On Mon, Sep 10, 2012 at 02:37:21PM -0400, Brian Foster wrote:
> This check is used in multiple places to determine whether we
> should check for (and potentially free) post EOF blocks on an
> inode. Add a helper to consolidate the check.
>
> Note that when we remove an inode from the cache (xfs_inactive()),
> we are required to trim post-EOF blocks even if the inode is marked
> preallocated or append-only to maintain correct space accounting.
> The 'force' parameter to xfs_can_free_eofblocks() specifies whether
> we should ignore the prealloc/append-only status of the inode.
>
> Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx>
Just quickly, I'd rewrite this convoluted logic:
> +/*
> + * Test whether it is appropriate to check an inode for and free post EOF
> + * blocks. The 'force' parameter determines whether we should also consider
> + * regular files that are marked preallocated or append-only.
> + */
> +static inline bool
> +xfs_can_free_eofblocks(struct xfs_inode *ip, bool force)
> +{
> + if (S_ISREG(ip->i_d.di_mode) &&
> + (VFS_I(ip)->i_size > 0 ||
> + (VN_CACHED(VFS_I(ip)) > 0 || ip->i_delayed_blks > 0)) &&
> + (ip->i_df.if_flags & XFS_IFEXTENTS) &&
> + (!(ip->i_d.di_flags & (XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)) ||
> + (force && ip->i_delayed_blks != 0)))
> + return true;
> +
> + return false;
> +}
in a manner that can means it no longer has to be analysed from first principles
every time it is read. e.g.:
static inline bool
xfs_can_free_eofblocks(struct xfs_inode *ip, bool force)
{
/* prealloc/delalloc exists only on regular files */
if (!S_ISREG(ip->i_d.di_mode))
return false;
/*
* Zero sized files with no cached page or delalloc blocks will not have
* any speculative prealloc/delalloc to remove.
*/
if (VFS_I(ip)->i_size == 0 &&
VFS_I(ip)->i_mapping->nr_pages == 0 &&
ip->i_delayed_blks == 0)
return false;
/* If we haven't read in the extent list, then don't do it now. */
if (!(ip->i_df.if_flags & XFS_IFEXTENTS))
return false;
/*
* Real preallocation or append only files do not get EOF blocks freed
* unless there are also delalloc blocks and we are forced to remove
* them.
*/
if ((ip->i_d.di_flags & (XFS_DIFLAG_PREALLOC | XFS_DIFLAG_APPEND)) {
if (!ip->i_delayed_blks)
return false;
if (!force)
return false;
}
return true;
}
--
Dave Chinner
david@xxxxxxxxxxxxx
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