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

Nikolay Borisov
2015-10-05T05:43:44Z

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)
> +{
> + 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;
> }
>
> /*
>