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  1. 16 8月, 2017 8 次提交
  3. 15 7月, 2017 2 次提交
  5. 30 6月, 2017 3 次提交
    • Q
      btrfs: qgroup: Fix qgroup reserved space underflow by only freeing reserved ranges · bc42bda2
      由 Qu Wenruo 提交于 
      [BUG]
For the following case, btrfs can underflow qgroup reserved space
at an error path:
(Page size 4K, function name without "btrfs_" prefix)

         Task A                  |             Task B
----------------------------------------------------------------------
Buffered_write [0, 2K)           |
|- check_data_free_space()       |
|  |- qgroup_reserve_data()      |
|     Range aligned to page      |
|     range [0, 4K)          <<< |
|     4K bytes reserved      <<< |
|- copy pages to page cache      |
                                 | Buffered_write [2K, 4K)
                                 | |- check_data_free_space()
                                 | |  |- qgroup_reserved_data()
                                 | |     Range alinged to page
                                 | |     range [0, 4K)
                                 | |     Already reserved by A <<<
                                 | |     0 bytes reserved      <<<
                                 | |- delalloc_reserve_metadata()
                                 | |  And it *FAILED* (Maybe EQUOTA)
                                 | |- free_reserved_data_space()
                                      |- qgroup_free_data()
                                         Range aligned to page range
                                         [0, 4K)
                                         Freeing 4K
(Special thanks to Chandan for the detailed report and analyse)

[CAUSE]
Above Task B is freeing reserved data range [0, 4K) which is actually
reserved by Task A.

And at writeback time, page dirty by Task A will go through writeback
routine, which will free 4K reserved data space at file extent insert
time, causing the qgroup underflow.

[FIX]
For btrfs_qgroup_free_data(), add @reserved parameter to only free
data ranges reserved by previous btrfs_qgroup_reserve_data().
So in above case, Task B will try to free 0 byte, so no underflow.
Reported-by: NChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com>
Reviewed-by: NChandan Rajendra <chandan@linux.vnet.ibm.com>
Tested-by: NChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>
      bc42bda2
    • Q
      btrfs: qgroup: Introduce extent changeset for qgroup reserve functions · 364ecf36
      由 Qu Wenruo 提交于 
      Introduce a new parameter, struct extent_changeset for
btrfs_qgroup_reserved_data() and its callers.

Such extent_changeset was used in btrfs_qgroup_reserve_data() to record
which range it reserved in current reserve, so it can free it in error
paths.

The reason we need to export it to callers is, at buffered write error
path, without knowing what exactly which range we reserved in current
allocation, we can free space which is not reserved by us.

This will lead to qgroup reserved space underflow.
Reviewed-by: NChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>
      364ecf36
    • Q
      btrfs: qgroup: Fix qgroup reserved space underflow caused by buffered write... · a12b877b
      由 Qu Wenruo 提交于 
      btrfs: qgroup: Fix qgroup reserved space underflow caused by buffered write and quotas being enabled

[BUG]
Under the following case, we can underflow qgroup reserved space.

            Task A                |            Task B
---------------------------------------------------------------
 Quota disabled                   |
 Buffered write                   |
 |- btrfs_check_data_free_space() |
 |  *NO* qgroup space is reserved |
 |  since quota is *DISABLED*     |
 |- All pages are copied to page  |
    cache                         |
                                  | Enable quota
                                  | Quota scan finished
                                  |
                                  | Sync_fs
                                  | |- run_delalloc_range
                                  | |- Write pages
                                  | |- btrfs_finish_ordered_io
                                  |    |- insert_reserved_file_extent
                                  |       |- btrfs_qgroup_release_data()
                                  |          Since no qgroup space is
                                             reserved in Task A, we
                                             underflow qgroup reserved
                                             space
This can be detected by fstest btrfs/104.

[CAUSE]
In insert_reserved_file_extent() we tell qgroup to release the @ram_bytes
size of qgroup reserved_space in all cases.
And btrfs_qgroup_release_data() will check if quotas are enabled.

However in the above case, the buffered write happens before quota is
enabled, so we don't have the reserved space for that range.

[FIX]
In insert_reserved_file_extent(), we tell qgroup to release the acctual
byte number it released.
In the above case, since we don't have the reserved space, we tell
qgroups to release 0 byte, so the problem can be fixed.

And thanks to the @reserved parameter introduced by the qgroup rework,
and previous patch to return released bytes, the fix can be as small as
10 lines.
Signed-off-by: NQu Wenruo <quwenruo@cn.fujitsu.com>
[ changelog updates ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>
      a12b877b
  7. 22 6月, 2017 1 次提交
    • S
      btrfs: Check name_len with boundary in verify dir_item · e79a3327
      由 Su Yue 提交于 
      Originally, verify_dir_item verifies name_len of dir_item with fixed
values but not item boundary.
If corrupted name_len was not bigger than the fixed value, for example
255, the function will think the dir_item is fine. And then reading
beyond boundary will cause crash.

