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Message-Id: <1309468923-5677-2-git-send-email-achender@linux.vnet.ibm.com>
Date:	Thu, 30 Jun 2011 14:22:02 -0700
From:	Allison Henderson <achender@...ux.vnet.ibm.com>
To:	linux-ext4@...r.kernel.org
Cc:	Allison Henderson <achender@...ux.vnet.ibm.com>
Subject: [PATCH 1/2 v3] EXT4: Secure Delete: Zero out file data

The first patch adds a new flag, EXT4_FREE_BLOCKS_ZERO,
to ext4_free_blocks. This flag causes causes blocks to be
zerod before they are freed.  Files that have the EXT4_SECRM_FL
attribute flag on will have their blocks zerod when
they are released.  The EXT4_SECRM_FL attribute flag can
be enabled useing chattr +s

Signed-off-by: Allison Henderson <achender@...ux.vnet.ibm.com>
---
v1->v2
Removed check for discard mount option and replaced with
check for secure discard and discard_zeroes_data

Added BLKDEV_DISCARD_SECURE to the sb_issue_discard call

v2->v3
Removed code for discard.  A seperate patch will
be done to add that code in the block layer

:100644 100644 1921392... 38a4d75... M	fs/ext4/ext4.h
:100644 100644 f815cc8... cf178f3... M	fs/ext4/extents.c
:100644 100644 62f86e7... 8fdae7d... M	fs/ext4/inode.c
:100644 100644 6ed859d... 94872b2... M	fs/ext4/mballoc.c
:100644 100644 c757adc... 1ff7532... M	fs/ext4/xattr.c
 fs/ext4/ext4.h    |    1 +
 fs/ext4/extents.c |    3 +++
 fs/ext4/inode.c   |    3 +++
 fs/ext4/mballoc.c |    8 ++++++++
 fs/ext4/xattr.c   |   12 ++++++++----
 5 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 1921392..38a4d75 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -526,6 +526,7 @@ struct ext4_new_group_data {
 #define EXT4_FREE_BLOCKS_METADATA	0x0001
 #define EXT4_FREE_BLOCKS_FORGET		0x0002
 #define EXT4_FREE_BLOCKS_VALIDATED	0x0004
+#define EXT4_FREE_BLOCKS_ZERO		0x0008
 
 /*
  * ioctl commands
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index f815cc8..cf178f3 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2231,6 +2231,9 @@ static int ext4_remove_blocks(handle_t *handle, struct inode *inode,
 
 	if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
 		flags |= EXT4_FREE_BLOCKS_METADATA;
+
+	if (EXT4_I(inode)->i_flags & EXT4_SECRM_FL)
+		flags |= EXT4_FREE_BLOCKS_ZERO;
 #ifdef EXTENTS_STATS
 	{
 		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 62f86e7..8fdae7d 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4182,6 +4182,9 @@ static int ext4_clear_blocks(handle_t *handle, struct inode *inode,
 	for (p = first; p < last; p++)
 		*p = 0;
 
+	if (EXT4_I(inode)->i_flags & EXT4_SECRM_FL)
+		flags |= EXT4_FREE_BLOCKS_ZERO;
+
 	ext4_free_blocks(handle, inode, NULL, block_to_free, count, flags);
 	return 0;
 out_err:
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 6ed859d..94872b2 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4485,6 +4485,14 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
 	ext4_debug("freeing block %llu\n", block);
 	trace_ext4_free_blocks(inode, block, count, flags);
 
+	if (flags & EXT4_FREE_BLOCKS_ZERO) {
+		err = sb_issue_zeroout(inode->i_sb, block, count, GFP_NOFS);
+		if (err < 0)
+			goto error_return;
+		else
+			err = 0;
+	}
+
 	if (flags & EXT4_FREE_BLOCKS_FORGET) {
 		struct buffer_head *tbh = bh;
 		int i;
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index c757adc..1ff7532 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -471,7 +471,7 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 			 struct buffer_head *bh)
 {
 	struct mb_cache_entry *ce = NULL;
-	int error = 0;
+	int free_blocks_flags, error = 0;
 
 	ce = mb_cache_entry_get(ext4_xattr_cache, bh->b_bdev, bh->b_blocknr);
 	error = ext4_journal_get_write_access(handle, bh);
@@ -484,9 +484,13 @@ ext4_xattr_release_block(handle_t *handle, struct inode *inode,
 		if (ce)
 			mb_cache_entry_free(ce);
 		get_bh(bh);
-		ext4_free_blocks(handle, inode, bh, 0, 1,
-				 EXT4_FREE_BLOCKS_METADATA |
-				 EXT4_FREE_BLOCKS_FORGET);
+		free_blocks_flags = EXT4_FREE_BLOCKS_METADATA |
+					EXT4_FREE_BLOCKS_FORGET;
+
+		if (EXT4_I(inode)->i_flags & EXT4_SECRM_FL)
+			free_blocks_flags |= EXT4_FREE_BLOCKS_ZERO;
+
+		ext4_free_blocks(handle, inode, bh, 0, 1, free_blocks_flags);
 	} else {
 		le32_add_cpu(&BHDR(bh)->h_refcount, -1);
 		error = ext4_handle_dirty_metadata(handle, inode, bh);
-- 
1.7.1

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