[v3,08/16] btrfs: dedup: Implement btrfs_dedup_calc_hash interface

Commit Message

Qu Wenruo Jan. 7, 2016, 1:08 a.m. UTC

From: Wang Xiaoguang <[e-mail]>

Unlike in-memory or on-disk dedup method, only SHA256 hash method is
supported yet, so implement btrfs_dedup_calc_hash() interface using
SHA256.

Signed-off-by: Qu Wenruo <[e-mail]>
Signed-off-by: Wang Xiaoguang <[e-mail]>
---
 fs/btrfs/dedup.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

Comments

kernel test robot Jan. 7, 2016, 1:21 p.m. UTC | #1

Hi Wang,

[auto build test WARNING on tip/perf/core]
[also build test WARNING on v4.4-rc8]
[cannot apply to btrfs/next next-20160106]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Qu-Wenruo/btrfs-dedup-Introduce-dedup-framework-and-its-header/20160107-091211
config: s390-allmodconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=s390 

All warnings (new ones prefixed by >>):

   fs/btrfs/dedup.c: In function 'btrfs_dedup_calc_hash':
>> fs/btrfs/dedup.c:558:1: warning: 'btrfs_dedup_calc_hash' uses dynamic stack allocation
    }
    ^

vim +/btrfs_dedup_calc_hash +558 fs/btrfs/dedup.c

   542			return -ENOMEM;
   543		for (i = 0; sectorsize * i < dedup_bs; i++) {
   544			char *d;
   545	
   546			/* TODO: Add support for subpage size case */
   547			p = find_get_page(inode->i_mapping,
   548					  (start >> PAGE_CACHE_SHIFT) + i);
   549			WARN_ON(!p);
   550			d = kmap_atomic(p);
   551			memcpy((data + sectorsize * i), d, sectorsize);
   552			kunmap_atomic(d);
   553			page_cache_release(p);
   554		}
   555		ret = hash_data(dedup_info, data, dedup_bs, hash);
   556		kfree(data);
   557		return ret;
 > 558	}

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

Patch

diff --git a/fs/btrfs/dedup.c b/fs/btrfs/dedup.c
index 4863cf2..4f24a2c 100644
--- a/fs/btrfs/dedup.c
+++ b/fs/btrfs/dedup.c
@@ -499,3 +499,60 @@  int btrfs_dedup_search(struct inode *inode, u64 file_pos,
 	}
 	return ret;
 }
+
+static int hash_data(struct btrfs_dedup_info *dedup_info, const char *data,
+		     u64 length, struct btrfs_dedup_hash *hash)
+{
+	struct crypto_shash *tfm = dedup_info->dedup_driver;
+	struct {
+		struct shash_desc desc;
+		char ctx[crypto_shash_descsize(tfm)];
+	} sdesc;
+	int ret;
+
+	sdesc.desc.tfm = tfm;
+	sdesc.desc.flags = 0;
+
+	ret = crypto_shash_digest(&sdesc.desc, data, length,
+				  (char *)(hash->hash));
+	return ret;
+}
+
+int btrfs_dedup_calc_hash(struct btrfs_root *root, struct inode *inode,
+			  u64 start, struct btrfs_dedup_hash *hash)
+{
+	struct page *p;
+	struct btrfs_dedup_info *dedup_info = root->fs_info->dedup_info;
+	char *data;
+	int i;
+	int ret;
+	u64 dedup_bs;
+	u64 sectorsize = root->sectorsize;
+
+	if (!dedup_info || !hash)
+		return 0;
+
+	WARN_ON(!IS_ALIGNED(start, sectorsize));
+
+	dedup_bs = dedup_info->blocksize;
+	sectorsize = root->sectorsize;
+
+	data = kmalloc(dedup_bs, GFP_NOFS);
+	if (!data)
+		return -ENOMEM;
+	for (i = 0; sectorsize * i < dedup_bs; i++) {
+		char *d;
+
+		/* TODO: Add support for subpage size case */
+		p = find_get_page(inode->i_mapping,
+				  (start >> PAGE_CACHE_SHIFT) + i);
+		WARN_ON(!p);
+		d = kmap_atomic(p);
+		memcpy((data + sectorsize * i), d, sectorsize);
+		kunmap_atomic(d);
+		page_cache_release(p);
+	}
+	ret = hash_data(dedup_info, data, dedup_bs, hash);
+	kfree(data);
+	return ret;
+}