Ensure that when creating a mapping that we adhere to all the atomic
write rules.
We check that the mapping covers the complete range of the write to ensure
that we'll be just creating a single mapping.
Currently minimum granularity is the FS block size, but it should be
possibly to support lower in future.
Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
---
I am setting this as an RFC as I am not sure on the change in
xfs_iomap_write_direct() - it gives the desired result AFAICS.
fs/xfs/xfs_iomap.c | 41 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 41 insertions(+)
diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c
index 18c8f168b153..758dc1c90a42 100644
--- a/fs/xfs/xfs_iomap.c
+++ b/fs/xfs/xfs_iomap.c
@@ -289,6 +289,9 @@ xfs_iomap_write_direct(
}
}
+ if (xfs_inode_atomicwrites(ip))
+ bmapi_flags = XFS_BMAPI_ZERO;
+
error = xfs_trans_alloc_inode(ip, &M_RES(mp)->tr_write, dblocks,
rblocks, force, &tp);
if (error)
@@ -812,6 +815,44 @@ xfs_direct_write_iomap_begin(
if (error)
goto out_unlock;
+ if (flags & IOMAP_ATOMIC) {
+ xfs_filblks_t unit_min_fsb, unit_max_fsb;
+ unsigned int unit_min, unit_max;
+
+ xfs_get_atomic_write_attr(ip, &unit_min, &unit_max);
+ unit_min_fsb = XFS_B_TO_FSBT(mp, unit_min);
+ unit_max_fsb = XFS_B_TO_FSBT(mp, unit_max);
+
+ if (!imap_spans_range(&imap, offset_fsb, end_fsb)) {
+ error = -EINVAL;
+ goto out_unlock;
+ }
+
+ if ((offset & mp->m_blockmask) ||
+ (length & mp->m_blockmask)) {
+ error = -EINVAL;
+ goto out_unlock;
+ }
+
+ if (imap.br_blockcount == unit_min_fsb ||
+ imap.br_blockcount == unit_max_fsb) {
+ /* ok if exactly min or max */
+ } else if (imap.br_blockcount < unit_min_fsb ||
+ imap.br_blockcount > unit_max_fsb) {
+ error = -EINVAL;
+ goto out_unlock;
+ } else if (!is_power_of_2(imap.br_blockcount)) {
+ error = -EINVAL;
+ goto out_unlock;
+ }
+
+ if (imap.br_startoff &&
+ imap.br_startoff & (imap.br_blockcount - 1)) {
+ error = -EINVAL;
+ goto out_unlock;
+ }
+ }
+
if (imap_needs_cow(ip, flags, &imap, nimaps)) {
error = -EAGAIN;
if (flags & IOMAP_NOWAIT)
--
2.31.1
