Re: [PATCH] Btrfs: fix invalid extent maps due to hole punching

[Filipe Manana]

On Tue, May 30, 2017 at 9:50 PM, Omar Sandoval  wrote:
> On Sun, May 28, 2017 at 05:31:53PM +0100, fdman...@kernel.org wrote:
>> From: Filipe Manana 
>
> [snip]
>
> Hey, Filipe,
>
> I saw this warning and tried to apply your patch, but it doesn't apply
> cleanly (seems to conflict with 9986277e0e4c ("Btrfs: handle only
> applicable errors returned by btrfs_get_extent")).

Yes, it was based on an older branch.
I'll rebase it. Thanks.

>
>> Fixes: d77815461f04 ("btrfs: Avoid trucating page or punching hole in a 
>> already existed hole.")
>> Cc: 
>> Signed-off-by: Filipe Manana 
>> ---
>>  fs/btrfs/file.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
>> index f7d022bc7998..2645d820422c 100644
>> --- a/fs/btrfs/file.c
>> +++ b/fs/btrfs/file.c
>> @@ -2390,10 +2390,12 @@ static int fill_holes(struct btrfs_trans_handle 
>> *trans,
>>   */
>>  static int find_first_non_hole(struct inode *inode, u64 *start, u64 *len)
>>  {
>> + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
>>   struct extent_map *em;
>>   int ret = 0;
>>
>> - em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, *start, *len, 0);
>> + em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, *start,
>> +   round_up(*len, fs_info->sectorsize), 0);
>>   if (IS_ERR_OR_NULL(em)) {
>>   if (!em)
>>   ret = -ENOMEM;
>> --
>> 2.11.0
>>
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
>> the body of a message to majord...@vger.kernel.org
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Re: [PATCH] Btrfs: fix invalid extent maps due to hole punching

[Omar Sandoval]

On Sun, May 28, 2017 at 05:31:53PM +0100, fdman...@kernel.org wrote:
> From: Filipe Manana 

[snip]

Hey, Filipe,

I saw this warning and tried to apply your patch, but it doesn't apply
cleanly (seems to conflict with 9986277e0e4c ("Btrfs: handle only
applicable errors returned by btrfs_get_extent")).

> Fixes: d77815461f04 ("btrfs: Avoid trucating page or punching hole in a 
> already existed hole.")
> Cc: 
> Signed-off-by: Filipe Manana 
> ---
>  fs/btrfs/file.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
> index f7d022bc7998..2645d820422c 100644
> --- a/fs/btrfs/file.c
> +++ b/fs/btrfs/file.c
> @@ -2390,10 +2390,12 @@ static int fill_holes(struct btrfs_trans_handle 
> *trans,
>   */
>  static int find_first_non_hole(struct inode *inode, u64 *start, u64 *len)
>  {
> + struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
>   struct extent_map *em;
>   int ret = 0;
>  
> - em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, *start, *len, 0);
> + em = btrfs_get_extent(BTRFS_I(inode), NULL, 0, *start,
> +   round_up(*len, fs_info->sectorsize), 0);
>   if (IS_ERR_OR_NULL(em)) {
>   if (!em)
>   ret = -ENOMEM;
> -- 
> 2.11.0
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majord...@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
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[PATCH] Btrfs: fix invalid extent maps due to hole punching

[fdmanana]

From: Filipe Manana 

While punching a hole in a range that is not aligned with the sector size
(currently the same as the page size) we can end up leaving an extent map
in memory with a length that is smaller then the sector size, which is
not expected and can lead to problems. This issue is easily detected
after the patch from commit a7e3b975a0f9 ("Btrfs: fix reported number of
inode blocks"), introduced in kernel 4.12-rc1, in a scenario like the
following for example:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt
  $ xfs_io -c "pwrite -S 0xaa -b 100K 0 100K" /mnt/foo
  $ xfs_io -c "fpunch 60K 90K" /mnt/foo
  $ xfs_io -c "pwrite -S 0xbb -b 100K 50K 100K" /mnt/foo
  $ xfs_io -c "pwrite -S 0xcc -b 50K 100K 50K" /mnt/foo
  $ umount /mnt

After the unmount operation we can see several warnings emmitted due to
underflows related to space reservation counters:

