* Eric Sandeen <sandeen@xxxxxxxxxx>:
> On 8/12/13 6:28 PM, Eric Sandeen wrote:
> > On 8/12/13 6:21 PM, Eric Sandeen wrote:
> >> On 7/21/13 3:28 PM, Eric Whitney wrote:
> >>> Commit d3f32c2db8 caused e2fsck misbehavior during xfstests runs.
> >>> It reported that uninitialized extents created by fallocate() at
> >>> the end of file with the FALLOC_FL_KEEP_SIZE flag were invalid.
> >>> Because FALLOC_FL_KEEP_SIZE does not increase the file size when
> >>> an extent is fallocated, an uninitialized extent can legally contain
> >>> blocks past the end of file.
> >>>
> >>> The information reported by ext2fs_extent_get() and used by the commit
> >>> to determine legal extent ranges is limited by the value of i_size
> >>> (determines end_blk in the root extent index), so block values greater
> >>> than that containing i_size were reported as invalid.
> >>>
> >>> To fix this, filter out possible invalid extent candidates if they are
> >>> uninitialized and extend past the block containing the end of file.
> >>>
> >>> Signed-off-by: Eric Whitney <enwlinux@xxxxxxxxx>
> >>> ---
> >>> e2fsck/pass1.c | 4 +++-
> >>> lib/ext2fs/ext2fs.h | 1 +
> >>> lib/ext2fs/extent.c | 1 +
> >>> 3 files changed, 5 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
> >>> index ba6025b..b84b0d0 100644
> >>> --- a/e2fsck/pass1.c
> >>> +++ b/e2fsck/pass1.c
> >>> @@ -1892,7 +1892,9 @@ static void scan_extent_node(e2fsck_t ctx, struct problem_context *pctx,
> >>> problem = PR_1_EXTENT_BAD_START_BLK;
> >>> else if (extent.e_lblk < start_block)
> >>> problem = PR_1_OUT_OF_ORDER_EXTENTS;
> >>> - else if (end_block && last_lblk > end_block)
> >>> + else if ((end_block && last_lblk > end_block) &&
> >>> + (!(extent.e_flags & EXT2_EXTENT_FLAGS_UNINIT &&
> >>> + last_lblk > info.eof_blk - 1)))
> >>> problem = PR_1_EXTENT_END_OUT_OF_BOUNDS;
> >>> else if (is_leaf && extent.e_len == 0)
> >>> problem = PR_1_EXTENT_LENGTH_ZERO;
> >>> diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
> >>> index 311ceda..85f2ac8 100644
> >>> --- a/lib/ext2fs/ext2fs.h
> >>> +++ b/lib/ext2fs/ext2fs.h
> >>> @@ -409,6 +409,7 @@ struct ext2_extent_info {
> >>> int bytes_avail;
> >>> blk64_t max_lblk;
> >>> blk64_t max_pblk;
> >>> + blk64_t eof_blk;
> >>> __u32 max_len;
> >>> __u32 max_uninit_len;
> >>> };
> >>
> >> I just realized, this affects the ABI, doesn't it? Hm.
> >>
> >> As a hack-around, can probably just use ehandle->path[0].end_blk directly
> >> in scan_extent_node and stash eof_blk locally?
> >
> > Nope, we can't crack an extent handle, it's an opaque type.
> >
> > Ned some V2 interfaces now? :(
> >
>
> or maybe just:
>
> + eof_blk = (EXT2_I_SIZE(pctx->inode) + ctx->fs->blocksize - 1) >>
> + EXT2_BLOCK_SIZE_BITS(ctx->fs->super);
>
> unless that's too ugly.
>
Clearly, I wasn't thinking about the ABI at all - thanks for pointing out
that misstep.
So, I'd like to withdraw that patch, please, and will post a V2 in a bit.
Computing the eof_blk in that manner is better than an initial patch I had
that worked but which was pretty ugly.
Thanks,
Eric
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