From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chris Mason Subject: Re: [PATCH] Btrfs: check items for correctness as we search V3 Date: Thu, 17 Mar 2011 20:52:37 -0400 Message-ID: <1300409520-sup-5343@think> References: <1300305863-2609-1-git-send-email-josef@redhat.com> <1300385915-3317-1-git-send-email-josef@redhat.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Cc: Josef Bacik , linux-btrfs To: Andrey Kuzmin Return-path: In-reply-to: List-ID: Excerpts from Andrey Kuzmin's message of 2011-03-17 15:12:32 -0400: > On Thu, Mar 17, 2011 at 9:18 PM, Josef Bacik wrote= : > > Currently if we have corrupted items things will blow up in spectac= ular ways. > > So as we read in blocks and they are leaves, check the entire leaf = to make sure > > all of the items are correct and point to valid parts in the leaf f= or the item > > data the are responsible for. =C2=A0If the item is corrupt we will = kick back EIO and > > not read any of the copies since they are likely to not be correct = either. =C2=A0This > > will catch generic corruptions, it will be up to the individual cal= lers of > > btrfs_search_slot to make sure their items are right. =C2=A0Thanks, > > > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > > index 495b1ac..9f31e11 100644 > > --- a/fs/btrfs/disk-io.c > > +++ b/fs/btrfs/disk-io.c > > @@ -323,6 +323,7 @@ static int btree_read_extent_buffer_pages(struc= t btrfs_root *root, > > =C2=A0 =C2=A0 =C2=A0 =C2=A0int num_copies =3D 0; > > =C2=A0 =C2=A0 =C2=A0 =C2=A0int mirror_num =3D 0; > > > > + =C2=A0 =C2=A0 =C2=A0 clear_bit(EXTENT_BUFFER_CORRUPT, &eb->bflags= ); > > =C2=A0 =C2=A0 =C2=A0 =C2=A0io_tree =3D &BTRFS_I(root->fs_info->btre= e_inode)->io_tree; > > =C2=A0 =C2=A0 =C2=A0 =C2=A0while (1) { > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0ret =3D read= _extent_buffer_pages(io_tree, eb, start, 1, > > @@ -331,6 +332,14 @@ static int btree_read_extent_buffer_pages(stru= ct btrfs_root *root, > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0= !verify_parent_transid(io_tree, eb, parent_transid)) > > =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0= =C2=A0 =C2=A0return ret; > > > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 /* > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0* This buf= fer's crc is fine, but its contents are corrupted, so > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0* there is= no reason to read the other copies, they won't be > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0* any less= wrong. > > + =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0*/ >=20 > This sounds like an overstatement to me. You may be dealing with an > error pattern CRC faled to catch, so giving up reading a mirror at > this point seems premature. But we have no way to tell which one is more correct, at least not without a full fsck. -chris -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" = in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html