Commit 57db4e8d authored by Thieu Le's avatar Thieu Le Committed by Tyler Hicks
Browse files

ecryptfs: modify write path to encrypt page in writepage 



Change the write path to encrypt the data only when the page is written to
disk in ecryptfs_writepage. Previously, ecryptfs encrypts the page in
ecryptfs_write_end which means that if there are multiple write requests to
the same page, ecryptfs ends up re-encrypting that page over and over again.
This patch minimizes the number of encryptions needed.

Signed-off-by: default avatarThieu Le <thieule@chromium.org>
[tyhicks: Changed NULL .drop_inode sop pointer to generic_drop_inode]
Signed-off-by: default avatarTyler Hicks <tyhicks@linux.vnet.ibm.com>
parent fed8859b

fs/ecryptfs/ecryptfs_kernel.h

+0 −1
Original line number Diff line number Diff line
@@ -296,7 +296,6 @@ struct ecryptfs_inode_info { 
	struct inode vfs_inode;

	struct inode *wii_inode;

	struct file *lower_file;

	struct mutex lower_file_mutex;

	struct ecryptfs_crypt_stat crypt_stat;

};

fs/ecryptfs/file.c

+8 −1
Original line number Diff line number Diff line
@@ -273,7 +273,14 @@ static int ecryptfs_release(struct inode *inode, struct file *file) 
static int

ecryptfs_fsync(struct file *file, int datasync)

{

	return vfs_fsync(ecryptfs_file_to_lower(file), datasync);

	int rc = 0;



	rc = generic_file_fsync(file, datasync);

	if (rc)

		goto out;

	rc = vfs_fsync(ecryptfs_file_to_lower(file), datasync);

out:

	return rc;

}



static int ecryptfs_fasync(int fd, struct file *file, int flag)

fs/ecryptfs/main.c

+0 −2
Original line number Diff line number Diff line
@@ -122,7 +122,6 @@ int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry) 
		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 =
@@ -138,7 +137,6 @@ int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry) 
			inode_info->lower_file = NULL;

		}

	}

	mutex_unlock(&inode_info->lower_file_mutex);

	return rc;

}

fs/ecryptfs/mmap.c

+27 −14
Original line number Diff line number Diff line
@@ -62,6 +62,18 @@ static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc) 
{

	int rc;



	/*

	 * Refuse to write the page out if we are called from reclaim context

	 * since our writepage() path may potentially allocate memory when

	 * calling into the lower fs vfs_write() which may in turn invoke

	 * us again.

	 */

	if (current->flags & PF_MEMALLOC) {

		redirty_page_for_writepage(wbc, page);

		rc = 0;

		goto out;

	}



	rc = ecryptfs_encrypt_page(page);

	if (rc) {

		ecryptfs_printk(KERN_WARNING, "Error encrypting "
@@ -70,8 +82,8 @@ static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc) 
		goto out;

	}

	SetPageUptodate(page);

	unlock_page(page);

out:

	unlock_page(page);

	return rc;

}
@@ -481,6 +493,7 @@ static int ecryptfs_write_end(struct file *file, 
	struct ecryptfs_crypt_stat *crypt_stat =

		&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;

	int rc;

	int need_unlock_page = 1;



	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"

			"(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
@@ -501,25 +514,25 @@ static int ecryptfs_write_end(struct file *file, 
			"zeros in page with index = [0x%.16lx]\n", index);

		goto out;

	}

	rc = ecryptfs_encrypt_page(page);

	if (rc) {

		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "

				"index [0x%.16lx])\n", index);

		goto out;

	}

	set_page_dirty(page);

	unlock_page(page);

	need_unlock_page = 0;

	if (pos + copied > i_size_read(ecryptfs_inode)) {

		i_size_write(ecryptfs_inode, pos + copied);

		ecryptfs_printk(KERN_DEBUG, "Expanded file size to "

			"[0x%.16llx]\n",

			(unsigned long long)i_size_read(ecryptfs_inode));

	}

		balance_dirty_pages_ratelimited(mapping);

		rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);

	if (rc)

		if (rc) {

			printk(KERN_ERR "Error writing inode size to metadata; "

			       "rc = [%d]\n", rc);

	else

			goto out;

		}

	}

	rc = copied;

out:

	if (need_unlock_page)

		unlock_page(page);

	page_cache_release(page);

	return rc;

fs/ecryptfs/read_write.c

+2 −10
Original line number Diff line number Diff line
@@ -44,15 +44,11 @@ int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data, 
	ssize_t rc;



	inode_info = ecryptfs_inode_to_private(ecryptfs_inode);

	mutex_lock(&inode_info->lower_file_mutex);

	BUG_ON(!inode_info->lower_file);

	inode_info->lower_file->f_pos = offset;

	fs_save = get_fs();

	set_fs(get_ds());

	rc = vfs_write(inode_info->lower_file, data, size,

		       &inode_info->lower_file->f_pos);

	rc = vfs_write(inode_info->lower_file, data, size, &offset);

	set_fs(fs_save);

	mutex_unlock(&inode_info->lower_file_mutex);

	mark_inode_dirty_sync(ecryptfs_inode);

	return rc;

}
@@ -234,15 +230,11 @@ int ecryptfs_read_lower(char *data, loff_t offset, size_t size, 
	mm_segment_t fs_save;

	ssize_t rc;



	mutex_lock(&inode_info->lower_file_mutex);

	BUG_ON(!inode_info->lower_file);

	inode_info->lower_file->f_pos = offset;

	fs_save = get_fs();

	set_fs(get_ds());

	rc = vfs_read(inode_info->lower_file, data, size,

		      &inode_info->lower_file->f_pos);

	rc = vfs_read(inode_info->lower_file, data, size, &offset);

	set_fs(fs_save);

	mutex_unlock(&inode_info->lower_file_mutex);

	return rc;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE