[PATCH] eCryptfs: Consolidate lower dentry_open's

Opens on lower dentry objects happen in several places in eCryptfs, and they
all involve the same steps (dget, mntget, dentry_open).  This patch
consolidates the lower open events into a single function call.
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/ecryptfs/crypto.c

@@ -1191,28 +1191,28 @@ int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
 int ecryptfs_read_header_region(char *data, struct dentry *dentry,
 				struct vfsmount *mnt)
 {
-	struct file *file;
+	struct file *lower_file;
 	mm_segment_t oldfs;
 	int rc;
 
-	mnt = mntget(mnt);
-	file = dentry_open(dentry, mnt, O_RDONLY);
-	if (IS_ERR(file)) {
-		ecryptfs_printk(KERN_DEBUG, "Error opening file to "
-				"read header region\n");
-		mntput(mnt);
-		rc = PTR_ERR(file);
+	if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt,
+					   O_RDONLY))) {
+		printk(KERN_ERR
+		       "Error opening lower_file to read header region\n");
 		goto out;
 	}
-	file->f_pos = 0;
+	lower_file->f_pos = 0;
 	oldfs = get_fs();
 	set_fs(get_ds());
 	/* For releases 0.1 and 0.2, all of the header information
 	 * fits in the first data extent-sized region. */
-	rc = file->f_op->read(file, (char __user *)data,
-			      ECRYPTFS_DEFAULT_EXTENT_SIZE, &file->f_pos);
+	rc = lower_file->f_op->read(lower_file, (char __user *)data,
+			      ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
 	set_fs(oldfs);
-	fput(file);
+	if ((rc = ecryptfs_close_lower_file(lower_file))) {
+		printk(KERN_ERR "Error closing lower_file\n");
+		goto out;
+	}
 	rc = 0;
 out:
 	return rc;

fs/ecryptfs/ecryptfs_kernel.h

@@ -482,5 +482,9 @@ ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name,
 int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode);
 int ecryptfs_inode_set(struct inode *inode, void *lower_inode);
 void ecryptfs_init_inode(struct inode *inode, struct inode *lower_inode);
+int ecryptfs_open_lower_file(struct file **lower_file,
+			     struct dentry *lower_dentry,
+			     struct vfsmount *lower_mnt, int flags);
+int ecryptfs_close_lower_file(struct file *lower_file);
 
 #endif /* #ifndef ECRYPTFS_KERNEL_H */

fs/ecryptfs/file.c

@@ -198,6 +198,33 @@ static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
 
 struct kmem_cache *ecryptfs_file_info_cache;
 
+int ecryptfs_open_lower_file(struct file **lower_file,
+			     struct dentry *lower_dentry,
+			     struct vfsmount *lower_mnt, int flags)
+{
+	int rc = 0;
+
+	dget(lower_dentry);
+	mntget(lower_mnt);
+	*lower_file = dentry_open(lower_dentry, lower_mnt, flags);
+	if (IS_ERR(*lower_file)) {
+		printk(KERN_ERR "Error opening lower file for lower_dentry "
+		       "[0x%p], lower_mnt [0x%p], and flags [0x%x]\n",
+		       lower_dentry, lower_mnt, flags);
+		rc = PTR_ERR(*lower_file);
+		*lower_file = NULL;
+		goto out;
+	}
+out:
+	return rc;
+}
+
+int ecryptfs_close_lower_file(struct file *lower_file)
+{
+	fput(lower_file);
+	return 0;
+}
+
 /**
  * ecryptfs_open
  * @inode: inode speciying file to open
@@ -244,19 +271,15 @@ static int ecryptfs_open(struct inode *inode, struct file *file)
 		ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
 	}
 	mutex_unlock(&crypt_stat->cs_mutex);
-	/* This mntget & dget is undone via fput when the file is released */
-	dget(lower_dentry);
 	lower_flags = file->f_flags;
 	if ((lower_flags & O_ACCMODE) == O_WRONLY)
 		lower_flags = (lower_flags & O_ACCMODE) | O_RDWR;
 	if (file->f_flags & O_APPEND)
 		lower_flags &= ~O_APPEND;
 	lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
-	mntget(lower_mnt);
 	/* Corresponding fput() in ecryptfs_release() */
-	lower_file = dentry_open(lower_dentry, lower_mnt, lower_flags);
-	if (IS_ERR(lower_file)) {
-		rc = PTR_ERR(lower_file);
+	if ((rc = ecryptfs_open_lower_file(&lower_file, lower_dentry, lower_mnt,
+					   lower_flags))) {
 		ecryptfs_printk(KERN_ERR, "Error opening lower file\n");
 		goto out_puts;
 	}
@@ -341,11 +364,16 @@ static int ecryptfs_release(struct inode *inode, struct file *file)
 	struct file *lower_file = ecryptfs_file_to_lower(file);
 	struct ecryptfs_file_info *file_info = ecryptfs_file_to_private(file);
 	struct inode *lower_inode = ecryptfs_inode_to_lower(inode);
+	int rc;
 
