[PATCH 10/21] Unionfs: Introduce unionfs_mnt{get,put}

[Josef 'Jeff' Sipek]

From: Erez Zadok <ezk@xxxxxxxxxxxxx>

Helper inline functions to perform Unionfs's mntget/put ops on lower
branches.

Signed-off-by: Erez Zadok <ezk@xxxxxxxxxxxxx>
[jsipek: cleanup branching in unionfs_mnt{get,put} and compile fixes]
Signed-off-by: Josef 'Jeff' Sipek <jsipek@xxxxxxxxxxxxx>
---
 fs/unionfs/commonfops.c |    8 ++++----
 fs/unionfs/copyup.c     |    6 +++---
 fs/unionfs/dentry.c     |    2 +-
 fs/unionfs/dirhelper.c  |    2 +-
 fs/unionfs/lookup.c     |   25 +++++++++++++------------
 fs/unionfs/main.c       |    7 ++++---
 fs/unionfs/union.h      |   35 ++++++++++++++++++++++++++++++++++-
 7 files changed, 60 insertions(+), 25 deletions(-)

diff --git a/fs/unionfs/commonfops.c b/fs/unionfs/commonfops.c
index 8d0f8d1..c20dd6f 100644
--- a/fs/unionfs/commonfops.c
+++ b/fs/unionfs/commonfops.c
@@ -169,7 +169,7 @@ static int open_all_files(struct file *file)
 			continue;
 
 		dget(hidden_dentry);
-		mntget(unionfs_lower_mnt_idx(dentry, bindex));
+		unionfs_mntget(dentry, bindex);
 		branchget(sb, bindex);
 
 		hidden_file = dentry_open(hidden_dentry,
@@ -214,7 +214,7 @@ static int open_highest_file(struct file *file, int willwrite)
 	}
 
 	dget(hidden_dentry);
-	mntget(unionfs_lower_mnt_idx(dentry, bstart));
+	unionfs_mntget(dentry, bstart);
 	branchget(sb, bstart);
 	hidden_file = dentry_open(hidden_dentry,
 			unionfs_lower_mnt_idx(dentry, bstart), file->f_flags);
@@ -371,7 +371,7 @@ static int __open_dir(struct inode *inode, struct file *file)
 			continue;
 
 		dget(hidden_dentry);
-		mntget(unionfs_lower_mnt_idx(file->f_dentry, bindex));
+		unionfs_mntget(file->f_dentry, bindex);
 		hidden_file = dentry_open(hidden_dentry,
 				unionfs_lower_mnt_idx(file->f_dentry, bindex),
 				file->f_flags);
@@ -431,7 +431,7 @@ static int __open_file(struct inode *inode, struct file *file)
 	/* dentry_open will decrement mnt refcnt if err.
 	 * otherwise fput() will do an mntput() for us upon file close.
 	 */
-	mntget(unionfs_lower_mnt_idx(file->f_dentry, bstart));
+	unionfs_mntget(file->f_dentry, bstart);
 	hidden_file = dentry_open(hidden_dentry,
 				  unionfs_lower_mnt_idx(file->f_dentry, bstart),
 				  hidden_flags);
diff --git a/fs/unionfs/copyup.c b/fs/unionfs/copyup.c
index e24d940..4ccef81 100644
--- a/fs/unionfs/copyup.c
+++ b/fs/unionfs/copyup.c
@@ -206,7 +206,7 @@ static int __copyup_reg_data(struct dentry *dentry,
 	int err = 0;
 
 	/* open old file */
-	mntget(unionfs_lower_mnt_idx(dentry, old_bindex));
+	unionfs_mntget(dentry, old_bindex);
 	branchget(sb, old_bindex);
 	input_file = dentry_open(old_hidden_dentry,
 				unionfs_lower_mnt_idx(dentry, old_bindex),
@@ -223,7 +223,7 @@ static int __copyup_reg_data(struct dentry *dentry,
 
 	/* open new file */
 	dget(new_hidden_dentry);
-	mntget(unionfs_lower_mnt_idx(dentry, new_bindex));
+	unionfs_mntget(dentry, new_bindex);
 	branchget(sb, new_bindex);
 	output_file = dentry_open(new_hidden_dentry,
 				unionfs_lower_mnt_idx(dentry, new_bindex),
@@ -555,7 +555,7 @@ static void __cleanup_dentry(struct dentry * dentry, int bindex,
 			dput(unionfs_lower_dentry_idx(dentry, i));
 			unionfs_set_lower_dentry_idx(dentry, i, NULL);
 
