[PATCH RFC 3/8] xfs: convert inode from extents to local format

[Shan Hai <shan.hai@oracle.com>]

Introduce a function to convert an inode from extents to local
format. The conversion happens at writeback time, this avoids
interfering with the delayed allocation and page cache vs
xfs_buf operations, the will be inlined data is directly got
from the page which was read and modified by the iomap write actor.

Signed-off-by: Shan Hai <shan.hai@oracle.com>
---
 fs/xfs/xfs_aops.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 8eb3ba3d4d00..ac5a7695f363 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -9,6 +9,7 @@
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_mount.h"
+#include "xfs_defer.h"
 #include "xfs_inode.h"
 #include "xfs_trans.h"
 #include "xfs_inode_item.h"
@@ -887,6 +888,55 @@ xfs_map_cow(
 	return 0;
 }
 
+static int
+xfs_inode_extents_to_local(
+	xfs_inode_t		*ip,
+	int			whichfork,
+	struct page		*page)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+	struct xfs_trans	*tp;
+	struct xfs_defer_ops	dfops;
+	xfs_fsblock_t		first_block;
+	int			logflags;
+	int			error = 0;
+
+	if (i_size_read(VFS_I(ip)) > XFS_IFORK_DSIZE(ip))
+		return 0;
+
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
+	if (error)
+		return error;
+
+	xfs_ilock(ip, XFS_ILOCK_EXCL);
+	xfs_trans_ijoin(tp, ip, 0);
+
+	xfs_defer_init(&dfops, &first_block);
+
+	logflags = 0;
+	error = xfs_bmap_extents_to_local(tp, ip, &dfops, &logflags,
+			XFS_DATA_FORK, page);
+	if (error)
+		goto trans_cancel;
+
+	xfs_trans_log_inode(tp, ip, logflags);
+	error = xfs_defer_finish(&tp, &dfops);
+	if (error)
+		goto trans_cancel;
+	error = xfs_trans_commit(tp);
+	if (error)
+		goto error0;
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+
+	return 0;
+
+trans_cancel:
+	xfs_defer_cancel(&dfops);
+	xfs_trans_cancel(tp);
+error0:
+	xfs_iunlock(ip, XFS_ILOCK_EXCL);
+	return error;
+}
 /*
  * We implement an immediate ioend submission policy here to avoid needing to
  * chain multiple ioends and hence nest mempool allocations which can violate
@@ -920,6 +970,8 @@ xfs_writepage_map(
 	int			count = 0;
 	int			uptodate = 1;
 	unsigned int		new_type;
+	xfs_inode_t		*ip = XFS_I(inode);
+	struct xfs_mount	*mp = ip->i_mount;
 
 	bh = head = page_buffers(page);
 	offset = page_offset(page);
@@ -1044,6 +1096,14 @@ xfs_writepage_map(
 		end_page_writeback(page);
 	}
 
+	if (!error) {
+		if (xfs_sb_version_hasinlinedata(&mp->m_sb) &&
+				i_size_read(inode) <= XFS_IFORK_DSIZE(ip)) {
+			error = xfs_inode_extents_to_local(ip, XFS_DATA_FORK,
+								page);
+		}
+	}
+
 	mapping_set_error(page->mapping, error);
 	return error;
 }
-- 
2.11.0