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Merge tag 'for-5.5-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few more fixes that have been in the works during last twp weeks.
All have a user visible effect and are stable material:
- scrub: properly update progress after calling cancel ioctl, calling
'resume' would start from the beginning otherwise
- fix subvolume reference removal, after moving out of the original
path the reference is not recognized and will lead to transaction
abort
- fix reloc root lifetime checks, could lead to crashes when there's
subvolume cleaning running in parallel
- fix memory leak when quotas get disabled in the middle of extent
accounting
- fix transaction abort in case of balance being started on degraded
mount on eg. RAID1"
* tag 'for-5.5-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: check rw_devices, not num_devices for balance
Btrfs: always copy scrub arguments back to user space
btrfs: relocation: fix reloc_root lifespan and access
btrfs: fix memory leak in qgroup accounting
btrfs: do not delete mismatched root refs
btrfs: fix invalid removal of root ref
btrfs: rework arguments of btrfs_unlink_subvol
The fstest btrfs/154 reports
[ 8675.381709] BTRFS: Transaction aborted (error -28)
[ 8675.383302] WARNING: CPU: 1 PID: 31900 at fs/btrfs/block-group.c:2038 btrfs_create_pending_block_groups+0x1e0/0x1f0 [btrfs]
[ 8675.390925] CPU: 1 PID: 31900 Comm: btrfs Not tainted 5.5.0-rc6-default+ #935
[ 8675.392780] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba527-rebuilt.opensuse.org 04/01/2014
[ 8675.395452] RIP: 0010:btrfs_create_pending_block_groups+0x1e0/0x1f0 [btrfs]
[ 8675.402672] RSP: 0018:ffffb2090888fb00 EFLAGS: 00010286
[ 8675.404413] RAX: 0000000000000000 RBX: ffff92026dfa91c8 RCX: 0000000000000001
[ 8675.406609] RDX: 0000000000000000 RSI: ffffffff8e100899 RDI: ffffffff8e100971
[ 8675.408775] RBP: ffff920247c61660 R08: 0000000000000000 R09: 0000000000000000
[ 8675.410978] R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffe4
[ 8675.412647] R13: ffff92026db74000 R14: ffff920247c616b8 R15: ffff92026dfbc000
[ 8675.413994] FS: 00007fd5e57248c0(0000) GS:ffff92027d800000(0000) knlGS:0000000000000000
[ 8675.416146] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 8675.417833] CR2: 0000564aa51682d8 CR3: 000000006dcbc004 CR4: 0000000000160ee0
[ 8675.419801] Call Trace:
[ 8675.420742] btrfs_start_dirty_block_groups+0x355/0x480 [btrfs]
[ 8675.422600] btrfs_commit_transaction+0xc8/0xaf0 [btrfs]
[ 8675.424335] reset_balance_state+0x14a/0x190 [btrfs]
[ 8675.425824] btrfs_balance.cold+0xe7/0x154 [btrfs]
[ 8675.427313] ? kmem_cache_alloc_trace+0x235/0x2c0
[ 8675.428663] btrfs_ioctl_balance+0x298/0x350 [btrfs]
[ 8675.430285] btrfs_ioctl+0x466/0x2550 [btrfs]
[ 8675.431788] ? mem_cgroup_charge_statistics+0x51/0xf0
[ 8675.433487] ? mem_cgroup_commit_charge+0x56/0x400
[ 8675.435122] ? do_raw_spin_unlock+0x4b/0xc0
[ 8675.436618] ? _raw_spin_unlock+0x1f/0x30
[ 8675.438093] ? __handle_mm_fault+0x499/0x740
[ 8675.439619] ? do_vfs_ioctl+0x56e/0x770
[ 8675.441034] do_vfs_ioctl+0x56e/0x770
[ 8675.442411] ksys_ioctl+0x3a/0x70
[ 8675.443718] ? trace_hardirqs_off_thunk+0x1a/0x1c
[ 8675.445333] __x64_sys_ioctl+0x16/0x20
[ 8675.446705] do_syscall_64+0x50/0x210
[ 8675.448059] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 8675.479187] BTRFS: error (device vdb) in btrfs_create_pending_block_groups:2038: errno=-28 No space left
We now use btrfs_can_overcommit() to see if we can flip a block group
read only. Before this would fail because we weren't taking into
account the usable un-allocated space for allocating chunks. With my
patches we were allowed to do the balance, which is technically correct.
The test is trying to start balance on degraded mount. So now we're
trying to allocate a chunk and cannot because we want to allocate a
RAID1 chunk, but there's only 1 device that's available for usage. This
results in an ENOSPC.
But we shouldn't even be making it this far, we don't have enough
devices to restripe. The problem is we're using btrfs_num_devices(),
that also includes missing devices. That's not actually what we want, we
need to use rw_devices.
The chunk_mutex is not needed here, rw_devices changes only in device
add, remove or replace, all are excluded by EXCL_OP mechanism.
Fixes: e4d8ec0f65 ("Btrfs: implement online profile changing")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ add stacktrace, update changelog, drop chunk_mutex ]
Signed-off-by: David Sterba <dsterba@suse.com>
If scrub returns an error we are not copying back the scrub arguments
structure to user space. This prevents user space to know how much
progress scrub has done if an error happened - this includes -ECANCELED
which is returned when users ask for scrub to stop. A particular use
case, which is used in btrfs-progs, is to resume scrub after it is
canceled, in that case it relies on checking the progress from the scrub
arguments structure and then use that progress in a call to resume
scrub.
So fix this by always copying the scrub arguments structure to user
space, overwriting the value returned to user space with -EFAULT only if
copying the structure failed to let user space know that either that
copying did not happen, and therefore the structure is stale, or it
happened partially and the structure is probably not valid and corrupt
due to the partial copy.
Reported-by: Graham Cobb <g.btrfs@cobb.uk.net>
Link: https://lore.kernel.org/linux-btrfs/d0a97688-78be-08de-ca7d-bcb4c7fb397e@cobb.uk.net/
Fixes: 06fe39ab15 ("Btrfs: do not overwrite scrub error with fault error in scrub ioctl")
CC: stable@vger.kernel.org # 5.1+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Tested-by: Graham Cobb <g.btrfs@cobb.uk.net>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
There are several different KASAN reports for balance + snapshot
workloads. Involved call paths include:
should_ignore_root+0x54/0xb0 [btrfs]
build_backref_tree+0x11af/0x2280 [btrfs]
relocate_tree_blocks+0x391/0xb80 [btrfs]
relocate_block_group+0x3e5/0xa00 [btrfs]
btrfs_relocate_block_group+0x240/0x4d0 [btrfs]
btrfs_relocate_chunk+0x53/0xf0 [btrfs]
btrfs_balance+0xc91/0x1840 [btrfs]
btrfs_ioctl_balance+0x416/0x4e0 [btrfs]
btrfs_ioctl+0x8af/0x3e60 [btrfs]
do_vfs_ioctl+0x831/0xb10
create_reloc_root+0x9f/0x460 [btrfs]
btrfs_reloc_post_snapshot+0xff/0x6c0 [btrfs]
create_pending_snapshot+0xa9b/0x15f0 [btrfs]
create_pending_snapshots+0x111/0x140 [btrfs]
btrfs_commit_transaction+0x7a6/0x1360 [btrfs]
btrfs_mksubvol+0x915/0x960 [btrfs]
btrfs_ioctl_snap_create_transid+0x1d5/0x1e0 [btrfs]
btrfs_ioctl_snap_create_v2+0x1d3/0x270 [btrfs]
btrfs_ioctl+0x241b/0x3e60 [btrfs]
do_vfs_ioctl+0x831/0xb10
btrfs_reloc_pre_snapshot+0x85/0xc0 [btrfs]
create_pending_snapshot+0x209/0x15f0 [btrfs]
create_pending_snapshots+0x111/0x140 [btrfs]
btrfs_commit_transaction+0x7a6/0x1360 [btrfs]
btrfs_mksubvol+0x915/0x960 [btrfs]
btrfs_ioctl_snap_create_transid+0x1d5/0x1e0 [btrfs]
btrfs_ioctl_snap_create_v2+0x1d3/0x270 [btrfs]
btrfs_ioctl+0x241b/0x3e60 [btrfs]
do_vfs_ioctl+0x831/0xb10
[CAUSE]
All these call sites are only relying on root->reloc_root, which can
undergo btrfs_drop_snapshot(), and since we don't have real refcount
based protection to reloc roots, we can reach already dropped reloc
root, triggering KASAN.
