xfs: fix fallocate functions when rtextsize is larger than 1rt-fixes-5.10_2020-10-10

In commit fe341eb151ec, I forgot that xfs_free_file_space isn't strictly
a "remove mapped blocks" function.  It is actually a function to zero
file space by punching out the middle and writing zeroes to the
unaligned ends of the specified range.  Therefore, putting a rtextsize
alignment check in that function is wrong because that breaks unaligned
ZERO_RANGE on the realtime volume.

Furthermore, xfs_file_fallocate already has alignment checks for the
functions require the file range to be aligned to the size of a
fundamental allocation unit (which is 1 FSB on the data volume and 1 rt
extent on the realtime volume).  Create a new helper to return the
desired allocation unit size, fix the fallocate frontend to use it,
fix free_file_space to delete the correct range, and remove a now
redundant check from insert_file_space.

Fixes: fe341eb151ec ("xfs: ensure that fpunch, fcollapse, and finsert operations are aligned to rt extent size")
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index 2bfbcf28b1bd..20bb5fae0d00 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -3813,3 +3813,16 @@ xfs_iunlock2_io_mmap(
 	if (!same_inode)
 		inode_unlock(VFS_I(ip1));
 }
+
+/* Returns the size of fundamental allocation unit for a file, in bytes. */
+unsigned int
+xfs_inode_alloc_blocksize(
+	struct xfs_inode	*ip)
+{
+	unsigned int		blocks = 1;
+
+	if (XFS_IS_REALTIME_INODE(ip))
+		blocks = ip->i_mount->m_sb.sb_rextsize;
+
+	return XFS_FSB_TO_B(ip->i_mount, blocks);
+}