xfs: allocate delayed extents in CoW fork
Modify the writepage handler to find and convert pending delalloc
extents to real allocations. Furthermore, when we're doing non-cow
writes to a part of a file that already has a CoW reservation (the
cowextsz hint that we set up in a subsequent patch facilitates this),
promote the write to copy-on-write so that the entire extent can get
written out as a single extent on disk, thereby reducing post-CoW
fragmentation.
Christoph moved the CoW support code in _map_blocks to a separate helper
function, refactored other functions, and reduced the number of CoW fork
lookups, so I merged those changes here to reduce churn.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/fs/xfs/xfs_aops.h b/fs/xfs/xfs_aops.h
index 1950e3b..b3c6634 100644
--- a/fs/xfs/xfs_aops.h
+++ b/fs/xfs/xfs_aops.h
@@ -28,13 +28,15 @@
XFS_IO_DELALLOC, /* covers delalloc region */
XFS_IO_UNWRITTEN, /* covers allocated but uninitialized data */
XFS_IO_OVERWRITE, /* covers already allocated extent */
+ XFS_IO_COW, /* covers copy-on-write extent */
};
#define XFS_IO_TYPES \
{ XFS_IO_INVALID, "invalid" }, \
{ XFS_IO_DELALLOC, "delalloc" }, \
{ XFS_IO_UNWRITTEN, "unwritten" }, \
- { XFS_IO_OVERWRITE, "overwrite" }
+ { XFS_IO_OVERWRITE, "overwrite" }, \
+ { XFS_IO_COW, "CoW" }
/*
* Structure for buffered I/O completions.
