It's been known for a while that the use of multiple lists
that are periodically merged was an algorithmic problem within
btrfs. There are several workloads that don't complete in any
reasonable amount of time (e.g. btrfs/130) and others that cause
soft lockups.
The solution is to use a set of rbtrees that do insertion merging
for both indirect and direct refs, with the former converting
refs into the latter. The result is a btrfs/130 workload that
used to take several hours now takes about half of that. This
runtime still isn't acceptable and a future patch will address that
by moving the rbtrees higher in the stack so the lookups can be
shared across multiple calls to find_parent_nodes.
Signed-off-by: Edmund Nadolski <enadolski@suse.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit afce772e87 ("btrfs: fix check_shared for fiemap ioctl") added
the ref_tree code in backref.c to reduce backref searching for
shared extents under the FIEMAP ioctl. This code will not be
compatible with the upcoming rbtree changes for improved backref
searching, so this patch removes the ref_tree code. The rbtree
changes will provide the equivalent functionality for FIEMAP.
The above commit also introduced transaction semantics around calls to
btrfs_check_shared() in order to accurately account for delayed refs.
This functionality needs to be retained, so a complete revert of the
above commit is not desirable. This patch therefore removes the
ref_tree portion of the commit as above, however it does not remove
the transaction portion.
Signed-off-by: Edmund Nadolski <enadolski@suse.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Commit afce772e87 ("btrfs: fix check_shared for fiemap ioctl") added
transaction semantics around calls to btrfs_check_shared() in order to
provide accurate accounting of delayed refs. The transaction management
should be done inside btrfs_check_shared(), so that callers do not need
to manage transactions individually.
Signed-off-by: Edmund Nadolski <enadolski@suse.com>
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We typically use __ to indicate a helper routine that shouldn't be
called directly without understanding the proper context required
to do so. We use static functions to indicate that a function is
private to a particular C file. The backref code uses static
function and __ prefixes on nearly everything, which makes the code
difficult to read and establishes a pattern for future code that
shouldn't be followed. This patch drops all the unnecessary prefixes.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Replacing the double cast and ternary conditional with a helper makes
the code easier on the eyes.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now that init_ipath is called either from a safe context or with
memalloc_nofs protection, we can switch to GFP_KERNEL allocations in
init_path and init_data_container.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Define the SEQ_LAST macro to replace (u64)-1 in places where said
value triggers a special-case ref search behavior.
Signed-off-by: Edmund Nadolski <enadolski@suse.com>
Reviewed-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Replace hardcoded numeric values for __merge_refs 'mode' argument
with descriptive constants.
Signed-off-by: Edmund Nadolski <enadolski@suse.com>
Reviewed-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
All we need is @delayed_refs, all callers have get it ahead of calling
btrfs_find_delayed_ref_head since lock needs to be acquired firstly,
there is no reason to deference it again inside the function.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Now we only use the root parameter to print the root objectid in
a tracepoint. We can use the root parameter from the transaction
handle for that. It's also used to join the transaction with
async commits, so we remove the comment that it's just for checking.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
There are loads of functions in btrfs that accept a root parameter
but only use it to obtain an fs_info pointer. Let's convert those to
just accept an fs_info pointer directly.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We track the node sizes per-root, but they never vary from the values
in the superblock. This patch messes with the 80-column style a bit,
but subsequent patches to factor out root->fs_info into a convenience
variable fix it up again.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For many printks, we want to know which file system issued the message.
This patch converts most pr_* calls to use the btrfs_* versions instead.
In some cases, this means adding plumbing to allow call sites access to
an fs_info pointer.
fs/btrfs/check-integrity.c is left alone for another day.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
CodingStyle chapter 2:
"[...] never break user-visible strings such as printk messages,
because that breaks the ability to grep for them."
This patch unsplits user-visible strings.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Only in the case of different root_id or different object_id, check_shared
identified extent as the shared. However, If a extent was referred by
different offset of same file, it should also be identified as shared.
In addition, check_shared's loop scale is at least n^3, so if a extent
has too many references, even causes soft hang up.
First, add all delayed_ref to the ref_tree and calculate the unqiue_refs,
if the unique_refs is greater than one, return BACKREF_FOUND_SHARED.
Then individually add the on-disk reference(inline/keyed) to the ref_tree
and calculate the unique_refs of the ref_tree to check if the unique_refs
is greater than one.Because once there are two references to return
SHARED, so the time complexity is close to the constant.
