use-transaction-when-adding-crypto-policy

   1 ext4 crypto: use a jbd2 transaction when adding a crypto policy
   2
   3 Start a jbd2 transaction, and mark the inode dirty on the inode under
   4 that transaction after setting the encrypt flag.  Otherwise if the
   5 directory isn't modified after setting the crypto policy, the
   6 encrypted flag might not survive the inode getting pushed out from
   7 memory, or the the file system getting unmounted and remounted.
   8
   9 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  10 ---
  11  fs/ext4/crypto_policy.c | 17 +++++++++++++++--
  12  1 file changed, 15 insertions(+), 2 deletions(-)
  13
  14 diff --git a/fs/ext4/crypto_policy.c b/fs/ext4/crypto_policy.c
  15 index 02c4e5d..a640ec2 100644
  16 --- a/fs/ext4/crypto_policy.c
  17 +++ b/fs/ext4/crypto_policy.c
  18 @@ -12,6 +12,7 @@
  19  #include <linux/string.h>
  20  #include <linux/types.h>
  21
  22 +#include "ext4_jbd2.h"
  23  #include "ext4.h"
  24  #include "xattr.h"
  25
  26 @@ -49,7 +50,8 @@ static int ext4_create_encryption_context_from_policy(
  27         struct inode *inode, const struct ext4_encryption_policy *policy)
  28  {
  29         struct ext4_encryption_context ctx;
  30 -       int res = 0;
  31 +       handle_t *handle;
  32 +       int res, res2;
  33
  34         res = ext4_convert_inline_data(inode);
  35         if (res)
  36 @@ -78,11 +80,22 @@ static int ext4_create_encryption_context_from_policy(
  37         BUILD_BUG_ON(sizeof(ctx.nonce) != EXT4_KEY_DERIVATION_NONCE_SIZE);
  38         get_random_bytes(ctx.nonce, EXT4_KEY_DERIVATION_NONCE_SIZE);
  39
  40 +       handle = ext4_journal_start(inode, EXT4_HT_MISC,
  41 +                                   ext4_jbd2_credits_xattr(inode));
  42 +       if (IS_ERR(handle))
  43 +               return PTR_ERR(handle);
  44         res = ext4_xattr_set(inode, EXT4_XATTR_INDEX_ENCRYPTION,
  45                              EXT4_XATTR_NAME_ENCRYPTION_CONTEXT, &ctx,
  46                              sizeof(ctx), 0);
  47 -       if (!res)
  48 +       if (!res) {
  49                 ext4_set_inode_flag(inode, EXT4_INODE_ENCRYPT);
  50 +               res = ext4_mark_inode_dirty(handle, inode);
  51 +               if (res)
  52 +                       EXT4_ERROR_INODE(inode, "Failed to mark inode dirty");
  53 +       }
  54 +       res2 = ext4_journal_stop(handle);
  55 +       if (!res)
  56 +               res = res2;
  57         return res;
  58  }
  59