On Mon, May 08, 2017 at 03:47:57PM -0700, Eric Biggers wrote:
> From: Eric Biggers <ebiggers@xxxxxxxxxx>
>
> When mk_hugefiles() was switched to use ext2fs_fallocate(), it was
> accidentally changed to ignore the 'zero_hugefiles = false' setting,
> which should cause hugefiles to be allocated without initializing their
> contents. Fix this by only passing EXT2_FALLOCATE_ZERO_BLOCKS to
> ext2fs_fallocate() when zero_hugefiles is true.
Soooo... I don't know that I like the potential for stale data exposure,
which predisposes me not to like this patch.
On the other hand, mkfs isn't a frequently used program and it clearly
supports this as a feature, so let's not have regressions.
Acked-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> Fixes: 4f868703f6f2 ("libext2fs: use fallocate for creating journals and hugefiles")
> Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> ---
> misc/mk_hugefiles.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/misc/mk_hugefiles.c b/misc/mk_hugefiles.c
> index 71a15c5d..049c6f41 100644
> --- a/misc/mk_hugefiles.c
> +++ b/misc/mk_hugefiles.c
> @@ -260,6 +260,7 @@ static errcode_t mk_hugefile(ext2_filsys fs, blk64_t num,
> {
> errcode_t retval;
> struct ext2_inode inode;
> + int falloc_flags;
>
> retval = ext2fs_new_inode(fs, 0, LINUX_S_IFREG, NULL, ino);
> if (retval)
> @@ -281,10 +282,11 @@ static errcode_t mk_hugefile(ext2_filsys fs, blk64_t num,
>
> if (ext2fs_has_feature_extents(fs->super))
> inode.i_flags |= EXT4_EXTENTS_FL;
> - retval = ext2fs_fallocate(fs,
> - EXT2_FALLOCATE_FORCE_INIT |
> - EXT2_FALLOCATE_ZERO_BLOCKS,
> - *ino, &inode, goal, 0, num);
> +
> + falloc_flags = EXT2_FALLOCATE_FORCE_INIT;
> + if (zero_hugefile)
> + falloc_flags |= EXT2_FALLOCATE_ZERO_BLOCKS;
> + retval = ext2fs_fallocate(fs, falloc_flags, *ino, &inode, goal, 0, num);
> if (retval)
> return retval;
> retval = ext2fs_inode_size_set(fs, &inode, num * fs->blocksize);
> --
> 2.13.0.rc2.291.g57267f2277-goog
>
