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Message-Id: <1317971465-8517-4-git-send-email-achender@linux.vnet.ibm.com>
Date: Fri, 7 Oct 2011 00:11:01 -0700
From: Allison Henderson <achender@...ux.vnet.ibm.com>
To: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org
Cc: Allison Henderson <achender@...ux.vnet.ibm.com>
Subject: [Ext4 Secure Delete 3/7v4] ext4: Secure Delete: Add secure delete functions
This patch adds two new routines: ext4_secure_delete_pblks
and ext4_secure_delete_lblks.
ext4_secure_delete_pblks() will write zeros to the specified
physical blocks or random data if the EXT4_SECRM_RANDOM_FL flag is
set. If the device supports secure discard, the secure
discard will be used instead. ext4_secure_delete_lblks handels walking
the logical blocks of a file and calling ext4_secure_delete_pblks()
as needed.
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
v3->v4
Discard code will be kept in the vfs layer. Code
for secure delete is now in its own function,
ext4_secure_delete_pblks and is called
by a new function ext4_secure_delete_lblks
before any blocks are released
:100644 100644 5c9f88c... 34f82a1... M fs/ext4/ext4.h
:100644 100644 095c36f... 10180e3... M fs/ext4/ext4_extents.h
:100644 100644 57cf568... 40d4e50... M fs/ext4/extents.c
:100644 100644 9dc8c14... 0a526c4... M fs/ext4/inode.c
fs/ext4/ext4.h | 5 +
fs/ext4/ext4_extents.h | 2 +
fs/ext4/extents.c | 2 +-
fs/ext4/inode.c | 196 ++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 204 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 5c9f88c..34f82a1 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2220,6 +2220,11 @@ extern int ext4_map_blocks(handle_t *handle, struct inode *inode,
struct ext4_map_blocks *map, int flags);
extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
__u64 start, __u64 len);
+extern int ext4_secure_delete_lblks(struct inode *inode,
+ ext4_lblk_t first_block, unsigned long count);
+extern int ext4_secure_delete_pblks(struct inode *inode,
+ ext4_fsblk_t block, unsigned long count);
+
/* move_extent.c */
extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
__u64 start_orig, __u64 start_donor,
diff --git a/fs/ext4/ext4_extents.h b/fs/ext4/ext4_extents.h
index 095c36f..10180e3 100644
--- a/fs/ext4/ext4_extents.h
+++ b/fs/ext4/ext4_extents.h
@@ -290,5 +290,7 @@ extern struct ext4_ext_path *ext4_ext_find_extent(struct inode *, ext4_lblk_t,
struct ext4_ext_path *);
extern void ext4_ext_drop_refs(struct ext4_ext_path *);
extern int ext4_ext_check_inode(struct inode *inode);
+extern int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
+ struct ext4_ext_cache *ex);
#endif /* _EXT4_EXTENTS */
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 57cf568..40d4e50 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -2034,7 +2034,7 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
*
* Return 0 if cache is invalid; 1 if the cache is valid
*/
-static int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
+int ext4_ext_check_cache(struct inode *inode, ext4_lblk_t block,
struct ext4_ext_cache *ex){
struct ext4_ext_cache *cex;
struct ext4_sb_info *sbi;
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9dc8c14..0a526c4 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -38,6 +38,7 @@
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/ratelimit.h>
+#include <linux/random.h>
#include "ext4_jbd2.h"
#include "xattr.h"
@@ -713,6 +714,201 @@ static int ext4_ind_hole_lookup(struct inode *inode, ext4_lblk_t block)
return 0;
}
+
+/*
+ * ext4_secure_delete_pblks
+ *
+ * Securely delete physical blocks.
