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authorTao Ma <boyu.mt@taobao.com>2012-07-09 16:29:27 -0400
committerTheodore Ts'o <tytso@mit.edu>2012-07-09 16:29:27 -0400
commit41eb70dde42b2360074a559a6f1fc49860a50179 (patch)
treeb3820a6fb03bac0d20f551da36c62913ef3ac94e /fs/ext4/xattr.c
parentef58f69c3c34f6377f1e21d3533c806dbd980ad0 (diff)
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op-kernel-dev-41eb70dde42b2360074a559a6f1fc49860a50179.tar.gz
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 <boyu.mt@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Acked-by: Darrick J. Wong <djwong@us.ibm.com>
Diffstat (limited to 'fs/ext4/xattr.c')
-rw-r--r--fs/ext4/xattr.c11
1 files changed, 4 insertions, 7 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index e56c9ed..2cdb98d 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);
}
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