On Jul 24, 2014, at 3:22 PM, Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote:
> Before converting an inline directory to a regular directory, check
> the directory entries to make sure they're not obviously broken.
> This helps us to avoid a BUG_ON if one of the dirents is trashed.
>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> ---
> fs/ext4/inline.c | 37 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 37 insertions(+)
>
> diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
> index 645205d..c79d8e7 100644
> --- a/fs/ext4/inline.c
> +++ b/fs/ext4/inline.c
> @@ -1157,6 +1157,31 @@ out:
> return err;
> }
>
> +static int ext4_check_all_de(struct inode *dir, struct buffer_head *bh,
> + void *buf, int buf_size)
It would seem that this function would be useful in ext4_readdir(), which
open-codes something very similar? It might be better to locate this
function in ext4/dir.c since it doesn't appear to have anything specific
to do with inline directories.
Cheers, Andreas
> +{
> + struct ext4_dir_entry_2 *de;
> + int nlen, rlen;
> + unsigned int offset = 0;
> + char *top;
> +
> + de = (struct ext4_dir_entry_2 *)buf;
> + top = buf + buf_size;
> + while ((char *) de < top) {
> + if (ext4_check_dir_entry(dir, NULL, de, bh,
> + buf, buf_size, offset))
> + return -EIO;
> + nlen = EXT4_DIR_REC_LEN(de->name_len);
> + rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
> + de = (struct ext4_dir_entry_2 *)((char *)de + rlen);
> + offset += rlen;
> + }
> + if ((char *) de > top)
> + return -EIO;
> +
> + return 0;
> +}
> +
> static int ext4_convert_inline_data_nolock(handle_t *handle,
> struct inode *inode,
> struct ext4_iloc *iloc)
> @@ -1178,6 +1203,18 @@ static int ext4_convert_inline_data_nolock(handle_t *handle,
> if (error < 0)
> goto out;
>
> + /*
> + * Make sure the inline directory entries pass checks before we try to
> + * convert them, so that we avoid touching stuff that needs fsck.
> + */
> + if (S_ISDIR(inode->i_mode)) {
> + error = ext4_check_all_de(inode, iloc->bh,
> + buf + EXT4_INLINE_DOTDOT_SIZE,
> + inline_size - EXT4_INLINE_DOTDOT_SIZE);
> + if (error)
> + goto out;
> + }
> +
> error = ext4_destroy_inline_data_nolock(handle, inode);
> if (error)
> goto out;
> --
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Cheers, Andreas
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