[PATCH 04/14] libxfs: block-mapper changes to support reflink

Darrick J. Wong
2015-06-25T23:39:45Z

Modify the XFS block mapper routine to know how to "allocate" blocks
that already exist, for the purpose of mapping them into a second
file.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/xfs/libxfs/xfs_bmap.c | 19 +++++++++++++++++++
fs/xfs/libxfs/xfs_bmap.h | 2 ++
2 files changed, 21 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 3f5e8da..05e8346 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -3897,6 +3897,13 @@ STATIC int
xfs_bmap_alloc(
struct xfs_bmalloca *ap) /* bmap alloc argument struct */
{
+ if (ap->flags & XFS_BMAPI_REFLINK) {
+ ap->blkno = *ap->firstblock;
+ ap->ip->i_d.di_nblocks += ap->length;
+ xfs_trans_log_inode(ap->tp, ap->ip, XFS_ILOG_CORE);
+ return 0;
+ }
+
if (XFS_IS_REALTIME_INODE(ap->ip) && ap->userdata)
return xfs_bmap_rtalloc(ap);
return xfs_bmap_btalloc(ap);
@@ -4519,6 +4526,12 @@ xfs_bmapi_write(
ASSERT(len > 0);
ASSERT(XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_LOCAL);
ASSERT(xfs_isilocked(ip, XFS_ILOCK_EXCL));
+ if (whichfork == XFS_ATTR_FORK)
+ ASSERT(!(flags & XFS_BMAPI_REFLINK));
+ if (flags & XFS_BMAPI_REFLINK) {
+ ASSERT(!(flags & XFS_BMAPI_PREALLOC));
+ ASSERT(!(flags & XFS_BMAPI_CONVERT));
+ }

if (unlikely(XFS_TEST_ERROR(
(XFS_IFORK_FORMAT(ip, whichfork) != XFS_DINODE_FMT_EXTENTS &&
@@ -4568,6 +4581,12 @@ xfs_bmapi_write(
wasdelay = !inhole && isnullstartblock(bma.got.br_startblock);

/*
+ * Make sure we only reflink into a hole.
+ */
+ if (flags & XFS_BMAPI_REFLINK)
+ ASSERT(inhole);
+
+ /*
* First, deal with the hole before the allocated space
* that we found, if any.
*/
diff --git a/fs/xfs/libxfs/xfs_bmap.h b/fs/xfs/libxfs/xfs_bmap.h
index 674819f..908caaf 100644
--- a/fs/xfs/libxfs/xfs_bmap.h
+++ b/fs/xfs/libxfs/xfs_bmap.h
@@ -110,6 +110,8 @@ typedef struct xfs_bmap_free
*/
#define XFS_BMAPI_CONVERT 0x040

+#define XFS_BMAPI_REFLINK 0x080 /* map the inode to this exact block. */
+
#define XFS_BMAPI_FLAGS \
{ XFS_BMAPI_ENTIRE, "ENTIRE" }, \
{ XFS_BMAPI_METADATA, "METADATA" }, \