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ext4: load the crc32c driver if necessary 

Obtain a reference to the cryptoapi and crc32c if we mount a
filesystem with metadata checksumming enabled.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Darrick J. Wong 2012-04-29 18:27:10 -04:00 committed by Theodore Ts'o
parent d25425f8e0
commit 0441984a33
3 changed files with 41 additions and 0 deletions
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2
fs/ext4/Kconfig
View File

@ -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.

23
fs/ext4/ext4.h
View File

@ -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
@ -1276,6 +1277,9 @@ struct ext4_sb_info {
/* record the last minlen when FITRIM is called. */
atomic_t s_last_trim_minblks;
/* 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)
@ -1639,6 +1643,25 @@ 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 */

16
fs/ext4/super.c
View File

@ -915,6 +915,8 @@ 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);
}
@ -3043,6 +3045,18 @@ 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)) {
ext4_msg(sb, KERN_ERR, "Cannot load crc32c 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);
@ -3728,6 +3742,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
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("options", sbi->s_proc);
remove_proc_entry(sb->s_id, ext4_proc_root);