On Tue, May 13, 2014 at 10:01:02PM +0100, Filipe David Borba Manana wrote:
> When running send, if an inode only has extended reference items
> associated to it and no regular references, send.c:get_first_ref()
> was incorrectly assuming the reference it found was of type
> BTRFS_INODE_REF_KEY due to use of the wrong key variable.
> This caused weird behaviour when using the found item has a regular
> reference, such as weird path string, and occasionally (when lucky)
> a crash:
>
> [ 190.600652] general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
> [ 190.600994] Modules linked in: btrfs xor raid6_pq binfmt_misc nfsd
> auth_rpcgss oid_registry nfs_acl nfs lockd fscache sunrpc psmouse serio_raw
> evbug pcspkr i2c_piix4 e1000 floppy
> [ 190.602565] CPU: 2 PID: 14520 Comm: btrfs Not tainted
> 3.13.0-fdm-btrfs-next-26+ #1
> [ 190.602728] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> [ 190.602868] task: ffff8800d447c920 ti: ffff8801fa79e000 task.ti:
> ffff8801fa79e000
> [ 190.603030] RIP: 0010:[<ffffffff813266b4>] [<ffffffff813266b4>]
> memcpy+0x54/0x110
> [ 190.603262] RSP: 0018:ffff8801fa79f880 EFLAGS: 00010202
> [ 190.603395] RAX: ffff8800d4326e3f RBX: 000000000000036a RCX:
> ffff880000000000
> [ 190.603553] RDX: 000000000000032a RSI: ffe708844042936a RDI:
> ffff8800d43271a9
> [ 190.603710] RBP: ffff8801fa79f8c8 R08: 00000000003a4ef0 R09:
> 0000000000000000
> [ 190.603867] R10: 793a4ef09f000000 R11: 9f0000000053726f R12:
> ffff8800d43271a9
> [ 190.604020] R13: 0000160000000000 R14: ffff8802110134f0 R15:
> 000000000000036a
> [ 190.604020] FS: 00007fb423d09b80(0000) GS:ffff880216200000(0000)
> knlGS:0000000000000000
> [ 190.604020] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> [ 190.604020] CR2: 00007fb4229d4b78 CR3: 00000001f5d76000 CR4:
> 00000000000006e0
> [ 190.604020] Stack:
> [ 190.604020] ffffffffa01f4d49 ffff8801fa79f8f0 00000000000009f9
> ffff8801fa79f8c8
> [ 190.604020] 00000000000009f9 ffff880211013260 000000000000f971
> ffff88021147dba8
> [ 190.604020] 00000000000009f9 ffff8801fa79f918 ffffffffa02367f5
> ffff8801fa79f928
> [ 190.604020] Call Trace:
> [ 190.604020] [<ffffffffa01f4d49>] ? read_extent_buffer+0xb9/0x120 [btrfs]
> [ 190.604020] [<ffffffffa02367f5>] fs_path_add_from_extent_buffer+0x45/0x60
> [btrfs]
> [ 190.604020] [<ffffffffa0238806>] get_first_ref+0x1f6/0x210 [btrfs]
> [ 190.604020] [<ffffffffa0238994>] __get_cur_name_and_parent+0x174/0x3a0
> [btrfs]
> [ 190.604020] [<ffffffff8118df3d>] ? kmem_cache_alloc_trace+0x11d/0x1e0
> [ 190.604020] [<ffffffffa0236674>] ? fs_path_alloc+0x24/0x60 [btrfs]
> [ 190.604020] [<ffffffffa0238c91>] get_cur_path+0xd1/0x240 [btrfs]
> (...)
>
> Steps to reproduce (either crash or some weirdness like an odd path string):
>
> mkfs.btrfs -f -O extref /dev/sdd
> mount /dev/sdd /mnt
>
> mkdir /mnt/testdir
> touch /mnt/testdir/foobar
>
> for i in `seq 1 2550`; do
> ln /mnt/testdir/foobar /mnt/testdir/foobar_link_`printf "%04d" $i`
> done
>
> ln /mnt/testdir/foobar /mnt/testdir/final_foobar_name
>
> rm -f /mnt/testdir/foobar
> for i in `seq 1 2550`; do
> rm -f /mnt/testdir/foobar_link_`printf "%04d" $i`
> done
>
> btrfs subvolume snapshot -r /mnt /mnt/mysnap
> btrfs send /mnt/mysnap -f /tmp/mysnap.send
Looks good.
Reviewed-by: Liu Bo <bo.li....@oracle.com>
-liubo
>
> Signed-off-by: Filipe David Borba Manana <fdman...@gmail.com>
> ---
> fs/btrfs/send.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
> index 40f353f..0035bdd 100644
> --- a/fs/btrfs/send.c
> +++ b/fs/btrfs/send.c
> @@ -1688,7 +1688,7 @@ static int get_first_ref(struct btrfs_root *root, u64
> ino,
> goto out;
> }
>
> - if (key.type == BTRFS_INODE_REF_KEY) {
> + if (found_key.type == BTRFS_INODE_REF_KEY) {
> struct btrfs_inode_ref *iref;
> iref = btrfs_item_ptr(path->nodes[0], path->slots[0],
> struct btrfs_inode_ref);
> --
> 1.9.1
>
> --
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