Example:
	1. Corrupt one dir_item name_len to be 255.
        2. Run 'ls -lar /mnt/test/ > /dev/null'
dmesg:
[   48.451449] BTRFS info (device vdb1): disk space caching is enabled
[   48.451453] BTRFS info (device vdb1): has skinny extents
[   48.489420] general protection fault: 0000 [#1] SMP
[   48.489571] Modules linked in: ext4 jbd2 mbcache btrfs xor raid6_pq
[   48.489716] CPU: 1 PID: 2710 Comm: ls Not tainted 4.10.0-rc1 #5
[   48.489853] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-20170228_101828-anatol 04/01/2014
[   48.490008] task: ffff880035df1bc0 task.stack: ffffc90004800000
[   48.490008] RIP: 0010:read_extent_buffer+0xd2/0x190 [btrfs]
[   48.490008] RSP: 0018:ffffc90004803d98 EFLAGS: 00010202
[   48.490008] RAX: 000000000000001b RBX: 000000000000001b RCX: 0000000000000000
[   48.490008] RDX: ffff880079dbf36c RSI: 0005080000000000 RDI: ffff880079dbf368
[   48.490008] RBP: ffffc90004803dc8 R08: ffff880078e8cc48 R09: ffff880000000000
[   48.490008] R10: 0000160000000000 R11: 0000000000001000 R12: ffff880079dbf288
[   48.490008] R13: ffff880078e8ca88 R14: 0000000000000003 R15: ffffc90004803e20
[   48.490008] FS:  00007fef50c60800(0000) GS:ffff88007d400000(0000) knlGS:0000000000000000
[   48.490008] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   48.490008] CR2: 000055f335ac2ff8 CR3: 000000007356d000 CR4: 00000000001406e0
[   48.490008] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   48.490008] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   48.490008] Call Trace:
[   48.490008]  btrfs_real_readdir+0x3b7/0x4a0 [btrfs]
[   48.490008]  iterate_dir+0x181/0x1b0
[   48.490008]  SyS_getdents+0xa7/0x150
[   48.490008]  ? fillonedir+0x150/0x150
[   48.490008]  entry_SYSCALL_64_fastpath+0x18/0xad
[   48.490008] RIP: 0033:0x7fef5032546b
[   48.490008] RSP: 002b:00007ffeafcdb830 EFLAGS: 00000206 ORIG_RAX: 000000000000004e
[   48.490008] RAX: ffffffffffffffda RBX: 00007fef5061db38 RCX: 00007fef5032546b
[   48.490008] RDX: 0000000000008000 RSI: 000055f335abaff0 RDI: 0000000000000003
[   48.490008] RBP: 00007fef5061dae0 R08: 00007fef5061db48 R09: 0000000000000000
[   48.490008] R10: 000055f335abafc0 R11: 0000000000000206 R12: 00007fef5061db38
[   48.490008] R13: 0000000000008040 R14: 00007fef5061db38 R15: 000000000000270e
[   48.490008] RIP: read_extent_buffer+0xd2/0x190 [btrfs] RSP: ffffc90004803d98
[   48.499455] ---[ end trace 321920d8e8339505 ]---

Fix it by adding a parameter @slot and check name_len with item boundary
by calling btrfs_is_name_len_valid.
Signed-off-by: NSu Yue <suy.fnst@cn.fujitsu.com>
rev
Signed-off-by: NDavid Sterba <dsterba@suse.com>
      e79a3327
  9. 21 6月, 2017 1 次提交
    • N
      percpu_counter: Rename __percpu_counter_add to percpu_counter_add_batch · 104b4e51
      由 Nikolay Borisov 提交于 
      Currently, percpu_counter_add is a wrapper around __percpu_counter_add
which is preempt safe due to explicit calls to preempt_disable.  Given
how __ prefix is used in percpu related interfaces, the naming
unfortunately creates the false sense that __percpu_counter_add is
less safe than percpu_counter_add.  In terms of context-safety,
they're equivalent.  The only difference is that the __ version takes
a batch parameter.

Make this a bit more explicit by just renaming __percpu_counter_add to
percpu_counter_add_batch.

This patch doesn't cause any functional changes.

tj: Minor updates to patch description for clarity.  Cosmetic
    indentation updates.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@fb.com>
Cc: linux-mm@kvack.org
Cc: "David S. Miller" <davem@davemloft.net>
      104b4e51
  11. 20 6月, 2017 21 次提交
  13. 10 6月, 2017 1 次提交
  15. 09 6月, 2017 2 次提交
  17. 01 6月, 2017 1 次提交
    • D
      btrfs: use correct types for page indices in btrfs_page_exists_in_range · cc2b702c
      由 David Sterba 提交于 
      Variables start_idx and end_idx are supposed to hold a page index
derived from the file offsets. The int type is not the right one though,
offsets larger than 1 << 44 will get silently trimmed off the high bits.
(1 << 44 is 16TiB)

What can go wrong, if start is below the boundary and end gets trimmed:
- if there's a page after start, we'll find it (radix_tree_gang_lookup_slot)
- the final check "if (page->index <= end_idx)" will unexpectedly fail

The function will return false, ie. "there's no page in the range",
although there is at least one.

btrfs_page_exists_in_range is used to prevent races in:

* in hole punching, where we make sure there are not pages in the
  truncated range, otherwise we'll wait for them to finish and redo
  truncation, but we're going to replace the pages with holes anyway so
  the only problem is the intermediate state

* lock_extent_direct: we want to make sure there are no pages before we
  lock and start DIO, to prevent stale data reads

For practical occurence of the bug, there are several constaints.  The
file must be quite large, the affected range must cross the 16TiB
boundary and the internal state of the file pages and pending operations
must match.  Also, we must not have started any ordered data in the
range, otherwise we don't even reach the buggy function check.

DIO locking tries hard in several places to avoid deadlocks with
buffered IO and avoids waiting for ranges. The worst consequence seems
to be stale data read.

CC: Liu Bo <bo.li.liu@oracle.com>
CC: stable@vger.kernel.org	# 3.16+
Fixes: fc4adbff ("btrfs: Drop EXTENT_UPTODATE check in hole punching and direct locking")
Reviewed-by: NLiu Bo <bo.li.liu@oracle.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>
      cc2b702c