[07/22] ext4: update .. for hash indexed directory

Commit Message

James Simmons July 22, 2019, 1:23 a.m. UTC

Handle special .. case.

Signed-off-by: James Simmons <[e-mail]>
---
 fs/ext4/namei.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

Comments

NeilBrown July 22, 2019, 4:45 a.m. UTC | #1

On Sun, Jul 21 2019, James Simmons wrote:

> Handle special .. case.

This seems to be for adding ".." to a directory.
That happens at "mkdir".  When else would you want to do that?
Is this an on-line fsck-repair thing?

NeilBrown

Patch

diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 91fc7fe..dd64a10 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -2133,6 +2133,73 @@  static int make_indexed_dir(handle_t *handle, struct ext4_filename *fname,
 	return retval;
 }
 
+/* update ".." for hash-indexed directory, split the item "." if necessary */
+static int ext4_update_dotdot(handle_t *handle, struct dentry *dentry,
+			      struct inode *inode)
+{
+	struct inode *dir = dentry->d_parent->d_inode;
+	struct buffer_head *dir_block;
+	struct ext4_dir_entry_2 *de;
+	int len, journal = 0, err = 0;
+
+	if (IS_ERR(handle))
+		return PTR_ERR(handle);
+
+	if (IS_DIRSYNC(dir))
+		handle->h_sync = 1;
+
+	dir_block = ext4_bread(handle, dir, 0, 0);
+	if (IS_ERR(dir_block)) {
+		err = PTR_ERR(dir_block);
+		goto out;
+	}
+
+	de = (struct ext4_dir_entry_2 *)dir_block->b_data;
+	/* the first item must be "." */
+	assert(de->name_len == 1 && de->name[0] == '.');
+	len = le16_to_cpu(de->rec_len);
+	assert(len >= EXT4_DIR_REC_LEN(1));
+	if (len > EXT4_DIR_REC_LEN(1)) {
+		BUFFER_TRACE(dir_block, "get_write_access");
+		err = ext4_journal_get_write_access(handle, dir_block);
+		if (err)
+			goto out_journal;
+
+		journal = 1;
+		de->rec_len = cpu_to_le16(EXT4_DIR_REC_LEN(1));
+	}
+
+	len -= EXT4_DIR_REC_LEN(1);
+	assert(len == 0 || len >= EXT4_DIR_REC_LEN(2));
+	de = (struct ext4_dir_entry_2 *)
+		((char *) de + le16_to_cpu(de->rec_len));
+	if (!journal) {
+		BUFFER_TRACE(dir_block, "get_write_access");
+		err = ext4_journal_get_write_access(handle, dir_block);
+		if (err)
+			goto out_journal;
+	}
+
+	de->inode = cpu_to_le32(inode->i_ino);
+	if (len > 0)
+		de->rec_len = cpu_to_le16(len);
+	else
+		assert(le16_to_cpu(de->rec_len) >= EXT4_DIR_REC_LEN(2));
+	de->name_len = 2;
+	strcpy(de->name, "..");
+	ext4_set_de_type(dir->i_sb, de, S_IFDIR);
+
+out_journal:
+	if (journal) {
+		BUFFER_TRACE(dir_block, "call ext4_handle_dirty_metadata");
+		err = ext4_handle_dirty_dirent_node(handle, dir, dir_block);
+		ext4_mark_inode_dirty(handle, dir);
+	}
+	brelse(dir_block);
+out:
+	return err;
+}
+
 /*
  *	ext4_add_entry()
  *
@@ -2189,6 +2256,9 @@  static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
 	}
 
 	if (is_dx(dir)) {
+		if (dentry->d_name.len == 2 &&
+		    memcmp(dentry->d_name.name, "..", 2) == 0)
+			return ext4_update_dotdot(handle, dentry, inode);
 		retval = ext4_dx_add_entry(handle, &fname, dir, inode);
 		if (!retval || (retval != ERR_BAD_DX_DIR))
 			goto out;