Re: Problem with mkfs.xfs on a regular file

[Eric Sandeen <sandeen@sandeen.net>]

On 11/27/13, 11:16 PM, Dave Chinner wrote:

<snip>

> So, it failed to write using direct IO because of IO alignment
> because I didn't tell mkfs that it was running on a file. i.e. I
> forgot the "-d file" option.
> 
> $ sudo mkfs.xfs -d size=1g,name=/storage/fubar.img
> meta-data=/storage/fubar.img     isize=256    agcount=4, agsize=65536 blks
>          =                       sectsz=512   attr=2, projid32bit=1
>          =                       crc=0
> data     =                       bsize=4096   blocks=262144, imaxpct=25
>          =                       sunit=0      swidth=0 blks
> naming   =version 2              bsize=4096   ascii-ci=0
> log      =internal log           bsize=4096   blocks=7344, version=2
>          =                       sectsz=512   sunit=0 blks, lazy-count=1
> realtime =none                   extsz=4096   blocks=0, rtextents=0
> mkfs.xfs: pwrite64 failed: Invalid argument
> mkfs.xfs: read failed: Invalid argument
> 
> Yup, still fails. Let's force it!
> 
> $ sudo mkfs.xfs -f -d size=1g,name=/storage/fubar.img
> meta-data=/storage/fubar.img     isize=256    agcount=4, agsize=65536 blks
>          =                       sectsz=512   attr=2, projid32bit=1
>          =                       crc=0
> data     =                       bsize=4096   blocks=262144, imaxpct=25
>          =                       sunit=0      swidth=0 blks
> naming   =version 2              bsize=4096   ascii-ci=0
> log      =internal log           bsize=4096   blocks=7344, version=2
>          =                       sectsz=512   sunit=0 blks, lazy-count=1
> realtime =none                   extsz=4096   blocks=0, rtextents=0
> existing superblock read failed: Invalid argument
> mkfs.xfs: pwrite64 failed: Invalid argument
> mkfs.xfs: read failed: Invalid argument
> 
> And there's the identical failure to what was reported.
> 
> So, user error - the user is telling mkfs.xfs that it is making a
> filesystem on a block device named "/storage/fubar.img".  The same
> thing happens with the normal method of specifying the block device:

If only we had some way to tell, programatically, whether the mkfs target
was a regular file or a block device, eh? ;)

Seriously, I always thought the requirment to specify "-d file" was silly.
And now I think it's even more silly, if it actually is required for
proper behavior...

> What mkfs needs to do is reject devices that are files when "-d
> file", "-l file" and "-r file" is not specified, and the problem
> will go away because it will catch users who forget to tell mkfs
> that it is supposed to be operating on an image file...

Or maybe just stat() it, and DTRT?

-Eric

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