nilfs2: add norecovery mount option

This adds "norecovery" mount option which disables temporal write
access to read-only mounts or snapshots during mount/recovery.
Without this option, write access will be even performed for those
types of mounts; the temporal write access is needed to mount root
file system read-only after an unclean shutdown.

This option will be helpful when user wants to prevent any write
access to the device.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Eric Sandeen <sandeen@redhat.com>

1 files changed, 18 insertions, 2 deletions

diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 890a8d3886cf..6241e1722efc 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -264,8 +264,14 @@ int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
         int valid_fs = nilfs_valid_fs(nilfs);
         int err;
 
-        if (nilfs_loaded(nilfs))
-                return 0;
+        if (nilfs_loaded(nilfs)) {
+                if (valid_fs ||
+                    ((s_flags & MS_RDONLY) && nilfs_test_opt(sbi, NORECOVERY)))
+                        return 0;
+                printk(KERN_ERR "NILFS: the filesystem is in an incomplete "
+                       "recovery state.\n");
+                return -EINVAL;
+        }
 
         if (!valid_fs) {
                 printk(KERN_WARNING "NILFS warning: mounting unchecked fs\n");
@@ -295,6 +301,11 @@ int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
                 goto skip_recovery;
 
         if (s_flags & MS_RDONLY) {
+                if (nilfs_test_opt(sbi, NORECOVERY)) {
+                        printk(KERN_INFO "NILFS: norecovery option specified. "
+                               "skipping roll-forward recovery\n");
+                        goto skip_recovery;
+                }
                 if (really_read_only) {
                         printk(KERN_ERR "NILFS: write access "
                                "unavailable, cannot proceed.\n");
@@ -302,6 +313,11 @@ int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
                         goto failed_unload;
                 }
                 sbi->s_super->s_flags &= ~MS_RDONLY;
+        } else if (nilfs_test_opt(sbi, NORECOVERY)) {
+                printk(KERN_ERR "NILFS: recovery cancelled because norecovery "
+                       "option was specified for a read/write mount\n");
+                err = -EINVAL;
+                goto failed_unload;
         }
 
         err = nilfs_recover_logical_segments(nilfs, sbi, &ri);