Reported-by: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Signed-off-by: Lu Fengqi <lufq.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When over 1000 file extents refers to one extent, find_parent_nodes()
will be obviously slow, due to the O(n^2)~O(n^3) loops inside
__merge_refs().
The following ftrace shows the cubic growth of execution time:
256 refs
5) + 91.768 us | __add_keyed_refs.isra.12 [btrfs]();
5) 1.447 us | __add_missing_keys.isra.13 [btrfs]();
5) ! 114.544 us | __merge_refs [btrfs]();
5) ! 136.399 us | __merge_refs [btrfs]();
512 refs
6) ! 279.859 us | __add_keyed_refs.isra.12 [btrfs]();
6) 3.164 us | __add_missing_keys.isra.13 [btrfs]();
6) ! 442.498 us | __merge_refs [btrfs]();
6) # 2091.073 us | __merge_refs [btrfs]();
and 1024 refs
7) ! 368.683 us | __add_keyed_refs.isra.12 [btrfs]();
7) 4.810 us | __add_missing_keys.isra.13 [btrfs]();
7) # 2043.428 us | __merge_refs [btrfs]();
7) * 18964.23 us | __merge_refs [btrfs]();
And sort them into the following char:
(Unit: us)
------------------------------------------------------------------------
Trace function | 256 ref | 512 refs | 1024 refs |
------------------------------------------------------------------------
__add_keyed_refs | 91 | 249 | 368 |
__add_missing_keys | 1 | 3 | 4 |
__merge_refs 1st call | 114 | 442 | 2043 |
__merge_refs 2nd call | 136 | 2091 | 18964 |
------------------------------------------------------------------------
We can see the that __add_keyed_refs() grows almost in linear behavior.
And __add_missing_keys() in this case doesn't change much or takes much
time.
While for the 1st __merge_refs() it's square growth
for the 2nd __merge_refs() call it's cubic growth.
It's no doubt that merge_refs() will take a long long time to execute if
the number of refs continues its grows.
So add a cond_resced() into the loop of __merge_refs().
Although this will solve the problem of soft lockup, we need to use the
new rb_tree based structure introduced by Lu Fengqi to really solve the
long execution time.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Now that we have a dummy fs_info associated with each test that
uses a root, we don't need the DUMMY_ROOT bit anymore. This lets
us make choices without needing an actual root like in e.g.
btrfs_find_create_tree_block.
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
BTRFS is using a variety of slab caches to satisfy internal needs.
Those slab caches are always allocated with the SLAB_RECLAIM_ACCOUNT,
meaning allocations from the caches are going to be accounted as
SReclaimable. At the same time btrfs is not registering any shrinkers
whatsoever, thus preventing memory from the slabs to be shrunk. This
means those caches are not in fact reclaimable.
To fix this remove the SLAB_RECLAIM_ACCOUNT on all caches apart from the
inode cache, since this one is being freed by the generic VFS super_block
shrinker. Also set the transaction related caches as SLAB_TEMPORARY,
to better document the lifetime of the objects (it just translates
to SLAB_RECLAIM_ACCOUNT).
Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Make sure to deallocate fspath with vfree() in case of error in
init_ipath().
fspath is allocated with vmalloc() in init_data_container() since
commit 425d17a290 ("Btrfs: use larger limit for translation of logical to
inode").
Signed-off-by: Vincent Stehlé <vincent.stehle@intel.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Cleanup.
kmem_cache_destroy has support NULL argument checking,
so drop the double null testing before calling it.
Signed-off-by: Kinglong Mee <kinglongmee@gmail.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The kernel provides a swap() that does the same thing as this code.
Signed-off-by: Dave Jones <dsj@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Fix the following error:
fs/btrfs/backref.c:565:1-20: iterator with update on line 577
Fixes: a7ca422('btrfs: use list_for_each_entry* in backref.c')
Signed-off-by: Geliang Tang <geliangtang@163.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Use list_for_each_entry*() to simplify the code.
Signed-off-by: Geliang Tang <geliangtang@163.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The backref code will look up the fs_root we're trying to resolve our indirect
refs for, unfortunately we use btrfs_read_fs_root_no_name, which returns -ENOENT
if the ref is 0. This isn't helpful for the qgroup stuff with snapshot delete
as it won't be able to search down the snapshot we are deleting, which will
cause us to miss roots. So use btrfs_get_fs_root and send false for check_ref
so we can always get the root we're looking for. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Chris Mason <clm@fb.com>
The code for btrfs inode-resolve has never worked properly for
files with enough hard links to trigger extrefs. It was trying to
get the leaf out of a path after freeing the path:
btrfs_release_path(path);
leaf = path->nodes[0];
item_size = btrfs_item_size_nr(leaf, slot);
The fix here is to use the extent buffer we cloned just a little higher
up to avoid deadlocks caused by using the leaf in the path.
