lkml.org 
[lkml]   [2012]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Subject[PATCH 04/23] ext4: Only call out to crc32c if necessary
From
Date
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 | 16 ++++++++++++++++
3 files changed, 41 insertions(+), 0 deletions(-)


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 0f0b0d5..a4b2689 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
@@ -1269,6 +1270,9 @@ 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)
@@ -1631,6 +1635,25 @@ 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 38de050..cfd8aa3 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);
}
@@ -3196,6 +3198,18 @@ 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);
@@ -3879,6 +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);
}


\
 
 \ /
  Last update: 2012-03-06 21:57    [W:0.142 / U:34.544 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site