nilfs2: shorten freeze period due to GC in write operation v3

[safe/jmp/linux-2.6] / fs / nilfs2 / super.c

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 9926a1d..50284ad 100644 (file)
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -67,7 +67,6 @@ MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
                   "(NILFS)");
 MODULE_LICENSE("GPL");
 
-static void nilfs_write_super(struct super_block *sb);
 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
 
 /**
@@ -335,54 +334,6 @@ static void nilfs_put_super(struct super_block *sb)
        unlock_kernel();
 }
 
-/**
- * nilfs_write_super - write super block(s) of NILFS
- * @sb: super_block
- *
- * nilfs_write_super() gets a fs-dependent lock, writes super block(s), and
- * clears s_dirt.  This function is called in the section protected by
- * lock_super().
- *
- * The s_dirt flag is managed by each filesystem and we protect it by ns_sem
- * of the struct the_nilfs.  Lock order must be as follows:
- *
- *   1. lock_super()
- *   2.    down_write(&nilfs->ns_sem)
- *
- * Inside NILFS, locking ns_sem is enough to protect s_dirt and the buffer
- * of the super block (nilfs->ns_sbp[]).
- *
- * In most cases, VFS functions call lock_super() before calling these
- * methods.  So we must be careful not to bring on deadlocks when using
- * lock_super();  see generic_shutdown_super(), write_super(), and so on.
- *
- * Note that order of lock_kernel() and lock_super() depends on contexts
- * of VFS.  We should also note that lock_kernel() can be used in its
- * protective section and only the outermost one has an effect.
- */
-static void nilfs_write_super(struct super_block *sb)
-{
-       struct nilfs_sb_info *sbi = NILFS_SB(sb);
-       struct the_nilfs *nilfs = sbi->s_nilfs;
-
-       down_write(&nilfs->ns_sem);
-       if (!(sb->s_flags & MS_RDONLY)) {
-               struct nilfs_super_block **sbp = nilfs->ns_sbp;
-               u64 t = get_seconds();
-               int dupsb;
-
-               if (!nilfs_discontinued(nilfs) && t >= nilfs->ns_sbwtime[0] &&
-                   t < nilfs->ns_sbwtime[0] + NILFS_SB_FREQ) {
-                       up_write(&nilfs->ns_sem);
-                       return;
-               }
-               dupsb = sbp[1] && t > nilfs->ns_sbwtime[1] + NILFS_ALTSB_FREQ;
-               nilfs_commit_super(sbi, dupsb);
-       }
-       sb->s_dirt = 0;
-       up_write(&nilfs->ns_sem);
-}
-
 static int nilfs_sync_fs(struct super_block *sb, int wait)
 {
        struct nilfs_sb_info *sbi = NILFS_SB(sb);
@@ -563,7 +514,7 @@ static struct super_operations nilfs_sops = {
        /* .drop_inode    = nilfs_drop_inode, */
        .delete_inode   = nilfs_delete_inode,
        .put_super      = nilfs_put_super,
-       .write_super    = nilfs_write_super,
+       /* .write_super    = nilfs_write_super, */
        .sync_fs        = nilfs_sync_fs,
        /* .write_super_lockfs */
        /* .unlockfs */
@@ -841,10 +792,15 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
 
        if (sb->s_flags & MS_RDONLY) {
                if (nilfs_test_opt(sbi, SNAPSHOT)) {
+                       down_read(&nilfs->ns_segctor_sem);
                        err = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile,
                                                       sbi->s_snapshot_cno);
-                       if (err < 0)
+                       up_read(&nilfs->ns_segctor_sem);
+                       if (err < 0) {
+                               if (err == -ENOENT)
+                                       err = -EINVAL;
                                goto failed_sbi;
+                       }
                        if (!err) {
                                printk(KERN_ERR
                                       "NILFS: The specified checkpoint is "
@@ -1152,10 +1108,6 @@ nilfs_get_sb(struct file_system_type *fs_type, int flags,
         */
        sd.sbi = nilfs_find_sbinfo(nilfs, !(flags & MS_RDONLY), sd.cno);
 
-       if (!sd.cno)
-               /* trying to get the latest checkpoint.  */
-               sd.cno = nilfs_last_cno(nilfs);
-
        /*
         * Get super block instance holding the nilfs_sb_info struct.
         * A new instance is allocated if no existing mount is present or