linux-kernel - [PATCH 10/17] Unionfs: factor out revalidation routine

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Message-Id: <1203217051613-git-send-email-ezk@cs.sunysb.edu>
Date:	Sat, 16 Feb 2008 21:57:19 -0500
From:	Erez Zadok <ezk@...sunysb.edu>
To:	akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	viro@....linux.org.uk, hch@...radead.org,
	Erez Zadok <ezk@...sunysb.edu>
Subject: [PATCH 10/17] Unionfs: factor out revalidation routine

To be used by rest of revalidation code, as well a callers who already
locked the child and parent dentry branch-configurations.

Signed-off-by: Erez Zadok <ezk@...sunysb.edu>
---
 fs/unionfs/dentry.c |   87 +++++++++++++++++++++++++++++++-------------------
 fs/unionfs/union.h  |    3 ++
 2 files changed, 57 insertions(+), 33 deletions(-)

diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index afa2120..3bd2dfb 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -285,6 +285,59 @@ void purge_sb_data(struct super_block *sb)
 }
 
 /*
+ * Revalidate a single file/symlink/special dentry.  Assume that info nodes
+ * of the dentry and its parent are locked.  Assume that parent(s) are all
+ * valid already, but the child may not yet be valid.  Returns true if
+ * valid, false otherwise.
+ */
+bool __unionfs_d_revalidate_one_locked(struct dentry *dentry,
+				       struct nameidata *nd,
+				       bool willwrite)
+{
+	bool valid = false;	/* default is invalid */
+	int sbgen, dgen, bindex;
+
+	verify_locked(dentry);
+	verify_locked(dentry->d_parent);
+
+	sbgen = atomic_read(&UNIONFS_SB(dentry->d_sb)->generation);
+	dgen = atomic_read(&UNIONFS_D(dentry)->generation);
+
+	if (unlikely(is_newer_lower(dentry))) {
+		/* root dentry special case as aforementioned */
+		if (IS_ROOT(dentry)) {
+			unionfs_copy_attr_times(dentry->d_inode);
+		} else {
+			/*
+			 * reset generation number to zero, guaranteed to be
+			 * "old"
+			 */
+			dgen = 0;
+			atomic_set(&UNIONFS_D(dentry)->generation, dgen);
+		}
+		if (!willwrite)
+			purge_inode_data(dentry->d_inode);
+	}
+	valid = __unionfs_d_revalidate_one(dentry, nd);
+
+	/*
+	 * If __unionfs_d_revalidate_one() succeeded above, then it will
+	 * have incremented the refcnt of the mnt's, but also the branch
+	 * indices of the dentry will have been updated (to take into
+	 * account any branch insertions/deletion.  So the current
+	 * dbstart/dbend match the current, and new, indices of the mnts
+	 * which __unionfs_d_revalidate_one has incremented.  Note: the "if"
+	 * test below does not depend on whether chain_len was 0 or greater.
+	 */
+	if (!valid || sbgen == dgen)
+		goto out;
+	for (bindex = dbstart(dentry); bindex <= dbend(dentry); bindex++)
+		unionfs_mntput(dentry, bindex);
+out:
+	return valid;
+}
+
+/*
  * Revalidate a parent chain of dentries, then the actual node.
  * Assumes that dentry is locked, but will lock all parents if/when needed.
  *
@@ -404,42 +457,10 @@ out_this:
 	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))) {
-		/* root dentry special case as aforementioned */
-		if (IS_ROOT(dentry)) {
-			unionfs_copy_attr_times(dentry->d_inode);
-		} else {
-			/*
-			 * reset generation number to zero, guaranteed to be
-			 * "old"
-			 */
-			dgen = 0;
-			atomic_set(&UNIONFS_D(dentry)->generation, dgen);
-		}
-		if (!willwrite)
-			purge_inode_data(dentry->d_inode);
-	}
-	valid = __unionfs_d_revalidate_one(dentry, nd);
+	valid = __unionfs_d_revalidate_one_locked(dentry, nd, willwrite);
 	if (dentry != dentry->d_parent)
 		unionfs_unlock_dentry(dentry->d_parent);
 
-	/*
-	 * If __unionfs_d_revalidate_one() succeeded above, then it will
-	 * have incremented the refcnt of the mnt's, but also the branch
-	 * indices of the dentry will have been updated (to take into
-	 * account any branch insertions/deletion.  So the current
-	 * dbstart/dbend match the current, and new, indices of the mnts
-	 * which __unionfs_d_revalidate_one has incremented.  Note: the "if"
-	 * test below does not depend on whether chain_len was 0 or greater.
-	 */
-	if (valid && sbgen != dgen)
-		for (bindex = dbstart(dentry);
-		     bindex <= dbend(dentry);
-		     bindex++)
-			unionfs_mntput(dentry, bindex);
-
 out_free:
 	/* unlock/dput all dentries in chain and return status */
 	if (chain_len > 0) {
diff --git a/fs/unionfs/union.h b/fs/unionfs/union.h
index 0e0ccde..5001b07 100644
--- a/fs/unionfs/union.h
+++ b/fs/unionfs/union.h
@@ -368,6 +368,9 @@ extern int unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 extern int unionfs_unlink(struct inode *dir, struct dentry *dentry);
 extern int unionfs_rmdir(struct inode *dir, struct dentry *dentry);
 
+extern bool __unionfs_d_revalidate_one_locked(struct dentry *dentry,
+					      struct nameidata *nd,
+					      bool willwrite);
 extern bool __unionfs_d_revalidate_chain(struct dentry *dentry,
 					 struct nameidata *nd, bool willwrite);
 extern bool is_newer_lower(const struct dentry *dentry);
-- 
1.5.2.2

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