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From: Chandan Rajendra <chandan@linux.vnet.ibm.com>
To: linux-ext4@vger.kernel.org
Cc: Chandan Rajendra <chandan@linux.vnet.ibm.com>,
	linux-fsdevel@vger.kernel.org, tytso@mit.edu
Subject: [RFC PATCH 4/8] ext4: decrypt all boundary blocks when doing buffered write
Date: Fri, 12 Jan 2018 19:41:25 +0530	[thread overview]
Message-ID: <20180112141129.27507-5-chandan@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180112141129.27507-1-chandan@linux.vnet.ibm.com>

With block size < page size, ext4_block_write_begin() may have two
blocks to decrypt. Hence this commit invokes fscrypt_decrypt_page() for
those blocks.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
---
 fs/ext4/inode.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 6f6589e..d3baa15 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1158,12 +1158,13 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 	unsigned to = from + len;
 	struct inode *inode = page->mapping->host;
 	unsigned block_start, block_end;
-	sector_t block;
+	sector_t block, page_blk_nr;
 	int err = 0;
 	unsigned blocksize = inode->i_sb->s_blocksize;
 	unsigned bbits;
 	struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
 	bool decrypt = false;
+	int i;
 
 	BUG_ON(!PageLocked(page));
 	BUG_ON(from > PAGE_SIZE);
@@ -1224,16 +1225,28 @@ static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
 	/*
 	 * If we issued read requests, let them complete.
 	 */
-	while (wait_bh > wait) {
-		wait_on_buffer(*--wait_bh);
-		if (!buffer_uptodate(*wait_bh))
+	for (i = 0; (wait + i) < wait_bh; i++) {
+		wait_on_buffer(wait[i]);
+		if (!buffer_uptodate(wait[i]))
 			err = -EIO;
 	}
-	if (unlikely(err))
+	if (unlikely(err)) {
 		page_zero_new_buffers(page, from, to);
-	else if (decrypt)
-		err = fscrypt_decrypt_page(page->mapping->host, page,
-				PAGE_SIZE, 0, page->index);
+	} else if (decrypt) {
+		page_blk_nr = (sector_t)page->index << (PAGE_SHIFT - bbits);
+
+		while (wait_bh > wait) {
+			--wait_bh;
+			block = page_blk_nr + (bh_offset(*wait_bh) >> bbits);
+			err = fscrypt_decrypt_page(page->mapping->host, page,
+						(*wait_bh)->b_size,
+						bh_offset(*wait_bh),
+						block);
+			if (err)
+				break;
+		}
+	}
+
 	return err;
 }
 #endif
-- 
2.9.5

  parent reply	other threads:[~2018-01-12 14:10 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-12 14:11 [RFC PATCH 0/8] Ext4 encryption support for blocksize < pagesize Chandan Rajendra
2018-01-12 14:11 ` [RFC PATCH 1/8] ext4: use EXT4_INODE_ENCRYPT flag to detect encrypted bio Chandan Rajendra
2018-01-12 19:04   ` Randy Dunlap
2018-01-13  5:22     ` Chandan Rajendra
2018-01-12 14:11 ` [RFC PATCH 2/8] fs/buffer.c: make some functions non-static Chandan Rajendra
2018-01-12 14:38   ` Matthew Wilcox
2018-01-13  5:25     ` Chandan Rajendra
2018-01-17  2:14   ` Eric Biggers
2018-01-12 14:11 ` [RFC PATCH 3/8] ext4: decrypt all contiguous blocks in a page Chandan Rajendra
2018-01-17  2:18   ` Eric Biggers
2018-01-12 14:11 ` Chandan Rajendra [this message]
2018-01-17  2:22   ` [RFC PATCH 4/8] ext4: decrypt all boundary blocks when doing buffered write Eric Biggers
2018-01-12 14:11 ` [RFC PATCH 5/8] ext4: decrypt the block that needs to be partially zeroed Chandan Rajendra
2018-01-17  2:23   ` Eric Biggers
2018-01-12 14:11 ` [RFC PATCH 6/8] ext4: encrypt blocks whose size is less than page size Chandan Rajendra
2018-01-17  2:33   ` Eric Biggers
2018-01-12 14:11 ` [RFC PATCH 7/8] ext4: decrypt " Chandan Rajendra
2018-01-17  2:39   ` Eric Biggers
2018-01-12 14:11 ` [RFC PATCH 8/8] ext4: enable encryption for blocksize " Chandan Rajendra
2018-01-17  2:40   ` Eric Biggers
2018-01-17 13:42     ` Chandan Rajendra
2018-01-12 19:07 ` [RFC PATCH 0/8] Ext4 encryption support for blocksize < pagesize Randy Dunlap
2018-01-13  5:28   ` Chandan Rajendra
2018-01-13 12:48     ` Matthew Wilcox
2018-01-13 18:20       ` Randy Dunlap
2018-01-17  2:10 ` Eric Biggers
2018-01-17 13:43   ` Chandan Rajendra

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