xfs: factor unwritten extent map manipulations out of xfs_bmapi

To further improve the readability of xfs_bmapi(), factor the
unwritten extent conversion out into a separate function. This
removes large block of logic from the xfs_bmapi() code loop and
makes it easier to see the operational logic flow for xfs_bmapi().

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Alex Elder <aelder@sgi.com>

1 files changed, 70 insertions, 37 deletions

diff --git a/fs/xfs/xfs_bmap.c b/fs/xfs/xfs_bmap.c
index 311cbc1d64c5..c2e49fd18bfd 100644
--- a/fs/xfs/xfs_bmap.c
+++ b/fs/xfs/xfs_bmap.c
@@ -4089,7 +4089,6 @@ xfs_bmap_read_extents(
                 xfs_extnum_t    num_recs;
                 xfs_extnum_t    start;
 
-
                 num_recs = xfs_btree_get_numrecs(block);
                 if (unlikely(i + num_recs > room)) {
                         ASSERT(i + num_recs <= room);
@@ -4746,6 +4745,69 @@ xfs_bmapi_allocate(
         return 0;
 }
 
+STATIC int
+xfs_bmapi_convert_unwritten(
+        struct xfs_bmalloca     *bma,
+        struct xfs_bmbt_irec    *mval,
+        xfs_filblks_t           len,
+        xfs_extnum_t            *lastx,
+        struct xfs_btree_cur    **cur,
+        xfs_fsblock_t           *firstblock,
+        struct xfs_bmap_free    *flist,
+        int                     flags,
+        int                     *logflags)
+{
+        int                     whichfork = (flags & XFS_BMAPI_ATTRFORK) ?
+                                                XFS_ATTR_FORK : XFS_DATA_FORK;
+        struct xfs_ifork        *ifp = XFS_IFORK_PTR(bma->ip, whichfork);
+        int                     error;
+
+        *logflags = 0;
+
+        /* check if we need to do unwritten->real conversion */
+        if (mval->br_state == XFS_EXT_UNWRITTEN &&
+            (flags & XFS_BMAPI_PREALLOC))
+                return 0;
+
+        /* check if we need to do real->unwritten conversion */
+        if (mval->br_state == XFS_EXT_NORM &&
+            (flags & (XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT)) !=
+                        (XFS_BMAPI_PREALLOC | XFS_BMAPI_CONVERT))
+                return 0;
+
+        /*
+         * Modify (by adding) the state flag, if writing.
+         */
+        ASSERT(mval->br_blockcount <= len);
+        if ((ifp->if_flags & XFS_IFBROOT) && !*cur) {
+                *cur = xfs_bmbt_init_cursor(bma->ip->i_mount, bma->tp,
+                                        bma->ip, whichfork);
+                (*cur)->bc_private.b.firstblock = *firstblock;
+                (*cur)->bc_private.b.flist = flist;
+        }
+        mval->br_state = (mval->br_state == XFS_EXT_UNWRITTEN)
+                                ? XFS_EXT_NORM : XFS_EXT_UNWRITTEN;
+
+        error = xfs_bmap_add_extent(bma->tp, bma->ip, lastx, cur, mval,
+                                firstblock, flist, logflags, whichfork);
+        if (error)
+                return error;
+
+        /*
+         * Update our extent pointer, given that xfs_bmap_add_extent  might
+         * have merged it into one of the neighbouring ones.
+         */
+        xfs_bmbt_get_all(xfs_iext_get_ext(ifp, *lastx), bma->gotp);
+
+        /*
+         * We may have combined previously unwritten space with written space,
+         * so generate another request.
+         */
+        if (mval->br_blockcount < len)
+                return EAGAIN;
+        return 0;
+}
+
 /*
  * Map file blocks to filesystem blocks.
  * File range is given by the bno/len pair.
@@ -4932,45 +4994,16 @@ xfs_bmapi(
                 /* Deal with the allocated space we found.  */
                 xfs_bmapi_trim_map(mval, &got, &bno, len, obno, end, n, flags);
 
-                /*
-                 * Check if writing previously allocated but
-                 * unwritten extents.
-                 */
-                if (wr &&
-                    ((mval->br_state == XFS_EXT_UNWRITTEN &&
-                      ((flags & XFS_BMAPI_PREALLOC) == 0)) ||
-                     (mval->br_state == XFS_EXT_NORM &&
-                      ((flags & (XFS_BMAPI_PREALLOC|XFS_BMAPI_CONVERT)) ==
-                                (XFS_BMAPI_PREALLOC|XFS_BMAPI_CONVERT))))) {
-                        /*
-                         * Modify (by adding) the state flag, if writing.
-                         */
-                        ASSERT(mval->br_blockcount <= len);
-                        if ((ifp->if_flags & XFS_IFBROOT) && !cur) {
-                                cur = xfs_bmbt_init_cursor(mp,
-                                        tp, ip, whichfork);
-                                cur->bc_private.b.firstblock =
-                                        *firstblock;
-                                cur->bc_private.b.flist = flist;
-                        }
-                        mval->br_state = (mval->br_state == XFS_EXT_UNWRITTEN)
-                                                ? XFS_EXT_NORM
-                                                : XFS_EXT_UNWRITTEN;
-                        error = xfs_bmap_add_extent(tp, ip, &lastx, &cur, mval,
-                                firstblock, flist, &tmp_logflags,
-                                whichfork);
+                /* Execute unwritten extent conversion if necessary */
+                if (wr) {
+                        error = xfs_bmapi_convert_unwritten(&bma, mval, len,
+                                                &lastx, &cur, firstblock, flist, flags,
+                                                &tmp_logflags);
                         logflags |= tmp_logflags;
+                        if (error == EAGAIN)
+                                continue;
                         if (error)
                                 goto error0;
-                        ep = xfs_iext_get_ext(ifp, lastx);
-                        xfs_bmbt_get_all(ep, &got);
-                        /*
-                         * We may have combined previously unwritten
-                         * space with written space, so generate
-                         * another request.
-                         */
-                        if (mval->br_blockcount < len)
-                                continue;
                 }
 
                 /* update the extent map to return */