Unionfs: Added several BUG_ONs to assert dentry validity

This should help catch races between the VFS and the branch-management code.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>

diff --git a/fs/unionfs/inode.c b/fs/unionfs/inode.c
index 5c452b6d87d59f9be54c681d04ab1dc0e73bc1c8..97dad8cccc1279a5717aeed972374ab701f718b1 100644 (file)
--- a/fs/unionfs/inode.c
+++ b/fs/unionfs/inode.c
@@ -249,6 +249,9 @@ static int unionfs_link(struct dentry *old_dentry, struct inode *dir,
        struct dentry *whiteout_dentry;
        char *name = NULL;
 
+       BUG_ON(!is_valid_dentry(new_dentry));
+       BUG_ON(!is_valid_dentry(old_dentry));
+
        double_lock_dentry(new_dentry, old_dentry);
 
        hidden_new_dentry = unionfs_lower_dentry(new_dentry);
@@ -373,6 +376,8 @@ static int unionfs_symlink(struct inode *dir, struct dentry *dentry,
        int bindex = 0, bstart;
        char *name = NULL;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
 
        /* We start out in the leftmost branch. */
@@ -495,6 +500,8 @@ static int unionfs_mkdir(struct inode *parent, struct dentry *dentry, int mode)
        int whiteout_unlinked = 0;
        struct sioq_args args;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
        bstart = dbstart(dentry);
 
@@ -622,6 +629,8 @@ static int unionfs_mknod(struct inode *dir, struct dentry *dentry, int mode,
        char *name = NULL;
        int whiteout_unlinked = 0;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
        bstart = dbstart(dentry);
 
@@ -724,6 +733,8 @@ static int unionfs_readlink(struct dentry *dentry, char __user * buf,
        int err;
        struct dentry *hidden_dentry;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
        hidden_dentry = unionfs_lower_dentry(dentry);
 
@@ -749,6 +760,8 @@ static void *unionfs_follow_link(struct dentry *dentry, struct nameidata *nd)
        int len = PAGE_SIZE, err;
        mm_segment_t old_fs;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        /* This is freed by the put_link method assuming a successful call. */
        buf = kmalloc(len, GFP_KERNEL);
        if (!buf) {
@@ -908,6 +921,8 @@ static int unionfs_setattr(struct dentry *dentry, struct iattr *ia)
        int i;
        int copyup = 0;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
        bstart = dbstart(dentry);
        bend = dbend(dentry);

diff --git a/fs/unionfs/rename.c b/fs/unionfs/rename.c
index c9aa0400a3fca2200d29593f2e19d908422039f5..00444929c7085db555d7225e7d4e3c46f4342ebe 100644 (file)
--- a/fs/unionfs/rename.c
+++ b/fs/unionfs/rename.c
@@ -379,6 +379,9 @@ int unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
        int err = 0;
        struct dentry *wh_dentry;
 
+       BUG_ON(!is_valid_dentry(old_dentry));
+       BUG_ON(!is_valid_dentry(new_dentry));
+
        double_lock_dentry(old_dentry, new_dentry);
 
        if (!S_ISDIR(old_dentry->d_inode->i_mode))

diff --git a/fs/unionfs/super.c b/fs/unionfs/super.c
index 5d1190887924cfd7184b6e4a6c877dc29b7704ab..ec5706b115f1d548aab36ea4c142c4276356e9e5 100644 (file)
--- a/fs/unionfs/super.c
+++ b/fs/unionfs/super.c
@@ -129,6 +129,8 @@ static int unionfs_statfs(struct dentry *dentry, struct kstatfs *buf)
        int err = 0;
        struct super_block *sb, *hidden_sb;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        sb = dentry->d_sb;
 
        unionfs_read_lock(sb);

diff --git a/fs/unionfs/union.h b/fs/unionfs/union.h
index faaa87e7640b5a3489670abee3a5f6c3570072ec..b6fa0a2d72fe19b8a6034d40ba29fe09d2a35c50 100644 (file)
--- a/fs/unionfs/union.h
+++ b/fs/unionfs/union.h
@@ -399,6 +399,19 @@ static inline int is_robranch(const struct dentry *dentry)
        return is_robranch_idx(dentry, index);
 }
 
+/*
+ * Check if dentry is valid or not, as per our generation numbers.
+ * @dentry: dentry to check.
+ * Returns 1 (valid) or 0 (invalid/stale).
+ */
+static inline int is_valid_dentry(struct dentry *dentry)
+{
+       BUG_ON(!UNIONFS_D(dentry));
+       BUG_ON(!UNIONFS_SB(dentry->d_sb));
+       return (atomic_read(&UNIONFS_D(dentry)->generation) ==
+               atomic_read(&UNIONFS_SB(dentry->d_sb)->generation));
+}
+
 /* What do we use for whiteouts. */
 #define UNIONFS_WHPFX ".wh."
 #define UNIONFS_WHLEN 4

diff --git a/fs/unionfs/unlink.c b/fs/unionfs/unlink.c
index f5b250ac0df719fa618b747c27be1a7d9b8bcf40..dd1dd9c3b53e7167658dfe665f9ace72571008ba 100644 (file)
--- a/fs/unionfs/unlink.c
+++ b/fs/unionfs/unlink.c
@@ -74,6 +74,8 @@ int unionfs_unlink(struct inode *dir, struct dentry *dentry)
 {
        int err = 0;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
 
        err = unionfs_unlink_whiteout(dir, dentry);
@@ -122,6 +124,8 @@ int unionfs_rmdir(struct inode *dir, struct dentry *dentry)
        int err = 0;
        struct unionfs_dir_state *namelist = NULL;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
 
        /* check if this unionfs directory is empty or not */

diff --git a/fs/unionfs/xattr.c b/fs/unionfs/xattr.c
index d57f079457e5abf4bc9688b42f4cfcf921ead843..6e1f4bd9877e82b70c1e9c553c0cb6426dc4dde0 100644 (file)
--- a/fs/unionfs/xattr.c
+++ b/fs/unionfs/xattr.c
@@ -56,6 +56,8 @@ ssize_t unionfs_getxattr(struct dentry * dentry, const char *name, void *value,
        struct dentry *hidden_dentry = NULL;
        int err = -EOPNOTSUPP;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
 
        hidden_dentry = unionfs_lower_dentry(dentry);
@@ -75,6 +77,8 @@ int unionfs_setxattr(struct dentry *dentry, const char *name, const void *value,
        struct dentry *hidden_dentry = NULL;
        int err = -EOPNOTSUPP;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
        hidden_dentry = unionfs_lower_dentry(dentry);
 
@@ -92,6 +96,8 @@ int unionfs_removexattr(struct dentry *dentry, const char *name)
        struct dentry *hidden_dentry = NULL;
        int err = -EOPNOTSUPP;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
        hidden_dentry = unionfs_lower_dentry(dentry);
 
@@ -110,6 +116,8 @@ ssize_t unionfs_listxattr(struct dentry * dentry, char *list, size_t size)
        int err = -EOPNOTSUPP;
        char *encoded_list = NULL;
 
+       BUG_ON(!is_valid_dentry(dentry));
+
        unionfs_lock_dentry(dentry);
 
        hidden_dentry = unionfs_lower_dentry(dentry);