Signed-off-by: Chris Mason <clm@fb.com>
cc: stable@vger.kernel.org # v3.7+
cc: Mark Fasheh <mfasheh@suse.de>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Signed-off-by: Chris Mason <clm@fb.com>
With my changes to allow us to find old roots when resolving indirect refs I
introduced a regression to the sanity tests. Since we don't really care to go
down into the fs roots we just need to have the old behavior of returning ENOENT
for dummy roots for the sanity tests. In the future if we want to get fancy we
can populate the test fs trees with the references as well. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
When we do backref walking, we search firstly in queued delayed refs
and then the on-disk backrefs, but we parse differently for shared
references, for delayed refs we also add 'ref->root' while for on-disk
backrefs we don't, this can prevent us from merging refs indexed
by the same bytenr and cause find_parent_nodes() to throw a warning at
'WARN_ON(ref->count < 0)', for example, when we have a shared data extent
with 'ref_cnt=1' and a delayed shared data with a BTRFS_DROP_DELAYED_REF,
that happens.
For shared references, no matter if it's delayed or on-disk, ref->root is
not at all used, instead it's ref->parent that really matters, so this has
delayed refs handled as the same way as on-disk refs.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
When cloning/deduplicating file extents (through the clone and extent_same
ioctls) we can get data back references with offset values that are a
result of an unsigned integer arithmetic underflow, that is, values that
are much larger then they could be otherwise.
This is not a problem when decrementing or dropping the back references
(happens when we overwrite the extents or punch a hole for example, through
__btrfs_drop_extents()), since we compute the same too large offset value,
but it is a problem for the backref walking code, used by an incremental
send and the ioctls that are used by the btrfs tool "inspect-internal"
commands, as it makes it miss the corresponding file extent items because
the search key is set for an extent item that starts at an offset matching
the exceptionally large offset value of the data back reference. For an
incremental send this causes the send ioctl to fail with -EIO.
So teach the backref walking code to deal with these cases by setting the
search key's offset to 0 if the backref's offset value is larger than
LLONG_MAX (the largest possible file offset). This makes sure the backref
walking code finds the corresponding file extent items at the expense of
scanning more items and leafs in the btree.
Fixing the clone/dedup ioctls to not produce such underflowed results would
require major changes breaking backward compatibility, updating user space
tools, etc.
Simple reproducer case for fstests:
seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"
tmp=/tmp/$$
status=1 # failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15
_cleanup()
