xfs: factor out free space extent length check

The longest extent length checks in xfs_alloc_fix_freelist() are now
essentially identical. Factor them out into a helper function, so we
know they are checking exactly the same thing before and after we
lock the AGF.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
index 9b3e3681dfa9b196bb29c56707c19f9e2e41f98c..c548bb022aa65193f0ffd922f2e3a017767ac9c4 100644 (file)
--- a/fs/xfs/libxfs/xfs_alloc.c
+++ b/fs/xfs/libxfs/xfs_alloc.c
@@ -1838,6 +1838,39 @@ xfs_alloc_longest_free_extent(
        return pag->pagf_flcount > 0 || pag->pagf_longest > 0;
 }
 
+/*
+ * Check if the operation we are fixing up the freelist for should go ahead or
+ * not. If we are freeing blocks, we always allow it, otherwise the allocation
+ * is dependent on whether the size and shape of free space available will
+ * permit the requested allocation to take place.
+ */
+static bool
+xfs_alloc_space_available(
+       struct xfs_alloc_arg    *args,
+       xfs_extlen_t            min_free,
+       int                     flags)
+{
+       struct xfs_perag        *pag = args->pag;
+       xfs_extlen_t            longest;
+       int                     available;
+
+       if (flags & XFS_ALLOC_FLAG_FREEING)
+               return true;
+
+       /* do we have enough contiguous free space for the allocation? */
+       longest = xfs_alloc_longest_free_extent(args->mp, pag, min_free);
+       if ((args->minlen + args->alignment + args->minalignslop - 1) > longest)
+               return false;
+
+       /* do have enough free space remaining for the allocation? */
+       available = (int)(pag->pagf_freeblks + pag->pagf_flcount -
+                         min_free - args->total);
+       if (available < (int)args->minleft)
+               return false;
+
+       return true;
+}
+
 /*
  * Decide whether to use this allocation group for this allocation.
  * If so, fix up the btree freelist's size.
@@ -1851,7 +1884,6 @@ xfs_alloc_fix_freelist(
        xfs_buf_t       *agflbp;/* agfl buffer pointer */
        xfs_agblock_t   bno;    /* freelist block */
        int             error;  /* error result code */
-       xfs_extlen_t    longest;/* longest extent in allocation group */
        xfs_mount_t     *mp;    /* file system mount point structure */
        xfs_extlen_t    need;   /* total blocks needed in freelist */
        xfs_perag_t     *pag;   /* per-ag information structure */
@@ -1887,22 +1919,12 @@ xfs_alloc_fix_freelist(
                return 0;
        }
 
-       if (!(flags & XFS_ALLOC_FLAG_FREEING)) {
-               /*
-                * If it looks like there isn't a long enough extent, or enough
-                * total blocks, reject it.
-                */
-               need = XFS_MIN_FREELIST_PAG(pag, mp);
-               longest = xfs_alloc_longest_free_extent(mp, pag, need);
-               if ((args->minlen + args->alignment + args->minalignslop - 1) >
-                               longest ||
-                   ((int)(pag->pagf_freeblks + pag->pagf_flcount -
-                          need - args->total) < (int)args->minleft)) {
-                       if (agbp)
-                               xfs_trans_brelse(tp, agbp);
-                       args->agbp = NULL;
-                       return 0;
-               }
+       need = XFS_MIN_FREELIST_PAG(pag, mp);
+       if (!xfs_alloc_space_available(args, need, flags)) {
+               if (agbp)
+                       xfs_trans_brelse(tp, agbp);
+               args->agbp = NULL;
+               return 0;
        }
 
        /*
@@ -1924,17 +1946,12 @@ xfs_alloc_fix_freelist(
 
        /* If there isn't enough total space or single-extent, reject it. */
        need = XFS_MIN_FREELIST_PAG(pag, mp);
-       if (!(flags & XFS_ALLOC_FLAG_FREEING)) {
-               longest = xfs_alloc_longest_free_extent(mp, pag, need);
-               if ((args->minlen + args->alignment + args->minalignslop - 1) >
-                               longest ||
-                   ((int)(pag->pagf_freeblks + pag->pagf_flcount -
-                          need - args->total) < (int)args->minleft)) {
-                       xfs_trans_brelse(tp, agbp);
-                       args->agbp = NULL;
-                       return 0;
-               }
+       if (!xfs_alloc_space_available(args, need, flags)) {
+               xfs_trans_brelse(tp, agbp);
+               args->agbp = NULL;
+               return 0;
        }
+
        /*
         * Make the freelist shorter if it's too long.
         *