xfs: add a new xfs_iext_lookup_extent_before helper

This helper looks up the last extent the covers space before the passed
in block number.  This is useful for truncate and similar operations that
operate backwards over the extent list.  For xfs_bunmapi it also is
a slight optimization as we can return early if there are not extents
at or below the end of the to be truncated range.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 26518aa7b9aec31d6f7f34b54f9f6d8830d80706..f45f05c45e1580dd74321f10b375ce31c969548f 100644 (file)
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -1386,17 +1386,8 @@ xfs_bmap_last_before(
                        return error;
        }
 
-       if (xfs_iext_lookup_extent(ip, ifp, *last_block - 1, &idx, &got)) {
-               if (got.br_startoff <= *last_block - 1)
-                       return 0;
-       }
-
-       if (xfs_iext_get_extent(ifp, idx - 1, &got)) {
-               *last_block = got.br_startoff + got.br_blockcount;
-               return 0;
-       }
-
-       *last_block = 0;
+       if (!xfs_iext_lookup_extent_before(ip, ifp, last_block, &idx, &got))
+               *last_block = 0;
        return 0;
 }
 
@@ -5171,17 +5162,13 @@ __xfs_bunmapi(
        }
        XFS_STATS_INC(mp, xs_blk_unmap);
        isrt = (whichfork == XFS_DATA_FORK) && XFS_IS_REALTIME_INODE(ip);
-       end = start + len - 1;
+       end = start + len;
 
-       /*
-        * Check to see if the given block number is past the end of the
-        * file, back up to the last block if so...
-        */
-       if (!xfs_iext_lookup_extent(ip, ifp, end, &lastx, &got)) {
-               ASSERT(lastx > 0);
-               xfs_iext_get_extent(ifp, --lastx, &got);
-               end = got.br_startoff + got.br_blockcount - 1;
+       if (!xfs_iext_lookup_extent_before(ip, ifp, &end, &lastx, &got)) {
+               *rlen = 0;
+               return 0;
        }
+       end--;
 
        logflags = 0;
        if (ifp->if_flags & XFS_IFBROOT) {

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 911ff791a896bb6183e296ac5f1fcdf87439e4df..bb63f38b97cc1e6cc7f4611da11c955da4f8e8d1 100644 (file)
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -1967,6 +1967,27 @@ xfs_iext_lookup_extent(
        return true;
 }
 
+/*
+ * Returns the last extent before end, and if this extent doesn't cover
+ * end, update end to the end of the extent.
+ */
+bool
+xfs_iext_lookup_extent_before(
+       struct xfs_inode        *ip,
+       struct xfs_ifork        *ifp,
+       xfs_fileoff_t           *end,
+       xfs_extnum_t            *idxp,
+       struct xfs_bmbt_irec    *gotp)
+{
+       if (xfs_iext_lookup_extent(ip, ifp, *end - 1, idxp, gotp) &&
+           gotp->br_startoff <= *end - 1)
+               return true;
+       if (!xfs_iext_get_extent(ifp, --*idxp, gotp))
+               return false;
+       *end = gotp->br_startoff + gotp->br_blockcount;
+       return true;
+}
+
 /*
  * Return true if there is an extent at index idx, and return the expanded
  * extent structure at idx in that case.  Else return false.

diff --git a/fs/xfs/libxfs/xfs_inode_fork.h b/fs/xfs/libxfs/xfs_inode_fork.h
index e0c42ea9b8d0c189e54089909c4a986c37229034..113fd42ec36dc04310076ad52aecd1c6024662a3 100644 (file)
--- a/fs/xfs/libxfs/xfs_inode_fork.h
+++ b/fs/xfs/libxfs/xfs_inode_fork.h
@@ -183,6 +183,10 @@ void               xfs_iext_irec_update_extoffs(struct xfs_ifork *, int, int);
 bool           xfs_iext_lookup_extent(struct xfs_inode *ip,
                        struct xfs_ifork *ifp, xfs_fileoff_t bno,
                        xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
+bool           xfs_iext_lookup_extent_before(struct xfs_inode *ip,
+                       struct xfs_ifork *ifp, xfs_fileoff_t *end,
+                       xfs_extnum_t *idxp, struct xfs_bmbt_irec *gotp);
+
 bool           xfs_iext_get_extent(struct xfs_ifork *ifp, xfs_extnum_t idx,
                        struct xfs_bmbt_irec *gotp);
 void           xfs_iext_update_extent(struct xfs_inode *ip, int state,

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index 37e603bf159137dfd38a1210b5d0bb31e5f4829f..1205747e140997a7a1472d3bcddb4c23044bcaa8 100644 (file)
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -733,18 +733,13 @@ xfs_reflink_end_cow(
        xfs_ilock(ip, XFS_ILOCK_EXCL);
        xfs_trans_ijoin(tp, ip, 0);
 
-       /* If there is a hole at end_fsb - 1 go to the previous extent */
-       if (!xfs_iext_lookup_extent(ip, ifp, end_fsb - 1, &idx, &got) ||
-           got.br_startoff > end_fsb) {
-               /*
-                * In case of racing, overlapping AIO writes no COW extents
-                * might be left by the time I/O completes for the loser of
-                * the race.  In that case we are done.
-                */
-               if (idx <= 0)
-                       goto out_cancel;
-               xfs_iext_get_extent(ifp, --idx, &got);
-       }
+       /*
+        * In case of racing, overlapping AIO writes no COW extents might be
+        * left by the time I/O completes for the loser of the race.  In that
+        * case we are done.
+        */
+       if (!xfs_iext_lookup_extent_before(ip, ifp, &end_fsb, &idx, &got))
+               goto out_cancel;
 
        /* Walk backwards until we're out of the I/O range... */
        while (got.br_startoff + got.br_blockcount > offset_fsb) {