[ 2837.443299] [ cut here ]
[ 2837.447395] WARNING: CPU: 8 PID: 2474 at fs/btrfs/inode.c:9444 
btrfs_destroy_inode+0xe8/0x27e [btrfs]
[ 2837.452108] Modules linked in: dm_flakey dm_mod ppdev parport_pc psmouse 
parport sg pcspkr acpi_cpufreq tpm_tis tpm_tis_core i2c_piix4 i2c_core evdev 
tpm button se
rio_raw sunrpc loop autofs4 ext4 crc16 jbd2 mbcache btrfs raid10 raid456 
async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq 
libcrc32c crc32c_gene
ric raid1 raid0 multipath linear md_mod sr_mod cdrom sd_mod ata_generic 
virtio_scsi ata_piix libata virtio_pci virtio_ring virtio e1000 scsi_mod floppy
[ 2837.458389] CPU: 8 PID: 2474 Comm: umount Tainted: GW   
4.10.0-rc8-btrfs-next-43+ #1
[ 2837.459754] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
rel-1.9.1-0-gb3ef39f-prebuilt.qemu-project.org 04/01/2014
[ 2837.462379] Call Trace:
[ 2837.462379]  dump_stack+0x68/0x92
[ 2837.462379]  __warn+0xc2/0xdd
[ 2837.462379]  warn_slowpath_null+0x1d/0x1f
[ 2837.462379]  btrfs_destroy_inode+0xe8/0x27e [btrfs]
[ 2837.462379]  destroy_inode+0x3d/0x55
[ 2837.462379]  evict+0x177/0x17e
[ 2837.462379]  dispose_list+0x50/0x71
[ 2837.462379]  evict_inodes+0x132/0x141
[ 2837.462379]  generic_shutdown_super+0x3f/0xeb
[ 2837.462379]  kill_anon_super+0x12/0x1c
[ 2837.462379]  btrfs_kill_super+0x16/0x21 [btrfs]
[ 2837.462379]  deactivate_locked_super+0x30/0x68
[ 2837.462379]  deactivate_super+0x36/0x39
[ 2837.462379]  cleanup_mnt+0x58/0x76
[ 2837.462379]  __cleanup_mnt+0x12/0x14
[ 2837.462379]  task_work_run+0x77/0x9b
[ 2837.462379]  prepare_exit_to_usermode+0x9d/0xc5
[ 2837.462379]  syscall_return_slowpath+0x196/0x1b9
[ 2837.462379]  entry_SYSCALL_64_fastpath+0xab/0xad
[ 2837.462379] RIP: 0033:0x7f3ef3e6b9a7
[ 2837.462379] RSP: 002b:7ffdd0d8de58 EFLAGS: 0246 ORIG_RAX: 
00a6
[ 2837.462379] RAX:  RBX: 556f76a39060 RCX: 7f3ef3e6b9a7
[ 2837.462379] RDX: 0001 RSI:  RDI: 556f76a3f910
[ 2837.462379] RBP: 556f76a3f910 R08: 556f76a3e670 R09: 0015
[ 2837.462379] R10: 06b4 R11: 0246 R12: 7f3ef436ce64
[ 2837.462379] R13:  R14: 556f76a39240 R15: 7ffdd0d8e0e0
[ 2837.519355] ---[ end trace e79345fe24b30b8d ]---
[ 2837.596256] [ cut here ]
[ 2837.597625] WARNING: CPU: 8 PID: 2474 at fs/btrfs/extent-tree.c:5699 
btrfs_free_block_groups+0x246/0x3eb [btrfs]
[ 2837.603547] Modules linked in: dm_flakey dm_mod ppdev parport_pc psmouse 
parport sg pcspkr acpi_cpufreq tpm_tis tpm_tis_core i2c_piix4 i2c_core evdev 
tpm button serio_raw sunrpc loop autofs4 ext4 crc16 jbd2 mbcache btrfs raid10 
raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq 
libcrc32c crc32c_generic raid1 raid0 multipath linear md_mod sr_mod cdrom 
sd_mod ata_generic virtio_scsi ata_piix libata virtio_pci virtio_ring virtio 
e1000 scsi_mod floppy
[ 2837.659372] CPU: 8 PID: 2474 Comm: umount Tainted: GW   
4.10.0-rc8-btrfs-next-43+ #1
[ 2837.663359] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
rel-1.9.1-0-gb3ef39f-prebuilt.qemu-project.org 04/01/2014
[ 2837.663359] Call Trace:
[ 2837.663359]  dump_stack+0x68/0x92
[ 2837.663359]  __warn+0xc2/0xdd
[ 2837.663359]  warn_slowpath_null+0x1d/0x1f
[ 2837.663359]  btrfs_free_block_groups+0x246/0x3eb [btrfs]
[ 2837.663359]  close_ctree+0x1dd/0x2e1 [btrfs]
[ 2837.663359]  ? evict_inodes+0x132/0x141
[ 2837.663359]  btrfs_put_super+0x15/0x17 [btrfs]
[ 2837.663359]  generic_shutdown_super+0x6a/0xeb
[ 2837.663359]  kill_anon_super+0x12/0x1c
[ 2837.663359]  btrfs_kill_super+0x16/0x21 [btrfs]
[ 2837.663359]  deactivate_locked_super+0x30/0x68
[ 2837.663359]  deactivate_super+0x36/0x39
[ 2837.663359]  cleanup_mnt+0x58/0x76
[ 2837.663359]  __cleanup_mnt+0x12/0x14
[ 2837.663359]  task_work_run+0x77/0x9b
[ 2837.663359]  prepare_exit_to_usermode+0x9d/0xc5
[ 2837.663359]  syscall_return_slowpath+0x196/0x1b9
[ 2837.663359]  entry_SYSCALL_64_fastpath+0xab/0xad
[ 2837.663359] RIP: