• Johannes Thumshirn's avatar
    btrfs: free exchange changeset on failures · da5e817d
    Johannes Thumshirn authored
    Fstests runs on my VMs have show several kmemleak reports like the following.
    
      unreferenced object 0xffff88811ae59080 (size 64):
        comm "xfs_io", pid 12124, jiffies 4294987392 (age 6.368s)
        hex dump (first 32 bytes):
          00 c0 1c 00 00 00 00 00 ff cf 1c 00 00 00 00 00  ................
          90 97 e5 1a 81 88 ff ff 90 97 e5 1a 81 88 ff ff  ................
        backtrace:
          [<00000000ac0176d2>] ulist_add_merge+0x60/0x150 [btrfs]
          [<0000000076e9f312>] set_state_bits+0x86/0xc0 [btrfs]
          [<0000000014fe73d6>] set_extent_bit+0x270/0x690 [btrfs]
          [<000000004f675208>] set_record_extent_bits+0x19/0x20 [btrfs]
          [<00000000b96137b1>] qgroup_reserve_data+0x274/0x310 [btrfs]
          [<0000000057e9dcbb>] btrfs_check_data_free_space+0x5c/0xa0 [btrfs]
          [<0000000019c4511d>] btrfs_delalloc_reserve_space+0x1b/0xa0 [btrfs]
          [<000000006d37e007>] btrfs_dio_iomap_begin+0x415/0x970 [btrfs]
          [<00000000fb8a74b8>] iomap_iter+0x161/0x1e0
          [<0000000071dff6ff>] __iomap_dio_rw+0x1df/0x700
          [<000000002567ba53>] iomap_dio_rw+0x5/0x20
          [<0000000072e555f8>] btrfs_file_write_iter+0x290/0x530 [btrfs]
          [<000000005eb3d845>] new_sync_write+0x106/0x180
          [<000000003fb505bf>] vfs_write+0x24d/0x2f0
          [<000000009bb57d37>] __x64_sys_pwrite64+0x69/0xa0
          [<000000003eba3fdf>] do_syscall_64+0x43/0x90
    
    In case brtfs_qgroup_reserve_data() or btrfs_delalloc_reserve_metadata()
    fail the allocated extent_changeset will not be freed.
    
    So in btrfs_check_data_free_space() and btrfs_delalloc_reserve_space()
    free the allocated extent_changeset to get rid of the allocated memory.
    
    The issue currently only happens in the direct IO write path, but only
    after 65b3c08606e5 ("btrfs: fix ENOSPC failure when attempting direct IO
    write into NOCOW range"), and also at defrag_one_locked_target(). Every
    other place is always calling extent_changeset_free() even if its call
    to btrfs_delalloc_reserve_space() or btrfs_check_data_free_space() has
    failed.
    
    CC: stable@vger.kernel.org # 5.15+
    Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
    Signed-off-by: default avatarJohannes Thumshirn <johannes.thumshirn@wdc.com>
    Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
    da5e817d
delalloc-space.c 16.8 KB