linux-kernel - [PATCH v7 7/8] xfs: Validate atomic writes

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Message-Id: <20241004092254.3759210-8-john.g.garry@oracle.com>
Date: Fri,  4 Oct 2024 09:22:53 +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, dchinner@...hat.com, hch@....de,
        cem@...nel.org
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,
        mcgrof@...nel.org, ritesh.list@...il.com, ojaswin@...ux.ibm.com,
        John Garry <john.g.garry@...cle.com>
Subject: [PATCH v7 7/8] xfs: Validate atomic writes

Validate that an atomic write adheres to length/offset rules. Currently
we can only write a single FS block.

For an IOCB with IOCB_ATOMIC set to get as far as xfs_file_write_iter(),
FMODE_CAN_ATOMIC_WRITE will need to be set for the file; for this,
ATOMICWRITES flags would also need to be set for the inode.

Signed-off-by: John Garry <john.g.garry@...cle.com>
---
 fs/xfs/xfs_file.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 412b1d71b52b..3a0a35e7826a 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -822,6 +822,14 @@ xfs_file_write_iter(
 	if (IS_DAX(inode))
 		return xfs_file_dax_write(iocb, from);
 
+	if (iocb->ki_flags & IOCB_ATOMIC) {
+		if (ocount != ip->i_mount->m_sb.sb_blocksize)
+			return -EINVAL;
+		ret = generic_atomic_write_valid(iocb, from);
+		if (ret)
+			return ret;
+	}
+
 	if (iocb->ki_flags & IOCB_DIRECT) {
 		/*
 		 * Allow a directio write to fall back to a buffered
-- 
2.31.1