| Message ID | 20111128232642.19194.80905.stgit@elm3c44.beaverton.ibm.com |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Mon, Nov 28, 2011 at 03:26:43PM -0800, Darrick J. Wong wrote: > + /* Load the checksum driver */ > + if (EXT4_HAS_RO_COMPAT_FEATURE(sb, > + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) { > + sbi->s_chksum_driver = crypto_alloc_shash("crc32c", 0, 0); > + if (IS_ERR(sbi->s_chksum_driver)) { > + ret = PTR_ERR(sbi->s_chksum_driver); > + sbi->s_chksum_driver = NULL; > + goto failed_mount; > + } > + } Unless the crypto engine printk's a message if the crc32c algorithm is not available (perhaps even if it does), it's probably going to be a good idea to issue an ext4_msg() saying that we're failing because we couldn't load the crc32c crypto module. Otherwise the user will get a mysterious failure (including a message from mount to check 'dmesg | tail'), and then when they look at the kernel messages, they won't see what might have gone wrong, and then they'll send a complaint to ext3-users or linux-ext4.... - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Dec 05, 2011 at 10:52:26AM -0500, Ted Ts'o wrote: > On Mon, Nov 28, 2011 at 03:26:43PM -0800, Darrick J. Wong wrote: > > + /* Load the checksum driver */ > > + if (EXT4_HAS_RO_COMPAT_FEATURE(sb, > > + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) { > > + sbi->s_chksum_driver = crypto_alloc_shash("crc32c", 0, 0); > > + if (IS_ERR(sbi->s_chksum_driver)) { > > + ret = PTR_ERR(sbi->s_chksum_driver); > > + sbi->s_chksum_driver = NULL; > > + goto failed_mount; > > + } > > + } > > Unless the crypto engine printk's a message if the crc32c algorithm is > not available (perhaps even if it does), it's probably going to be a > good idea to issue an ext4_msg() saying that we're failing because we > couldn't load the crc32c crypto module. Otherwise the user will get a > mysterious failure (including a message from mount to check 'dmesg | > tail'), and then when they look at the kernel messages, they won't see > what might have gone wrong, and then they'll send a complaint to > ext3-users or linux-ext4.... Ok. --D -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig index 9ed1bb1..c22f170 100644 --- a/fs/ext4/Kconfig +++ b/fs/ext4/Kconfig @@ -2,6 +2,8 @@ config EXT4_FS tristate "The Extended 4 (ext4) filesystem" select JBD2 select CRC16 + select CRYPTO + select CRYPTO_CRC32C help This is the next generation of the ext3 filesystem. diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index e496e72..eab64c2 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -29,6 +29,7 @@ #include <linux/wait.h> #include <linux/blockgroup_lock.h> #include <linux/percpu_counter.h> +#include <crypto/hash.h> #ifdef __KERNEL__ #include <linux/compat.h> #endif @@ -1255,6 +1256,9 @@ struct ext4_sb_info { /* Precomputed FS UUID checksum */ __u32 s_uuid_csum; + + /* Reference to checksum algorithm driver via cryptoapi */ + struct crypto_shash *s_chksum_driver; }; static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb) @@ -1596,6 +1600,25 @@ static inline __le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize) #define DX_HASH_HALF_MD4_UNSIGNED 4 #define DX_HASH_TEA_UNSIGNED 5 +static inline u32 ext4_chksum(struct ext4_sb_info *sbi, u32 crc, + const void *address, unsigned int length) +{ + struct { + struct shash_desc shash; + char ctx[crypto_shash_descsize(sbi->s_chksum_driver)]; + } desc; + int err; + + desc.shash.tfm = sbi->s_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__ /* hash info structure used by the directory hash */ diff --git a/fs/ext4/super.c b/fs/ext4/super.c index a56c14e..a555811 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -887,6 +887,8 @@ static void ext4_put_super(struct super_block *sb) unlock_super(sb); kobject_put(&sbi->s_kobj); wait_for_completion(&sbi->s_kobj_unregister); + if (sbi->s_chksum_driver) + crypto_free_shash(sbi->s_chksum_driver); kfree(sbi->s_blockgroup_lock); kfree(sbi); } @@ -3200,6 +3202,17 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) goto cantfind_ext4; } + /* Load the checksum driver */ + if (EXT4_HAS_RO_COMPAT_FEATURE(sb, + EXT4_FEATURE_RO_COMPAT_METADATA_CSUM)) { + sbi->s_chksum_driver = crypto_alloc_shash("crc32c", 0, 0); + if (IS_ERR(sbi->s_chksum_driver)) { + ret = PTR_ERR(sbi->s_chksum_driver); + sbi->s_chksum_driver = NULL; + goto failed_mount; + } + } + /* Set defaults before we parse the mount options */ def_mount_opts = le32_to_cpu(es->s_default_mount_opts); set_opt(sb, INIT_INODE_TABLE); @@ -3880,6 +3893,8 @@ failed_mount2: brelse(sbi->s_group_desc[i]); ext4_kvfree(sbi->s_group_desc); failed_mount: + if (sbi->s_chksum_driver) + crypto_free_shash(sbi->s_chksum_driver); if (sbi->s_proc) { remove_proc_entry(sb->s_id, ext4_proc_root); }
Only obtain a reference to the cryptoapi and crc32c if we happen to mount a filesystem with metadata checksumming enabled. Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> --- fs/ext4/Kconfig | 2 ++ fs/ext4/ext4.h | 23 +++++++++++++++++++++++ fs/ext4/super.c | 15 +++++++++++++++ 3 files changed, 40 insertions(+), 0 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html