{
rm -fr $send_files_dir
rm -f $tmp.*
}
# get standard environment, filters and checks
. ./common/rc
. ./common/filter
# real QA test starts here
_supported_fs btrfs
_supported_os Linux
_require_scratch
_require_cloner
_need_to_be_root
send_files_dir=$TEST_DIR/btrfs-test-$seq
rm -f $seqres.full
rm -fr $send_files_dir
mkdir $send_files_dir
_scratch_mkfs >>$seqres.full 2>&1
_scratch_mount
# Create our test file with a single extent of 64K starting at file
# offset 128K.
$XFS_IO_PROG -f -c "pwrite -S 0xaa 128K 64K" $SCRATCH_MNT/foo \
| _filter_xfs_io
_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT \
$SCRATCH_MNT/mysnap1
# Now clone parts of the original extent into lower offsets of the file.
#
# The first clone operation adds a file extent item to file offset 0
# that points to our initial extent with a data offset of 16K. The
# corresponding data back reference in the extent tree has an offset of
# 18446744073709535232, which is the result of file_offset - data_offset
# = 0 - 16K.
#
# The second clone operation adds a file extent item to file offset 16K
# that points to our initial extent with a data offset of 48K. The
# corresponding data back reference in the extent tree has an offset of
# 18446744073709518848, which is the result of file_offset - data_offset
# = 16K - 48K.
#
# Those large back reference offsets (result of unsigned arithmetic
# underflow) confused the back reference walking code (used by an
# incremental send and the multiple inspect-internal ioctls) and made it
# miss the back references, which for the case of an incremental send it
# made it fail with -EIO and print a message like the following to
# dmesg:
#
# "BTRFS error (device sdc): did not find backref in send_root. \
# inode=257, offset=0, disk_byte=12845056 found extent=12845056"
#
$CLONER_PROG -s $(((128 + 16) * 1024)) -d 0 -l $((16 * 1024)) \
$SCRATCH_MNT/foo $SCRATCH_MNT/foo
$CLONER_PROG -s $(((128 + 48) * 1024)) -d $((16 * 1024)) \
-l $((16 * 1024)) $SCRATCH_MNT/foo $SCRATCH_MNT/foo
_run_btrfs_util_prog subvolume snapshot -r $SCRATCH_MNT \
$SCRATCH_MNT/mysnap2
_run_btrfs_util_prog send $SCRATCH_MNT/mysnap1 -f $send_files_dir/1.snap
_run_btrfs_util_prog send -p $SCRATCH_MNT/mysnap1 $SCRATCH_MNT/mysnap2 \
-f $send_files_dir/2.snap
echo "File digest in the original filesystem:"
md5sum $SCRATCH_MNT/mysnap2/foo | _filter_scratch
# Now recreate the filesystem by receiving both send streams and verify
# we get the same file contents that the original filesystem had.
_scratch_unmount
_scratch_mkfs >>$seqres.full 2>&1
_scratch_mount
_run_btrfs_util_prog receive $SCRATCH_MNT -f $send_files_dir/1.snap
_run_btrfs_util_prog receive $SCRATCH_MNT -f $send_files_dir/2.snap
echo "File digest in the new filesystem:"
md5sum $SCRATCH_MNT/mysnap2/foo | _filter_scratch
status=0
exit
The test's expected golden output is:
wrote 65536/65536 bytes at offset 131072
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
File digest in the original filesystem:
6c6079335cff141b8a31233ead04cbff SCRATCH_MNT/mysnap2/foo
File digest in the new filesystem:
6c6079335cff141b8a31233ead04cbff SCRATCH_MNT/mysnap2/foo
But it failed with:
(...)
@@ -1,7 +1,5 @@
QA output created by 097
wrote 65536/65536 bytes at offset 131072
XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-File digest in the original filesystem:
-6c6079335cff141b8a31233ead04cbff SCRATCH_MNT/mysnap2/foo
-File digest in the new filesystem:
-6c6079335cff141b8a31233ead04cbff SCRATCH_MNT/mysnap2/foo
...
$ cat /home/fdmanana/git/hub/xfstests/results//btrfs/097.full
(...)
ERROR: send ioctl failed with -5: Input/output error
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs_find_all_roots().
Allow btrfs_find_all_roots() to skip all delayed_ref_head lock and tree
lock to do tree search.
This is important for later qgroup implement which will call
find_all_roots() after fs trees are committed.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
This patch replace the rbtree used in ref_head to list.
This has the following advantage:
1) Easier merge logic.
With the new list implement, we only need to care merging the tail
ref_node with the new ref_node.
And this can be done quite easy at insert time, no need to do a
indicated merge at run_delayed_refs().
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
Old __merge_refs() in backref.c will even merge refs whose root_id are
different, which makes qgroup gives wrong result.
Fix it by checking ref_for_same_block() before any mode specific works.
Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
The return value of read_tree_block() can confuse callers as it always
returns NULL for either -ENOMEM or -EIO, so it's likely that callers
parse it to a wrong error, for instance, in btrfs_read_tree_root().
This fixes the above issue.
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs_check_shared() is leaking a return value of '1' from
find_parent_nodes(). As a result, callers (in this case, extent_fiemap())
are told extents are shared when they are not. This in turn broke fiemap on
btrfs for kernels v3.18 and up.
The fix is simple - we just have to clear 'ret' after we are done processing
the results of find_parent_nodes().
It wasn't clear to me at first what was happening with return values in
btrfs_check_shared() and find_parent_nodes() - thanks to Josef for the help
on irc. I added documentation to both functions to make things more clear
for the next hacker who might come across them.
If we could queue this up for -stable too that would be great.
Signed-off-by: Mark Fasheh <mfasheh@suse.de>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Using {} as initializer for struct seq_elem does not properly initialize
the list_head member, but it currently works because it gets set through
btrfs_get_tree_mod_seq if 'seq' is 0.
Signed-off-by: David Sterba <dsterba@suse.cz>
If we are using skinny metadata, the block's tree level is in the offset
of the key and not in a btrfs_tree_block_info structure following the
extent item (it doesn't exist). Therefore fix it.
