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| author | Louis Rilling <Louis.Rilling@kerlabs.com> | 2008-06-16 19:00:59 +0200 |
|---|---|---|
| committer | Mark Fasheh <mfasheh@suse.com> | 2008-07-14 13:57:16 -0700 |
| commit | 5301a77da2da1e4c22573e0e8d394a653b8ad9f9 (patch) | |
| tree | c2a6186510c3a4502d923cf3f5d445fa821cb277 | |
| parent | 6f61076406251626be39651d114fac412b1e0c39 (diff) | |
| download | linux-5301a77da2da1e4c22573e0e8d394a653b8ad9f9.tar.gz linux-5301a77da2da1e4c22573e0e8d394a653b8ad9f9.tar.bz2 linux-5301a77da2da1e4c22573e0e8d394a653b8ad9f9.zip | |
configfs: Protect configfs_dirent s_links list mutations
Symlinks to a config_item are listed under its configfs_dirent s_links, but the
list mutations are not protected by any common lock.
This patch uses the configfs_dirent_lock spinlock to add the necessary
protection.
Note: we should also protect the list_empty() test in configfs_detach_prep() but
1/ the lock should not be released immediately because nothing would prevent the
list from being filled after a successful list_empty() test, making the problem
tricky,
2/ this will be solved by the rmdir() vs rename() deadlock bugfix.
Signed-off-by: Louis Rilling <Louis.Rilling@kerlabs.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
| -rw-r--r-- | fs/configfs/dir.c | 5 | ||||
| -rw-r--r-- | fs/configfs/symlink.c | 8 |
2 files changed, 9 insertions, 4 deletions
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 2619f485bc3d..a08e5c2f25e8 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -37,10 +37,11 @@ DECLARE_RWSEM(configfs_rename_sem); /* * Protects mutations of configfs_dirent linkage together with proper i_mutex + * Also protects mutations of symlinks linkage to target configfs_dirent * Mutators of configfs_dirent linkage must *both* have the proper inode locked * and configfs_dirent_lock locked, in that order. - * This allows one to safely traverse configfs_dirent trees without having to - * lock inodes. + * This allows one to safely traverse configfs_dirent trees and symlinks without + * having to lock inodes. */ DEFINE_SPINLOCK(configfs_dirent_lock); diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c index 676c84c416da..faeb4417a10d 100644 --- a/fs/configfs/symlink.c +++ b/fs/configfs/symlink.c @@ -77,12 +77,15 @@ static int create_link(struct config_item *parent_item, sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL); if (sl) { sl->sl_target = config_item_get(item); - /* FIXME: needs a lock, I'd bet */ + spin_lock(&configfs_dirent_lock); list_add(&sl->sl_list, &target_sd->s_links); + spin_unlock(&configfs_dirent_lock); ret = configfs_create_link(sl, parent_item->ci_dentry, dentry); if (ret) { + spin_lock(&configfs_dirent_lock); list_del_init(&sl->sl_list); + spin_unlock(&configfs_dirent_lock); config_item_put(item); kfree(sl); } @@ -186,8 +189,9 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry) type->ct_item_ops->drop_link(parent_item, sl->sl_target); - /* FIXME: Needs lock */ + spin_lock(&configfs_dirent_lock); list_del_init(&sl->sl_list); + spin_unlock(&configfs_dirent_lock); /* Put reference from create_link() */ config_item_put(sl->sl_target); |