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authorTyler Hicks <tyhicks@linux.vnet.ibm.com>2011-04-14 15:35:11 -0500
committerTyler Hicks <tyhicks@linux.vnet.ibm.com>2011-04-25 18:32:37 -0500
commit332ab16f830f59e7621ae8eb2c353dc135a316f6 (patch)
treec5b249f34dcacf2aa5ee24de8d332d8171398203 /fs/ecryptfs/main.c
parentdd55c89852481a0708c3fd4b48f3081f4280d9d3 (diff)
downloadop-kernel-dev-332ab16f830f59e7621ae8eb2c353dc135a316f6.zip
op-kernel-dev-332ab16f830f59e7621ae8eb2c353dc135a316f6.tar.gz
eCryptfs: Add reference counting to lower files
For any given lower inode, eCryptfs keeps only one lower file open and multiplexes all eCryptfs file operations through that lower file. The lower file was considered "persistent" and stayed open from the first lookup through the lifetime of the inode. This patch keeps the notion of a single, per-inode lower file, but adds reference counting around the lower file so that it is closed when not currently in use. If the reference count is at 0 when an operation (such as open, create, etc.) needs to use the lower file, a new lower file is opened. Since the file is no longer persistent, all references to the term persistent file are changed to lower file. Locking is added around the sections of code that opens the lower file and assign the pointer in the inode info, as well as the code the fputs the lower file when all eCryptfs users are done with it. This patch is needed to fix issues, when mounted on top of the NFSv3 client, where the lower file is left silly renamed until the eCryptfs inode is destroyed. Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Diffstat (limited to 'fs/ecryptfs/main.c')
-rw-r--r--fs/ecryptfs/main.c72
1 files changed, 50 insertions, 22 deletions
diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
index fdb2eb0..89b9338 100644
--- a/fs/ecryptfs/main.c
+++ b/fs/ecryptfs/main.c
@@ -96,7 +96,7 @@ void __ecryptfs_printk(const char *fmt, ...)
}
/**
- * ecryptfs_init_persistent_file
+ * ecryptfs_init_lower_file
* @ecryptfs_dentry: Fully initialized eCryptfs dentry object, with
* the lower dentry and the lower mount set
*
@@ -104,42 +104,70 @@ void __ecryptfs_printk(const char *fmt, ...)
* 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.
+ * lower file struct and associates it with the eCryptfs
+ * inode. When all eCryptfs files associated with the inode are released, the
+ * file is closed.
*
- * The persistent file will be opened with read/write permissions, if
+ * The lower 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
+ * This function does nothing if a lower file is already
* associated with the eCryptfs inode.
*
* Returns zero on success; non-zero otherwise
*/
-int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry)
+static int ecryptfs_init_lower_file(struct dentry *dentry,
+ struct file **lower_file)
{
const struct cred *cred = current_cred();
- struct ecryptfs_inode_info *inode_info =
- ecryptfs_inode_to_private(ecryptfs_dentry->d_inode);
- int rc = 0;
+ struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
+ struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
+ int rc;
- if (!inode_info->lower_file) {
- struct dentry *lower_dentry;
- struct vfsmount *lower_mnt =
- ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
+ rc = ecryptfs_privileged_open(lower_file, lower_dentry, lower_mnt,
+ cred);
+ if (rc) {
+ printk(KERN_ERR "Error opening lower file "
+ "for lower_dentry [0x%p] and lower_mnt [0x%p]; "
+ "rc = [%d]\n", lower_dentry, lower_mnt, rc);
+ (*lower_file) = NULL;
+ }
+ return rc;
+}
- lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
- rc = ecryptfs_privileged_open(&inode_info->lower_file,
- lower_dentry, lower_mnt, cred);
- if (rc) {
- printk(KERN_ERR "Error opening lower persistent file "
- "for lower_dentry [0x%p] and lower_mnt [0x%p]; "
- "rc = [%d]\n", lower_dentry, lower_mnt, rc);
- inode_info->lower_file = NULL;
- }
+int ecryptfs_get_lower_file(struct dentry *dentry)
+{
+ struct ecryptfs_inode_info *inode_info =
+ ecryptfs_inode_to_private(dentry->d_inode);
+ int count, rc = 0;
+
+ mutex_lock(&inode_info->lower_file_mutex);
+ count = atomic_inc_return(&inode_info->lower_file_count);
+ if (WARN_ON_ONCE(count < 1))
+ rc = -EINVAL;
+ else if (count == 1) {
+ rc = ecryptfs_init_lower_file(dentry,
+ &inode_info->lower_file);
+ if (rc)
+ atomic_set(&inode_info->lower_file_count, 0);
}
+ mutex_unlock(&inode_info->lower_file_mutex);
return rc;
}
+void ecryptfs_put_lower_file(struct inode *inode)
+{
+ struct ecryptfs_inode_info *inode_info;
+
+ inode_info = ecryptfs_inode_to_private(inode);
+ if (atomic_dec_and_mutex_lock(&inode_info->lower_file_count,
+ &inode_info->lower_file_mutex)) {
+ fput(inode_info->lower_file);
+ inode_info->lower_file = NULL;
+ mutex_unlock(&inode_info->lower_file_mutex);
+ }
+}
+
static struct inode *ecryptfs_get_inode(struct inode *lower_inode,
struct super_block *sb)
{
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