From: Andreas Dilger Subject: Re: [PATCH 1/2 v3] EXT4: Secure Delete: Zero out file data Date: Thu, 30 Jun 2011 16:15:58 -0600 Message-ID: <0B56FD8D-DCE5-4FB1-A97D-25EC1CD3CA14@dilger.ca> References: <1309468923-5677-1-git-send-email-achender@linux.vnet.ibm.com> <1309468923-5677-2-git-send-email-achender@linux.vnet.ibm.com> Mime-Version: 1.0 (Apple Message framework v1082) Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8BIT Cc: linux-ext4@vger.kernel.org To: Allison Henderson Return-path: Received: from idcmail-mo1so.shaw.ca ([24.71.223.10]:47803 "EHLO idcmail-mo1so.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752775Ab1F3WQB convert rfc822-to-8bit (ORCPT ); Thu, 30 Jun 2011 18:16:01 -0400 In-Reply-To: <1309468923-5677-2-git-send-email-achender@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2011-06-30, at 3:22 PM, 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 > > Signed-off-by: Allison Henderson > --- > 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); Does sb_issue_zeroout() use the SCSI "write same" feature in the background? That would avoid busying the CPU/controller/bus with writing out zeroes, which might be expensive for a large file. > + 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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-ext4" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Cheers, Andreas