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Subject[PATCH 5/11] eCryptfs: Set up and destroy persistent lower file
This patch sets up and destroys the persistent lower file for each
eCryptfs inode.

Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
---
fs/ecryptfs/inode.c | 23 +++++++++++++++---
fs/ecryptfs/main.c | 65 +++++++++++++++++++++++++++++++++++++++++++++++++++
fs/ecryptfs/super.c | 22 +++++++++++++++--
3 files changed, 103 insertions(+), 7 deletions(-)
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 7192a81..c746b5d 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -119,10 +119,23 @@ ecryptfs_do_create(struct inode *directory_inode,
}
rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
ecryptfs_dentry, mode, nd);
- if (unlikely(rc)) {
- ecryptfs_printk(KERN_ERR,
- "Failure to create underlying file\n");
- goto out_lock;
+ if (rc) {
+ struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
+ struct ecryptfs_inode_info *inode_info =
+ ecryptfs_inode_to_private(ecryptfs_inode);
+
+ printk(KERN_WARNING "%s: Error creating underlying file; "
+ "rc = [%d]; checking for existing\n", __FUNCTION__, rc);
+ if (inode_info) {
+ mutex_lock(&inode_info->lower_file_mutex);
+ if (!inode_info->lower_file) {
+ mutex_unlock(&inode_info->lower_file_mutex);
+ printk(KERN_ERR "%s: Failure to set underlying "
+ "file; rc = [%d]\n", __FUNCTION__, rc);
+ goto out_lock;
+ }
+ mutex_unlock(&inode_info->lower_file_mutex);
+ }
}
rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
directory_inode->i_sb, 0);
@@ -252,6 +265,8 @@ ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
{
int rc;

+ /* ecryptfs_do_create() calls ecryptfs_interpose(), which opens
+ * the crypt_stat->lower_file (persistent file) */
rc = ecryptfs_do_create(directory_inode, ecryptfs_dentry, mode, nd);
if (unlikely(rc)) {
ecryptfs_printk(KERN_WARNING, "Failed to create file in"
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index 967bad0..3e324f8 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -98,6 +98,64 @@ void __ecryptfs_printk(const char *fmt, ...)
}

/**
+ * ecryptfs_init_persistent_file
+ * @ecryptfs_dentry: Fully initialized eCryptfs dentry object, with
+ * the lower dentry and the lower mount set
+ *
+ * eCryptfs only ever keeps a single open file for every lower
+ * inode. All I/O operations to the lower inode occur through that
+ * file. When the first eCryptfs dentry that interposes with the first
+ * lower dentry for that inode is created, this function creates the
+ * persistent file struct and associates it with the eCryptfs
+ * inode. When the eCryptfs inode is destroyed, the file is closed.
+ *
+ * The persistent file will be opened with read/write permissions, if
+ * possible. Otherwise, it is opened read-only.
+ *
+ * This function does nothing if a lower persistent file is already
+ * associated with the eCryptfs inode.
+ *
+ * Returns zero on success; non-zero otherwise
+ */
+int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
+{
+ struct ecryptfs_inode_info *inode_info =
+ ecryptfs_inode_to_private(ecryptfs_dentry->d_inode);
+ int rc = 0;
+
+ mutex_lock(&inode_info->lower_file_mutex);
+ if (!inode_info->lower_file) {
+ struct dentry *lower_dentry;
+ struct vfsmount *lower_mnt =
+ ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
+
+ lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
+ /* Corresponding dput() and mntput() are done when the
+ * persistent file is fput() when the eCryptfs inode
+ * is destroyed. */
+ dget(lower_dentry);
+ mntget(lower_mnt);
+ inode_info->lower_file = dentry_open(lower_dentry,
+ lower_mnt,
+ (O_RDWR | O_LARGEFILE));
+ if (IS_ERR(inode_info->lower_file))
+ inode_info->lower_file = dentry_open(lower_dentry,
+ lower_mnt,
+ (O_RDONLY
+ | O_LARGEFILE));
+ if (IS_ERR(inode_info->lower_file)) {
+ printk(KERN_ERR "Error opening lower persistent file "
+ "for lower_dentry [0x%p] and lower_mnt [0x%p]\n",
+ lower_dentry, lower_mnt);
+ rc = PTR_ERR(inode_info->lower_file);
+ inode_info->lower_file = NULL;
+ }
+ }
+ mutex_unlock(&inode_info->lower_file_mutex);
+ return rc;
+}
+
+/**
* ecryptfs_interpose
* @lower_dentry: Existing dentry in the lower filesystem
* @dentry: ecryptfs' dentry
@@ -154,6 +212,13 @@ int ecryptfs_interpose(struct dentry *lower_dentry, struct dentry *dentry,
/* This size will be overwritten for real files w/ headers and
* other metadata */
fsstack_copy_inode_size(inode, lower_inode);
+ rc = ecryptfs_init_persistent_file(dentry);
+ if (rc) {
+ printk(KERN_ERR "%s: Error attempting to initialize the "
+ "persistent file for the dentry with name [%s]; "
+ "rc = [%d]\n", __FUNCTION__, dentry->d_name.name, rc);
+ goto out;
+ }
out:
return rc;
}
diff --git a/fs/ecryptfs/super.c b/fs/ecryptfs/super.c
index 18d77f8..b97e210 100644
--- a/fs/ecryptfs/super.c
+++ b/fs/ecryptfs/super.c
@@ -27,6 +27,7 @@
#include <linux/mount.h>
#include <linux/key.h>
#include <linux/seq_file.h>
+#include <linux/file.h>
#include <linux/crypto.h>
#include "ecryptfs_kernel.h"

@@ -63,9 +64,10 @@ out:
* ecryptfs_destroy_inode
* @inode: The ecryptfs inode
*
- * This is used during the final destruction of the inode.
- * All allocation of memory related to the inode, including allocated
- * memory in the crypt_stat struct, will be released here.
+ * This is used during the final destruction of the inode. All
+ * allocation of memory related to the inode, including allocated
+ * memory in the crypt_stat struct, will be released here. This
+ * function also fput()'s the persistent file for the lower inode.
* There should be no chance that this deallocation will be missed.
*/
static void ecryptfs_destroy_inode(struct inode *inode)
@@ -73,6 +75,20 @@ static void ecryptfs_destroy_inode(struct inode *inode)
struct ecryptfs_inode_info *inode_info;

inode_info = ecryptfs_inode_to_private(inode);
+ mutex_lock(&inode_info->lower_file_mutex);
+ if (inode_info->lower_file) {
+ struct dentry *lower_dentry =
+ inode_info->lower_file->f_dentry;
+
+ BUG_ON(!lower_dentry);
+ if (lower_dentry->d_inode) {
+ fput(inode_info->lower_file);
+ inode_info->lower_file = NULL;
+ d_drop(lower_dentry);
+ d_delete(lower_dentry);
+ }
+ }
+ mutex_unlock(&inode_info->lower_file_mutex);
ecryptfs_destroy_crypt_stat(&inode_info->crypt_stat);
kmem_cache_free(ecryptfs_inode_info_cache, inode_info);
}
--
1.5.1.6
-
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