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[PATCH 11/27] xfs: factor unwritten extent map manipulations out of xfs_

To: xfs@xxxxxxxxxxx
Subject: [PATCH 11/27] xfs: factor unwritten extent map manipulations out of xfs_bmapi
From: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Date: Sun, 18 Sep 2011 16:40:51 -0400
Cc: Dave Chinner <dchinner@xxxxxxxxxx>
References: <20110918204040.266805129@xxxxxxxxxxxxxxxxxxxxxx>
User-agent: quilt/0.48-1
From: Dave Chinner <dchinner@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Alex Elder <aelder@xxxxxxx>

Index: xfs/fs/xfs/xfs_bmap.c
===================================================================
--- xfs.orig/fs/xfs/xfs_bmap.c  2011-09-11 08:43:13.169789855 -0400
+++ xfs/fs/xfs/xfs_bmap.c       2011-09-11 08:43:14.726456511 -0400
@@ -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 */

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