[FIX]
To avoid such access to unstable root->reloc_root, we should check
BTRFS_ROOT_DEAD_RELOC_TREE bit first.
This patch introduces wrappers that provide the correct way to check the
bit with memory barriers protection.
Most callers don't distinguish merged reloc tree and no reloc tree. The
only exception is should_ignore_root(), as merged reloc tree can be
ignored, while no reloc tree shouldn't.
[CRITICAL SECTION ANALYSIS]
Although test_bit()/set_bit()/clear_bit() doesn't imply a barrier, the
DEAD_RELOC_TREE bit has extra help from transaction as a higher level
barrier, the lifespan of root::reloc_root and DEAD_RELOC_TREE bit are:
NULL: reloc_root is NULL PTR: reloc_root is not NULL
0: DEAD_RELOC_ROOT bit not set DEAD: DEAD_RELOC_ROOT bit set
(NULL, 0) Initial state __
| /\ Section A
btrfs_init_reloc_root() \/
| __
(PTR, 0) reloc_root initialized /\
| |
btrfs_update_reloc_root() | Section B
| |
(PTR, DEAD) reloc_root has been merged \/
| __
=== btrfs_commit_transaction() ====================
| /\
clean_dirty_subvols() |
| | Section C
(NULL, DEAD) reloc_root cleanup starts \/
| __
btrfs_drop_snapshot() /\
| | Section D
(NULL, 0) Back to initial state \/
Every have_reloc_root() or test_bit(DEAD_RELOC_ROOT) caller holds
transaction handle, so none of such caller can cross transaction boundary.
In Section A, every caller just found no DEAD bit, and grab reloc_root.
In the cross section A-B, caller may get no DEAD bit, but since reloc_root
is still completely valid thus accessing reloc_root is completely safe.
No test_bit() caller can cross the boundary of Section B and Section C.
In Section C, every caller found the DEAD bit, so no one will access
reloc_root.
In the cross section C-D, either caller gets the DEAD bit set, avoiding
access reloc_root no matter if it's safe or not. Or caller get the DEAD
bit cleared, then access reloc_root, which is already NULL, nothing will
be wrong.
The memory write barriers are between the reloc_root updates and bit
set/clear, the pairing read side is before test_bit.
Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Fixes: d2311e6985 ("btrfs: relocation: Delay reloc tree deletion after merge_reloc_roots")
CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
[ barriers ]
Signed-off-by: David Sterba <dsterba@suse.com>
When running xfstests on the current btrfs I get the following splat from
kmemleak:
unreferenced object 0xffff88821b2404e0 (size 32):
comm "kworker/u4:7", pid 26663, jiffies 4295283698 (age 8.776s)
hex dump (first 32 bytes):
01 00 00 00 00 00 00 00 10 ff fd 26 82 88 ff ff ...........&....
10 ff fd 26 82 88 ff ff 20 ff fd 26 82 88 ff ff ...&.... ..&....
backtrace:
[<00000000f94fd43f>] ulist_alloc+0x25/0x60 [btrfs]
[<00000000fd023d99>] btrfs_find_all_roots_safe+0x41/0x100 [btrfs]
[<000000008f17bd32>] btrfs_find_all_roots+0x52/0x70 [btrfs]
[<00000000b7660afb>] btrfs_qgroup_rescan_worker+0x343/0x680 [btrfs]
[<0000000058e66778>] btrfs_work_helper+0xac/0x1e0 [btrfs]
[<00000000f0188930>] process_one_work+0x1cf/0x350
[<00000000af5f2f8e>] worker_thread+0x28/0x3c0
[<00000000b55a1add>] kthread+0x109/0x120
[<00000000f88cbd17>] ret_from_fork+0x35/0x40
This corresponds to:
(gdb) l *(btrfs_find_all_roots_safe+0x41)
0x8d7e1 is in btrfs_find_all_roots_safe (fs/btrfs/backref.c:1413).
1408
1409 tmp = ulist_alloc(GFP_NOFS);
1410 if (!tmp)
1411 return -ENOMEM;
1412 *roots = ulist_alloc(GFP_NOFS);
1413 if (!*roots) {
1414 ulist_free(tmp);
1415 return -ENOMEM;
1416 }
1417
Following the lifetime of the allocated 'roots' ulist, it gets freed
again in btrfs_qgroup_account_extent().
But this does not happen if the function is called with the
'BTRFS_FS_QUOTA_ENABLED' flag cleared, then btrfs_qgroup_account_extent()
does a short leave and directly returns.
Instead of directly returning we should jump to the 'out_free' in order to
free all resources as expected.
CC: stable@vger.kernel.org # 4.14+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
[ add comment ]
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_del_root_ref() will simply WARN_ON() if the ref doesn't match in
any way, and then continue to delete the reference. This shouldn't
happen, we have these values because there's more to the reference than
the original root and the sub root. If any of these checks fail, return
-ENOENT.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we have the following sequence of events
btrfs sub create A
btrfs sub create A/B
btrfs sub snap A C
mkdir C/foo
mv A/B C/foo
rm -rf *
We will end up with a transaction abort.
The reason for this is because we create a root ref for B pointing to A.
When we create a snapshot of C we still have B in our tree, but because
the root ref points to A and not C we will make it appear to be empty.
The problem happens when we move B into C. This removes the root ref
for B pointing to A and adds a ref of B pointing to C. When we rmdir C
we'll see that we have a ref to our root and remove the root ref,
despite not actually matching our reference name.
Now btrfs_del_root_ref() allowing this to work is a bug as well, however
we know that this inode does not actually point to a root ref in the
first place, so we shouldn't be calling btrfs_del_root_ref() in the
first place and instead simply look up our dir index for this item and
do the rest of the removal.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
btrfs_unlink_subvol takes the name of the dentry and the root objectid
based on what kind of inode this is, either a real subvolume link or a
empty one that we inherited as a snapshot. We need to fix how we unlink
in the case for BTRFS_EMPTY_SUBVOL_DIR_OBJECTID in the future, so rework
btrfs_unlink_subvol to just take the dentry and handle getting the right
objectid given the type of inode this is. There is no functional change
here, simply pushing the work into btrfs_unlink_subvol() proper.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-5.5-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A few fixes for btrfs:
- blkcg accounting problem with compression that could stall writes
- setting up blkcg bio for compression crashes due to NULL bdev
pointer
- fix possible infinite loop in writeback for nocow files (here
possible means almost impossible, 13 things that need to happen to
trigger it)"
* tag 'for-5.5-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
Btrfs: fix infinite loop during nocow writeback due to race
btrfs: fix compressed write bio blkcg attribution
btrfs: punt all bios created in btrfs_submit_compressed_write()
When starting writeback for a range that covers part of a preallocated
extent, due to a race with writeback for another range that also covers
another part of the same preallocated extent, we can end up in an infinite
loop.
Consider the following example where for inode 280 we have two dirty
ranges:
range A, from 294912 to 303103, 8192 bytes
range B, from 348160 to 438271, 90112 bytes
and we have the following file extent item layout for our inode:
leaf 38895616 gen 24544 total ptrs 29 free space 13820 owner 5
(...)
item 27 key (280 108 200704) itemoff 14598 itemsize 53
extent data disk bytenr 0 nr 0 type 1 (regular)
extent data offset 0 nr 94208 ram 94208
item 28 key (280 108 294912) itemoff 14545 itemsize 53
extent data disk bytenr 10433052672 nr 81920 type 2 (prealloc)
extent data offset 0 nr 81920 ram 81920
Then the following happens:
1) Writeback starts for range B (from 348160 to 438271), execution of
run_delalloc_nocow() starts;
2) The first iteration of run_delalloc_nocow()'s whil loop leaves us at
the extent item at slot 28, pointing to the prealloc extent item
covering the range from 294912 to 376831. This extent covers part of
our range;
3) An ordered extent is created against that extent, covering the file
range from 348160 to 376831 (28672 bytes);
4) We adjust 'cur_offset' to 376832 and move on to the next iteration of
the while loop;
5) The call to btrfs_lookup_file_extent() leaves us at the same leaf,
pointing to slot 29, 1 slot after the last item (the extent item
we processed in the previous iteration);
6) Because we are a slot beyond the last item, we call btrfs_next_leaf(),
which releases the search path before doing a another search for the
last key of the leaf (280 108 294912);
7) Right after btrfs_next_leaf() released the path, and before it did
another search for the last key of the leaf, writeback for the range
A (from 294912 to 303103) completes (it was previously started at
some point);
8) Upon completion of the ordered extent for range A, the prealloc extent
we previously found got split into two extent items, one covering the
range from 294912 to 303103 (8192 bytes), with a type of regular extent
(and no longer prealloc) and another covering the range from 303104 to
376831 (73728 bytes), with a type of prealloc and an offset of 8192
bytes. So our leaf now has the following layout:
leaf 38895616 gen 24544 total ptrs 31 free space 13664 owner 5
(...)
item 27 key (280 108 200704) itemoff 14598 itemsize 53
extent data disk bytenr 0 nr 0 type 1
extent data offset 0 nr 8192 ram 94208
item 28 key (280 108 208896) itemoff 14545 itemsize 53
extent data disk bytenr 10433142784 nr 86016 type 1
extent data offset 0 nr 86016 ram 86016
item 29 key (280 108 294912) itemoff 14492 itemsize 53
extent data disk bytenr 10433052672 nr 81920 type 1
extent data offset 0 nr 8192 ram 81920
item 30 key (280 108 303104) itemoff 14439 itemsize 53
extent data disk bytenr 10433052672 nr 81920 type 2
extent data offset 8192 nr 73728 ram 81920
9) After btrfs_next_leaf() returns, we have our path pointing to that same
leaf and at slot 30, since it has a key we didn't have before and it's
the first key greater then the key that was previously the last key of
the leaf (key (280 108 294912));
10) The extent item at slot 30 covers the range from 303104 to 376831
which is in our target range, so we process it, despite having already
created an ordered extent against this extent for the file range from
348160 to 376831. This is because we skip to the next extent item only
if its end is less than or equals to the start of our delalloc range,
and not less than or equals to the current offset ('cur_offset');
11) As a result we compute 'num_bytes' as:
num_bytes = min(end + 1, extent_end) - cur_offset;
= min(438271 + 1, 376832) - 376832 = 0
12) We then call create_io_em() for a 0 bytes range starting at offset
376832;
13) Then create_io_em() enters an infinite loop because its calls to
btrfs_drop_extent_cache() do nothing due to the 0 length range
passed to it. So no existing extent maps that cover the offset
376832 get removed, and therefore calls to add_extent_mapping()
return -EEXIST, resulting in an infinite loop. This loop from
create_io_em() is the following:
do {
btrfs_drop_extent_cache(BTRFS_I(inode), em->start,
em->start + em->len - 1, 0);
write_lock(&em_tree->lock);
ret = add_extent_mapping(em_tree, em, 1);
write_unlock(&em_tree->lock);
/*
* The caller has taken lock_extent(), who could race with us
* to add em?
*/
} while (ret == -EEXIST);
Also, each call to btrfs_drop_extent_cache() triggers a warning because
the start offset passed to it (376832) is smaller then the end offset
(376832 - 1) passed to it by -1, due to the 0 length:
[258532.052621] ------------[ cut here ]------------
[258532.052643] WARNING: CPU: 0 PID: 9987 at fs/btrfs/file.c:602 btrfs_drop_extent_cache+0x3f4/0x590 [btrfs]
(...)
[258532.052672] CPU: 0 PID: 9987 Comm: fsx Tainted: G W 5.4.0-rc7-btrfs-next-64 #1
[258532.052673] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
[258532.052691] RIP: 0010:btrfs_drop_extent_cache+0x3f4/0x590 [btrfs]
(...)
[258532.052695] RSP: 0018:ffffb4be0153f860 EFLAGS: 00010287
[258532.052700] RAX: ffff975b445ee360 RBX: ffff975b44eb3e08 RCX: 0000000000000000
[258532.052700] RDX: 0000000000038fff RSI: 0000000000039000 RDI: ffff975b445ee308
[258532.052700] RBP: 0000000000038fff R08: 0000000000000000 R09: 0000000000000001
[258532.052701] R10: ffff975b513c5c10 R11: 00000000e3c0cfa9 R12: 0000000000039000
[258532.052703] R13: ffff975b445ee360 R14: 00000000ffffffef R15: ffff975b445ee308
[258532.052705] FS: 00007f86a821de80(0000) GS:ffff975b76a00000(0000) knlGS:0000000000000000
[258532.052707] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[258532.052708] CR2: 00007fdacf0f3ab4 CR3: 00000001f9d26002 CR4: 00000000003606f0
[258532.052712] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[258532.052717] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[258532.052717] Call Trace:
[258532.052718] ? preempt_schedule_common+0x32/0x70
[258532.052722] ? ___preempt_schedule+0x16/0x20
[258532.052741] create_io_em+0xff/0x180 [btrfs]
[258532.052767] run_delalloc_nocow+0x942/0xb10 [btrfs]
[258532.052791] btrfs_run_delalloc_range+0x30b/0x520 [btrfs]
[258532.052812] ? find_lock_delalloc_range+0x221/0x250 [btrfs]
[258532.052834] writepage_delalloc+0xe4/0x140 [btrfs]
[258532.052855] __extent_writepage+0x110/0x4e0 [btrfs]
[258532.052876] extent_write_cache_pages+0x21c/0x480 [btrfs]
[258532.052906] extent_writepages+0x52/0xb0 [btrfs]
[258532.052911] do_writepages+0x23/0x80
[258532.052915] __filemap_fdatawrite_range+0xd2/0x110
[258532.052938] btrfs_fdatawrite_range+0x1b/0x50 [btrfs]
[258532.052954] start_ordered_ops+0x57/0xa0 [btrfs]
[258532.052973] ? btrfs_sync_file+0x225/0x490 [btrfs]
[258532.052988] btrfs_sync_file+0x225/0x490 [btrfs]
[258532.052997] __x64_sys_msync+0x199/0x200
[258532.053004] do_syscall_64+0x5c/0x250
[258532.053007] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[258532.053010] RIP: 0033:0x7f86a7dfd760
(...)
[258532.053014] RSP: 002b:00007ffd99af0368 EFLAGS: 00000246 ORIG_RAX: 000000000000001a
[258532.053016] RAX: ffffffffffffffda RBX: 0000000000000ec9 RCX: 00007f86a7dfd760
[258532.053017] RDX: 0000000000000004 RSI: 000000000000836c RDI: 00007f86a8221000
[258532.053019] RBP: 0000000000021ec9 R08: 0000000000000003 R09: 00007f86a812037c
[258532.053020] R10: 0000000000000001 R11: 0000000000000246 R12: 00000000000074a3
[258532.053021] R13: 00007f86a8221000 R14: 000000000000836c R15: 0000000000000001
[258532.053032] irq event stamp: 1653450494
[258532.053035] hardirqs last enabled at (1653450493): [<ffffffff9dec69f9>] _raw_spin_unlock_irq+0x29/0x50
[258532.053037] hardirqs last disabled at (1653450494): [<ffffffff9d4048ea>] trace_hardirqs_off_thunk+0x1a/0x20
[258532.053039] softirqs last enabled at (1653449852): [<ffffffff9e200466>] __do_softirq+0x466/0x6bd
[258532.053042] softirqs last disabled at (1653449845): [<ffffffff9d4c8a0c>] irq_exit+0xec/0x120
[258532.053043] ---[ end trace 8476fce13d9ce20a ]---
Which results in flooding dmesg/syslog since btrfs_drop_extent_cache()
uses WARN_ON() and not WARN_ON_ONCE().
So fix this issue by changing run_delalloc_nocow()'s loop to move to the
next extent item when the current extent item ends at at offset less than
or equals to the current offset instead of the start offset.
Fixes: 80ff385665 ("Btrfs: update nodatacow code v2")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Bio attribution is handled at bio_set_dev() as once we have a device, we
have a corresponding request_queue and then can derive the current css.
In special cases, we want to attribute to bio to someone else. This can
be done by calling bio_associate_blkg_from_css() or
kthread_associate_blkcg() depending on the scenario. Btrfs does this for
compressed writeback as they are handled by kworkers, so the latter can
be done here.
Commit 1a41802701 ("btrfs: drop bio_set_dev where not needed") removes
early bio_set_dev() calls prior to submit_stripe_bio(). This breaks the
above assumption that we'll have a request_queue when we are doing
association. To fix this, switch to using kthread_associate_blkcg().
