ext2: Implement freezing

The only missing piece to make freezing work reliably with ext2 is to
stop iput() of unlinked inode from deleting the inode on frozen filesystem.
So add a necessary protection to ext2_evict_inode().

We also provide appropriate ->freeze_fs and ->unfreeze_fs functions.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 264d315f6c4753d6bee17f28ea86c6497b560449..6363ac66fafa48c1c697d993a948fa1a5ff7cf78 100644 (file)
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -79,6 +79,7 @@ void ext2_evict_inode(struct inode * inode)
        truncate_inode_pages(&inode->i_data, 0);
 
        if (want_delete) {
+               sb_start_intwrite(inode->i_sb);
                /* set dtime */
                EXT2_I(inode)->i_dtime  = get_seconds();
                mark_inode_dirty(inode);
@@ -98,8 +99,10 @@ void ext2_evict_inode(struct inode * inode)
        if (unlikely(rsv))
                kfree(rsv);
 
-       if (want_delete)
+       if (want_delete) {
                ext2_free_inode(inode);
+               sb_end_intwrite(inode->i_sb);
+       }
 }
 
 typedef struct {

diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 5df3d2d8169c25c1af4f45ce77a5f062517049de..15761e638dae5e1a4fdc4d37094dee0abbacf2f7 100644 (file)
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -42,6 +42,8 @@ static void ext2_sync_super(struct super_block *sb,
 static int ext2_remount (struct super_block * sb, int * flags, char * data);
 static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);
 static int ext2_sync_fs(struct super_block *sb, int wait);
+static int ext2_freeze(struct super_block *sb);
+static int ext2_unfreeze(struct super_block *sb);
 
 void ext2_error(struct super_block *sb, const char *function,
                const char *fmt, ...)
@@ -305,6 +307,8 @@ static const struct super_operations ext2_sops = {
        .evict_inode    = ext2_evict_inode,
        .put_super      = ext2_put_super,
        .sync_fs        = ext2_sync_fs,
+       .freeze_fs      = ext2_freeze,
+       .unfreeze_fs    = ext2_unfreeze,
        .statfs         = ext2_statfs,
        .remount_fs     = ext2_remount,
        .show_options   = ext2_show_options,
@@ -1200,6 +1204,35 @@ static int ext2_sync_fs(struct super_block *sb, int wait)
        return 0;
 }
 
+static int ext2_freeze(struct super_block *sb)
+{
+       struct ext2_sb_info *sbi = EXT2_SB(sb);
+
+       /*
+        * Open but unlinked files present? Keep EXT2_VALID_FS flag cleared
+        * because we have unattached inodes and thus filesystem is not fully
+        * consistent.
+        */
+       if (atomic_long_read(&sb->s_remove_count)) {
+               ext2_sync_fs(sb, 1);
+               return 0;
+       }
+       /* Set EXT2_FS_VALID flag */
+       spin_lock(&sbi->s_lock);
+       sbi->s_es->s_state = cpu_to_le16(sbi->s_mount_state);
+       spin_unlock(&sbi->s_lock);
+       ext2_sync_super(sb, sbi->s_es, 1);
+
+       return 0;
+}
+
+static int ext2_unfreeze(struct super_block *sb)
+{
+       /* Just write sb to clear EXT2_VALID_FS flag */
+       ext2_write_super(sb);
+
+       return 0;
+}
 
 void ext2_write_super(struct super_block *sb)
 {