Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull second vfs pile from Al Viro:
 "The stuff in there: fsfreeze deadlock fixes by Jan (essentially, the
  deadlock reproduced by xfstests 068), symlink and hardlink restriction
  patches, plus assorted cleanups and fixes.

  Note that another fsfreeze deadlock (emergency thaw one) is *not*
  dealt with - the series by Fernando conflicts a lot with Jan's, breaks
  userland ABI (FIFREEZE semantics gets changed) and trades the deadlock
  for massive vfsmount leak; this is going to be handled next cycle.
  There probably will be another pull request, but that stuff won't be
  in it."

Fix up trivial conflicts due to unrelated changes next to each other in
drivers/{staging/gdm72xx/usb_boot.c, usb/gadget/storage_common.c}

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits)
  delousing target_core_file a bit
  Documentation: Correct s_umount state for freeze_fs/unfreeze_fs
  fs: Remove old freezing mechanism
  ext2: Implement freezing
  btrfs: Convert to new freezing mechanism
  nilfs2: Convert to new freezing mechanism
  ntfs: Convert to new freezing mechanism
  fuse: Convert to new freezing mechanism
  gfs2: Convert to new freezing mechanism
  ocfs2: Convert to new freezing mechanism
  xfs: Convert to new freezing code
  ext4: Convert to new freezing mechanism
  fs: Protect write paths by sb_start_write - sb_end_write
  fs: Skip atime update on frozen filesystem
  fs: Add freezing handling to mnt_want_write() / mnt_drop_write()
  fs: Improve filesystem freezing handling
  switch the protection of percpu_counter list to spinlock
  nfsd: Push mnt_want_write() outside of i_mutex
  btrfs: Push mnt_want_write() outside of i_mutex
  fat: Push mnt_want_write() outside of i_mutex
  ...

2 files changed, 37 insertions, 1 deletions

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 264d315f6c47..6363ac66fafa 100644
--- 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 9f311d27b16f..af74d9e27b71 100644
--- 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)
 {