+ * If the devices supports secure discard,
+ * blocks will be discarded. Otherwise
+ * the blocks will be either zeroed or
+ * randomized if the random secure delete
+ * flag is on
+ *
+ * inode: The files inode
+ * block: The physical block at which to start deleteing
+ * count: The number of blocks to delete
+ *
+ * Returns 0 on sucess or negative on error
+ */
+int ext4_secure_delete_pblks(struct inode *inode, ext4_fsblk_t block,
+ unsigned long count){
+
+ struct fstrim_range range;
+ ext4_fsblk_t iblock, last_block;
+ struct buffer_head *bh;
+ struct super_block *sb = inode->i_sb;
+ struct request_queue *q = bdev_get_queue(sb->s_bdev);
+ struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es;
+ int err = 0;
+
+ last_block = block + count;
+ /*
+ * Check to see if the device supports secure discard,
+ * And also that read after discard returns zeros
+ */
+ if (blk_queue_secdiscard(q) && q->limits.discard_zeroes_data) {
+ err = sb_issue_discard(sb, block, count,
+ GFP_NOFS, BLKDEV_DISCARD_SECURE);
+ if (err)
+ goto zero_out;
+
+ range.start = block;
+ range.len = count;
+ range.minlen = 1;
+ err = ext4_trim_fs(sb, &range);
+
+ if (err)
+ goto zero_out;
+
+ return 0;
+ }
+
+ if (EXT4_I(inode)->i_flags & EXT4_SECRM_RANDOM_FL) {
+ for (iblock = block; iblock < last_block; iblock++) {
+ bh = sb_getblk(sb, iblock);
+ get_random_bytes(bh->b_data, bh->b_size);
+ set_buffer_dirty(bh);
+
+ sync_dirty_buffer(bh);
+ if (buffer_req(bh) && !buffer_uptodate(bh)) {
+ es->s_last_error_block =
+ cpu_to_le64(bh->b_blocknr);
+ ext4_error_inode(inode, __func__,
+ __LINE__, bh->b_blocknr,
+ "IO error syncing itable block");
+ err = -EIO;
+ brelse(bh);
+ goto zero_out;
+ }
+ brelse(bh);
+ }
+ return 0;
+ }
+
+zero_out:
+ return sb_issue_zeroout(sb, block, count, GFP_NOFS);
+
+}
+
+/*
+ * ext4_secure_delete_lblks
+ *
+ * Secure deletes the data blocks of a file
+ * starting at the given logical block
+ *
+ * @inode: The files inode
+ * @first_block: Starting logical block
+ * @count: The number of blocks to secure delete
+ *
+ * Returns 0 on sucess or negative on error
+ */
+int ext4_secure_delete_lblks(struct inode *inode, ext4_lblk_t first_block,
+ unsigned long count){
+ handle_t *handle;
+ struct ext4_map_blocks map;
+ struct ext4_ext_cache cache_ex;
+ ext4_lblk_t num_blocks, max_blocks = 0;
+ ext4_lblk_t last_block = first_block + count;
+ ext4_lblk_t iblock = first_block;
+ int ret, credits, hole_len, err = 0;
+
+ credits = ext4_writepage_trans_blocks(inode);
+ handle = ext4_journal_start(inode, credits);
+ if (IS_ERR(handle))
+ return PTR_ERR(handle);
+
+ down_write(&EXT4_I(inode)->i_data_sem);
+ ext4_ext_invalidate_cache(inode);
+ ext4_discard_preallocations(inode);
+
+ /* Do not allow last_block to wrap when caller passes EXT_MAX_BLOCK */
+ if (last_block < first_block)
+ last_block = EXT_MAX_BLOCKS;
+
+ while (iblock < last_block) {
+ max_blocks = last_block - iblock;
+ num_blocks = 1;
+ memset(&map, 0, sizeof(map));
+ map.m_lblk = iblock;
+ map.m_len = max_blocks;
+
+ if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
+ ret = ext4_ext_map_blocks(handle, inode, &map, 0);
+ else
+ ret = ext4_ind_map_blocks(handle, inode, &map, 0);
+
+ if (ret > 0) {
+ err = ext4_secure_delete_pblks(inode,
+ map.m_pblk, map.m_len);
+ if (err)
+ break;
+ num_blocks = ret;
+ } else if (ret == 0) {
+ if (ext4_test_inode_flag(inode,
+ EXT4_INODE_EXTENTS)) {
+ /*
+ * If map blocks could not find the block,
+ * then it is in a hole. If the hole was
+ * not already cached, then map blocks should
+ * put it in the cache. So we can get the hole
+ * out of the cache
+ */
+ memset(&cache_ex, 0, sizeof(cache_ex));
+ if ((ext4_ext_check_cache(inode, iblock,
+ &cache_ex)) && !cache_ex.ec_start) {
+
+ /* The hole is cached */
+ num_blocks = cache_ex.ec_block +
+ cache_ex.ec_len - iblock;
+
+ } else {
+ /* reached EOF of extent file */
+ break;
+ }
+ } else {
+ hole_len = ext4_ind_hole_lookup(inode, iblock);
+
+ if (hole_len > 0) {
+ /* Skip over the hole */
+ num_blocks = hole_len;
+ } else if (hole_len == 0) {
+ /* No hole, EOF reached */
+ break;
+ } else {
+ /* Hole look up err */
+ err = hole_len;
+ break;
+ }
+ }
+ } else {
+ /* Map blocks error */
+ err = ret;
+ break;
+ }
+
+ if (num_blocks == 0) {
+ /* This condition should never happen */
+ ext_debug("Block lookup failed");
+ err = -EIO;
+ break;
+ }
+
+ iblock += num_blocks;
+ }
+
+ if (IS_SYNC(inode))
+ ext4_handle_sync(handle);
+
+ up_write(&EXT4_I(inode)->i_data_sem);
+
+ inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
+ ext4_mark_inode_dirty(handle, inode);
+ ext4_journal_stop(handle);
+
+ return err;
+}
+
struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
ext4_lblk_t block, int create, int *err)
{
--
1.7.1
--
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