Without this, we crash in btrfs/024:
[ 3052.093088] BUG: kernel NULL pointer dereference, address: 0000000000000510
[ 3052.107013] #PF: supervisor read access in kernel mode
[ 3052.107014] #PF: error_code(0x0000) - not-present page
[ 3052.107015] PGD 0 P4D 0
[ 3052.107021] Oops: 0000 [#1] SMP
[ 3052.138904] CPU: 42 PID: 201270 Comm: kworker/u161:0 Kdump: loaded Not tainted 5.5.0-rc1-00062-g4852d8ac90a9 #712
[ 3052.138905] Hardware name: Quanta Tioga Pass Single Side 01-0032211004/Tioga Pass Single Side, BIOS F08_3A18 12/20/2018
[ 3052.138912] Workqueue: btrfs-delalloc btrfs_work_helper
[ 3052.191375] RIP: 0010:bio_associate_blkg_from_css+0x1e/0x3c0
[ 3052.191379] RSP: 0018:ffffc900210cfc90 EFLAGS: 00010282
[ 3052.191380] RAX: 0000000000000000 RBX: ffff88bfe5573c00 RCX: 0000000000000000
[ 3052.191382] RDX: ffff889db48ec2f0 RSI: ffff88bfe5573c00 RDI: ffff889db48ec2f0
[ 3052.191386] RBP: 0000000000000800 R08: 0000000000203bb0 R09: ffff889db16b2400
[ 3052.293364] R10: 0000000000000000 R11: ffff88a07fffde80 R12: ffff889db48ec2f0
[ 3052.293365] R13: 0000000000001000 R14: ffff889de82bc000 R15: ffff889e2b7bdcc8
[ 3052.293367] FS: 0000000000000000(0000) GS:ffff889ffba00000(0000) knlGS:0000000000000000
[ 3052.293368] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 3052.293369] CR2: 0000000000000510 CR3: 0000000002611001 CR4: 00000000007606e0
[ 3052.293370] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 3052.293371] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 3052.293372] PKRU: 55555554
[ 3052.293376] Call Trace:
[ 3052.402552] btrfs_submit_compressed_write+0x137/0x390
[ 3052.402558] submit_compressed_extents+0x40f/0x4c0
[ 3052.422401] btrfs_work_helper+0x246/0x5a0
[ 3052.422408] process_one_work+0x200/0x570
[ 3052.438601] ? process_one_work+0x180/0x570
[ 3052.438605] worker_thread+0x4c/0x3e0
[ 3052.438614] kthread+0x103/0x140
[ 3052.460735] ? process_one_work+0x570/0x570
[ 3052.460737] ? kthread_mod_delayed_work+0xc0/0xc0
[ 3052.460744] ret_from_fork+0x24/0x30
Fixes: 1a41802701 ("btrfs: drop bio_set_dev where not needed")
Reported-by: Chris Murphy <chris@colorremedies.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Compressed writes happen in the background via kworkers. However, this
causes bios to be attributed to root bypassing any cgroup limits from
the actual writer. We tag the first bio with REQ_CGROUP_PUNT, which will
punt the bio to an appropriate cgroup specific workqueue and attribute
the IO properly. However, if btrfs_submit_compressed_write() creates a
new bio, we don't tag it the same way. Add the appropriate tagging for
subsequent bios.
Fixes: ec39f7696c ("Btrfs: use REQ_CGROUP_PUNT for worker thread submitted bios")
Reviewed-by: Chris Mason <clm@fb.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Merge tag 'for-5.5-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fixes from David Sterba:
"A mix of regression fixes and regular fixes for stable trees:
- fix swapped error messages for qgroup enable/rescan
- fixes for NO_HOLES feature with clone range
- fix deadlock between iget/srcu lock/synchronize srcu while freeing
an inode
- fix double lock on subvolume cross-rename
- tree log fixes
* fix missing data checksums after replaying a log tree
* also teach tree-checker about this problem
* skip log replay on orphaned roots
- fix maximum devices constraints for RAID1C -3 and -4
- send: don't print warning on read-only mount regarding orphan
cleanup
- error handling fixes"
* tag 'for-5.5-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: send: remove WARN_ON for readonly mount
btrfs: do not leak reloc root if we fail to read the fs root
btrfs: skip log replay on orphaned roots
btrfs: handle ENOENT in btrfs_uuid_tree_iterate
btrfs: abort transaction after failed inode updates in create_subvol
Btrfs: fix hole extent items with a zero size after range cloning
Btrfs: fix removal logic of the tree mod log that leads to use-after-free issues
Btrfs: make tree checker detect checksum items with overlapping ranges
Btrfs: fix missing data checksums after replaying a log tree
btrfs: return error pointer from alloc_test_extent_buffer
btrfs: fix devs_max constraints for raid1c3 and raid1c4
btrfs: tree-checker: Fix error format string for size_t
btrfs: don't double lock the subvol_sem for rename exchange
btrfs: handle error in btrfs_cache_block_group
btrfs: do not call synchronize_srcu() in inode_tree_del
Btrfs: fix cloning range with a hole when using the NO_HOLES feature
btrfs: Fix error messages in qgroup_rescan_init
We log warning if root::orphan_cleanup_state is not set to
ORPHAN_CLEANUP_DONE in btrfs_ioctl_send(). However if the filesystem is
mounted as readonly we skip the orphan item cleanup during the lookup
and root::orphan_cleanup_state remains at the init state 0 instead of
ORPHAN_CLEANUP_DONE (2). So during send in btrfs_ioctl_send() we hit the
warning as below.
WARN_ON(send_root->orphan_cleanup_state != ORPHAN_CLEANUP_DONE);
WARNING: CPU: 0 PID: 2616 at /Volumes/ws/btrfs-devel/fs/btrfs/send.c:7090 btrfs_ioctl_send+0xb2f/0x18c0 [btrfs]
::
RIP: 0010:btrfs_ioctl_send+0xb2f/0x18c0 [btrfs]
::
Call Trace:
::
_btrfs_ioctl_send+0x7b/0x110 [btrfs]
btrfs_ioctl+0x150a/0x2b00 [btrfs]
::
do_vfs_ioctl+0xa9/0x620
? __fget+0xac/0xe0
ksys_ioctl+0x60/0x90
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x49/0x130
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Reproducer:
mkfs.btrfs -fq /dev/sdb
mount /dev/sdb /btrfs
btrfs subvolume create /btrfs/sv1
btrfs subvolume snapshot -r /btrfs/sv1 /btrfs/ss1
umount /btrfs
mount -o ro /dev/sdb /btrfs
btrfs send /btrfs/ss1 -f /tmp/f
The warning exists because having orphan inodes could confuse send and
cause it to fail or produce incorrect streams. The two cases that would
cause such send failures, which are already fixed are:
1) Inodes that were unlinked - these are orphanized and remain with a
link count of 0. These caused send operations to fail because it
expected to always find at least one path for an inode. However this
is no longer a problem since send is now able to deal with such
inodes since commit 46b2f4590a ("Btrfs: fix send failure when root
has deleted files still open") and treats them as having been
completely removed (the state after an orphan cleanup is performed).
2) Inodes that were in the process of being truncated. These resulted in
send not knowing about the truncation and potentially issue write
operations full of zeroes for the range from the new file size to the
old file size. This is no longer a problem because we no longer
create orphan items for truncation since commit f7e9e8fc79 ("Btrfs:
stop creating orphan items for truncate").
As such before these commits, the WARN_ON here provided a clue in case
something went wrong. Instead of being a warning against the
root::orphan_cleanup_state value, it could have been more accurate by
checking if there were actually any orphan items, and then issue a
warning only if any exists, but that would be more expensive to check.
Since orphanized inodes no longer cause problems for send, just remove
the warning.
Reported-by: Christoph Anton Mitterer <calestyo@scientia.net>
Link: https://lore.kernel.org/linux-btrfs/21cb5e8d059f6e1496a903fa7bfc0a297e2f5370.camel@scientia.net/
CC: stable@vger.kernel.org # 4.19+
Suggested-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we fail to read the fs root corresponding with a reloc root we'll
just break out and free the reloc roots. But we remove our current
reloc_root from this list higher up, which means we'll leak this
reloc_root. Fix this by adding ourselves back to the reloc_roots list
so we are properly cleaned up.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
My fsstress modifications coupled with generic/475 uncovered a failure
to mount and replay the log if we hit a orphaned root. We do not want
to replay the log for an orphan root, but it's completely legitimate to
have an orphaned root with a log attached. Fix this by simply skipping
replaying the log. We still need to pin it's root node so that we do
not overwrite it while replaying other logs, as we re-read the log root
at every stage of the replay.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we get an -ENOENT back from btrfs_uuid_iter_rem when iterating the
uuid tree we'll just continue and do btrfs_next_item(). However we've
done a btrfs_release_path() at this point and no longer have a valid
path. So increment the key and go back and do a normal search.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We can just abort the transaction here, and in fact do that for every
other failure in this function except these two cases.