-			mntput(unionfs_lower_mnt_idx(dentry, i));
+			unionfs_mntput(dentry, i);
 			unionfs_set_lower_mnt_idx(dentry, i, NULL);
 		} else {
 			if (new_bstart < 0)
diff --git a/fs/unionfs/dentry.c b/fs/unionfs/dentry.c
index cae4897..5ee1451 100644
--- a/fs/unionfs/dentry.c
+++ b/fs/unionfs/dentry.c
@@ -206,7 +206,7 @@ static void unionfs_d_release(struct dentry *dentry)
 	bend = dbend(dentry);
 	for (bindex = bstart; bindex <= bend; bindex++) {
 		dput(unionfs_lower_dentry_idx(dentry, bindex));
-		mntput(unionfs_lower_mnt_idx(dentry, bindex));
+		unionfs_mntput(dentry, bindex);
 
 		unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
 		unionfs_set_lower_mnt_idx(dentry, bindex, NULL);
diff --git a/fs/unionfs/dirhelper.c b/fs/unionfs/dirhelper.c
index 0da8a8e..bb5f7bc 100644
--- a/fs/unionfs/dirhelper.c
+++ b/fs/unionfs/dirhelper.c
@@ -225,7 +225,7 @@ int check_empty(struct dentry *dentry, struct unionfs_dir_state **namelist)
 			continue;
 
 		dget(hidden_dentry);
-		mntget(unionfs_lower_mnt_idx(dentry, bindex));
+		unionfs_mntget(dentry, bindex);
 		branchget(sb, bindex);
 		hidden_file =
 		    dentry_open(hidden_dentry, unionfs_lower_mnt_idx(dentry, bindex),
diff --git a/fs/unionfs/lookup.c b/fs/unionfs/lookup.c
index 967bb5b..0572247 100644
--- a/fs/unionfs/lookup.c
+++ b/fs/unionfs/lookup.c
@@ -79,7 +79,8 @@ struct dentry *unionfs_lookup_backend(struct dentry *dentry, struct nameidata *n
 	struct dentry *parent_dentry = NULL;
 	int bindex, bstart, bend, bopaque;
 	int dentry_count = 0;	/* Number of positive dentries. */
-	int first_dentry_offset = -1;
+	int first_dentry_offset = -1; /* -1 is uninitialized */
+	struct dentry *first_dentry = NULL;
 	struct dentry *first_hidden_dentry = NULL;
 	struct vfsmount *first_hidden_mnt = NULL;
 	int locked_parent = 0;
@@ -176,7 +177,7 @@ struct dentry *unionfs_lookup_backend(struct dentry *dentry, struct nameidata *n
 						  namelen + UNIONFS_WHLEN);
 		if (IS_ERR(wh_hidden_dentry)) {
 			dput(first_hidden_dentry);
-			mntput(first_hidden_mnt);
+			unionfs_mntput(first_dentry, first_dentry_offset);
 			err = PTR_ERR(wh_hidden_dentry);
 			goto out_free;
 		}
@@ -194,7 +195,7 @@ struct dentry *unionfs_lookup_backend(struct dentry *dentry, struct nameidata *n
 			       " %d.\n", wh_hidden_dentry->d_inode->i_mode);
 			dput(wh_hidden_dentry);
 			dput(first_hidden_dentry);
-			mntput(first_hidden_mnt);
+			unionfs_mntput(first_dentry, first_dentry_offset);
 			goto out_free;
 		}
 
@@ -210,7 +211,7 @@ struct dentry *unionfs_lookup_backend(struct dentry *dentry, struct nameidata *n
 					       namelen, nd);
 		if (IS_ERR(hidden_dentry)) {
 			dput(first_hidden_dentry);
-			mntput(first_hidden_mnt);
+			unionfs_mntput(first_dentry, first_dentry_offset);
 			err = PTR_ERR(hidden_dentry);
 			goto out_free;
 		}
@@ -224,9 +225,8 @@ struct dentry *unionfs_lookup_backend(struct dentry *dentry, struct nameidata *n
 				/* FIXME: following line needs to be changed
 				 * to allow mountpoint crossing
 				 */
-				first_hidden_mnt = mntget(
-					unionfs_lower_mnt_idx(parent_dentry,
-								bindex));
+				first_dentry = parent_dentry;
+				first_hidden_mnt = unionfs_mntget(parent_dentry, bindex);
 				first_dentry_offset = bindex;
 			} else
 				dput(hidden_dentry);
@@ -245,7 +245,7 @@ struct dentry *unionfs_lookup_backend(struct dentry *dentry, struct nameidata *n
 		 * mountpoint crossing
 		 */
 		unionfs_set_lower_mnt_idx(dentry, bindex,
-			mntget(unionfs_lower_mnt_idx(parent_dentry, bindex)));
+					  unionfs_mntget(parent_dentry, bindex));
 		set_dbend(dentry, bindex);
 
