xfs: merge filestream AG lookup into xfs_filestream_select_ag()

The lookup currently either returns the cached filestream AG or it
calls xfs_filestreams_select_lengths() to looks up a new AG. This
has verify the AG that is selected, so we end up doing "select a new
AG loop in a couple of places when only one really is needed.  Merge
the initial lookup functionality with the length selection so that
we only need to do a single pick loop on lookup or verification
failure.

This undoes a lot of the factoring that enabled the selection to be
moved over to the filestreams code. It makes
xfs_filestream_select_ag() an awful messier, but it has to be made
worse before it can get better in future patches...

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
index a641404..23044da 100644 (file)
--- a/fs/xfs/xfs_filestream.c
+++ b/fs/xfs/xfs_filestream.c
@@ -259,55 +259,6 @@ out:
 }
 
 /*
- * Find the right allocation group for a file, either by finding an
- * existing file stream or creating a new one.
- *
- * Returns NULLAGNUMBER in case of an error.
- */
-static xfs_agnumber_t
-xfs_filestream_lookup_ag(
-       struct xfs_inode        *ip)
-{
-       struct xfs_mount        *mp = ip->i_mount;
-       struct xfs_inode        *pip = NULL;
-       xfs_agnumber_t          startag, ag = NULLAGNUMBER;
-       struct xfs_mru_cache_elem *mru;
-
-       ASSERT(S_ISREG(VFS_I(ip)->i_mode));
-
-       pip = xfs_filestream_get_parent(ip);
-       if (!pip)
-               return NULLAGNUMBER;
-
-       mru = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino);
-       if (mru) {
-               ag = container_of(mru, struct xfs_fstrm_item, mru)->ag;
-               xfs_mru_cache_done(mp->m_filestream);
-
-               trace_xfs_filestream_lookup(mp, ip->i_ino, ag);
-               goto out;
-       }
-
-       /*
-        * Set the starting AG using the rotor for inode32, otherwise
-        * use the directory inode's AG.
-        */
-       if (xfs_is_inode32(mp)) {
-               xfs_agnumber_t   rotorstep = xfs_rotorstep;
-               startag = (mp->m_agfrotor / rotorstep) % mp->m_sb.sb_agcount;
-               mp->m_agfrotor = (mp->m_agfrotor + 1) %
-                                (mp->m_sb.sb_agcount * rotorstep);
-       } else
-               startag = XFS_INO_TO_AGNO(mp, pip->i_ino);
-
-       if (xfs_filestream_pick_ag(pip, startag, &ag, 0, 0))
-               ag = NULLAGNUMBER;
-out:
-       xfs_irele(pip);
-       return ag;
-}
-
-/*
  * Pick a new allocation group for the current file and its file stream.
  *
  * This is called when the allocator can't find a suitable extent in the
@@ -359,83 +310,70 @@ exit:
        return err;
 }
 
-static int
-xfs_filestreams_select_lengths(
+/*
+ * Search for an allocation group with a single extent large enough for
+ * the request.  If one isn't found, then the largest available free extent is
+ * returned as the best length possible.
+ */
+int
+xfs_filestream_select_ag(
        struct xfs_bmalloca     *ap,
        struct xfs_alloc_arg    *args,
        xfs_extlen_t            *blen)
 {
        struct xfs_mount        *mp = ap->ip->i_mount;
        struct xfs_perag        *pag;
-       xfs_agnumber_t          start_agno;
+       struct xfs_inode        *pip = NULL;
+       xfs_agnumber_t          agno = NULLAGNUMBER;
+       struct xfs_mru_cache_elem *mru;
        int                     error;
 
        args->total = ap->total;
+       *blen = 0;
 
-       start_agno = XFS_FSB_TO_AGNO(mp, ap->blkno);
-       if (start_agno == NULLAGNUMBER)
-               start_agno = 0;
-
-       pag = xfs_perag_grab(mp, start_agno);
-       if (pag) {
-               error = xfs_bmap_longest_free_extent(pag, args->tp, blen);
-               xfs_perag_rele(pag);
-               if (error) {
-                       if (error != -EAGAIN)
-                               return error;
-                       *blen = 0;
-               }
+       pip = xfs_filestream_get_parent(ap->ip);
+       if (!pip) {
+               agno = 0;
+               goto new_ag;
        }
 
