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Commit bd42998a authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ext4: add cross rename support 



Implement RENAME_EXCHANGE flag in renameat2 syscall.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
parent bd1af145

fs/ext4/namei.c

+138 −1
Original line number Diff line number Diff line
@@ -3004,6 +3004,8 @@ struct ext4_renament { 
	struct inode *dir;

	struct dentry *dentry;

	struct inode *inode;

	bool is_dir;

	int dir_nlink_delta;



	/* entry for "dentry" */

	struct buffer_head *bh;
@@ -3135,6 +3137,17 @@ static void ext4_rename_delete(handle_t *handle, struct ext4_renament *ent) 
	}

}



static void ext4_update_dir_count(handle_t *handle, struct ext4_renament *ent)

{

	if (ent->dir_nlink_delta) {

		if (ent->dir_nlink_delta == -1)

			ext4_dec_count(handle, ent->dir);

		else

			ext4_inc_count(handle, ent->dir);

		ext4_mark_inode_dirty(handle, ent->dir);

	}

}



/*

 * Anybody can rename anything with this: the permission checks are left to the

 * higher-level routines.
@@ -3274,13 +3287,137 @@ static int ext4_rename(struct inode *old_dir, struct dentry *old_dentry, 
	return retval;

}



static int ext4_cross_rename(struct inode *old_dir, struct dentry *old_dentry,

			     struct inode *new_dir, struct dentry *new_dentry)

{

	handle_t *handle = NULL;

	struct ext4_renament old = {

		.dir = old_dir,

		.dentry = old_dentry,

		.inode = old_dentry->d_inode,

	};

	struct ext4_renament new = {

		.dir = new_dir,

		.dentry = new_dentry,

		.inode = new_dentry->d_inode,

	};

	u8 new_file_type;

	int retval;



	dquot_initialize(old.dir);

	dquot_initialize(new.dir);



	old.bh = ext4_find_entry(old.dir, &old.dentry->d_name,

				 &old.de, &old.inlined);

	/*

	 *  Check for inode number is _not_ due to possible IO errors.

	 *  We might rmdir the source, keep it as pwd of some process

	 *  and merrily kill the link to whatever was created under the

	 *  same name. Goodbye sticky bit ;-<

	 */

	retval = -ENOENT;

	if (!old.bh || le32_to_cpu(old.de->inode) != old.inode->i_ino)

		goto end_rename;



	new.bh = ext4_find_entry(new.dir, &new.dentry->d_name,

				 &new.de, &new.inlined);



	/* RENAME_EXCHANGE case: old *and* new must both exist */

	if (!new.bh || le32_to_cpu(new.de->inode) != new.inode->i_ino)

		goto end_rename;



	handle = ext4_journal_start(old.dir, EXT4_HT_DIR,

		(2 * EXT4_DATA_TRANS_BLOCKS(old.dir->i_sb) +

		 2 * EXT4_INDEX_EXTRA_TRANS_BLOCKS + 2));

	if (IS_ERR(handle))

		return PTR_ERR(handle);



	if (IS_DIRSYNC(old.dir) || IS_DIRSYNC(new.dir))

		ext4_handle_sync(handle);



	if (S_ISDIR(old.inode->i_mode)) {

		old.is_dir = true;

		retval = ext4_rename_dir_prepare(handle, &old);

		if (retval)

			goto end_rename;

	}

	if (S_ISDIR(new.inode->i_mode)) {

		new.is_dir = true;

		retval = ext4_rename_dir_prepare(handle, &new);

		if (retval)

			goto end_rename;

	}



	/*

	 * Other than the special case of overwriting a directory, parents'

	 * nlink only needs to be modified if this is a cross directory rename.

	 */

	if (old.dir != new.dir && old.is_dir != new.is_dir) {

		old.dir_nlink_delta = old.is_dir ? -1 : 1;

		new.dir_nlink_delta = -old.dir_nlink_delta;

		retval = -EMLINK;

		if ((old.dir_nlink_delta > 0 && EXT4_DIR_LINK_MAX(old.dir)) ||

		    (new.dir_nlink_delta > 0 && EXT4_DIR_LINK_MAX(new.dir)))

			goto end_rename;

	}



	new_file_type = new.de->file_type;

	retval = ext4_setent(handle, &new, old.inode->i_ino, old.de->file_type);

	if (retval)

		goto end_rename;



	retval = ext4_setent(handle, &old, new.inode->i_ino, new_file_type);

	if (retval)

		goto end_rename;



	/*

	 * Like most other Unix systems, set the ctime for inodes on a

	 * rename.

	 */

	old.inode->i_ctime = ext4_current_time(old.inode);

	new.inode->i_ctime = ext4_current_time(new.inode);

	ext4_mark_inode_dirty(handle, old.inode);

	ext4_mark_inode_dirty(handle, new.inode);



	if (old.dir_bh) {

		retval = ext4_rename_dir_finish(handle, &old, new.dir->i_ino);

		if (retval)

			goto end_rename;

	}

	if (new.dir_bh) {

		retval = ext4_rename_dir_finish(handle, &new, old.dir->i_ino);

		if (retval)

			goto end_rename;

	}

	ext4_update_dir_count(handle, &old);

	ext4_update_dir_count(handle, &new);

	retval = 0;



end_rename:

	brelse(old.dir_bh);

	brelse(new.dir_bh);

	brelse(old.bh);

	brelse(new.bh);

	if (handle)

		ext4_journal_stop(handle);

	return retval;

}



static int ext4_rename2(struct inode *old_dir, struct dentry *old_dentry,

			struct inode *new_dir, struct dentry *new_dentry,

			unsigned int flags)

{

	if (flags & ~RENAME_NOREPLACE)

	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE))

		return -EINVAL;



	if (flags & RENAME_EXCHANGE) {

		return ext4_cross_rename(old_dir, old_dentry,

					 new_dir, new_dentry);

	}

	/*

	 * Existence checking was done by the VFS, otherwise "RENAME_NOREPLACE"

	 * is equivalent to regular rename.

	 */

	return ext4_rename(old_dir, old_dentry, new_dir, new_dentry);

}