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Normally when cloning a file range if we find an implicit hole at the end
of the range we assume it is because the NO_HOLES feature is enabled.
However that is not always the case. One well known case [1] is when we
have a power failure after mixing buffered and direct IO writes against
the same file.
In such cases we need to punch a hole in the destination file, and if
the NO_HOLES feature is not enabled, we need to insert explicit file
extent items to represent the hole. After commit 690a5dbfc5
("Btrfs: fix ENOSPC errors, leading to transaction aborts, when cloning
extents"), we started to insert file extent items representing the hole
with an item size of 0, which is invalid and should be 53 bytes (the size
of a btrfs_file_extent_item structure), resulting in all sorts of
corruptions and invalid memory accesses. This is detected by the tree
checker when we attempt to write a leaf to disk.
The problem can be sporadically triggered by test case generic/561 from
fstests. That test case does not exercise power failure and creates a new
filesystem when it starts, so it does not use a filesystem created by any
previous test that tests power failure. However the test does both
buffered and direct IO writes (through fsstress) and it's precisely that
which is creating the implicit holes in files. That happens even before
the commit mentioned earlier. I need to investigate why we get those
implicit holes to check if there is a real problem or not. For now this
change fixes the regression of introducing file extent items with an item
size of 0 bytes.
Fix the issue by calling btrfs_punch_hole_range() without passing a
btrfs_clone_extent_info structure, which ensures file extent items are
inserted to represent the hole with a correct item size. We were passing
a btrfs_clone_extent_info with a value of 0 for its 'item_size' field,
which was causing the insertion of file extent items with an item size
of 0.
[1] https://www.spinics.net/lists/linux-btrfs/msg75350.html
Reported-by: David Sterba <dsterba@suse.com>
Fixes: 690a5dbfc5 ("Btrfs: fix ENOSPC errors, leading to transaction aborts, when cloning extents")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When a tree mod log user no longer needs to use the tree it calls
btrfs_put_tree_mod_seq() to remove itself from the list of users and
delete all no longer used elements of the tree's red black tree, which
should be all elements with a sequence number less then our equals to
the caller's sequence number. However the logic is broken because it
can delete and free elements from the red black tree that have a
sequence number greater then the caller's sequence number:
1) At a point in time we have sequence numbers 1, 2, 3 and 4 in the
tree mod log;
2) The task which got assigned the sequence number 1 calls
btrfs_put_tree_mod_seq();
3) Sequence number 1 is deleted from the list of sequence numbers;
4) The current minimum sequence number is computed to be the sequence
number 2;
5) A task using sequence number 2 is at tree_mod_log_rewind() and gets
a pointer to one of its elements from the red black tree through
a call to tree_mod_log_search();
6) The task with sequence number 1 iterates the red black tree of tree
modification elements and deletes (and frees) all elements with a
sequence number less then or equals to 2 (the computed minimum sequence
number) - it ends up only leaving elements with sequence numbers of 3
and 4;
7) The task with sequence number 2 now uses the pointer to its element,
already freed by the other task, at __tree_mod_log_rewind(), resulting
in a use-after-free issue. When CONFIG_DEBUG_PAGEALLOC=y it produces
a trace like the following:
[16804.546854] general protection fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI
[16804.547451] CPU: 0 PID: 28257 Comm: pool Tainted: G W 5.4.0-rc8-btrfs-next-51 #1
[16804.548059] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-0-ga698c8995f-prebuilt.qemu.org 04/01/2014
[16804.548666] RIP: 0010:rb_next+0x16/0x50
(...)
[16804.550581] RSP: 0018:ffffb948418ef9b0 EFLAGS: 00010202
[16804.551227] RAX: 6b6b6b6b6b6b6b6b RBX: ffff90e0247f6600 RCX: 6b6b6b6b6b6b6b6b
[16804.551873] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff90e0247f6600
[16804.552504] RBP: ffff90dffe0d4688 R08: 0000000000000001 R09: 0000000000000000
[16804.553136] R10: ffff90dffa4a0040 R11: 0000000000000000 R12: 000000000000002e
[16804.553768] R13: ffff90e0247f6600 R14: 0000000000001663 R15: ffff90dff77862b8
[16804.554399] FS: 00007f4b197ae700(0000) GS:ffff90e036a00000(0000) knlGS:0000000000000000
[16804.555039] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[16804.555683] CR2: 00007f4b10022000 CR3: 00000002060e2004 CR4: 00000000003606f0
[16804.556336] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[16804.556968] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[16804.557583] Call Trace:
[16804.558207] __tree_mod_log_rewind+0xbf/0x280 [btrfs]
[16804.558835] btrfs_search_old_slot+0x105/0xd00 [btrfs]
[16804.559468] resolve_indirect_refs+0x1eb/0xc70 [btrfs]
[16804.560087] ? free_extent_buffer.part.19+0x5a/0xc0 [btrfs]
[16804.560700] find_parent_nodes+0x388/0x1120 [btrfs]
[16804.561310] btrfs_check_shared+0x115/0x1c0 [btrfs]
[16804.561916] ? extent_fiemap+0x59d/0x6d0 [btrfs]
[16804.562518] extent_fiemap+0x59d/0x6d0 [btrfs]
[16804.563112] ? __might_fault+0x11/0x90
[16804.563706] do_vfs_ioctl+0x45a/0x700
[16804.564299] ksys_ioctl+0x70/0x80
[16804.564885] ? trace_hardirqs_off_thunk+0x1a/0x20
[16804.565461] __x64_sys_ioctl+0x16/0x20
[16804.566020] do_syscall_64+0x5c/0x250
[16804.566580] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[16804.567153] RIP: 0033:0x7f4b1ba2add7
(...)
[16804.568907] RSP: 002b:00007f4b197adc88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[16804.569513] RAX: ffffffffffffffda RBX: 00007f4b100210d8 RCX: 00007f4b1ba2add7
[16804.570133] RDX: 00007f4b100210d8 RSI: 00000000c020660b RDI: 0000000000000003
[16804.570726] RBP: 000055de05a6cfe0 R08: 0000000000000000 R09: 00007f4b197add44
[16804.571314] R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4b197add48
[16804.571905] R13: 00007f4b197add40 R14: 00007f4b100210d0 R15: 00007f4b197add50
(...)
[16804.575623] ---[ end trace 87317359aad4ba50 ]---
Fix this by making btrfs_put_tree_mod_seq() skip deletion of elements that
have a sequence number equals to the computed minimum sequence number, and
not just elements with a sequence number greater then that minimum.
Fixes: bd989ba359 ("Btrfs: add tree modification log functions")
CC: stable@vger.kernel.org # 4.4+
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Having checksum items, either on the checksums tree or in a log tree, that
represent ranges that overlap each other is a sign of a corruption. Such
case confuses the checksum lookup code and can result in not being able to
find checksums or find stale checksums.
So add a check for such case.
This is motivated by a recent fix for a case where a log tree had checksum
items covering ranges that overlap each other due to extent cloning, and
resulted in missing checksums after replaying the log tree. It also helps
detect past issues such as stale and outdated checksums due to overlapping,
commit 27b9a8122f ("Btrfs: fix csum tree corruption, duplicate and
outdated checksums").
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When logging a file that has shared extents (reflinked with other files or
with itself), we can end up logging multiple checksum items that cover
overlapping ranges. This confuses the search for checksums at log replay
time causing some checksums to never be added to the fs/subvolume tree.
Consider the following example of a file that shares the same extent at
offsets 0 and 256Kb:
[ bytenr 13893632, offset 64Kb, len 64Kb ]
0 64Kb
[ bytenr 13631488, offset 64Kb, len 192Kb ]
64Kb 256Kb
[ bytenr 13893632, offset 0, len 256Kb ]
256Kb 512Kb
When logging the inode, at tree-log.c:copy_items(), when processing the
file extent item at offset 0, we log a checksum item covering the range
13959168 to 14024704, which corresponds to 13893632 + 64Kb and 13893632 +
64Kb + 64Kb, respectively.
