From: Pavel Raiskup <praiskup@redhat.com>
To: bug-tar@gnu.org
Cc: "Andrew J. Schorr" <aschorr@telemetry-investments.com>,
Paul Eggert <eggert@cs.ucla.edu>,
linux-fsdevel@vger.kernel.org, Andreas Dilger <adilger@dilger.ca>
Subject: Re: [Bug-tar] --sparse is broken on filesystems where small files may have zero blocks
Date: Tue, 29 Oct 2013 16:27:02 +0100 [thread overview]
Message-ID: <6917534.P50uorHOUu@nb.usersys.redhat.com> (raw)
In-Reply-To: <10978717.9ApR7zKiv0@nb.usersys.redhat.com>
On Tuesday, October 29, 2013 09:59:56 Pavel Raiskup wrote:
> > #define ST_IS_SPARSE(st) \
> > (ST_NBLOCKS (st) \
> > - < ((st).st_size / ST_NBLOCKSIZE + ((st).st_size % ST_NBLOCKSIZE != 0)))
> > + < ((st).st_size / ST_NBLOCKSIZE \
> > + + ((st).st_size % ST_NBLOCKSIZE != 0 \
> > + && (st).st_size / ST_NBLOCKSIZE != 0)))
>
> May the st.st_size / ST_NBLOCKSIZE be greater than 1 and data still stored
> in inode directly? Seems like on ext4 filesystem it is not possible [1]
> but does anybody know about exception?
>
> [1] https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout#Inline_Data
Well, I now recalled somehow relevant Red Hat bug, sorry I have not
mentioned it before:
https://bugzilla.redhat.com/show_bug.cgi?id=757557
CC'ing fs-devel: The question is whether that ^^^^ is not a bug in
filesystem — whether filesystem should not _always_ return to fstat()
block count at least 1 if there are at least some data (even if these data
are inlined in inode)? Just for catching the context, this thread starts
here: http://lists.gnu.org/archive/html/bug-tar/2013-10/msg00030.html
If that is not a bug in fs, is there possible to detect that particular
file is completely sparse?
Pavel
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next parent reply other threads:[~2013-10-29 15:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20131028211739.GA26741@ti119.telemetry-investments.com>
[not found] ` <526F376E.5030307@cs.ucla.edu>
[not found] ` <10978717.9ApR7zKiv0@nb.usersys.redhat.com>
2013-10-29 15:27 ` Pavel Raiskup [this message]
2013-10-29 15:32 ` --sparse is broken on filesystems where small files may have zero blocks Joerg Schilling
2013-10-29 17:12 ` [Bug-tar] " Christoph Hellwig
2013-10-29 17:37 ` Jan Kara
2013-10-29 22:01 ` Andreas Dilger
2013-10-31 12:11 ` Carlos Maiolino
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