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From: Michael Walle <michael@walle.cc>
To: linux-ext4@vger.kernel.org, linux-mmc@vger.kernel.org,
	linux-block@vger.kernel.org
Subject: discard feature, mkfs.ext4 and mmc default fallback to normal erase op
Date: Mon, 07 Dec 2020 16:10:27 +0100	[thread overview]
Message-ID: <97c4bb65c8a3e688b191d57e9f06aa5a@walle.cc> (raw)

Hi,

The problem I'm having is that I'm trying to install debian on
an embedded system onto an sdcard. During installation it will
format the target filesystem, but the "mkfs.ext4 -F /dev/mmcblk0p2"
takes ages.

What I've found out so far:
  - mkfs.ext4 tries to discard all blocks on the target device
  - with my target device being an sdcard it seems to fallback
    to normal erase [1], with erase_arg being set to what the card
    is capable of [2]

Now I'm trying to figure out if this behavior is intended. I guess
one can reduce it to "blkdiscard /dev/mmcblk0p2". Should this
actually fall back to normal erasing or should it return -EOPNOTSUPP?

-michael

[1] 
https://elixir.bootlin.com/linux/v5.9.12/source/drivers/mmc/core/block.c#L1063
[2] 
https://elixir.bootlin.com/linux/v5.9.12/source/drivers/mmc/core/mmc.c#L1751

             reply	other threads:[~2020-12-07 15:11 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-07 15:10 Michael Walle [this message]
2020-12-07 18:35 ` discard feature, mkfs.ext4 and mmc default fallback to normal erase op Theodore Y. Ts'o
2020-12-07 20:39   ` Michael Walle
2020-12-08  2:40     ` Theodore Y. Ts'o
2020-12-08  9:49       ` Ulf Hansson
2020-12-08 11:26         ` Michael Walle
2020-12-08 16:17           ` Ulf Hansson
2020-12-08 20:57             ` Michael Walle
2020-12-08 16:52           ` Theodore Y. Ts'o
2020-12-09 14:51             ` Ulf Hansson
2020-12-09 16:35               ` Theodore Y. Ts'o

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