-	fput(lower_file);
+	if ((rc = ecryptfs_close_lower_file(lower_file))) {
+		printk(KERN_ERR "Error closing lower_file\n");
+		goto out;
+	}
 	inode->i_blocks = lower_inode->i_blocks;
 	kmem_cache_free(ecryptfs_file_info_cache, file_info);
-	return 0;
+out:
+	return rc;
 }
 
 static int

fs/ecryptfs/inode.c

@@ -231,7 +231,6 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
 	int lower_flags;
 	struct ecryptfs_crypt_stat *crypt_stat;
 	struct dentry *lower_dentry;
-	struct dentry *tlower_dentry = NULL;
 	struct file *lower_file;
 	struct inode *inode, *lower_inode;
 	struct vfsmount *lower_mnt;
@@ -241,30 +240,19 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
 			lower_dentry->d_name.name);
 	inode = ecryptfs_dentry->d_inode;
 	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
-	tlower_dentry = dget(lower_dentry);
-	if (!tlower_dentry) {
-		rc = -ENOMEM;
-		ecryptfs_printk(KERN_ERR, "Error dget'ing lower_dentry\n");
-		goto out;
-	}
 	lower_flags = ((O_CREAT | O_WRONLY | O_TRUNC) & O_ACCMODE) | O_RDWR;
 #if BITS_PER_LONG != 32
 	lower_flags |= O_LARGEFILE;
 #endif
 	lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
-	mntget(lower_mnt);
 	/* Corresponding fput() at end of this function */
-	lower_file = dentry_open(tlower_dentry, lower_mnt, lower_flags);
-	if (IS_ERR(lower_file)) {
-		rc = PTR_ERR(lower_file);
+	if ((rc = ecryptfs_open_lower_file(&lower_file, lower_dentry, lower_mnt,
+					   lower_flags))) {
 		ecryptfs_printk(KERN_ERR,
 				"Error opening dentry; rc = [%i]\n", rc);
 		goto out;
 	}
-	/* fput(lower_file) should handle the puts if we do this */
-	lower_file->f_dentry = tlower_dentry;
-	lower_file->f_vfsmnt = lower_mnt;
-	lower_inode = tlower_dentry->d_inode;
+	lower_inode = lower_dentry->d_inode;
 	if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
 		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
 		ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
@@ -285,7 +273,8 @@ static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
 	}
 	rc = grow_file(ecryptfs_dentry, lower_file, inode, lower_inode);
 out_fput:
-	fput(lower_file);
+	if ((rc = ecryptfs_close_lower_file(lower_file)))
+		printk(KERN_ERR "Error closing lower_file\n");
 out:
 	return rc;
 }
@@ -832,12 +821,11 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 	}
 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
 	/* This dget & mntget is released through fput at out_fput: */
-	dget(lower_dentry);
 	lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
-	mntget(lower_mnt);
-	lower_file = dentry_open(lower_dentry, lower_mnt, O_RDWR);
-	if (unlikely(IS_ERR(lower_file))) {
-		rc = PTR_ERR(lower_file);
+	if ((rc = ecryptfs_open_lower_file(&lower_file, lower_dentry, lower_mnt,
+					   O_RDWR))) {
+		ecryptfs_printk(KERN_ERR,
+				"Error opening dentry; rc = [%i]\n", rc);
 		goto out_free;
 	}
 	ecryptfs_set_file_lower(&fake_ecryptfs_file, lower_file);
@@ -879,7 +867,8 @@ int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
 		= CURRENT_TIME;
 	mark_inode_dirty_sync(inode);
 out_fput:
-	fput(lower_file);
+	if ((rc = ecryptfs_close_lower_file(lower_file)))
+		printk(KERN_ERR "Error closing lower_file\n");
 out_free:
 	if (ecryptfs_file_to_private(&fake_ecryptfs_file))
 		kmem_cache_free(ecryptfs_file_info_cache,