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authorLouis Rilling <louis.rilling@kerlabs.com>2008-06-23 14:16:17 +0200
committerMark Fasheh <mfasheh@suse.com>2008-07-31 16:21:12 -0700
commit4768e9b18dc63719209c68920d4ae52dc49b6161 (patch)
treeee9e805c405ea6a6cdf44ba30fd66047bc522b1b /fs/configfs/symlink.c
parentdacdd0e04768da1fd2b24a6ee274c582b40d0c5b (diff)
downloadop-kernel-dev-4768e9b18dc63719209c68920d4ae52dc49b6161.zip
op-kernel-dev-4768e9b18dc63719209c68920d4ae52dc49b6161.tar.gz
[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>
Diffstat (limited to 'fs/configfs/symlink.c')
-rw-r--r--fs/configfs/symlink.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c
index 0004d18..c12801a 100644
--- a/fs/configfs/symlink.c
+++ b/fs/configfs/symlink.c
@@ -78,6 +78,12 @@ static int create_link(struct config_item *parent_item,
if (sl) {
sl->sl_target = config_item_get(item);
spin_lock(&configfs_dirent_lock);
+ if (target_sd->s_type & CONFIGFS_USET_DROPPING) {
+ spin_unlock(&configfs_dirent_lock);
+ config_item_put(item);
+ kfree(sl);
+ return -ENOENT;
+ }
list_add(&sl->sl_list, &target_sd->s_links);
spin_unlock(&configfs_dirent_lock);
ret = configfs_create_link(sl, parent_item->ci_dentry,
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