linux-kernel - [PATCH v2 3/7] iomap: Lift blocksize restriction on atomic writes

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Message-Id: <20241210125737.786928-4-john.g.garry@oracle.com>
Date: Tue, 10 Dec 2024 12:57:33 +0000
From: John Garry <john.g.garry@...cle.com>
To: brauner@...nel.org, djwong@...nel.org, cem@...nel.org, dchinner@...hat.com,
        hch@....de, ritesh.list@...il.com
Cc: linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, martin.petersen@...cle.com,
        John Garry <john.g.garry@...cle.com>
Subject: [PATCH v2 3/7] iomap: Lift blocksize restriction on atomic writes

From: "Ritesh Harjani (IBM)" <ritesh.list@...il.com>

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@...il.com>
jpg: Tweak commit message
Signed-off-by: John Garry <john.g.garry@...cle.com>
---
 fs/iomap/direct-io.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 18c888f0c11f..6510bb5d5a6f 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -314,7 +314,7 @@ static loff_t iomap_dio_bio_iter(const struct iomap_iter *iter,
 	size_t copied = 0;
 	size_t orig_count;
 
-	if (atomic && length != fs_block_size)
+	if (atomic && length != iter->len)
 		return -EINVAL;
 
 	if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
-- 
2.31.1