Later when processing the extent item at offset 256K, we log the checksums
for the range from 13893632 to 14155776 (which corresponds to 13893632 +
256Kb). These checksums get merged with the checksum item for the range
from 13631488 to 13893632 (13631488 + 256Kb), logged by a previous fsync.
So after this we get the two following checksum items in the log tree:
(...)
item 6 key (EXTENT_CSUM EXTENT_CSUM 13631488) itemoff 3095 itemsize 512
range start 13631488 end 14155776 length 524288
item 7 key (EXTENT_CSUM EXTENT_CSUM 13959168) itemoff 3031 itemsize 64
range start 13959168 end 14024704 length 65536
The first one covers the range from the second one, they overlap.
So far this does not cause a problem after replaying the log, because
when replaying the file extent item for offset 256K, we copy all the
checksums for the extent 13893632 from the log tree to the fs/subvolume
tree, since searching for an checksum item for bytenr 13893632 leaves us
at the first checksum item, which covers the whole range of the extent.
However if we write 64Kb to file offset 256Kb for example, we will
not be able to find and copy the checksums for the last 128Kb of the
extent at bytenr 13893632, referenced by the file range 384Kb to 512Kb.
After writing 64Kb into file offset 256Kb we get the following extent
layout for our file:
[ bytenr 13893632, offset 64K, len 64Kb ]
0 64Kb
[ bytenr 13631488, offset 64Kb, len 192Kb ]
64Kb 256Kb
[ bytenr 14155776, offset 0, len 64Kb ]
256Kb 320Kb
[ bytenr 13893632, offset 64Kb, len 192Kb ]
320Kb 512Kb
After fsync'ing the file, if we have a power failure and then mount
the filesystem to replay the log, the following happens:
1) When replaying the file extent item for file offset 320Kb, we
lookup for the checksums for the extent range from 13959168
(13893632 + 64Kb) to 14155776 (13893632 + 256Kb), through a call
to btrfs_lookup_csums_range();
2) btrfs_lookup_csums_range() finds the checksum item that starts
precisely at offset 13959168 (item 7 in the log tree, shown before);
3) However that checksum item only covers 64Kb of data, and not 192Kb
of data;
4) As a result only the checksums for the first 64Kb of data referenced
by the file extent item are found and copied to the fs/subvolume tree.
The remaining 128Kb of data, file range 384Kb to 512Kb, doesn't get
the corresponding data checksums found and copied to the fs/subvolume
tree.
5) After replaying the log userspace will not be able to read the file
range from 384Kb to 512Kb, because the checksums are missing and
resulting in an -EIO error.
The following steps reproduce this scenario:
$ mkfs.btrfs -f /dev/sdc
$ mount /dev/sdc /mnt/sdc
$ xfs_io -f -c "pwrite -S 0xa3 0 256K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar
$ xfs_io -c "pwrite -S 0xc7 256K 256K" /mnt/sdc/foobar
$ xfs_io -c "reflink /mnt/sdc/foobar 320K 0 64K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar
$ xfs_io -c "pwrite -S 0xe5 256K 64K" /mnt/sdc/foobar
$ xfs_io -c "fsync" /mnt/sdc/foobar
<power failure>
$ mount /dev/sdc /mnt/sdc
$ md5sum /mnt/sdc/foobar
md5sum: /mnt/sdc/foobar: Input/output error
$ dmesg | tail
[165305.003464] BTRFS info (device sdc): no csum found for inode 257 start 401408
[165305.004014] BTRFS info (device sdc): no csum found for inode 257 start 405504
[165305.004559] BTRFS info (device sdc): no csum found for inode 257 start 409600
[165305.005101] BTRFS info (device sdc): no csum found for inode 257 start 413696
[165305.005627] BTRFS info (device sdc): no csum found for inode 257 start 417792
[165305.006134] BTRFS info (device sdc): no csum found for inode 257 start 421888
[165305.006625] BTRFS info (device sdc): no csum found for inode 257 start 425984
[165305.007278] BTRFS info (device sdc): no csum found for inode 257 start 430080
[165305.008248] BTRFS warning (device sdc): csum failed root 5 ino 257 off 393216 csum 0x1337385e expected csum 0x00000000 mirror 1
[165305.009550] BTRFS warning (device sdc): csum failed root 5 ino 257 off 393216 csum 0x1337385e expected csum 0x00000000 mirror 1
Fix this simply by deleting first any checksums, from the log tree, for the
range of the extent we are logging at copy_items(). This ensures we do not
get checksum items in the log tree that have overlapping ranges.
This is a long time issue that has been present since we have the clone
(and deduplication) ioctl, and can happen both when an extent is shared
between different files and within the same file.
A test case for fstests follows soon.
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Callers of alloc_test_extent_buffer have not correctly interpreted the
return value as error pointer, as alloc_test_extent_buffer should behave
as alloc_extent_buffer. The self-tests were unaffected but
btrfs_find_create_tree_block could call both functions and that would
cause problems up in the call chain.
Fixes: faa2dbf004 ("Btrfs: add sanity tests for new qgroup accounting code")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The value 0 for devs_max means to spread the allocated chunks over all
available devices, eg. stripe for RAID0 or RAID5. This got mistakenly
copied to the RAID1C3/4 profiles. The intention is to have exactly 3 and
4 copies respectively.
Fixes: 47e6f7423b ("btrfs: add support for 3-copy replication (raid1c3)")
Fixes: 8d6fac0087 ("btrfs: add support for 4-copy replication (raid1c4)")
Signed-off-by: David Sterba <dsterba@suse.com>
Argument BTRFS_FILE_EXTENT_INLINE_DATA_START is defined as offsetof(),
which returns type size_t, so we need %zu instead of %lu.
This fixes a build warning on 32-bit ARM:
../fs/btrfs/tree-checker.c: In function 'check_extent_data_item':
../fs/btrfs/tree-checker.c:230:43: warning: format '%lu' expects argument of type 'long unsigned int', but argument 5 has type 'unsigned int' [-Wformat=]
230 | "invalid item size, have %u expect [%lu, %u)",
| ~~^
| long unsigned int
| %u
Fixes: 153a6d2999 ("btrfs: tree-checker: Check item size before reading file extent type")
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andreas Färber <afaerber@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
If we're rename exchanging two subvols we'll try to lock this lock
twice, which is bad. Just lock once if either of the ino's are subvols.
Fixes: cdd1fedf82 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
We have a BUG_ON(ret < 0) in find_free_extent from
btrfs_cache_block_group. If we fail to allocate our ctl we'll just
panic, which is not good. Instead just go on to another block group.
If we fail to find a block group we don't want to return ENOSPC, because
really we got a ENOMEM and that's the root of the problem. Save our
return from btrfs_cache_block_group(), and then if we still fail to make
our allocation return that ret so we get the right error back.
Tested with inject-error.py from bcc.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Testing with the new fsstress uncovered a pretty nasty deadlock with
lookup and snapshot deletion.
Process A
unlink
-> final iput
-> inode_tree_del
-> synchronize_srcu(subvol_srcu)
Process B
btrfs_lookup <- srcu_read_lock() acquired here
-> btrfs_iget
-> find inode that has I_FREEING set
-> __wait_on_freeing_inode()
We're holding the srcu_read_lock() while doing the iget in order to make
sure our fs root doesn't go away, and then we are waiting for the inode
to finish freeing. However because the free'ing process is doing a
synchronize_srcu() we deadlock.
Fix this by dropping the synchronize_srcu() in inode_tree_del(). We
don't need people to stop accessing the fs root at this point, we're
only adding our empty root to the dead roots list.
A larger much more invasive fix is forthcoming to address how we deal
with fs roots, but this fixes the immediate problem.
Fixes: 76dda93c6a ("Btrfs: add snapshot/subvolume destroy ioctl")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When using the NO_HOLES feature if we clone a range that contains a hole
and a temporary ENOSPC happens while dropping extents from the target
inode's range, we can end up failing and aborting the transaction with
-EEXIST or with a corrupt file extent item, that has a length greater
than it should and overlaps with other extents. For example when cloning
the following range from inode A to inode B:
Inode A:
extent A1 extent A2
[ ----------- ] [ hole, implicit, 4MB length ] [ ------------- ]
0 1MB 5MB 6MB
Range to clone: [1MB, 6MB)
Inode B:
extent B1 extent B2 extent B3 extent B4
[ ---------- ] [ --------- ] [ ---------- ] [ ---------- ]
0 1MB 1MB 2MB 2MB 5MB 5MB 6MB
Target range: [1MB, 6MB) (same as source, to make it easier to explain)
The following can happen:
1) btrfs_punch_hole_range() gets -ENOSPC from __btrfs_drop_extents();
2) At that point, 'cur_offset' is set to 1MB and __btrfs_drop_extents()
set 'drop_end' to 2MB, meaning it was able to drop only extent B2;
3) We then compute 'clone_len' as 'drop_end' - 'cur_offset' = 2MB - 1MB =
1MB;
4) We then attempt to insert a file extent item at inode B with a file
offset of 5MB, which is the value of clone_info->file_offset. This
fails with error -EEXIST because there's already an extent at that
offset (extent B4);
5) We abort the current transaction with -EEXIST and return that error
to user space as well.