 		/* update parent directory's atime with the bindex */
@@ -266,7 +266,7 @@ struct dentry *unionfs_lookup_backend(struct dentry *dentry, struct nameidata *n
 		opaque = is_opaque_dir(dentry, bindex);
 		if (opaque < 0) {
 			dput(first_hidden_dentry);
-			mntput(first_hidden_mnt);
+			unionfs_mntput(first_dentry, first_dentry_offset);
 			err = opaque;
 			goto out_free;
 		} else if (opaque) {
@@ -309,7 +309,8 @@ out_negative:
 		/* FIXME: the following line needs to be changed to allow
 		 * mountpoint crossing
 		 */
-		first_hidden_mnt = mntget(unionfs_lower_mnt_idx(dentry, bindex));
+		first_dentry = dentry;
+		first_hidden_mnt = unionfs_mntget(dentry, bindex);
 	}
 	unionfs_set_lower_dentry_idx(dentry, first_dentry_offset, first_hidden_dentry);
 	unionfs_set_lower_mnt_idx(dentry, first_dentry_offset, first_hidden_mnt);
@@ -330,7 +331,7 @@ out_positive:
 	 * vfsmount - throw it out.
 	 */
 	dput(first_hidden_dentry);
-	mntput(first_hidden_mnt);
+	unionfs_mntput(first_dentry, first_dentry_offset);
 
 	/* Partial lookups need to reinterpose, or throw away older negs. */
 	if (lookupmode == INTERPOSE_PARTIAL) {
@@ -365,7 +366,7 @@ out_free:
 		bend = dbend(dentry);
 		for (bindex = bstart; bindex <= bend; bindex++) {
 			dput(unionfs_lower_dentry_idx(dentry, bindex));
-			mntput(unionfs_lower_mnt_idx(dentry, bindex));
+			unionfs_mntput(dentry, bindex);
 		}
 	}
 	kfree(UNIONFS_D(dentry)->lower_paths);
diff --git a/fs/unionfs/main.c b/fs/unionfs/main.c
index 1c93b13..b80b554 100644
--- a/fs/unionfs/main.c
+++ b/fs/unionfs/main.c
@@ -358,6 +358,7 @@ out:
 		for (i = 0; i < branches; i++)
 			if (hidden_root_info->lower_paths[i].dentry) {
 				dput(hidden_root_info->lower_paths[i].dentry);
+				/* initializing: can't use unionfs_mntput here */
 				mntput(hidden_root_info->lower_paths[i].mnt);
 			}
 
@@ -466,9 +467,8 @@ out_error:
 			m = hidden_root_info->lower_paths[bindex].mnt;
 
 			dput(d);
-
-			if (m)
-				mntput(m);
+			/* initializing: can't use unionfs_mntput here */
+			mntput(m);
 		}
 	}
 
@@ -618,6 +618,7 @@ out_dput:
 			m = hidden_root_info->lower_paths[bindex].mnt;
 
 			dput(d);
+			/* initializing: can't use unionfs_mntput here */
 			mntput(m);
 		}
 		kfree(hidden_root_info->lower_paths);
diff --git a/fs/unionfs/union.h b/fs/unionfs/union.h
index 715a3ad..53c7c2c 100644
--- a/fs/unionfs/union.h
+++ b/fs/unionfs/union.h
@@ -434,5 +434,38 @@ static inline void unlock_dir(struct dentry *dir)
 
 extern int make_dir_opaque(struct dentry *dir, int bindex);
 
-#endif	/* not _UNION_H_ */
+static inline struct vfsmount *unionfs_mntget(struct dentry *dentry, int bindex)
+{
+	struct vfsmount *mnt;
+	if (!dentry) {
+		if (bindex < 0)
+			return NULL;
+		BUG_ON(bindex < 0);
+	}
+	mnt = unionfs_lower_mnt_idx(dentry, bindex);
+	if (!mnt) {
+		if (bindex < 0)
+			return NULL;
+		BUG_ON(mnt && bindex < 0);
+	}
+	mnt = mntget(mnt);
+	return mnt;
+}
 
+static inline void unionfs_mntput(struct dentry *dentry, int bindex)
+{
+	struct vfsmount *mnt;
+	if (!dentry) {
+		if (bindex < 0)
+			return;
+		BUG_ON(dentry && bindex < 0);
+	}
+	mnt = unionfs_lower_mnt_idx(dentry, bindex);
+	if (!mnt) {
+		if (bindex < 0)
+			return;
+		BUG_ON(mnt && bindex < 0);
+	}
+	mntput(mnt);
+}
+#endif	/* not _UNION_H_ */
-- 
1.5.0.3.268.g3dda

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