iomap: Lift blocksize restriction on atomic writes

Filesystems like ext4 can submit writes in multiples of blocksizes.
But we still can't allow the writes to be split. Hence let's check if
the iomap_length() is same as iter->len or not.

It is the role of the FS to ensure that a single mapping may be created
for an atomic write. The FS will also continue to check size and alignment
legality.

Signed-off-by: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
jpg: Tweak commit message
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250303171120.2837067-7-john.g.garry@oracle.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index c594f2cf3ab4729b82b6e848942fd5388101563f..5299f70428efb90d48871893421bf2384b8a9090 100644 (file)
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -351,7 +351,7 @@ static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
        u64 copied = 0;
        size_t orig_count;
 
-       if (atomic_hw && length != fs_block_size)
+       if (atomic_hw && length != iter->len)
                return -EINVAL;
 
        if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||