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

Darrick J. Wong
2015-10-05T06:21:46Z

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 ^^^^^^^^^^^^^^^

--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;
> > }
> >
> > /*
> >