commit 4768e9b18dc63719209c68920d4ae52dc49b6161
author Louis Rilling <louis.rilling@kerlabs.com> Mon Jun 23 14:16:17 2008 +0200
committer Mark Fasheh <mfasheh@suse.com> Thu Jul 31 16:21:12 2008 -0700
tree ee9e805c405ea6a6cdf44ba30fd66047bc522b1b
parent dacdd0e04768da1fd2b24a6ee274c582b40d0c5b

[PATCH] configfs: Fix symlink() to a removing item

The rule for configfs symlinks is that symlinks always point to valid
config_items, and prevent the target from being removed. However,
configfs_symlink() only checks that it can grab a reference on the target item,
without ensuring that it remains alive until the symlink is correctly attached.

This patch makes configfs_symlink() fail whenever the target is being removed,
using the CONFIGFS_USET_DROPPING flag set by configfs_detach_prep() and
protected by configfs_dirent_lock.

This patch introduces a similar (weird?) behavior as with mkdir failures making
rmdir fail: if symlink() races with rmdir() of the parent directory (or its
youngest user-created ancestor if parent is a default group) or rmdir() of the
target directory, and then fails in configfs_create(), this can make the racing
rmdir() fail despite the concerned directory having no user-created entry (resp.
no symlink pointing to it or one of its default groups) in the end.
This behavior is fixed in later patches.

Signed-off-by: Louis Rilling <louis.rilling@kerlabs.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.com>