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Groups > linux.kernel > #1301808
| From | Jiri Slaby <jslaby@suse.cz> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 3.12 53/91] Btrfs: fix race leading to BUG_ON when running delalloc for nodatacow |
| Date | 2016-01-05 19:10 +0100 |
| Message-ID | <qNEdt-6sw-39@gated-at.bofh.it> (permalink) |
| References | <qNDU6-65D-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Filipe Manana <fdmanana@suse.com>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit 1d512cb77bdbda80f0dd0620a3b260d697fd581d upstream.
If we are using the NO_HOLES feature, we have a tiny time window when
running delalloc for a nodatacow inode where we can race with a concurrent
link or xattr add operation leading to a BUG_ON.
This happens because at run_delalloc_nocow() we end up casting a leaf item
of type BTRFS_INODE_[REF|EXTREF]_KEY or of type BTRFS_XATTR_ITEM_KEY to a
file extent item (struct btrfs_file_extent_item) and then analyse its
extent type field, which won't match any of the expected extent types
(values BTRFS_FILE_EXTENT_[REG|PREALLOC|INLINE]) and therefore trigger an
explicit BUG_ON(1).
The following sequence diagram shows how the race happens when running a
no-cow dellaloc range [4K, 8K[ for inode 257 and we have the following
neighbour leafs:
Leaf X (has N items) Leaf Y
[ ... (257 INODE_ITEM 0) (257 INODE_REF 256) ] [ (257 EXTENT_DATA 8192), ... ]
slot N - 2 slot N - 1 slot 0
(Note the implicit hole for inode 257 regarding the [0, 8K[ range)
CPU 1 CPU 2
run_dealloc_nocow()
btrfs_lookup_file_extent()
--> searches for a key with value
(257 EXTENT_DATA 4096) in the
fs/subvol tree
--> returns us a path with
path->nodes[0] == leaf X and
path->slots[0] == N
because path->slots[0] is >=
btrfs_header_nritems(leaf X), it
calls btrfs_next_leaf()
btrfs_next_leaf()
--> releases the path
hard link added to our inode,
with key (257 INODE_REF 500)
added to the end of leaf X,
so leaf X now has N + 1 keys
--> searches for the key
(257 INODE_REF 256), because
it was the last key in leaf X
before it released the path,
with path->keep_locks set to 1
--> ends up at leaf X again and
it verifies that the key
(257 INODE_REF 256) is no longer
the last key in the leaf, so it
returns with path->nodes[0] ==
leaf X and path->slots[0] == N,
pointing to the new item with
key (257 INODE_REF 500)
the loop iteration of run_dealloc_nocow()
does not break out the loop and continues
because the key referenced in the path
at path->nodes[0] and path->slots[0] is
for inode 257, its type is < BTRFS_EXTENT_DATA_KEY
and its offset (500) is less then our delalloc
range's end (8192)
the item pointed by the path, an inode reference item,
is (incorrectly) interpreted as a file extent item and
we get an invalid extent type, leading to the BUG_ON(1):
if (extent_type == BTRFS_FILE_EXTENT_REG ||
extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
(...)
} else if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
(...)
} else {
BUG_ON(1)
}
The same can happen if a xattr is added concurrently and ends up having
a key with an offset smaller then the delalloc's range end.
