ext4: dynamically allocate the jbd2_inode in ext4_inode_info as necessary

Replace the jbd2_inode structure (which is 48 bytes) with a pointer
and only allocate the jbd2_inode when it is needed --- that is, when
the file system has a journal present and the inode has been opened
for writing.  This allows us to further slim down the ext4_inode_info
structure.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 7 insertions, 9 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index f5960d673e4e..1cd4326c530b 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -818,12 +818,6 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
         memset(&ei->i_cached_extent, 0, sizeof(struct ext4_ext_cache));
         INIT_LIST_HEAD(&ei->i_prealloc_list);
         spin_lock_init(&ei->i_prealloc_lock);
-        /*
-         * Note:  We can be called before EXT4_SB(sb)->s_journal is set,
-         * therefore it can be null here.  Don't check it, just initialize
-         * jinode.
-         */
-        jbd2_journal_init_jbd_inode(&ei->jinode, &ei->vfs_inode);
         ei->i_reserved_data_blocks = 0;
         ei->i_reserved_meta_blocks = 0;
         ei->i_allocated_meta_blocks = 0;
@@ -832,6 +826,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
 #ifdef CONFIG_QUOTA
         ei->i_reserved_quota = 0;
 #endif
+        ei->jinode = NULL;
         INIT_LIST_HEAD(&ei->i_completed_io_list);
         spin_lock_init(&ei->i_completed_io_lock);
         ei->cur_aio_dio = NULL;
@@ -900,9 +895,12 @@ void ext4_clear_inode(struct inode *inode)
         end_writeback(inode);
         dquot_drop(inode);
         ext4_discard_preallocations(inode);
-        if (EXT4_JOURNAL(inode))
-                jbd2_journal_release_jbd_inode(EXT4_SB(inode->i_sb)->s_journal,
-                                       &EXT4_I(inode)->jinode);
+        if (EXT4_I(inode)->jinode) {
+                jbd2_journal_release_jbd_inode(EXT4_JOURNAL(inode),
+                                               EXT4_I(inode)->jinode);
+                jbd2_free_inode(EXT4_I(inode)->jinode);
+                EXT4_I(inode)->jinode = NULL;
+        }
 }
 
 static inline void ext4_show_quota_options(struct seq_file *seq,