xfs: refactor xfs_reflink_end_cow_extent()

Refactor xfs_reflink_end_cow_extent() into separate parts which process
the CoW range and commit the transaction.

This refactoring will be used in future for when it is required to commit
a range of extents as a single transaction, similar to how it was done
pre-commit d6f215f359637.

Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>

diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c
index cc3b4df8811074640b18c8a95fd8537365349986..bd711c5bb6bb2e6acf36666dbe6334a7a8508b9b 100644 (file)
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -786,35 +786,19 @@ xfs_reflink_update_quota(
  * requirements as low as possible.
  */
 STATIC int
-xfs_reflink_end_cow_extent(
+xfs_reflink_end_cow_extent_locked(
+       struct xfs_trans        *tp,
        struct xfs_inode        *ip,
        xfs_fileoff_t           *offset_fsb,
        xfs_fileoff_t           end_fsb)
 {
        struct xfs_iext_cursor  icur;
        struct xfs_bmbt_irec    got, del, data;
-       struct xfs_mount        *mp = ip->i_mount;
-       struct xfs_trans        *tp;
        struct xfs_ifork        *ifp = xfs_ifork_ptr(ip, XFS_COW_FORK);
-       unsigned int            resblks;
        int                     nmaps;
        bool                    isrt = XFS_IS_REALTIME_INODE(ip);
        int                     error;
 
-       resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
-       error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
-                       XFS_TRANS_RESERVE, &tp);
-       if (error)
-               return error;
-
-       /*
-        * Lock the inode.  We have to ijoin without automatic unlock because
-        * the lead transaction is the refcountbt record deletion; the data
-        * fork update follows as a deferred log item.
-        */
-       xfs_ilock(ip, XFS_ILOCK_EXCL);
-       xfs_trans_ijoin(tp, ip, 0);
-
        /*
         * 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
@@ -823,7 +807,7 @@ xfs_reflink_end_cow_extent(
        if (!xfs_iext_lookup_extent(ip, ifp, *offset_fsb, &icur, &got) ||
            got.br_startoff >= end_fsb) {
                *offset_fsb = end_fsb;
-               goto out_cancel;
+               return 0;
        }
 
        /*
@@ -837,7 +821,7 @@ xfs_reflink_end_cow_extent(
                if (!xfs_iext_next_extent(ifp, &icur, &got) ||
                    got.br_startoff >= end_fsb) {
                        *offset_fsb = end_fsb;
-                       goto out_cancel;
+                       return 0;
                }
        }
        del = got;
@@ -846,14 +830,14 @@ xfs_reflink_end_cow_extent(
        error = xfs_iext_count_extend(tp, ip, XFS_DATA_FORK,
                        XFS_IEXT_REFLINK_END_COW_CNT);
        if (error)
-               goto out_cancel;
+               return error;
 
        /* Grab the corresponding mapping in the data fork. */
        nmaps = 1;
        error = xfs_bmapi_read(ip, del.br_startoff, del.br_blockcount, &data,
                        &nmaps, 0);
        if (error)
-               goto out_cancel;
+               return error;
 
        /* We can only remap the smaller of the two extent sizes. */
        data.br_blockcount = min(data.br_blockcount, del.br_blockcount);
@@ -882,7 +866,7 @@ xfs_reflink_end_cow_extent(
                error = xfs_bunmapi(NULL, ip, data.br_startoff,
                                data.br_blockcount, 0, 1, &done);
                if (error)
-                       goto out_cancel;
+                       return error;
                ASSERT(done);
        }
 
@@ -899,17 +883,45 @@ xfs_reflink_end_cow_extent(
        /* Remove the mapping from the CoW fork. */
        xfs_bmap_del_extent_cow(ip, &icur, &got, &del);
 
-       error = xfs_trans_commit(tp);
-       xfs_iunlock(ip, XFS_ILOCK_EXCL);
-       if (error)
-               return error;
-
        /* Update the caller about how much progress we made. */
        *offset_fsb = del.br_startoff + del.br_blockcount;
        return 0;
+}
 
-out_cancel:
-       xfs_trans_cancel(tp);
+/*
+ * Remap part of the CoW fork into the data fork.
+ *
+ * We aim to remap the range starting at @offset_fsb and ending at @end_fsb
+ * into the data fork; this function will remap what it can (at the end of the
+ * range) and update @end_fsb appropriately.  Each remap gets its own
+ * transaction because we can end up merging and splitting bmbt blocks for
+ * every remap operation and we'd like to keep the block reservation
+ * requirements as low as possible.
+ */
+STATIC int
+xfs_reflink_end_cow_extent(
+       struct xfs_inode        *ip,
+       xfs_fileoff_t           *offset_fsb,
+       xfs_fileoff_t           end_fsb)
+{
+       struct xfs_mount        *mp = ip->i_mount;
+       struct xfs_trans        *tp;
+       unsigned int            resblks;
+       int                     error;
+
+       resblks = XFS_EXTENTADD_SPACE_RES(mp, XFS_DATA_FORK);
+       error = xfs_trans_alloc(mp, &M_RES(mp)->tr_write, resblks, 0,
+                       XFS_TRANS_RESERVE, &tp);
+       if (error)
+               return error;
+       xfs_ilock(ip, XFS_ILOCK_EXCL);
+       xfs_trans_ijoin(tp, ip, 0);
+
+       error = xfs_reflink_end_cow_extent_locked(tp, ip, offset_fsb, end_fsb);
+       if (error)
+               xfs_trans_cancel(tp);
+       else
+               error = xfs_trans_commit(tp);
        xfs_iunlock(ip, XFS_ILOCK_EXCL);
        return error;
 }