Another example, for extent corruption:
Inode A:
extent A1 extent A2
[ ----------- ] [ hole, implicit, 10MB length ] [ ------------- ]
0 1MB 11MB 12MB
Inode B:
extent B1 extent B2
[ ----------- ] [ --------- ] [ ----------------------------- ]
0 1MB 1MB 5MB 5MB 12MB
Target range: [1MB, 12MB) (same as source, to make it easier to explain)
1) btrfs_punch_hole_range() gets -ENOSPC from __btrfs_drop_extents();
2) At that point, 'cur_offset' is set to 1MB and __btrfs_drop_extents()
set 'drop_end' to 5MB, meaning it was able to drop only extent B2;
3) We then compute 'clone_len' as 'drop_end' - 'cur_offset' = 5MB - 1MB =
4MB;
4) We then insert a file extent item at inode B with a file offset of 11MB
which is the value of clone_info->file_offset, and a length of 4MB (the
value of 'clone_len'). So we get 2 extents items with ranges that
overlap and an extent length of 4MB, larger then the extent A2 from
inode A (1MB length);
5) After that we end the transaction, balance the btree dirty pages and
then start another or join the previous transaction. It might happen
that the transaction which inserted the incorrect extent was committed
by another task so we end up with extent corruption if a power failure
happens.
So fix this by making sure we attempt to insert the extent to clone at
the destination inode only if we are past dropping the sub-range that
corresponds to a hole.
Fixes: 690a5dbfc5 ("Btrfs: fix ENOSPC errors, leading to transaction aborts, when cloning extents")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The branch of qgroup_rescan_init which is executed from the mount
path prints wrong errors messages. The textual print out in case
BTRFS_QGROUP_STATUS_FLAG_RESCAN/BTRFS_QGROUP_STATUS_FLAG_ON are not
set are transposed. Fix it by exchanging their place.
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Because the BLAKE2B code went through a different tree, it was not
available at the time the btrfs part was merged. Now that the Kconfig
symbol exists, add it to the list.
Signed-off-by: David Sterba <dsterba@suse.com>
As part of the cleanup of some remaining y2038 issues, I came to
fs/compat_ioctl.c, which still has a couple of commands that need support
for time64_t.
In completely unrelated work, I spent time on cleaning up parts of this
file in the past, moving things out into drivers instead.
After Al Viro reviewed an earlier version of this series and did a lot
more of that cleanup, I decided to try to completely eliminate the rest
of it and move it all into drivers.
This series incorporates some of Al's work and many patches of my own,
but in the end stops short of actually removing the last part, which is
the scsi ioctl handlers. I have patches for those as well, but they need
more testing or possibly a rewrite.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Merge tag 'compat-ioctl-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground
Pull removal of most of fs/compat_ioctl.c from Arnd Bergmann:
"As part of the cleanup of some remaining y2038 issues, I came to
fs/compat_ioctl.c, which still has a couple of commands that need
support for time64_t.
In completely unrelated work, I spent time on cleaning up parts of
this file in the past, moving things out into drivers instead.
After Al Viro reviewed an earlier version of this series and did a lot
more of that cleanup, I decided to try to completely eliminate the
rest of it and move it all into drivers.
This series incorporates some of Al's work and many patches of my own,
but in the end stops short of actually removing the last part, which
is the scsi ioctl handlers. I have patches for those as well, but they
need more testing or possibly a rewrite"
* tag 'compat-ioctl-5.5' of git://git.kernel.org:/pub/scm/linux/kernel/git/arnd/playground: (42 commits)
scsi: sd: enable compat ioctls for sed-opal
pktcdvd: add compat_ioctl handler
compat_ioctl: move SG_GET_REQUEST_TABLE handling
compat_ioctl: ppp: move simple commands into ppp_generic.c
compat_ioctl: handle PPPIOCGIDLE for 64-bit time_t
compat_ioctl: move PPPIOCSCOMPRESS to ppp_generic
compat_ioctl: unify copy-in of ppp filters
tty: handle compat PPP ioctls
compat_ioctl: move SIOCOUTQ out of compat_ioctl.c
compat_ioctl: handle SIOCOUTQNSD
af_unix: add compat_ioctl support
compat_ioctl: reimplement SG_IO handling
compat_ioctl: move WDIOC handling into wdt drivers
fs: compat_ioctl: move FITRIM emulation into file systems
gfs2: add compat_ioctl support
compat_ioctl: remove unused convert_in_user macro
compat_ioctl: remove last RAID handling code
compat_ioctl: remove /dev/raw ioctl translation
compat_ioctl: remove PCI ioctl translation
compat_ioctl: remove joystick ioctl translation
...
After previous patches removing bdev being passed around to set it to
bio, it has become unused in submit_extent_page. So it now has "only" 13
parameters.
Signed-off-by: David Sterba <dsterba@suse.com>
We can now remove the bdev from extent_map. Previous patches made sure
that bio_set_dev is correctly in all places and that we don't need to
grab it from latest_bdev or pass it around inside the extent map.
Signed-off-by: David Sterba <dsterba@suse.com>
bio_set_dev sets a bdev to a bio and is not only setting a pointer bug
also changing some state bits if there was a different bdev set before.
This is one thing that's not needed.
Another thing is that setting a bdev at bio allocation time is too early
and actually does not work with plain redundancy profiles, where each
time we submit a bio to a device, the bdev is set correctly.
In many places the bio bdev is set to latest_bdev that seems to serve as
a stub pointer "just to put something to bio". But we don't have to do
that.
Where do we know which bdev to set:
* for regular IO: submit_stripe_bio that's called by btrfs_map_bio
* repair IO: repair_io_failure, read or write from specific device
* super block write (using buffer_heads but uses raw bdev) and barriers
* scrub: this does not use all regular IO paths as it needs to reach all
copies, verify and fixup eventually, and for that all bdev management
is independent
* raid56: rbio_add_io_page, for the RMW write
* integrity-checker: does it's own low-level block tracking
Signed-off-by: David Sterba <dsterba@suse.com>
This is preparatory patch to remove @bdev parameter from
submit_extent_page. It can't be removed completely, because the cgroups
need it for wbc when initializing the bio
wbc_init_bio
bio_associate_blkg_from_css
dereference bdev->bi_disk->queue
The bdev pointer is the same as latest_bdev, thus no functional change.
We can retrieve it from fs_devices that's reachable through several
dereferences. The local variable shadows the parameter, but that's only
temporary.
Signed-off-by: David Sterba <dsterba@suse.com>
Testing with the new fsstress support for subvolumes uncovered a pretty
bad problem with rename exchange on subvolumes. We're modifying two
different subvolumes, but we only start the transaction on one of them,
so the other one is not added to the dirty root list. This is caught by
btrfs_cow_block() with a warning because the root has not been updated,
however if we do not modify this root again we'll end up pointing at an
invalid root because the root item is never updated.
Fix this by making sure we add the destination root to the trans list,
the same as we do with normal renames. This fixes the corruption.
Fixes: cdd1fedf82 ("btrfs: add support for RENAME_EXCHANGE and RENAME_WHITEOUT")
CC: stable@vger.kernel.org # 4.9+
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When doing a device replace, while at scrub.c:scrub_enumerate_chunks(), we
set the block group to RO mode and then wait for any ongoing writes into
extents of the block group to complete. While doing that wait we overwrite
the value of the variable 'ret' and can break out of the loop if an error
happens without turning the block group back into RW mode. So what happens
is the following:
1) btrfs_inc_block_group_ro() returns 0, meaning it set the block group
to RO mode (its ->ro field set to 1 or incremented to some value > 1);
2) Then btrfs_wait_ordered_roots() returns a value > 0;
3) Then if either joining or committing the transaction fails, we break
out of the loop wihtout calling btrfs_dec_block_group_ro(), leaving
the block group in RO mode forever.
