ext4: copy i_flags to inode flags on write

    
Propagate flags such as S_APPEND, S_IMMUTABLE, etc. from i_flags into
ext4-specific i_flags.  Quota code changes these flags on quota files
(to make it harder for sysadmin to screw himself) and these changes were
not correctly propagated into the filesystem.

(This is a forward port patch from ext3)

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Mingming Cao <cmm@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/inode.c

@@ -2583,6 +2583,25 @@ void ext4_set_inode_flags(struct inode *inode)
 		inode->i_flags |= S_DIRSYNC;
 }
 
+/* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
+void ext4_get_inode_flags(struct ext4_inode_info *ei)
+{
+	unsigned int flags = ei->vfs_inode.i_flags;
+
+	ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
+			EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|EXT4_DIRSYNC_FL);
+	if (flags & S_SYNC)
+		ei->i_flags |= EXT4_SYNC_FL;
+	if (flags & S_APPEND)
+		ei->i_flags |= EXT4_APPEND_FL;
+	if (flags & S_IMMUTABLE)
+		ei->i_flags |= EXT4_IMMUTABLE_FL;
+	if (flags & S_NOATIME)
+		ei->i_flags |= EXT4_NOATIME_FL;
+	if (flags & S_DIRSYNC)
+		ei->i_flags |= EXT4_DIRSYNC_FL;
+}
+
 void ext4_read_inode(struct inode * inode)
 {
 	struct ext4_iloc iloc;
@@ -2744,6 +2763,7 @@ static int ext4_do_update_inode(handle_t *handle,
 	if (ei->i_state & EXT4_STATE_NEW)
 		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
 
+	ext4_get_inode_flags(ei);
 	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
 	if(!(test_opt(inode->i_sb, NO_UID32))) {
 		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));

fs/ext4/ioctl.c

@@ -28,6 +28,7 @@ int ext4_ioctl (struct inode * inode, struct file * filp, unsigned int cmd,
 
 	switch (cmd) {
 	case EXT4_IOC_GETFLAGS:
+		ext4_get_inode_flags(ei);
 		flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
 		return put_user(flags, (int __user *) arg);
 	case EXT4_IOC_SETFLAGS: {

include/linux/ext4_fs.h

@@ -868,6 +868,7 @@ extern int ext4_change_inode_journal_flag(struct inode *, int);
 extern int ext4_get_inode_loc(struct inode *, struct ext4_iloc *);
 extern void ext4_truncate (struct inode *);
 extern void ext4_set_inode_flags(struct inode *);
+extern void ext4_get_inode_flags(struct ext4_inode_info *);
 extern void ext4_set_aops(struct inode *inode);
 extern int ext4_writepage_trans_blocks(struct inode *);
 extern int ext4_block_truncate_page(handle_t *handle, struct page *page,