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Date: Fri, 01 Jul 2011 09:21:20 -0700
From: Allison Henderson <achender@...ux.vnet.ibm.com>
To: Lukas Czerner <lczerner@...hat.com>
CC: linux-ext4@...r.kernel.org
Subject: Re: [PATCH 1/2 v3] EXT4: Secure Delete: Zero out file data
On 07/01/2011 03:26 AM, Lukas Czerner wrote:
> On Thu, 30 Jun 2011, Allison Henderson wrote:
>
>> 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
>
> Hi Allison,
>
> the patch looks good, however I have one little nitpick bellow:)
>>
>> 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;
>
> No need to set err=0. sb_issue_zeroout() will return zero on success.
>
> Thanks!
> -Lukas
Ah, alrighty, I will pull that out. Thx! :)
Allison
>
>> + }
>> +
>> 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);
>>
>
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