xfs: consolidate preallocation in xfs_file_fallocate

Remove xfs_zero_file_space and reorganize xfs_file_fallocate so that a
single call to xfs_alloc_file_space covers all modes that preallocate
blocks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_bmap_util.c

@@ -1133,43 +1133,6 @@ xfs_free_file_space(
 	return error;
 }
 
-/*
- * Preallocate and zero a range of a file. This mechanism has the allocation
- * semantics of fallocate and in addition converts data in the range to zeroes.
- */
-int
-xfs_zero_file_space(
-	struct xfs_inode	*ip,
-	xfs_off_t		offset,
-	xfs_off_t		len)
-{
-	struct xfs_mount	*mp = ip->i_mount;
-	uint			blksize;
-	int			error;
-
-	trace_xfs_zero_file_space(ip);
-
-	blksize = 1 << mp->m_sb.sb_blocklog;
-
-	/*
-	 * Punch a hole and prealloc the range. We use hole punch rather than
-	 * unwritten extent conversion for two reasons:
-	 *
-	 * 1.) Hole punch handles partial block zeroing for us.
-	 *
-	 * 2.) If prealloc returns ENOSPC, the file range is still zero-valued
-	 * by virtue of the hole punch.
-	 */
-	error = xfs_free_file_space(ip, offset, len);
-	if (error || xfs_is_always_cow_inode(ip))
-		return error;
-
-	return xfs_alloc_file_space(ip, round_down(offset, blksize),
-				     round_up(offset + len, blksize) -
-				     round_down(offset, blksize),
-				     XFS_BMAPI_PREALLOC);
-}
-
 static int
 xfs_prepare_shift(
 	struct xfs_inode	*ip,

fs/xfs/xfs_bmap_util.h

@@ -59,8 +59,6 @@ int	xfs_alloc_file_space(struct xfs_inode *ip, xfs_off_t offset,
 			     xfs_off_t len, int alloc_type);
 int	xfs_free_file_space(struct xfs_inode *ip, xfs_off_t offset,
 			    xfs_off_t len);
-int	xfs_zero_file_space(struct xfs_inode *ip, xfs_off_t offset,
-			    xfs_off_t len);
 int	xfs_collapse_file_space(struct xfs_inode *, xfs_off_t offset,
 				xfs_off_t len);
 int	xfs_insert_file_space(struct xfs_inode *, xfs_off_t offset,

fs/xfs/xfs_file.c

@@ -880,16 +880,30 @@ xfs_file_fallocate(
 		}
 
 		if (mode & FALLOC_FL_ZERO_RANGE) {
-			error = xfs_zero_file_space(ip, offset, len);
+			/*
+			 * Punch a hole and prealloc the range.  We use a hole
+			 * punch rather than unwritten extent conversion for two
+			 * reasons:
+			 *
+			 *   1.) Hole punch handles partial block zeroing for us.
+			 *   2.) If prealloc returns ENOSPC, the file range is
+			 *       still zero-valued by virtue of the hole punch.
+			 */
+			unsigned int blksize = i_blocksize(inode);
+
+			trace_xfs_zero_file_space(ip);
+
+			error = xfs_free_file_space(ip, offset, len);
+			if (error)
+				goto out_unlock;
+
+			len = round_up(offset + len, blksize) -
+			      round_down(offset, blksize);
+			offset = round_down(offset, blksize);
 		} else if (mode & FALLOC_FL_UNSHARE_RANGE) {
 			error = xfs_reflink_unshare(ip, offset, len);
 			if (error)
 				goto out_unlock;
-
-			if (!xfs_is_always_cow_inode(ip)) {
-				error = xfs_alloc_file_space(ip, offset, len,
-						XFS_BMAPI_PREALLOC);
-			}
 		} else {
 			/*
 			 * If always_cow mode we can't use preallocations and
@@ -899,12 +913,14 @@ xfs_file_fallocate(
 				error = -EOPNOTSUPP;
 				goto out_unlock;
 			}
+		}
 
+		if (!xfs_is_always_cow_inode(ip)) {
 			error = xfs_alloc_file_space(ip, offset, len,
 						     XFS_BMAPI_PREALLOC);
+			if (error)
+				goto out_unlock;
 		}
-		if (error)
-			goto out_unlock;
 	}
 
 	if (file->f_flags & O_DSYNC)