From: Mikulas Patocka <mpatocka@redhat.com>
To: Vojtech Trefny <vtrefny@redhat.com>, Karel Zak <kzak@redhat.com>
Cc: Mike Snitzer <msnitzer@redhat.com>,
dm-devel@redhat.com, lvm-devel@redhat.com,
util-linux@vger.kernel.org
Subject: libblkid filesystem block size
Date: Wed, 3 Oct 2018 17:41:59 -0400 (EDT) [thread overview]
Message-ID: <alpine.LRH.2.02.1810031724070.7859@file01.intranet.prod.int.rdu2.redhat.com> (raw)
Hi
As you maintain libblkid, I'd like to ask - would it be possible to add
detection of filesystem block size to it? libblkid already has description
of various filesystem superblocks, so it shouldn't be too hard.
LVM needs to know the block size because when it enables caching for a
logical volume using the dm-writecache target or integrity protection
using the dm-integrity target, the block size of the device mapper target
should match the block size of the underlying filesystem (if the cache has
smaller block size than the filesystem, it is inefficient, if the cache
has larger block size than the filesystem, the filesystem won't mount).
Caching or integrity protection can be enabled on the fly for existing
logical volumes (mounted or not mounted). XFS creates filesystems with
512-byte block size even on some modern SSDs, so the problem with small
block size exists even today.
Mikulas
WARNING: multiple messages have this Message-ID (diff)
From: Mikulas Patocka <mpatocka@redhat.com>
To: Vojtech Trefny <vtrefny@redhat.com>, Karel Zak <kzak@redhat.com>
Cc: util-linux@vger.kernel.org, Mike Snitzer <msnitzer@redhat.com>,
dm-devel@redhat.com, lvm-devel@redhat.com
Subject: libblkid filesystem block size
Date: Wed, 3 Oct 2018 17:41:59 -0400 (EDT) [thread overview]
Message-ID: <alpine.LRH.2.02.1810031724070.7859@file01.intranet.prod.int.rdu2.redhat.com> (raw)
Hi
As you maintain libblkid, I'd like to ask - would it be possible to add
detection of filesystem block size to it? libblkid already has description
of various filesystem superblocks, so it shouldn't be too hard.
LVM needs to know the block size because when it enables caching for a
logical volume using the dm-writecache target or integrity protection
using the dm-integrity target, the block size of the device mapper target
should match the block size of the underlying filesystem (if the cache has
smaller block size than the filesystem, it is inefficient, if the cache
has larger block size than the filesystem, the filesystem won't mount).
Caching or integrity protection can be enabled on the fly for existing
logical volumes (mounted or not mounted). XFS creates filesystems with
512-byte block size even on some modern SSDs, so the problem with small
block size exists even today.
Mikulas
--
lvm-devel mailing list
lvm-devel@redhat.com
https://www.redhat.com/mailman/listinfo/lvm-devel
WARNING: multiple messages have this Message-ID (diff)
From: Mikulas Patocka <mpatocka@redhat.com>
To: lvm-devel@redhat.com
Subject: libblkid filesystem block size
Date: Wed, 3 Oct 2018 17:41:59 -0400 (EDT) [thread overview]
Message-ID: <alpine.LRH.2.02.1810031724070.7859@file01.intranet.prod.int.rdu2.redhat.com> (raw)
Hi
As you maintain libblkid, I'd like to ask - would it be possible to add
detection of filesystem block size to it? libblkid already has description
of various filesystem superblocks, so it shouldn't be too hard.
LVM needs to know the block size because when it enables caching for a
logical volume using the dm-writecache target or integrity protection
using the dm-integrity target, the block size of the device mapper target
should match the block size of the underlying filesystem (if the cache has
smaller block size than the filesystem, it is inefficient, if the cache
has larger block size than the filesystem, the filesystem won't mount).
Caching or integrity protection can be enabled on the fly for existing
logical volumes (mounted or not mounted). XFS creates filesystems with
512-byte block size even on some modern SSDs, so the problem with small
block size exists even today.
Mikulas
next reply other threads:[~2018-10-04 4:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-03 21:41 Mikulas Patocka [this message]
2018-10-03 21:41 ` libblkid filesystem block size Mikulas Patocka
2018-10-03 21:41 ` Mikulas Patocka
2018-10-04 9:43 ` Karel Zak
2018-10-04 9:43 ` Karel Zak
2018-10-04 9:43 ` Karel Zak
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