Commit 2e81a4ee authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
Browse files

ext4: avoid deadlock when expanding inode size 



When we need to move xattrs into external xattr block, we call
ext4_xattr_block_set() from ext4_expand_extra_isize_ea(). That may end
up calling ext4_mark_inode_dirty() again which will recurse back into
the inode expansion code leading to deadlocks.

Protect from recursion using EXT4_STATE_NO_EXPAND inode flag and move
its management into ext4_expand_extra_isize_ea() since its manipulation
is safe there (due to xattr_sem) from possible races with
ext4_xattr_set_handle() which plays with it as well.

CC: stable@vger.kernel.org   # 4.4.x
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 443a8c41

fs/ext4/inode.c

+0 −2
Original line number Diff line number Diff line
@@ -5466,8 +5466,6 @@ int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode) 
						      sbi->s_want_extra_isize,

						      iloc, handle);

			if (ret) {

				ext4_set_inode_state(inode,

						     EXT4_STATE_NO_EXPAND);

				if (mnt_count !=

					le16_to_cpu(sbi->s_es->s_mnt_count)) {

					ext4_warning(inode->i_sb,

fs/ext4/xattr.c

+13 −6
Original line number Diff line number Diff line
@@ -1358,12 +1358,14 @@ int ext4_expand_extra_isize_ea(struct inode *inode, int new_extra_isize, 
	int isize_diff;	/* How much do we need to grow i_extra_isize */



	down_write(&EXT4_I(inode)->xattr_sem);

	/*

	 * Set EXT4_STATE_NO_EXPAND to avoid recursion when marking inode dirty

	 */

	ext4_set_inode_state(inode, EXT4_STATE_NO_EXPAND);

retry:

	isize_diff = new_extra_isize - EXT4_I(inode)->i_extra_isize;

	if (EXT4_I(inode)->i_extra_isize >= new_extra_isize) {

		up_write(&EXT4_I(inode)->xattr_sem);

		return 0;

	}

	if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)

		goto out;



	header = IHDR(inode, raw_inode);

	entry = IFIRST(header);
@@ -1392,8 +1394,7 @@ retry: 
				(void *)header, total_ino,

				inode->i_sb->s_blocksize);

		EXT4_I(inode)->i_extra_isize = new_extra_isize;

		error = 0;

		goto cleanup;

		goto out;

	}



	/*
@@ -1553,6 +1554,8 @@ retry: 
		kfree(bs);

	}

	brelse(bh);

out:

	ext4_clear_inode_state(inode, EXT4_STATE_NO_EXPAND);

	up_write(&EXT4_I(inode)->xattr_sem);

	return 0;
@@ -1564,6 +1567,10 @@ cleanup: 
	kfree(is);

	kfree(bs);

	brelse(bh);

	/*

	 * We deliberately leave EXT4_STATE_NO_EXPAND set here since inode

	 * size expansion failed.

	 */

	up_write(&EXT4_I(inode)->xattr_sem);

	return error;

}

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