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Message-ID: <4E0D1AC4.6020003@linux.vnet.ibm.com> Date: Thu, 30 Jun 2011 17:54:28 -0700 From: Allison Henderson <achender@...ux.vnet.ibm.com> To: Andreas Dilger <adilger@...ger.ca> CC: linux-ext4@...r.kernel.org Subject: Re: [PATCH 1/2 v3] EXT4: Secure Delete: Zero out file data On 06/30/2011 03:15 PM, Andreas Dilger wrote: > 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<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); > > 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. > Hmm, that's a good question, I will dig into it and see if I can find out. >> + 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@...r.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > > > Cheers, Andreas > > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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