-       if (*blen < args->maxlen) {
-               xfs_agnumber_t  agno = start_agno;
+       mru = xfs_mru_cache_lookup(mp->m_filestream, pip->i_ino);
+       if (mru) {
+               agno = container_of(mru, struct xfs_fstrm_item, mru)->ag;
+               xfs_mru_cache_done(mp->m_filestream);
 
-               error = xfs_filestream_new_ag(ap, &agno);
-               if (error)
-                       return error;
-               if (agno == NULLAGNUMBER)
-                       goto out_select;
+               trace_xfs_filestream_lookup(mp, ap->ip->i_ino, agno);
+               xfs_irele(pip);
 
-               pag = xfs_perag_grab(mp, agno);
-               if (!pag)
-                       goto out_select;
+               ap->blkno = XFS_AGB_TO_FSB(args->mp, agno, 0);
+               xfs_bmap_adjacent(ap);
 
-               error = xfs_bmap_longest_free_extent(pag, args->tp, blen);
-               xfs_perag_rele(pag);
-               if (error) {
-                       if (error != -EAGAIN)
-                               return error;
-                       *blen = 0;
+               pag = xfs_perag_grab(mp, agno);
+               if (pag) {
+                       error = xfs_bmap_longest_free_extent(pag, args->tp, blen);
+                       xfs_perag_rele(pag);
+                       if (error) {
+                               if (error != -EAGAIN)
+                                       return error;
+                               *blen = 0;
+                       }
                }
-               start_agno = agno;
+               if (*blen >= args->maxlen)
+                       goto out_select;
+       } else if (xfs_is_inode32(mp)) {
+               xfs_agnumber_t   rotorstep = xfs_rotorstep;
+               agno = (mp->m_agfrotor / rotorstep) %
+                               mp->m_sb.sb_agcount;
+               mp->m_agfrotor = (mp->m_agfrotor + 1) %
+                                (mp->m_sb.sb_agcount * rotorstep);
+               xfs_irele(pip);
+       } else {
+               agno = XFS_INO_TO_AGNO(mp, pip->i_ino);
+               xfs_irele(pip);
        }
 
-out_select:
-       /*
-        * Set the failure fallback case to look in the selected AG as stream
-        * may have moved.
-        */
-       ap->blkno = args->fsbno = XFS_AGB_TO_FSB(mp, start_agno, 0);
-       return 0;
-}
-
-/*
- * Search for an allocation group with a single extent large enough for
- * the request.  If one isn't found, then the largest available free extent is
- * returned as the best length possible.
- */
-int
-xfs_filestream_select_ag(
-       struct xfs_bmalloca     *ap,
-       struct xfs_alloc_arg    *args,
-       xfs_extlen_t            *blen)
-{
-       xfs_agnumber_t          start_agno = xfs_filestream_lookup_ag(ap->ip);
-
-       /* Determine the initial block number we will target for allocation. */
-       if (start_agno == NULLAGNUMBER)
-               start_agno = 0;
-       ap->blkno = XFS_AGB_TO_FSB(args->mp, start_agno, 0);
+new_ag:
+       ap->blkno = XFS_AGB_TO_FSB(args->mp, agno, 0);
        xfs_bmap_adjacent(ap);
 
        /*
@@ -446,14 +384,32 @@ xfs_filestream_select_ag(
        if (ap->tp->t_flags & XFS_TRANS_LOWMODE)
                return 0;
 
-       /*
-        * Search for an allocation group with a single extent large enough for
-        * the request.  If one isn't found, then adjust the minimum allocation
-        * size to the largest space found.
-        */
-       return xfs_filestreams_select_lengths(ap, args, blen);
+       error = xfs_filestream_new_ag(ap, &agno);
+       if (error)
+               return error;
+       if (agno == NULLAGNUMBER) {
+               agno = 0;
+               goto out_select;
+       }
+
+       pag = xfs_perag_grab(mp, agno);
+       if (!pag)
+               goto out_select;
+
+       error = xfs_bmap_longest_free_extent(pag, args->tp, blen);
+       xfs_perag_rele(pag);
+       if (error) {
+               if (error != -EAGAIN)
+                       return error;
+               *blen = 0;
+       }
+
+out_select:
+       ap->blkno = XFS_AGB_TO_FSB(mp, agno, 0);
+       return 0;
 }
 
+
 void
 xfs_filestream_deassociate(
        struct xfs_inode        *ip)