So fix this by skipping keys with a type smaller than
BTRFS_EXTENT_DATA_KEY.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
fs/btrfs/inode.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 50f08d5f9cbb..5074a1607812 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1221,8 +1221,14 @@ next_slot:
num_bytes = 0;
btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
- if (found_key.objectid > ino ||
- found_key.type > BTRFS_EXTENT_DATA_KEY ||
+ if (found_key.objectid > ino)
+ break;
+ if (WARN_ON_ONCE(found_key.objectid < ino) ||
+ found_key.type < BTRFS_EXTENT_DATA_KEY) {
+ path->slots[0]++;
+ goto next_slot;
+ }
+ if (found_key.type > BTRFS_EXTENT_DATA_KEY ||
found_key.offset > end)
break;
--
2.6.4
--
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[PATCH 3.12 58/91] nfs: if we have no valid attrs, then don't declare the attribute cache valid Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:00 +0100
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[PATCH 3.12 90/91] gpio/omap: raw read and write endian fix Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:00 +0100
[PATCH 3.12 36/91] can: sja1000: clear interrupts on start Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 29/91] mac80211: fix driver RSSI event calculations Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
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[PATCH 3.12 27/91] x86/cpu: Call verify_cpu() after having entered long mode too Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
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[PATCH 3.12 46/91] tty: fix stall caused by missing memory barrier in drivers/tty/n_tty.c Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 37/91] arm64: Fix compat register mappings Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 30/91] net: mvneta: Fix CPU_MAP registers initialisation Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 26/91] x86/setup: Fix low identity map for >= 2GB kernel range Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 53/91] Btrfs: fix race leading to BUG_ON when running delalloc for nodatacow Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 55/91] ext4, jbd2: ensure entering into panic after recording an error in superblock Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
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[PATCH 3.12 24/91] ARM: common: edma: Fix channel parameter for irq callbacks Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
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[PATCH 3.12 52/91] Btrfs: fix race leading to incorrect item deletion when dropping extents Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
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[PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Paolo Bonzini <pbonzini@redhat.com> - 2016-01-06 11:50 +0100
Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Matt Fleming <matt@codeblueprint.co.uk> - 2016-01-06 12:10 +0100
Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Luis Henriques <luis.henriques@canonical.com> - 2016-01-06 12:30 +0100
Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Matt Fleming <matt@codeblueprint.co.uk> - 2016-01-06 14:40 +0100
Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Luis Henriques <luis.henriques@canonical.com> - 2016-01-06 15:30 +0100
Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Matt Fleming <matt@codeblueprint.co.uk> - 2016-01-08 13:00 +0100
Re: [PATCH 3.12 25/91] x86/setup: Extend low identity map to cover whole kernel range Luis Henriques <luis.henriques@canonical.com> - 2016-01-08 14:40 +0100
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[PATCH 3.12 44/91] ALSA: usb-audio: prevent CH345 multiport output SysEx corruption Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 35/91] Bluetooth: ath3k: Add support of AR3012 0cf3:817b device Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 28/91] x86/cpu: Fix SMAP check in PVOPS environments Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 49/91] netfilter: ip6t_SYNPROXY: fix NULL pointer dereference Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 42/91] USB: option: add XS Stick W100-2 from 4G Systems Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:10 +0100
[PATCH 3.12 10/91] net: qmi_wwan: add XS Stick W100-2 from 4G Systems Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 11/91] tcp: md5: fix lockdep annotation Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 19/91] net/neighbour: fix crash at dumping device-agnostic proxy entries Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 23/91] ARM: 8427/1: dma-mapping: add support for offset parameter in dma_mmap() Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 07/91] packet: infer protocol from ethernet header if unset Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 21/91] Bluetooth: ath3k: Add support of 04ca:300d AR3012 device Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 08/91] sctp: translate host order to network order when setting a hmacid Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 22/91] ARM: 8426/1: dma-mapping: add missing range check in dma_mmap() Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 05/91] unix: avoid use-after-free in ep_remove_wait_queue Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 02/91] MIPS: KVM: Fix ASID restoration logic Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 20/91] ipv6: sctp: implement sctp_v6_destroy_sock() Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 13/91] net, scm: fix PaX detected msg_controllen overflow in scm_detach_fds Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 18/91] ipv6: add complete rcu protection around np->opt Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 12/91] tcp: initialize tp->copied_seq in case of cross SYN connection Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 04/91] MIPS: KVM: Uninit VCPU in vcpu_create error path Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
[PATCH 3.12 06/91] packet: do skb_probe_transport_header when we actually have data Jiri Slaby <jslaby@suse.cz> - 2016-01-05 19:20 +0100
Re: [PATCH 3.12 00/91] 3.12.52-stable review Guenter Roeck <linux@roeck-us.net> - 2016-01-05 21:50 +0100
Re: [PATCH 3.12 00/91] 3.12.52-stable review Jiri Slaby <jslaby@suse.cz> - 2016-01-09 09:50 +0100
Re: [PATCH 3.12 00/91] 3.12.52-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2016-01-05 22:20 +0100
Re: [PATCH 3.12 00/91] 3.12.52-stable review Nikolay Borisov <kernel@kyup.com> - 2016-01-06 08:40 +0100
Re: [PATCH 3.12 00/91] 3.12.52-stable review Greg KH <gregkh@linuxfoundation.org> - 2016-01-06 09:20 +0100
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