linux-kernel - [PATCH v5 7/7] xfs: Support setting FMODE_CAN_ATOMIC

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Message-Id: <20240817094800.776408-8-john.g.garry@oracle.com>
Date: Sat, 17 Aug 2024 09:48:00 +0000
From: John Garry <john.g.garry@...cle.com>
To: axboe@...nel.dk, brauner@...nel.org, djwong@...nel.org,
        viro@...iv.linux.org.uk, jack@...e.cz, chandan.babu@...cle.com,
        dchinner@...hat.com, hch@....de
Cc: linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org, hare@...e.de,
        martin.petersen@...cle.com, catherine.hoang@...cle.com,
        kbusch@...nel.org, John Garry <john.g.garry@...cle.com>
Subject: [PATCH v5 7/7] xfs: Support setting FMODE_CAN_ATOMIC_WRITE

For when an inode is enabled for atomic writes, set FMODE_CAN_ATOMIC_WRITE
flag. Only direct IO is currently supported, so check for that also.

We rely on the block layer to reject atomic writes which exceed the bdev
request_queue limits, so don't bother checking any such thing here.

Signed-off-by: John Garry <john.g.garry@...cle.com>
---
 fs/xfs/xfs_file.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 9b6530a4eb4a..3489d478809e 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1149,6 +1149,18 @@ xfs_file_remap_range(
 	return remapped > 0 ? remapped : ret;
 }
 
+static bool xfs_file_open_can_atomicwrite(
+	struct inode		*inode,
+	struct file		*file)
+{
+	struct xfs_inode	*ip = XFS_I(inode);
+
+	if (!(file->f_flags & O_DIRECT))
+		return false;
+
+	return xfs_inode_has_atomicwrites(ip);
+}
+
 STATIC int
 xfs_file_open(
 	struct inode	*inode,
@@ -1157,6 +1169,8 @@ xfs_file_open(
 	if (xfs_is_shutdown(XFS_M(inode->i_sb)))
 		return -EIO;
 	file->f_mode |= FMODE_NOWAIT | FMODE_CAN_ODIRECT;
+	if (xfs_file_open_can_atomicwrite(inode, file))
+		file->f_mode |= FMODE_CAN_ATOMIC_WRITE;
 	return generic_file_open(inode, file);
 }
 
-- 
2.31.1