Besides returning the correct level in the tree, this also prevents reading
past the leaf's end in the case where the extent item is the last item in
the leaf (eb) and it has only 1 inline reference - this is because
sizeof(struct btrfs_tree_block_info) is greater than
sizeof(struct btrfs_extent_inline_ref).
Got it while running a scrub which produced the following warning:
BTRFS: checksum error at logical 42123264 on dev /dev/sde, sector 15840: metadata node (level 24) in tree 5
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>
We have been iterating all references for each extent we have in a file when we
do fiemap to see if it is shared. This is fine when you have a few clones or a
few snapshots, but when you have 5k snapshots suddenly fiemap just sits there
and stares at you. So add btrfs_check_shared which will use the backref walking
code but will short circuit as soon as it finds a root or inode that doesn't
match the one we currently have. This makes fiemap on my testbox go from
looking at me blankly for a day to spitting out actual output in a reasonable
amount of time. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
The nodesize and leafsize were never of different values. Unify the
usage and make nodesize the one. Cleanup the redundant checks and
helpers.
Shaves a few bytes from .text:
text data bss dec hex filename
852418 24560 23112 900090 dbbfa btrfs.ko.before
851074 24584 23112 898770 db6d2 btrfs.ko.after
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
btrfs_set_key_type and btrfs_key_type are used inconsistently along with
open coded variants. Other members of btrfs_key are accessed directly
without any helpers anyway.
Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
We've got bug reports that btrfs crashes when quota is enabled on
32bit kernel, typically with the Oops like below:
BUG: unable to handle kernel NULL pointer dereference at 00000004
IP: [<f9234590>] find_parent_nodes+0x360/0x1380 [btrfs]
*pde = 00000000
Oops: 0000 [#1] SMP
CPU: 0 PID: 151 Comm: kworker/u8:2 Tainted: G S W 3.15.2-1.gd43d97e-default #1
Workqueue: btrfs-qgroup-rescan normal_work_helper [btrfs]
task: f1478130 ti: f147c000 task.ti: f147c000
EIP: 0060:[<f9234590>] EFLAGS: 00010213 CPU: 0
EIP is at find_parent_nodes+0x360/0x1380 [btrfs]
EAX: f147dda8 EBX: f147ddb0 ECX: 00000011 EDX: 00000000
ESI: 00000000 EDI: f147dda4 EBP: f147ddf8 ESP: f147dd38
DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
CR0: 8005003b CR2: 00000004 CR3: 00bf3000 CR4: 00000690
Stack:
00000000 00000000 f147dda4 00000050 00000001 00000000 00000001 00000050
00000001 00000000 d3059000 00000001 00000022 000000a8 00000000 00000000
00000000 000000a1 00000000 00000000 00000001 00000000 00000000 11800000
Call Trace:
[<f923564d>] __btrfs_find_all_roots+0x9d/0xf0 [btrfs]
[<f9237bb1>] btrfs_qgroup_rescan_worker+0x401/0x760 [btrfs]
[<f9206148>] normal_work_helper+0xc8/0x270 [btrfs]
[<c025e38b>] process_one_work+0x11b/0x390
[<c025eea1>] worker_thread+0x101/0x340
[<c026432b>] kthread+0x9b/0xb0
[<c0712a71>] ret_from_kernel_thread+0x21/0x30
[<c0264290>] kthread_create_on_node+0x110/0x110
This indicates a NULL corruption in prefs_delayed list. The further
investigation and bisection pointed that the call of ulist_add_merge()
results in the corruption.
ulist_add_merge() takes u64 as aux and writes a 64bit value into
old_aux. The callers of this function in backref.c, however, pass a
pointer of a pointer to old_aux. That is, the function overwrites
64bit value on 32bit pointer. This caused a NULL in the adjacent
variable, in this case, prefs_delayed.
Here is a quick attempt to band-aid over this: a new function,
ulist_add_merge_ptr() is introduced to pass/store properly a pointer
value instead of u64. There are still ugly void ** cast remaining
in the callers because void ** cannot be taken implicitly. But, it's
safer than explicit cast to u64, anyway.
Bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=887046
Cc: <stable@vger.kernel.org> [v3.11+]
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Chris Mason <clm@fb.com>
Before processing the extent buffer, acquire a read lock on it, so
that we're safe against concurrent updates on the extent buffer.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Edmund Nadolski