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>
diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 5a5c55d..bb003dc 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -104,6 +104,7 @@
{
struct super_block *sb = inode->i_sb;
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ struct ext4_inode_info *ei = EXT4_I(inode);
struct vfsmount *mnt = filp->f_path.mnt;
struct path path;
char buf[64], *cp;
@@ -127,6 +128,27 @@
ext4_mark_super_dirty(sb);
}
}
+ /*
+ * Set up the jbd2_inode if we are opening the inode for
+ * writing and the journal is present
+ */
+ if (sbi->s_journal && !ei->jinode && (filp->f_mode & FMODE_WRITE)) {
+ struct jbd2_inode *jinode = jbd2_alloc_inode(GFP_KERNEL);
+
+ spin_lock(&inode->i_lock);
+ if (!ei->jinode) {
+ if (!jinode) {
+ spin_unlock(&inode->i_lock);
+ return -ENOMEM;
+ }
+ ei->jinode = jinode;
+ jbd2_journal_init_jbd_inode(ei->jinode, inode);
+ jinode = NULL;
+ }
+ spin_unlock(&inode->i_lock);
+ if (unlikely(jinode != NULL))
+ jbd2_free_inode(jinode);
+ }
return dquot_file_open(inode, filp);
}