ext4_xattr_inode_create(handle_t *handle,
 	 * 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;
-- 
2.13.0.219.gdb65acc882-goog