Unionfs: locking fixes

Lock parent dentries during revalidation.
Reduce total number of lockdep classes used.

Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>

diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index b4c964d9fc344633517a593e23241f9a6c9d0398..971605f87b8ffaa9d7c0ca6b305880e930ae9a53 100644 (file)
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -42,6 +42,7 @@ static bool __unionfs_d_revalidate_one(struct dentry *dentry,
                memset(&lowernd, 0, sizeof(struct nameidata));
 
        verify_locked(dentry);
+       verify_locked(dentry->d_parent);
 
        /* if the dentry is unhashed, do NOT revalidate */
        if (d_deleted(dentry))
@@ -346,7 +347,10 @@ bool __unionfs_d_revalidate_chain(struct dentry *dentry, struct nameidata *nd,
         * to child order.
         */
        for (i = 0; i < chain_len; i++) {
-               unionfs_lock_dentry(chain[i], UNIONFS_DMUTEX_REVAL+i);
+               unionfs_lock_dentry(chain[i], UNIONFS_DMUTEX_REVAL_CHILD);
+               if (chain[i] != chain[i]->d_parent)
+                       unionfs_lock_dentry(chain[i]->d_parent,
+                                           UNIONFS_DMUTEX_REVAL_PARENT);
                saved_bstart = dbstart(chain[i]);
                saved_bend = dbend(chain[i]);
                sbgen = atomic_read(&UNIONFS_SB(dentry->d_sb)->generation);
@@ -361,6 +365,8 @@ bool __unionfs_d_revalidate_chain(struct dentry *dentry, struct nameidata *nd,
                             bindex++)
                                unionfs_mntput(chain[i], bindex);
                }
+               if (chain[i] != chain[i]->d_parent)
+                       unionfs_unlock_dentry(chain[i]->d_parent);
                unionfs_unlock_dentry(chain[i]);
 
                if (unlikely(!valid))
@@ -371,6 +377,9 @@ bool __unionfs_d_revalidate_chain(struct dentry *dentry, struct nameidata *nd,
 out_this:
        /* finally, lock this dentry and revalidate it */
        verify_locked(dentry);
+       if (dentry != dentry->d_parent)
+               unionfs_lock_dentry(dentry->d_parent,
+                                   UNIONFS_DMUTEX_REVAL_PARENT);
        dgen = atomic_read(&UNIONFS_D(dentry)->generation);
 
        if (unlikely(is_newer_lower(dentry))) {
@@ -389,6 +398,8 @@ out_this:
                        purge_inode_data(dentry->d_inode);
        }
        valid = __unionfs_d_revalidate_one(dentry, nd);
+       if (dentry != dentry->d_parent)
+               unionfs_unlock_dentry(dentry->d_parent);
 
        /*
         * If __unionfs_d_revalidate_one() succeeded above, then it will

diff --git a/fs/unionfs/fanout.h b/fs/unionfs/fanout.h
index 07eb223e504147e479d102b6d16c42b2441c3acd..86b194e91f618e62e80a89b5b81231c22afca309 100644 (file)
--- a/fs/unionfs/fanout.h
+++ b/fs/unionfs/fanout.h
@@ -291,7 +291,8 @@ enum unionfs_dentry_lock_class {
        UNIONFS_DMUTEX_PARENT,
        UNIONFS_DMUTEX_CHILD,
        UNIONFS_DMUTEX_WHITEOUT,
-       UNIONFS_DMUTEX_REVAL,   /* for file/dentry revalidate */
+       UNIONFS_DMUTEX_REVAL_PARENT, /* for file/dentry revalidate */
+       UNIONFS_DMUTEX_REVAL_CHILD,   /* for file/dentry revalidate */
 };
 
 static inline void unionfs_lock_dentry(struct dentry *d,