From 060d4eaa0bf30a8fc2d189e4d4922f6e9027857b Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Wed, 11 Jul 2018 22:26:01 -0700
Subject: [PATCH] xfs: remove xfs_reflink_find_cow_mapping
Git-commit: 060d4eaa0bf30a8fc2d189e4d4922f6e9027857b
Patch-mainline: v4.19-rc1
References: bsc#1138010

We only have one caller left, and open coding the simple extent list
lookup in it allows us to make the code both more understandable and
reuse calculations and variables already present.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Acked-by: Anthony Iliopoulos <ailiopoulos@suse.com>

---
 fs/xfs/xfs_aops.c    |   19 +++++++++++++------
 fs/xfs/xfs_reflink.c |   29 -----------------------------
 fs/xfs/xfs_reflink.h |    2 --
 fs/xfs/xfs_trace.h   |    1 -
 4 files changed, 13 insertions(+), 38 deletions(-)

--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -382,9 +382,10 @@
 	struct xfs_inode	*ip = XFS_I(inode);
 	struct xfs_mount	*mp = ip->i_mount;
 	ssize_t			count = i_blocksize(inode);
-	xfs_fileoff_t		offset_fsb = XFS_B_TO_FSBT(mp, offset), end_fsb;
+	xfs_fileoff_t		offset_fsb, end_fsb;
 	struct xfs_bmbt_irec	imap;
 	int			whichfork = XFS_DATA_FORK;
+	struct xfs_iext_cursor	icur;
 	int			error = 0;
 	int			nimaps = 1;
 
@@ -396,8 +397,18 @@
 	       (ip->i_df.if_flags & XFS_IFEXTENTS));
 	ASSERT(offset <= mp->m_super->s_maxbytes);
 
+	if (offset > mp->m_super->s_maxbytes - count)
+		count = mp->m_super->s_maxbytes - offset;
+	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
+	offset_fsb = XFS_B_TO_FSBT(mp, offset);
+
+	/*
+	 * Check if this is offset is covered by a COW extents, and if yes use
+	 * it directly instead of looking up anything in the data fork.
+	 */
 	if (xfs_is_reflink_inode(ip) &&
-	    xfs_reflink_find_cow_mapping(ip, offset, &imap)) {
+	    xfs_iext_lookup_extent(ip, ip->i_cowfp, offset_fsb, &icur, &imap) &&
+	    imap.br_startoff <= offset_fsb) {
 		xfs_iunlock(ip, XFS_ILOCK_SHARED);
 		/*
 		 * Truncate can race with writeback since writeback doesn't
@@ -432,10 +443,6 @@
 	 * offset.  This will convert delayed allocations (including COW ones)
 	 * into real extents.
 	 */
-	if (offset > mp->m_super->s_maxbytes - count)
-		count = mp->m_super->s_maxbytes - offset;
-	end_fsb = XFS_B_TO_FSB(mp, (xfs_ufsize_t)offset + count);
-	offset_fsb = XFS_B_TO_FSBT(mp, offset);
 	error = xfs_bmapi_read(ip, offset_fsb, end_fsb - offset_fsb,
 				&imap, &nimaps, XFS_BMAPI_ENTIRE);
 	xfs_iunlock(ip, XFS_ILOCK_SHARED);
--- a/fs/xfs/xfs_reflink.c
+++ b/fs/xfs/xfs_reflink.c
@@ -476,35 +476,6 @@
 }
 
 /*
- * Find the CoW reservation for a given byte offset of a file.
- */
-bool
-xfs_reflink_find_cow_mapping(
-	struct xfs_inode		*ip,
-	xfs_off_t			offset,
-	struct xfs_bmbt_irec		*imap)
-{
-	struct xfs_ifork		*ifp = XFS_IFORK_PTR(ip, XFS_COW_FORK);
-	xfs_fileoff_t			offset_fsb;
-	struct xfs_bmbt_irec		got;
-	struct xfs_iext_cursor		icur;
-
-	ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL | XFS_ILOCK_SHARED));
-	ASSERT(xfs_is_reflink_inode(ip));
-
-	offset_fsb = XFS_B_TO_FSBT(ip->i_mount, offset);
-	if (!xfs_iext_lookup_extent(ip, ifp, offset_fsb, &icur, &got))
-		return false;
-	if (got.br_startoff > offset_fsb)
-		return false;
-
-	trace_xfs_reflink_find_cow_mapping(ip, offset, 1, XFS_IO_OVERWRITE,
-			&got);
-	*imap = got;
-	return true;
-}
-
-/*
  * Cancel CoW reservations for some block range of an inode.
  *
  * If cancel_real is true this function cancels all COW fork extents for the
--- a/fs/xfs/xfs_reflink.h
+++ b/fs/xfs/xfs_reflink.h
@@ -32,8 +32,6 @@
 		struct xfs_bmbt_irec *imap, bool *shared, uint *lockmode);
 extern int xfs_reflink_convert_cow(struct xfs_inode *ip, xfs_off_t offset,
 		xfs_off_t count);
-extern bool xfs_reflink_find_cow_mapping(struct xfs_inode *ip, xfs_off_t offset,
-		struct xfs_bmbt_irec *imap);
 
 extern int xfs_reflink_cancel_cow_blocks(struct xfs_inode *ip,
 		struct xfs_trans **tpp, xfs_fileoff_t offset_fsb,
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -3220,7 +3220,6 @@
 DEFINE_RW_EVENT(xfs_reflink_reserve_cow);
 
 DEFINE_SIMPLE_IO_EVENT(xfs_reflink_bounce_dio_write);
-DEFINE_IOMAP_EVENT(xfs_reflink_find_cow_mapping);
 
 DEFINE_SIMPLE_IO_EVENT(xfs_reflink_cancel_cow_range);
 DEFINE_SIMPLE_IO_EVENT(xfs_reflink_end_cow);