NFS: Fix a race between mmap() and O_DIRECT

trondmypd · trondmypd · commit e231c6879cfd · 2018-01-28T22:00:15.000-05:00
When locking the file in order to do O_DIRECT on it, we must unmap any mmapped ranges on the pagecache so that we can flush out the dirty data. Fixes: a5864c9 ("NFS: Do not serialise O_DIRECT reads and writes") Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Cc: stable@vger.kernel.org # v4.8+
diff --git a/fs/nfs/io.c b/fs/nfs/io.c
@@ -99,7 +99,7 @@ static void nfs_block_buffered(struct nfs_inode *nfsi, struct inode *inode)
 {
 	if (!test_bit(NFS_INO_ODIRECT, &nfsi->flags)) {
 		set_bit(NFS_INO_ODIRECT, &nfsi->flags);
-		nfs_wb_all(inode);
+		nfs_sync_mapping(inode->i_mapping);
 	}
 }
 

Original file line number	Diff line number	Diff line change
`@@ -99,7 +99,7 @@ static void nfs_block_buffered(struct nfs_inode nfsi, struct inode inode)`
`99`	`99`	`{`
`100`	`100`	`if (!test_bit(NFS_INO_ODIRECT, &nfsi->flags)) {`
`101`	`101`	`set_bit(NFS_INO_ODIRECT, &nfsi->flags);`
`102`		`- nfs_wb_all(inode);`
	`102`	`+ nfs_sync_mapping(inode->i_mapping);`
`103`	`103`	`}`
`104`	`104`	`}`
`105`	`105`