Re: [PATCH v3] btrfs: fiemap: Cache and merge fiemap extent before submit it to user

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2017年06月18日 05:24, Adam Borowski wrote:
> On Sat, Jun 17, 2017 at 09:28:30PM +0800, Qu Wenruo wrote:
>>> I for one get this a lot even in regular use.  Somehow, it always has Comm:
>>> dpkg, despite the vast majority of activity on the system obviously not
>>> being dpkg.
> 
>> linus/master without any extra patch is still the same?
>> And which commit?
>> I'm using 1439ccf73d9c07654fdd5b4969fd53c2feb8684d, at least it doesn't
>> cause any warning the related test case, and I tried several combination
>> with preallocated and written and hole, still no chance.
> 
> Current linus/master:
> 
> [   39.726099] ------------[ cut here ]------------
> [   39.726109] WARNING: CPU: 5 PID: 3382 at fs/btrfs/extent_io.c:4484 extent_fiemap+0x651/0x710
> [   39.726110] Modules linked in: cp210x pl2303 usbserial nouveau video ttm
> [   39.726120] CPU: 5 PID: 3382 Comm: dpkg Not tainted 4.12.0-rc5-debug-00219-gadc311034c35 #1
> [   39.726122] Hardware name: System manufacturer System Product Name/M4A77T, BIOS 2401    05/18/2011
> [   39.726124] task: ffff880220844140 task.stack: ffffc90001b88000
> [   39.726127] RIP: 0010:extent_fiemap+0x651/0x710
> [   39.726129] RSP: 0018:ffffc90001b8bd60 EFLAGS: 00010202
> [   39.726131] RAX: ffff88021824c800 RBX: 0000000000020000 RCX: 0000000000000000
> [   39.726132] RDX: 0000000000000000 RSI: ffff880217fae9a0 RDI: ffff8802205d6000
> [   39.726134] RBP: ffffc90001b8be60 R08: 0000000000020000 R09: 0000000000000000
> [   39.726135] R10: ffffffffffffffff R11: ffff880217fae9a0 R12: 0000000000020000
> [   39.726137] R13: 0000000000000000 R14: ffff880223685480 R15: ffff880223685480
> [   39.726139] FS:  00007f45c1726400(0000) GS:ffff88022fd40000(0000) knlGS:0000000000000000
> [   39.726140] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   39.726142] CR2: 000055e152d64000 CR3: 0000000213a8c000 CR4: 00000000000006e0
> [   39.726143] Call Trace:
> [   39.726149]  ? btrfs_get_extent+0xa60/0xa60
> [   39.726153]  btrfs_fiemap+0x4d/0x60
> [   39.726156]  do_vfs_ioctl+0x3bc/0x5e0
> [   39.726159]  SyS_ioctl+0x86/0xa0
> [   39.726163]  entry_SYSCALL_64_fastpath+0x17/0x98
> [   39.726165] RIP: 0033:0x7f45c103fe07
> [   39.726166] RSP: 002b:00007ffe327ecd88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> [   39.726169] RAX: ffffffffffffffda RBX: 000055e1528a8d60 RCX: 00007f45c103fe07
> [   39.726170] RDX: 00007ffe327ecdd0 RSI: 00000000c020660b RDI: 000000000000000a
> [   39.726171] RBP: 0000000000000548 R08: 000000000000002b R09: 0000000000000052
> [   39.726173] R10: 000000000000000a R11: 0000000000000246 R12: 00007ffe327ecda0
> [   39.726174] R13: 000055e150c12147 R14: ffffffffffffffff R15: 00000000000000a9
> [   39.726175] Code: 04 fe ff ff 45 85 ed 4d 89 f7 0f 85 a6 fd ff ff 45 31 ed 80 7d 8f 00 48 8b 85 40 ff ff ff 48 8b b8 f0 01 00 00 0f 84 8b fd ff ff <0f> ff 4c 8b 6d a8 44 8b 65 88 48 c7 c6 90 c9 db 81 4c 8b 75 80
> [   39.726210] ---[ end trace 25106b0204355180 ]---
> [   39.726215] BTRFS warning (device sda1): unhandled fiemap cache detected: offset=phys$35798867968 len\x131072 flags=0x2008
>

Shared and encoded?

The length seems to be quite strange, maybe a compressed inline extent.

I'll try that when I'm back from LinuxCon China.

Thanks,
Qu

>> I also ran btrfs/* with my patch applied on v4.11-rc2 (sorry, that's the
>> correct original patch base), and except some known bug, it doesn't cause
>> anything special.
> 
> 4.11-rc2 with nothing but 4751832d applied:
> 
> [  151.838761] ------------[ cut here ]------------
> [  151.839176] WARNING: CPU: 0 PID: 2074 at fs/btrfs/extent_io.c:4460 extent_fiemap+0x662/0x740
> [  151.840465] Modules linked in: pl2303 cp210x usbserial nouveau video ttm
> [  151.842509] CPU: 0 PID: 2074 Comm: dpkg Not tainted 4.11.0-rc2-debug-00001-g2dbdec6c76b4 #1
> [  151.844457] Hardware name: System manufacturer System Product Name/M4A77T, BIOS 2401    05/18/2011
> [  151.846551] Call Trace:
> [  151.848625]  dump_stack+0x4d/0x6d
> [  151.850636]  __warn+0xd3/0xf0
> [  151.852589]  warn_slowpath_null+0x18/0x20
> [  151.854552]  extent_fiemap+0x662/0x740
> [  151.856466]  ? btrfs_get_extent+0xa60/0xa60
> [  151.858400]  btrfs_fiemap+0x4d/0x60
> [  151.860323]  do_vfs_ioctl+0x3bc/0x5e0
> [  151.862216]  SyS_ioctl+0x86/0xa0
> [  151.864183]  entry_SYSCALL_64_fastpath+0x17/0x98
> [  151.866071] RIP: 0033:0x7f542e763e07
> [  151.868045] RSP: 002b:00007fff9d737188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> [  151.869995] RAX: ffffffffffffffda RBX: 000055cbf323bd80 RCX: 00007f542e763e07
> [  151.872086] RDX: 00007fff9d7371d0 RSI: 00000000c020660b RDI: 000000000000000a
> [  151.874127] RBP: 0000000000000548 R08: 000000000000002b R09: 0000000000000052
> [  151.876246] R10: 000000000000000a R11: 0000000000000246 R12: 00007fff9d7371a0
> [  151.878292] R13: 000055cbf28aa147 R14: ffffffffffffffff R15: 00000000000000a9
> [  151.880487] ---[ end trace 135594ab8f41eada ]---
> [  151.882586] BTRFS warning (device sda1): unhandled fiemap cache detected: offset=phys$35798867968 len\x131072 flags=0x2008
> 
> 
> 喵!
>