Commit c43be108 authored by Artem Bityutskiy's avatar Artem Bityutskiy
Browse files

UBIFS: do not use inc_link when i_nlink is zero 



This patch changes the 'i_nlink' counter handling in 'ubifs_unlink()',
'ubifs_rmdir()' and 'ubifs_rename()'. In these function  'i_nlink' may become 0,
and if 'ubifs_jnl_update()' failed, we would use 'inc_nlink()' to restore
the previous 'i_nlink' value, which is incorrect from the VFS point of view and
would cause a 'WARN_ON()' (see 'inc_nlink() implementation).

This patches saves the previous 'i_nlink' value in a local variable and uses it
at the error path instead of calling 'inc_nlink()'. We do this only for the
inodes where 'i_nlink' may potentially become zero.

This change has been requested by Al Viro <viro@ZenIV.linux.org.uk>.

Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
parent b06283c7

fs/ubifs/dir.c

+9 −9
Original line number Diff line number Diff line
@@ -566,6 +566,7 @@ static int ubifs_unlink(struct inode *dir, struct dentry *dentry) 
	int sz_change = CALC_DENT_SIZE(dentry->d_name.len);

	int err, budgeted = 1;

	struct ubifs_budget_req req = { .mod_dent = 1, .dirtied_ino = 2 };

	unsigned int saved_nlink = inode->i_nlink;



	/*

	 * Budget request settings: deletion direntry, deletion inode (+1 for
@@ -613,7 +614,7 @@ static int ubifs_unlink(struct inode *dir, struct dentry *dentry) 
out_cancel:

	dir->i_size += sz_change;

	dir_ui->ui_size = dir->i_size;

	inc_nlink(inode);

	set_nlink(inode, saved_nlink);

	unlock_2_inodes(dir, inode);

	if (budgeted)

		ubifs_release_budget(c, &req);
@@ -704,8 +705,7 @@ out_cancel: 
	dir->i_size += sz_change;

	dir_ui->ui_size = dir->i_size;

	inc_nlink(dir);

	inc_nlink(inode);

	inc_nlink(inode);

	set_nlink(inode, 2);

	unlock_2_inodes(dir, inode);

	if (budgeted)

		ubifs_release_budget(c, &req);
@@ -977,6 +977,7 @@ static int ubifs_rename(struct inode *old_dir, struct dentry *old_dentry, 
	struct ubifs_budget_req ino_req = { .dirtied_ino = 1,

			.dirtied_ino_d = ALIGN(old_inode_ui->data_len, 8) };

	struct timespec time;

	unsigned int saved_nlink;



	/*

	 * Budget request settings: deletion direntry, new direntry, removing
@@ -1059,13 +1060,14 @@ static int ubifs_rename(struct inode *old_dir, struct dentry *old_dentry, 
	if (unlink) {

		/*

		 * Directories cannot have hard-links, so if this is a

		 * directory, decrement its @i_nlink twice because an empty

		 * directory has @i_nlink 2.

		 * directory, just clear @i_nlink.

		 */

		saved_nlink = new_inode->i_nlink;

		if (is_dir)

			clear_nlink(new_inode);

		else

			drop_nlink(new_inode);

		new_inode->i_ctime = time;

		drop_nlink(new_inode);

	} else {

		new_dir->i_size += new_sz;

		ubifs_inode(new_dir)->ui_size = new_dir->i_size;
@@ -1102,9 +1104,7 @@ static int ubifs_rename(struct inode *old_dir, struct dentry *old_dentry, 


out_cancel:

	if (unlink) {

		if (is_dir)

			inc_nlink(new_inode);

		inc_nlink(new_inode);

		set_nlink(new_inode, saved_nlink);

	} else {

		new_dir->i_size -= new_sz;

		ubifs_inode(new_dir)->ui_size = new_dir->i_size;

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