nilfs2: fix possible recovery failure due to block creation without writer

Some function calls in nilfs_prepare_segment_for_recovery() may fail
because they can create blocks on meta data files without configuring
a writable FS-instance.  Concretely, nilfs_mdt_create_block() routine
of meta data files will fail in that case.

This fixes the problem by temporarily attaching a writable FS-instace
during the function is called.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

diff --git a/fs/nilfs2/recovery.c b/fs/nilfs2/recovery.c
index 4fc081e..57afa9d 100644 (file)
--- a/fs/nilfs2/recovery.c
+++ b/fs/nilfs2/recovery.c
@@ -407,6 +407,7 @@ void nilfs_dispose_segment_list(struct list_head *head)
 }
 
 static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs,
+                                             struct nilfs_sb_info *sbi,
                                              struct nilfs_recovery_info *ri)
 {
        struct list_head *head = &ri->ri_used_segments;
@@ -421,6 +422,7 @@ static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs,
        segnum[2] = ri->ri_segnum;
        segnum[3] = ri->ri_nextnum;
 
+       nilfs_attach_writer(nilfs, sbi);
        /*
         * Releasing the next segment of the latest super root.
         * The next segment is invalidated by this recovery.
@@ -459,10 +461,10 @@ static int nilfs_prepare_segment_for_recovery(struct the_nilfs *nilfs,
        nilfs->ns_pseg_offset = 0;
        nilfs->ns_seg_seq = ri->ri_seq + 2;
        nilfs->ns_nextnum = nilfs->ns_segnum = segnum[0];
-       return 0;
 
  failed:
        /* No need to recover sufile because it will be destroyed on error */
+       nilfs_detach_writer(nilfs, sbi);
        return err;
 }
 
@@ -728,7 +730,7 @@ int nilfs_recover_logical_segments(struct the_nilfs *nilfs,
                goto failed;
 
        if (ri->ri_need_recovery == NILFS_RECOVERY_ROLLFORWARD_DONE) {
-               err = nilfs_prepare_segment_for_recovery(nilfs, ri);
+               err = nilfs_prepare_segment_for_recovery(nilfs, sbi, ri);
                if (unlikely(err)) {
                        printk(KERN_ERR "NILFS: Error preparing segments for "
                               "recovery.\n");