From 41eb70dde42b2360074a559a6f1fc49860a50179 Mon Sep 17 00:00:00 2001 From: Tao Ma Date: Mon, 9 Jul 2012 16:29:27 -0400 Subject: [PATCH] ext4: use s_csum_seed instead of i_csum_seed for xattr block In xattr block operation, we use h_refcount to indicate whether the xattr block is shared among many inodes. And xattr block csum uses s_csum_seed if it is shared and i_csum_seed if it belongs to one inode. But this has a problem. So consider the block is shared first bewteen inode A and B, and B has some xattr update and CoW the xattr block. When it updates the *old* xattr block(because of the h_refcount change) and calls ext4_xattr_release_block, we has no idea that inode A is the real owner of the *old* xattr block and we can't use the i_csum_seed of inode A either in xattr block csum calculation. And I don't think we have an easy way to find inode A. So this patch just removes the tricky i_csum_seed and we now uses s_csum_seed every time for the xattr block csum. The corresponding patch for the e2fsprogs will be sent in another patch. This is spotted by xfstests 117. Signed-off-by: Tao Ma Signed-off-by: "Theodore Ts'o" Acked-by: Darrick J. Wong --- fs/ext4/xattr.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index e56c9ed7d6e3..2cdb98d62980 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -127,19 +127,16 @@ static __le32 ext4_xattr_block_csum(struct inode *inode, struct ext4_xattr_header *hdr) { struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); - struct ext4_inode_info *ei = EXT4_I(inode); __u32 csum, old; old = hdr->h_checksum; hdr->h_checksum = 0; - if (le32_to_cpu(hdr->h_refcount) != 1) { - block_nr = cpu_to_le64(block_nr); - csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&block_nr, - sizeof(block_nr)); - } else - csum = ei->i_csum_seed; + block_nr = cpu_to_le64(block_nr); + csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&block_nr, + sizeof(block_nr)); csum = ext4_chksum(sbi, csum, (__u8 *)hdr, EXT4_BLOCK_SIZE(inode->i_sb)); + hdr->h_checksum = old; return cpu_to_le32(csum); } -- 2.20.1