linux-ext4 - delayed allocation vs WRITE SAME issue

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Date:   Thu, 12 Apr 2018 16:38:59 +0200
From:   Nikola Ciprich <nikola.ciprich@...uxbox.cz>
To:     linux-ext4@...r.kernel.org
Cc:     nik@...uxbox.cz
Subject: delayed allocation vs WRITE SAME issue

Hi,

i noticed following  warnings:

[52455.961319] sd 4:1:4:0: [sda] tag#11 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
[52455.961322] sd 4:1:4:0: [sda] tag#11 Sense Key : Illegal Request [current]
[52455.961324] sd 4:1:4:0: [sda] tag#11 Add. Sense: No additional sense information
[52455.961327] sd 4:1:4:0: [sda] tag#11 CDB: Write Same(10) 41 00 01 1c 3b 28 00 00 08 00
[52455.961329] print_req_error: I/O error, dev sda, sector 18627368
[52455.961339] EXT4-fs (dm-3): Delayed block allocation failed for inode 393338 at logical offset 1125 with max blocks 1 with error 5
[52455.961342] EXT4-fs (dm-3): This should not happen!! Data will be lost

the culprit is FUSION-MPT SAS adapter, which apparently doesn't implement
WRITE SAME correctly. I've reported this to linux-scsi list (and fixed
it by blaklisting the feature  for the module for now).

but my concern is whether this case should not be handled somehow by ext4 delayed
allocation code as well? (well actually I wasn't able to verify any real fs corruption
so maybe it's just false warning, but still it's not very nice :))

I can easily reproduce the problem if it can help. tested on 4.14.16 kernel.

If I can provide any further info, please let me know.

BR

nik

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