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-rw-r--r--fs/nfs/super.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 9eea9e62afc9..91b5503b6f74 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -1052,6 +1052,16 @@ int nfs_reconfigure(struct fs_context *fc)
sync_filesystem(sb);
/*
+ * The SB_RDONLY flag has been removed from the superblock during
+ * mounts to prevent interference between different filesystems.
+ * Similarly, it is also necessary to ignore the SB_RDONLY flag
+ * during reconfiguration; otherwise, it may also result in the
+ * creation of redundant superblocks when mounting a directory with
+ * different rw and ro flags multiple times.
+ */
+ fc->sb_flags_mask &= ~SB_RDONLY;
+
+ /*
* Userspace mount programs that send binary options generally send
* them populated with default values. We have no way to know which
* ones were explicitly specified. Fall back to legacy behavior and
@@ -1308,8 +1318,17 @@ int nfs_get_tree_common(struct fs_context *fc)
if (IS_ERR(server))
return PTR_ERR(server);
+ /*
+ * When NFS_MOUNT_UNSHARED is not set, NFS forces the sharing of a
+ * superblock among each filesystem that mounts sub-directories
+ * belonging to a single exported root path.
+ * To prevent interference between different filesystems, the
+ * SB_RDONLY flag should be removed from the superblock.
+ */
if (server->flags & NFS_MOUNT_UNSHARED)
compare_super = NULL;
+ else
+ fc->sb_flags &= ~SB_RDONLY;
/* -o noac implies -o sync */
if (server->flags & NFS_MOUNT_NOAC)