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Commit 0441984a authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Theodore Ts'o
Browse files

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: default avatarDarrick J. Wong <djwong@us.ibm.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent d25425f8

fs/ext4/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -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.

fs/ext4/ext4.h

+23 −0
Original line number Diff line number Diff line
@@ -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 */

fs/ext4/super.c

+16 −0
Original line number Diff line number Diff line
@@ -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);