From: Eric Biggers <ebiggers@kernel.org>
To: Daeho Jeong <daeho43@gmail.com>
Cc: linux-kernel@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net, kernel-team@android.com,
Daeho Jeong <daehojeong@google.com>
Subject: Re: [f2fs-dev] [PATCH] f2fs: change fiemap way in printing compression chunk
Date: Wed, 21 Jul 2021 14:35:43 -0700 [thread overview]
Message-ID: <YPiTLwB3d8BWSKje@gmail.com> (raw)
In-Reply-To: <20210721072048.3035928-1-daeho43@gmail.com>
On Wed, Jul 21, 2021 at 12:20:48AM -0700, Daeho Jeong wrote:
> From: Daeho Jeong <daehojeong@google.com>
>
> When we print out a discontinuous compression chunk, it shows like a
> continuous chunk now. To show it more correctly, I've changed the way of
> printing fiemap info like below. Plus, eliminated NEW_ADDR(-1) in fiemap
> info, since it is not in fiemap user api manual.
>
> 0: 0000000000000000 0000000000000000 0000000000001000 1008 (M/E)
> 1: 0000000000001000 0000000f15c0f000 0000000000001000 1008 (M/E)
> 2: 0000000000002000 0000000000000000 0000000000002000 1808 (M/U/E)
> 3: 0000000000004000 0000000000000000 0000000000001000 1008 (M/E)
> 4: 0000000000005000 0000000f15c10000 0000000000001000 1008 (M/E)
> 5: 0000000000006000 0000000000000000 0000000000002000 1808 (M/U/E)
> 6: 0000000000008000 0000000000000000 0000000000001000 1008 (M/E)
Please label these columns.
Anyway, this doesn't appear to work quite in the way I had in mind. With this
patch, what I'm seeing is:
$ head -c 16384 /dev/zero > file; xfs_io -c "fiemap -v" file
file:
EXT: FILE-OFFSET BLOCK-RANGE TOTAL FLAGS
0: [0..7]: 0..7 8 0x1008
1: [8..15]: 2683128..2683135 8 0x1008
2: [16..31]: 0..15 16 0x1809
So, working in 512-byte sectors, the logical sectors 0-31 are stored as one
compressed cluster in the 8 physical sectors 2683128-2683135.
The problem is, with this patch these physical sectors are reported at logical
sectors 8-15 instead of 0-7. Obviously, this isn't particularly well-defined,
but I thought it was logical for the physical blocks to be associated with the
first logical blocks. That is what the tests I've written (xfstest f2fs/002,
and the Android vts_kernel_encryption_test) assume.
Is there any particular reason why you wouldn't report instead:
0: [0..7]: 2683128..2683135 8 0x1008
1: [8..31]: 0..23 8 0x1809
- Eric
next prev parent reply other threads:[~2021-07-21 21:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 7:20 [PATCH] f2fs: change fiemap way in printing compression chunk Daeho Jeong
2021-07-21 21:35 ` Eric Biggers [this message]
2021-07-21 22:30 ` [f2fs-dev] " Daeho Jeong
2021-07-22 0:15 ` Eric Biggers
2021-07-22 1:04 ` Daeho Jeong
2021-07-22 1:15 ` Eric Biggers
2021-07-22 1:40 ` Daeho Jeong
2021-07-22 1:56 ` Eric Biggers
2021-07-22 3:59 ` Daeho Jeong
2021-07-22 6:24 ` Christoph Hellwig
2021-07-22 6:39 ` Daeho Jeong
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