Re: btrfs on bcache

[Chris Mason <clm@fb.com>]

On Fri, 2013-12-20 at 10:42 -0200, Fábio Pfeifer wrote:
> Hello,
> 
> I put the "WARN_ON(1);" after the printk lines (incomplete page read
> and incomplete page write) in extent_io.c.
> 
> here some call traces:
> 
> [   19.509497] incomplete page read in btrfs with offset 2560 and length 1536
> [   19.509500] ------------[ cut here ]------------
> [   19.509528] WARNING: CPU: 2 PID: 220 at fs/btrfs/extent_io.c:2441
> end_bio_extent_readpage+0x788/0xc20 [btrfs]()
> [   19.509530] Modules linked in: cdc_acm fuse iTCO_wdt
> iTCO_vendor_support snd_hda_codec_analog coretemp kvm_intel kvm raid1
> ext4 crc16 md_mod mbcache jbd2 microcode nvidia(PO) psmouse pcspkr
> evdev serio_raw i2c_i801 lpc_ich i2c_core snd_hda_intel sky2 skge
> i82975x_edac button asus_atk0110 snd_hda_codec snd_hwdep shpchp
> snd_pcm snd_page_alloc snd_timer acpi_cpufreq snd edac_core soundcore
> processor vboxdrv(O) sr_mod cdrom ata_generic pata_acpi hid_generic
> usbhid hid usb_storage sd_mod pata_marvell firewire_ohci uhci_hcd ahci
> ehci_pci firewire_core ata_piix libahci crc_itu_t ehci_hcd libata
> scsi_mod usbcore usb_common btrfs crc32c libcrc32c xor raid6_pq bcache
> [   19.509578] CPU: 2 PID: 220 Comm: btrfs-endio-met Tainted: P
> W  O 3.12.5-1-ARCH #1
> [   19.509580] Hardware name: System manufacturer System Product
> Name/P5WDG2 WS Pro, BIOS 0905    03/06/2008
> [   19.509581]  0000000000000009 ffff880231a63cb0 ffffffff814ee37b
> 0000000000000000
> [   19.509585]  ffff880231a63ce8 ffffffff81062bcd ffffea00085eaec0
> 0000000000000000
> [   19.509587]  ffff8802320cc9c0 0000000000000000 ffff880233b0e000
> ffff880231a63cf8
> [   19.509590] Call Trace:
> [   19.509596]  [<ffffffff814ee37b>] dump_stack+0x54/0x8d
> [   19.509601]  [<ffffffff81062bcd>] warn_slowpath_common+0x7d/0xa0
> [   19.509603]  [<ffffffff81062caa>] warn_slowpath_null+0x1a/0x20
> [   19.509614]  [<ffffffffa00b7ba8>] end_bio_extent_readpage+0x788/0xc20 [btrfs]

This should mean that bcache is either failing to read some blocks
properly or is fiddling with the bv_len/bv_offset fields.

Could someone from bcache comment?

-chris