[PATCH] btrfs: reject encoded write if inode has nodatasum flag set

[PATCH] btrfs: reject encoded write if inode has nodatasum flag set

[fdmanana]

From: Filipe Manana <fdmanana@suse.com>

Currently we allow an encoded write against inodes that have the NODATASUM
flag set, either because they are NOCOW files or they were created while
the filesystem was mounted with "-o nodatasum". This results in having
compressed extents without corresponding checksums, which is a filesystem
inconsistency reported by 'btrfs check'.

For example, running btrfs/281 with MOUNT_OPTIONS="-o nodatacow" triggers
this and 'btrfs check' errors out with:

   [1/7] checking root items
   [2/7] checking extents
   [3/7] checking free space tree
   [4/7] checking fs roots
   root 256 inode 257 errors 1040, bad file extent, some csum missing
   root 256 inode 258 errors 1040, bad file extent, some csum missing
   ERROR: errors found in fs roots
   (...)

So reject encoded writes if the target inode has NODATASUM set.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
 fs/btrfs/inode.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 50aea888d977..2329bff33d4b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -10289,6 +10289,13 @@ ssize_t btrfs_do_encoded_write(struct kiocb *iocb, struct iov_iter *from,
 	if (encoded->encryption != BTRFS_ENCODED_IO_ENCRYPTION_NONE)
 		return -EINVAL;
 
+	/*
+	 * Compressed extents should always have checksums, so error out if we
+	 * have a NOCOW file or inode was created while mounted with NODATASUM.
+	 */
+	if (inode->flags & BTRFS_INODE_NODATASUM)
+		return -EINVAL;
+
 	orig_count = iov_iter_count(from);
 
 	/* The extent size must be sane. */
-- 
2.40.1

Re: [PATCH] btrfs: reject encoded write if inode has nodatasum flag set

[Johannes Thumshirn]

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>

Re: [PATCH] btrfs: reject encoded write if inode has nodatasum flag set

[David Sterba]

On Fri, Feb 02, 2024 at 12:22:53PM +0000, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> Currently we allow an encoded write against inodes that have the NODATASUM
> flag set, either because they are NOCOW files or they were created while
> the filesystem was mounted with "-o nodatasum". This results in having
> compressed extents without corresponding checksums, which is a filesystem
> inconsistency reported by 'btrfs check'.
> 
> For example, running btrfs/281 with MOUNT_OPTIONS="-o nodatacow" triggers
> this and 'btrfs check' errors out with:
> 
>    [1/7] checking root items
>    [2/7] checking extents
>    [3/7] checking free space tree
>    [4/7] checking fs roots
>    root 256 inode 257 errors 1040, bad file extent, some csum missing
>    root 256 inode 258 errors 1040, bad file extent, some csum missing
>    ERROR: errors found in fs roots
>    (...)
> 
> So reject encoded writes if the target inode has NODATASUM set.
> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>

Reviewed-by: David Sterba <dsterba@suse.com>