To fix this, just remove the code that waits for ongoing writes to extents
of the block group, since it's not needed because in the initial setup
phase of a device replace operation, before starting to find all chunks
and their extents, we set the target device for replace while holding
fs_info->dev_replace->rwsem, which ensures that after releasing that
semaphore, any writes into the source device are made to the target device
as well (__btrfs_map_block() guarantees that). So while at
scrub_enumerate_chunks() we only need to worry about finding and copying
extents (from the source device to the target device) that were written
before we started the device replace operation.
Fixes: f0e9b7d640 ("Btrfs: fix race setting block group readonly during device replace")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
[BUG]
When running btrfs/072 with only one online CPU, it has a pretty high
chance to fail:
btrfs/072 12s ... _check_dmesg: something found in dmesg (see xfstests-dev/results//btrfs/072.dmesg)
- output mismatch (see xfstests-dev/results//btrfs/072.out.bad)
--- tests/btrfs/072.out 2019-10-22 15:18:14.008965340 +0800
+++ /xfstests-dev/results//btrfs/072.out.bad 2019-11-14 15:56:45.877152240 +0800
@@ -1,2 +1,3 @@
QA output created by 072
Silence is golden
+Scrub find errors in "-m dup -d single" test
...
And with the following call trace:
BTRFS info (device dm-5): scrub: started on devid 1
------------[ cut here ]------------
BTRFS: Transaction aborted (error -27)
WARNING: CPU: 0 PID: 55087 at fs/btrfs/block-group.c:1890 btrfs_create_pending_block_groups+0x3e6/0x470 [btrfs]
CPU: 0 PID: 55087 Comm: btrfs Tainted: G W O 5.4.0-rc1-custom+ #13
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:btrfs_create_pending_block_groups+0x3e6/0x470 [btrfs]
Call Trace:
__btrfs_end_transaction+0xdb/0x310 [btrfs]
btrfs_end_transaction+0x10/0x20 [btrfs]
btrfs_inc_block_group_ro+0x1c9/0x210 [btrfs]
scrub_enumerate_chunks+0x264/0x940 [btrfs]
btrfs_scrub_dev+0x45c/0x8f0 [btrfs]
btrfs_ioctl+0x31a1/0x3fb0 [btrfs]
do_vfs_ioctl+0x636/0xaa0
ksys_ioctl+0x67/0x90
__x64_sys_ioctl+0x43/0x50
do_syscall_64+0x79/0xe0
entry_SYSCALL_64_after_hwframe+0x49/0xbe
---[ end trace 166c865cec7688e7 ]---
[CAUSE]
The error number -27 is -EFBIG, returned from the following call chain:
btrfs_end_transaction()
|- __btrfs_end_transaction()
|- btrfs_create_pending_block_groups()
|- btrfs_finish_chunk_alloc()
|- btrfs_add_system_chunk()
This happens because we have used up all space of
btrfs_super_block::sys_chunk_array.
The root cause is, we have the following bad loop of creating tons of
system chunks:
1. The only SYSTEM chunk is being scrubbed
It's very common to have only one SYSTEM chunk.
2. New SYSTEM bg will be allocated
As btrfs_inc_block_group_ro() will check if we have enough space
after marking current bg RO. If not, then allocate a new chunk.
3. New SYSTEM bg is still empty, will be reclaimed
During the reclaim, we will mark it RO again.
4. That newly allocated empty SYSTEM bg get scrubbed
We go back to step 2, as the bg is already mark RO but still not
cleaned up yet.
If the cleaner kthread doesn't get executed fast enough (e.g. only one
CPU), then we will get more and more empty SYSTEM chunks, using up all
the space of btrfs_super_block::sys_chunk_array.
[FIX]
Since scrub/dev-replace doesn't always need to allocate new extent,
especially chunk tree extent, so we don't really need to do chunk
pre-allocation.
To break above spiral, here we introduce a new parameter to
btrfs_inc_block_group(), @do_chunk_alloc, which indicates whether we
need extra chunk pre-allocation.
For relocation, we pass @do_chunk_alloc=true, while for scrub, we pass
@do_chunk_alloc=false.
This should keep unnecessary empty chunks from popping up for scrub.
Also, since there are two parameters for btrfs_inc_block_group_ro(),
add more comment for it.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
struct btrfs_fs_devices::rotating currently is declared as an integer
variable but only used as a boolean.
Change the variable definition to bool and update to code touching it to
set 'true' and 'false'.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
struct btrfs_fs_devices::seeding currently is declared as an integer
variable but only used as a boolean.
Change the variable definition to bool and update to code touching it to
set 'true' and 'false'.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
The type name is misleading, a single entry is named 'cache' while this
normally means a collection of objects. Rename that everywhere. Also the
identifier was quite long, making function prototypes harder to format.
Suggested-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
For read_one_block_group(), its only caller has already got the item key
to search next block group item.
So we can use that key directly without doing our own convertion on
stack.
Also, since that key used in btrfs_read_block_groups() is vital for
block group item search, add 'const' keyword for that parameter to
prevent read_one_block_group() to modify it.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Refactor the work inside the loop of btrfs_read_block_groups() into one
separate function, read_one_block_group().
This allows read_one_block_group to be reused for later BG_TREE feature.
The refactor does the following extra fix:
- Use btrfs_fs_incompat() to replace open-coded feature check
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
A nice writeup of the LKMM (Linux Kernel Memory Model) rules for access
once policies can be found here
https://lwn.net/Articles/799218/#Access-Marking%20Policies .
The locked and unlocked access to eb::blocking_writers should be
annotated accordingly, following this:
Writes:
- locked write must use ONCE, may use plain read
- unlocked write must use ONCE
Reads:
- unlocked read must use ONCE
- locked read may use plain read iff not mixed with unlocked read
- unlocked read then locked must use ONCE
There's one difference on the assembly level, where
btrfs_tree_read_lock_atomic and btrfs_try_tree_read_lock used the cached
value and did not reevaluate it after taking the lock. This could have
missed some opportunities to take the lock in case blocking writers
changed between the calls, but the window is just a few instructions
long. As this is in try-lock, the callers handle that.
Signed-off-by: David Sterba <dsterba@suse.com>
The increment and decrement was inherited from previous version that
used atomics, switched in commit 06297d8cef ("btrfs: switch
extent_buffer blocking_writers from atomic to int"). The only possible
values are 0 and 1 so we can set them directly.
The generated assembly (gcc 9.x) did the direct value assignment in
btrfs_set_lock_blocking_write (asm diff after change in 06297d8cef):
5d: test %eax,%eax
5f: je 62 <btrfs_set_lock_blocking_write+0x22>
61: retq
- 62: lock incl 0x44(%rdi)
- 66: add $0x50,%rdi
- 6a: jmpq 6f <btrfs_set_lock_blocking_write+0x2f>
+ 62: movl $0x1,0x44(%rdi)
+ 69: add $0x50,%rdi
+ 6d: jmpq 72 <btrfs_set_lock_blocking_write+0x32>
The part in btrfs_tree_unlock did a decrement because
BUG_ON(blockers > 1) is probably not a strong hint for the compiler, but
otherwise the output looks safe:
- lock decl 0x44(%rdi)
+ sub $0x1,%eax
+ mov %eax,0x44(%rdi)
Signed-off-by: David Sterba <dsterba@suse.com>
There are two ifs that use eb::blocking_writers. As this is a variable
modified inside and outside of locks, we could minimize number of
accesses to avoid problems with getting different results at different
times.
The access here is locked so this can only race with btrfs_tree_unlock
that sets blocking_writers to 0 without lock and unsets the lock owner.
The first branch is taken only if the same thread already holds the
lock, the second if checks for blocking writers. Here we'd either unlock
and wait, or proceed. Both are valid states of the locking protocol.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: David Sterba <dsterba@suse.com>
When there are no raid1c3 or raid1c4 block groups left after balance
(either convert or with other filters applied), remove the incompat bit.
This is already done for RAID56, do the same for RAID1C34.
Signed-off-by: David Sterba <dsterba@suse.com>
The new raid1c3 and raid1c4 profiles are backward incompatible and the
name shall be 'raid1c34', the status can be found in the global
supported features in /sys/fs/btrfs/features or in the per-filesystem
directory.
Signed-off-by: David Sterba <dsterba@suse.com>
Linus Torvalds