Re: [PATCH v2] jbd2: gate checksum calculations on crc driver presence, not sb flags

Nikolay Borisov
2015-10-05T06:28:47Z

On 10/05/2015 09:21 AM, Darrick J. Wong wrote:
> On Mon, Oct 05, 2015 at 08:43:34AM +0300, Nikolay Borisov wrote:
>> It is just me or am I not seeing this feature test helper in this patch ?
>>
>> On 10/03/2015 06:46 AM, Darrick J. Wong wrote:
>>> Change the journal's checksum functions to gate on whether or not the
>>> crc32c driver is loaded, and gate the loading on the superblock bits.
>>> This prevents a journal crash if someone loads a journal in no-csum
>>> mode and then randomizes the superblock, thus flipping on the feature
>>> bits.
>>>
>>> v2: Create a feature-test helper, use it everywhere.
>>>
>>> Tested-By: Nikolay Borisov <kernel@kyup.com>
>>> Reported-by: Nikolay Borisov <kernel@kyup.com>
>>> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
>>> ---
>>> fs/jbd2/journal.c | 6 +++---
>>> include/linux/jbd2.h | 13 +++++++++----
>>> 2 files changed, 12 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
>>> index 8270fe9..00f7dbd 100644
>>> --- a/fs/jbd2/journal.c
>>> +++ b/fs/jbd2/journal.c
>>> @@ -124,7 +124,7 @@ EXPORT_SYMBOL(__jbd2_debug);
>>> /* Checksumming functions */
>>> static int jbd2_verify_csum_type(journal_t *j, journal_superblock_t *sb)
>>> {
>>> - if (!jbd2_journal_has_csum_v2or3(j))
>>> + if (!jbd2_journal_has_csum_v2or3_feature(j))
>>> return 1;
>>>
>>> return sb->s_checksum_type == JBD2_CRC32C_CHKSUM;
>>> @@ -1531,7 +1531,7 @@ static int journal_get_superblock(journal_t *journal)
>>> goto out;
>>> }
>>>
>>> - if (jbd2_journal_has_csum_v2or3(journal) &&
>>> + if (jbd2_journal_has_csum_v2or3_feature(journal) &&
>>> JBD2_HAS_COMPAT_FEATURE(journal, JBD2_FEATURE_COMPAT_CHECKSUM)) {
>>> /* Can't have checksum v1 and v2 on at the same time! */
>>> printk(KERN_ERR "JBD2: Can't enable checksumming v1 and v2/3 "
>>> @@ -1545,7 +1545,7 @@ static int journal_get_superblock(journal_t *journal)
>>> }
>>>
>>> /* Load the checksum driver */
>>> - if (jbd2_journal_has_csum_v2or3(journal)) {
>>> + if (jbd2_journal_has_csum_v2or3_feature(journal)) {
>>> journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0);
>>> if (IS_ERR(journal->j_chksum_driver)) {
>>> printk(KERN_ERR "JBD2: Cannot load crc32c driver.\n");
>>> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
>>> index df07e78..6da6f89 100644
>>> --- a/include/linux/jbd2.h
>>> +++ b/include/linux/jbd2.h
>>> @@ -1338,13 +1338,18 @@ static inline int tid_geq(tid_t x, tid_t y)
>>> extern int jbd2_journal_blocks_per_page(struct inode *inode);
>>> extern size_t journal_tag_bytes(journal_t *journal);
>>>
>>> +static inline bool jbd2_journal_has_csum_v2or3_feature(journal_t *j)
>
> Here ^^^^^^^^^^^^^^^
>

But you had this function in v1 as well? I thought you had integrated
Andreas' suggestion?

> --D
>
>>> +{
>>> + return JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2) ||
>>> + JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V3);
>>> +}
>>> +
>>> static inline int jbd2_journal_has_csum_v2or3(journal_t *journal)
>>> {
>>> - if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2) ||
>>> - JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V3))
>>> - return 1;
>>> + WARN_ON_ONCE(jbd2_journal_has_csum_v2or3_feature(journal) &&
>>> + journal->j_chksum_driver == NULL);
>>>
>>> - return 0;
>>> + return journal->j_chksum_driver != NULL;
>>> }
>>>
>>> /*
>>>