From: "Darrick J. Wong" Subject: [PATCH 17/23] jbd2: Grab a reference to the crc32c driver only when necessary Date: Tue, 06 Mar 2012 12:49:55 -0800 Message-ID: <20120306204955.1663.23204.stgit@elm3b70.beaverton.ibm.com> References: <20120306204750.1663.96751.stgit@elm3b70.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: Sunil Mushran , Martin K Petersen , Greg Freemyer , Amir Goldstein , linux-kernel , Andi Kleen , Mingming Cao , Joel Becker , linux-fsdevel , linux-ext4@vger.kernel.org, Coly Li To: Andreas Dilger , Theodore Tso , "Darrick J. Wong" Return-path: In-Reply-To: <20120306204750.1663.96751.stgit@elm3b70.beaverton.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Obtain a reference to the crc32c driver only when the journal needs it for checksum v2. Signed-off-by: Darrick J. Wong --- fs/jbd2/Kconfig | 2 ++ fs/jbd2/journal.c | 25 +++++++++++++++++++++++++ include/linux/jbd2.h | 23 +++++++++++++++++++++++ 3 files changed, 50 insertions(+), 0 deletions(-) diff --git a/fs/jbd2/Kconfig b/fs/jbd2/Kconfig index f32f346..69a48c2 100644 --- a/fs/jbd2/Kconfig +++ b/fs/jbd2/Kconfig @@ -1,6 +1,8 @@ config JBD2 tristate select CRC32 + select CRYPTO + select CRYPTO_CRC32C help This is a generic journaling layer for block devices that support both 32-bit and 64-bit block numbers. It is currently used by diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index ac276b0..554f899 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1284,6 +1284,17 @@ static int journal_get_superblock(journal_t *journal) goto out; } + /* Load the checksum driver */ + if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) { + journal->j_chksum_driver = crypto_alloc_shash("crc32c", 0, 0); + if (IS_ERR(journal->j_chksum_driver)) { + printk(KERN_ERR "JBD: Cannot load crc32c driver.\n"); + err = PTR_ERR(journal->j_chksum_driver); + journal->j_chksum_driver = NULL; + goto out; + } + } + set_buffer_verified(bh); return 0; @@ -1440,6 +1451,8 @@ int jbd2_journal_destroy(journal_t *journal) iput(journal->j_inode); if (journal->j_revoke) jbd2_journal_destroy_revoke(journal); + if (journal->j_chksum_driver) + crypto_free_shash(journal->j_chksum_driver); kfree(journal->j_wbuf); kfree(journal); @@ -1556,6 +1569,18 @@ int jbd2_journal_set_features (journal_t *journal, unsigned long compat, sb->s_checksum_type = JBD2_CRC32C_CHKSUM; sb->s_feature_compat &= ~cpu_to_be32(JBD2_FEATURE_COMPAT_CHECKSUM); + + /* Load the checksum driver */ + if (journal->j_chksum_driver == NULL) { + journal->j_chksum_driver = crypto_alloc_shash("crc32c", + 0, 0); + if (IS_ERR(journal->j_chksum_driver)) { + printk(KERN_ERR "JBD: Cannot load crc32c " + "driver.\n"); + journal->j_chksum_driver = NULL; + return 0; + } + } } /* If enabling v1 checksums, downgrade superblock */ diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h index c286153..320de7d 100644 --- a/include/linux/jbd2.h +++ b/include/linux/jbd2.h @@ -31,6 +31,7 @@ #include #include #include +#include #endif #define journal_oom_retry 1 @@ -965,6 +966,9 @@ struct journal_s * superblock pointer here */ void *j_private; + + /* Reference to checksum algorithm driver via cryptoapi */ + struct crypto_shash *j_chksum_driver; }; /* @@ -1284,6 +1288,25 @@ static inline int jbd_space_needed(journal_t *journal) extern int jbd_blocks_per_page(struct inode *inode); +static inline u32 jbd2_chksum(journal_t *journal, u32 crc, + const void *address, unsigned int length) +{ + struct { + struct shash_desc shash; + char ctx[crypto_shash_descsize(journal->j_chksum_driver)]; + } desc; + int err; + + desc.shash.tfm = journal->j_chksum_driver; + desc.shash.flags = 0; + *(u32 *)desc.ctx = crc; + + err = crypto_shash_update(&desc.shash, address, length); + BUG_ON(err); + + return *(u32 *)desc.ctx; +} + #ifdef __KERNEL__ #define buffer_trace_init(bh) do {} while (0)