From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>
Subject: Re: [PATCH] ext4: lock the the xattr block before calculating its checksum
Date: Tue, 28 Feb 2017 08:12:08 -0800 [thread overview]
Message-ID: <20170228161208.GC5266@birch.djwong.org> (raw)
In-Reply-To: <20170228135650.28045-1-tytso@mit.edu>
On Tue, Feb 28, 2017 at 08:56:50AM -0500, Theodore Ts'o wrote:
> We must lock the xattr block in order to avoid spurious checksum
> failures.
>
> https://bugzilla.kernel.org/show_bug.cgi?id=193661
>
> Reported-by: Colin Ian King <colin.king@canonical.com>
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Looks good,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
--D
> ---
> fs/ext4/xattr.c | 31 ++++++++++++++-----------------
> 1 file changed, 14 insertions(+), 17 deletions(-)
>
> diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
> index 67636acf7624..3247057ef5ff 100644
> --- a/fs/ext4/xattr.c
> +++ b/fs/ext4/xattr.c
> @@ -131,30 +131,27 @@ static __le32 ext4_xattr_block_csum(struct inode *inode,
> }
>
> static int ext4_xattr_block_csum_verify(struct inode *inode,
> - sector_t block_nr,
> - struct ext4_xattr_header *hdr)
> + struct buffer_head *bh)
> {
> - if (ext4_has_metadata_csum(inode->i_sb) &&
> - (hdr->h_checksum != ext4_xattr_block_csum(inode, block_nr, hdr)))
> - return 0;
> - return 1;
> -}
> -
> -static void ext4_xattr_block_csum_set(struct inode *inode,
> - sector_t block_nr,
> - struct ext4_xattr_header *hdr)
> -{
> - if (!ext4_has_metadata_csum(inode->i_sb))
> - return;
> + struct ext4_xattr_header *hdr = BHDR(bh);
> + int ret = 1;
>
> - hdr->h_checksum = ext4_xattr_block_csum(inode, block_nr, hdr);
> + if (ext4_has_metadata_csum(inode->i_sb)) {
> + lock_buffer(bh);
> + ret = hdr->h_checksum == ext4_xattr_block_csum(inode,
> + bh->b_blocknr, hdr);
> + unlock_buffer(bh);
> + }
> + return ret;
> }
>
> static inline int ext4_handle_dirty_xattr_block(handle_t *handle,
> struct inode *inode,
> struct buffer_head *bh)
> {
> - ext4_xattr_block_csum_set(inode, bh->b_blocknr, BHDR(bh));
> + if (ext4_has_metadata_csum(inode->i_sb))
> + BHDR(bh)->h_checksum = ext4_xattr_block_csum(inode,
> + bh->b_blocknr, BHDR(bh));
> return ext4_handle_dirty_metadata(handle, inode, bh);
> }
>
> @@ -233,7 +230,7 @@ ext4_xattr_check_block(struct inode *inode, struct buffer_head *bh)
> if (BHDR(bh)->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC) ||
> BHDR(bh)->h_blocks != cpu_to_le32(1))
> return -EFSCORRUPTED;
> - if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
> + if (!ext4_xattr_block_csum_verify(inode, bh))
> return -EFSBADCRC;
> error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size,
> bh->b_data);
> --
> 2.11.0.rc0.7.gbe5a750
>
next prev parent reply other threads:[~2017-02-28 16:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-28 13:56 [PATCH] ext4: lock the the xattr block before calculating its checksum Theodore Ts'o
2017-02-28 16:12 ` Darrick J. Wong [this message]
2017-03-25 21:24 ` [PATCH -v2] ext4: lock the xattr block before checksuming it Theodore Ts'o
2017-03-26 0:20 ` Colin Ian King
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