[PATCH] Btrfs: return error when we specify wrong start

[PATCH] Btrfs: return error when we specify wrong start

[Liu Bo]

We need such a sanity check for wrong start, otherwise, even with
a wrong start that's larger than file size, we can end up not only
changing inode's force compress flag but also FS's incompat flags.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
---
 fs/btrfs/ioctl.c |   11 +++++++----
 1 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 69cd80d..262d9db 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1152,8 +1152,11 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 	u64 new_align = ~((u64)128 * 1024 - 1);
 	struct page **pages = NULL;
 
-	if (extent_thresh == 0)
-		extent_thresh = 256 * 1024;
+	if (isize == 0)
+		return 0;
+
+	if (range->start >= isize)
+		return -EINVAL;
 
 	if (range->flags & BTRFS_DEFRAG_RANGE_COMPRESS) {
 		if (range->compress_type > BTRFS_COMPRESS_TYPES)
@@ -1162,8 +1165,8 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 			compress_type = range->compress_type;
 	}
 
-	if (isize == 0)
-		return 0;
+	if (extent_thresh == 0)
+		extent_thresh = 256 * 1024;
 
 	/*
 	 * if we were not given a file, allocate a readahead
-- 
1.7.7

Re: [PATCH] Btrfs: return error when we specify wrong start

[Jan Schmidt]

On Tue, April 16, 2013 at 10:40 (+0200), Liu Bo wrote:
> We need such a sanity check for wrong start, otherwise, even with
> a wrong start that's larger than file size, we can end up not only
> changing inode's force compress flag but also FS's incompat flags.

That reads out very cryptic. Can you please add something hinting at "defrag" to
the title or at least the description?

Thanks,
-Jan

Re: [PATCH] Btrfs: return error when we specify wrong start

[Liu Bo]

On Tue, Apr 16, 2013 at 10:44:33AM +0200, Jan Schmidt wrote:
> On Tue, April 16, 2013 at 10:40 (+0200), Liu Bo wrote:
> > We need such a sanity check for wrong start, otherwise, even with
> > a wrong start that's larger than file size, we can end up not only
> > changing inode's force compress flag but also FS's incompat flags.
> 
> That reads out very cryptic. Can you please add something hinting at "defrag" to
> the title or at least the description?

Oh yeah, my bad.

thanks,
liubo

> 
> Thanks,
> -Jan