[PATCH 15/37 V3] libxfs: fix root inode handling inconsistencies

[Christoph Hellwig]

On Thu, Nov 07, 2013 at 03:58:30PM +1100, Dave Chinner wrote:
> From: Dave Chinner <dchinner at redhat.com>
> 
> When "mounting" a filesystem via libxfs_mount(), callers can tell
> libxfs to read the root and realtime inodes into cache. However,
> when unmounting the filesystem, libxfs_unmount() used to
> unconditionally free root inodes if they were present.
> 
> This leads to interesting issues like in mkfs, when it handles
> creation, reading and freeing of the root and rt inodes itself.
> It, however, passes in the flag to tell libxfs_mount() to read the
> root inodes and so can result in unbalanced freeing of inodes when
> cleaning up during the unmount proceedure.
> 
> As it turns out, nothing ever uses mp->m_rootip and so we don't need
> to read it in or free it, or even have a pointer to it in the struct
> xfs_mount. Similarly, the only user of the realtime inodes is mkfs,
> and it initialises them itself. Hence we can kill the m_rootip and
> the realtime inode mounting code.
> 
> This leaves one user of LIBXFS_MOUNT_ROOTINOS - xfs_db - and that is
> only used to initialise the in-core superblock counter values from
> the ag header for xfs_check. Move this code to the xfs_db init
> functions so we can get rid of the mount parameter previously used
> to trigger all these behavours (LIBXFS_MOUNT_ROOTINOS) completely.
> 
> Signed-off-by: Dave Chinner <dchinner at redhat.com>


Looks good,

Reviewed-by: Christoph Hellwig <hch at lst.de>