[PATCH] ext3: support for EA in inode

1) intent of the patch is to get possibility to store EAs in the body of large
   inode. it saves space and improves performance in some cases

2) the patch is quite simple: it works the same way original xattr does, but
   using other storage (inode body). body has priority over separate block.
   original routines (ext3_xattr_get, ext3_xattr_list, ext3_xattr_set) are
   renamed to ext3_xattr_block_*. new routines that handle inode storate are
   added (ext3_xattr_ibody_get, ext3_xattr_ibody_list, ext3_xattr_ibody_set).
   routines ext3_xattr_get, ext3_xattr_list and ext3_xattr_set allow user to
   accesss both the storages transparently

3) the change makes sense on filesystem with inode size >= 256 bytes only.
   2.4 kernels don't support such a filesystems, AFAIK. 2.6 kernels do support
   and ignore EAs stored in a body w/o the patch

4) debugfs and e2fsck need to be patched to deal with EAs in inode
   the patch will be sent later

5) testing results:
	a) Andrew Samba Master (tridge) has done successful tests
	b) we've been using ea-in-inode feature in Lustre for many months
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Signed-off-by: Alex Tomas <alex@clusterfs.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/ext3/ialloc.c

@@ -596,6 +596,11 @@ struct inode *ext3_new_inode(handle_t *handle, struct inode * dir, int mode)
 	spin_unlock(&sbi->s_next_gen_lock);
 
 	ei->i_state = EXT3_STATE_NEW;
+	if (EXT3_INODE_SIZE(inode->i_sb) > EXT3_GOOD_OLD_INODE_SIZE) {
+		ei->i_extra_isize = sizeof(__u16)	/* i_extra_isize */
+				+ sizeof(__u16);	/* i_pad1 */
+	} else
+		ei->i_extra_isize = 0;
 
 	ret = inode;
 	if(DQUOT_ALLOC_INODE(inode)) {

fs/ext3/inode.c

@@ -2275,7 +2275,7 @@ static unsigned long ext3_get_inode_block(struct super_block *sb,
  * trying to determine the inode's location on-disk and no read need be
  * performed.
  */
-static int ext3_get_inode_loc(struct inode *inode,
+int ext3_get_inode_loc(struct inode *inode,
 				struct ext3_iloc *iloc, int in_mem)
 {
 	unsigned long block;
@@ -2483,6 +2483,11 @@ void ext3_read_inode(struct inode * inode)
 		ei->i_data[block] = raw_inode->i_block[block];
 	INIT_LIST_HEAD(&ei->i_orphan);
 
+	if (EXT3_INODE_SIZE(inode->i_sb) > EXT3_GOOD_OLD_INODE_SIZE)
+		ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
+	else
+		ei->i_extra_isize = 0;
+
 	if (S_ISREG(inode->i_mode)) {
 		inode->i_op = &ext3_file_inode_operations;
 		inode->i_fop = &ext3_file_operations;
@@ -2618,6 +2623,9 @@ static int ext3_do_update_inode(handle_t *handle,
 	} else for (block = 0; block < EXT3_N_BLOCKS; block++)
 		raw_inode->i_block[block] = ei->i_data[block];
 
+	if (EXT3_INODE_SIZE(inode->i_sb) > EXT3_GOOD_OLD_INODE_SIZE)
+		raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
+
 	BUFFER_TRACE(bh, "call ext3_journal_dirty_metadata");
 	rc = ext3_journal_dirty_metadata(handle, bh);
 	if (!err)

fs/ext3/xattr.h

@@ -67,7 +67,8 @@ extern ssize_t ext3_listxattr(struct dentry *, char *, size_t);
 extern int ext3_xattr_get(struct inode *, int, const char *, void *, size_t);
 extern int ext3_xattr_list(struct inode *, char *, size_t);
 extern int ext3_xattr_set(struct inode *, int, const char *, const void *, size_t, int);
-extern int ext3_xattr_set_handle(handle_t *, struct inode *, int, const char *, const void *, size_t, int);
+extern int ext3_xattr_set_handle(handle_t *, struct inode *, int, const char *,const void *,size_t,int);
+extern int ext3_xattr_block_set(handle_t *, struct inode *, int, const char *,const void *,size_t,int);
 
 extern void ext3_xattr_delete_inode(handle_t *, struct inode *);
 extern void ext3_xattr_put_super(struct super_block *);

include/linux/ext3_fs.h

@@ -293,6 +293,8 @@ struct ext3_inode {
 			__u32	m_i_reserved2[2];
 		} masix2;
 	} osd2;				/* OS dependent 2 */
+	__u16	i_extra_isize;
+	__u16	i_pad1;
 };
 
 #define i_size_high	i_dir_acl
@@ -755,6 +757,7 @@ extern int ext3_forget(handle_t *, int, struct inode *, struct buffer_head *, in
 extern struct buffer_head * ext3_getblk (handle_t *, struct inode *, long, int, int *);
 extern struct buffer_head * ext3_bread (handle_t *, struct inode *, int, int, int *);
 
+extern int ext3_get_inode_loc(struct inode *, struct ext3_iloc *, int);
 extern void ext3_read_inode (struct inode *);
 extern int  ext3_write_inode (struct inode *, int);
 extern int  ext3_setattr (struct dentry *, struct iattr *);

include/linux/ext3_fs_i.h

@@ -113,6 +113,9 @@ struct ext3_inode_info {
 	 */
 	loff_t	i_disksize;
 
+	/* on-disk additional length */
+	__u16 i_extra_isize;
+
 	/*
 	 * truncate_sem is for serialising ext3_truncate() against
 	 * ext3_getblock().  In the 2.4 ext2 design, great chunks of inode's