[PATCH v2 1/4] xfs: factor out isize updates from xfs_dio_write_end_io

[cem@kernel.org]

From: Carlos Maiolino <cem@kernel.org>

This is the only code needed for zoned inodes, so factor it out so
we can move zoned inodes ioend to its own callback.

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
---
v2: Don't call xfs_setfilesize() unnecessarily

 fs/xfs/xfs_file.c | 60 +++++++++++++++++++++++++++++------------------
 1 file changed, 37 insertions(+), 23 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 6246f34df9fd..fce6be55d90c 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -560,6 +560,42 @@ xfs_zoned_write_space_reserve(
 			flags, ac);
 }
 
+/*
+ * We need to lock the test/set EOF update as we can be racing with
+ * other IO completions here to update the EOF. Failing to serialise
+ * here can result in EOF moving backwards and Bad Things Happen when
+ * that occurs.
+ *
+ * As IO completion only ever extends EOF, we can do an unlocked check
+ * here to avoid taking the spinlock. If we land within the current EOF,
+ * then we do not need to do an extending update at all, and we don't
+ * need to take the lock to check this. If we race with an update moving
+ * EOF, then we'll either still be beyond EOF and need to take the lock,
+ * or we'll be within EOF and we don't need to take it at all.
+ */
+static int
+xfs_dio_endio_set_isize(
+	struct inode		*inode,
+	loff_t			offset,
+	ssize_t			size)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+
+	if (offset + size <= i_size_read(inode))
+		return 0;
+
+	spin_lock(&ip->i_flags_lock);
+	if (offset + size <= i_size_read(inode)) {
+		spin_unlock(&ip->i_flags_lock);
+		return 0;
+	}
+
+	i_size_write(inode, offset + size);
+	spin_unlock(&ip->i_flags_lock);
+
+	return xfs_setfilesize(ip, offset, size);
+}
+
 static int
 xfs_dio_write_end_io(
 	struct kiocb		*iocb,
@@ -623,30 +659,8 @@ xfs_dio_write_end_io(
 	 * with the on-disk inode size being outside the in-core inode size. We
 	 * have no other method of updating EOF for AIO, so always do it here
 	 * if necessary.
-	 *
-	 * We need to lock the test/set EOF update as we can be racing with
-	 * other IO completions here to update the EOF. Failing to serialise
-	 * here can result in EOF moving backwards and Bad Things Happen when
-	 * that occurs.
-	 *
-	 * As IO completion only ever extends EOF, we can do an unlocked check
-	 * here to avoid taking the spinlock. If we land within the current EOF,
-	 * then we do not need to do an extending update at all, and we don't
-	 * need to take the lock to check this. If we race with an update moving
-	 * EOF, then we'll either still be beyond EOF and need to take the lock,
-	 * or we'll be within EOF and we don't need to take it at all.
 	 */
-	if (offset + size <= i_size_read(inode))
-		goto out;
-
-	spin_lock(&ip->i_flags_lock);
-	if (offset + size > i_size_read(inode)) {
-		i_size_write(inode, offset + size);
-		spin_unlock(&ip->i_flags_lock);
-		error = xfs_setfilesize(ip, offset, size);
-	} else {
-		spin_unlock(&ip->i_flags_lock);
-	}
+	error = xfs_dio_endio_set_isize(inode, offset, size);
 
 out:
 	memalloc_nofs_restore(nofs_flag);
-- 
2.53.0