From: Bharata B Rao <[EMAIL PROTECTED]>
Subject: ext3 whiteout support

Introduce whiteout support for ext3.

Signed-off-by: Bharata B Rao <[EMAIL PROTECTED]>
Signed-off-by: Jan Blunck <[EMAIL PROTECTED]>
---
 fs/ext3/dir.c           |    2 -
 fs/ext3/namei.c         |   62 ++++++++++++++++++++++++++++++++++++++++++++----
 fs/ext3/super.c         |   11 +++++++-
 include/linux/ext3_fs.h |    5 +++
 4 files changed, 72 insertions(+), 8 deletions(-)

--- a/fs/ext3/dir.c
+++ b/fs/ext3/dir.c
@@ -29,7 +29,7 @@
 #include <linux/rbtree.h>
 
 static unsigned char ext3_filetype_table[] = {
-       DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
+       DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK, 
DT_WHT
 };
 
 static int ext3_readdir(struct file *, void *, filldir_t);
--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -1071,6 +1071,7 @@ static unsigned char ext3_type_by_mode[S
        [S_IFIFO >> S_SHIFT]    = EXT3_FT_FIFO,
        [S_IFSOCK >> S_SHIFT]   = EXT3_FT_SOCK,
        [S_IFLNK >> S_SHIFT]    = EXT3_FT_SYMLINK,
+       [S_IFWHT >> S_SHIFT]    = EXT3_FT_WHT,
 };
 
 static inline void ext3_set_de_type(struct super_block *sb,
@@ -1786,7 +1787,7 @@ out_stop:
 /*
  * routine to check that the specified directory is empty (for rmdir)
  */
-static int empty_dir (struct inode * inode)
+static int empty_dir (handle_t *handle, struct inode * inode)
 {
        unsigned long offset;
        struct buffer_head * bh;
@@ -1848,8 +1849,28 @@ static int empty_dir (struct inode * ino
                        continue;
                }
                if (le32_to_cpu(de->inode)) {
-                       brelse (bh);
-                       return 0;
+                       /* If this is a whiteout, remove it */
+                       if (de->file_type == EXT3_FT_WHT) {
+                               unsigned long ino = le32_to_cpu(de->inode);
+                               struct inode *tmp_inode = iget(inode->i_sb, 
ino);
+                               if (!tmp_inode) {
+                                       brelse (bh);
+                                       return 0;
+                               }
+
+                               if (ext3_delete_entry(handle, inode, de, bh)) {
+                                       iput(tmp_inode);
+                                       brelse (bh);
+                                       return 0;
+                               }
+
+                               tmp_inode->i_ctime = inode->i_ctime;
+                               tmp_inode->i_nlink--;
+                               iput(tmp_inode);
+                       } else {
+                               brelse (bh);
+                               return 0;
+                       }
                }
                offset += le16_to_cpu(de->rec_len);
                de = (struct ext3_dir_entry_2 *)
@@ -2031,7 +2052,7 @@ static int ext3_rmdir (struct inode * di
                goto end_rmdir;
 
        retval = -ENOTEMPTY;
-       if (!empty_dir (inode))
+       if (!empty_dir (handle, inode))
                goto end_rmdir;
 
        retval = ext3_delete_entry(handle, dir, de, bh);
@@ -2060,6 +2081,36 @@ end_rmdir:
        return retval;
 }
 
+static int ext3_whiteout(struct inode *dir, struct dentry *dentry)
+{
+       struct inode * inode;
+       int err, retries = 0;
+       handle_t *handle;
+
+retry:
+       handle = ext3_journal_start(dir, EXT3_DATA_TRANS_BLOCKS(dir->i_sb) +
+                                       EXT3_INDEX_EXTRA_TRANS_BLOCKS + 3 +
+                                       2*EXT3_QUOTA_INIT_BLOCKS(dir->i_sb));
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+
+       if (IS_DIRSYNC(dir))
+               handle->h_sync = 1;
+
+       inode = ext3_new_inode (handle, dir, S_IFWHT | S_IRUGO);
+       err = PTR_ERR(inode);
+       if (IS_ERR(inode))
+               goto out_stop;
+
+       err = ext3_add_nondir(handle, dentry, inode);
+
+out_stop:
+       ext3_journal_stop(handle);
+       if (err == -ENOSPC && ext3_should_retry_alloc(dir->i_sb, &retries))
+               goto retry;
+       return err;
+}
+
 static int ext3_unlink(struct inode * dir, struct dentry *dentry)
 {
        int retval;
@@ -2261,7 +2312,7 @@ static int ext3_rename (struct inode * o
        if (S_ISDIR(old_inode->i_mode)) {
                if (new_inode) {
                        retval = -ENOTEMPTY;
-                       if (!empty_dir (new_inode))
+                       if (!empty_dir (handle, new_inode))
                                goto end_rename;
                }
                retval = -EIO;
@@ -2377,6 +2428,7 @@ const struct inode_operations ext3_dir_i
        .mkdir          = ext3_mkdir,
        .rmdir          = ext3_rmdir,
        .mknod          = ext3_mknod,
+       .whiteout       = ext3_whiteout,
        .rename         = ext3_rename,
        .setattr        = ext3_setattr,
 #ifdef CONFIG_EXT3_FS_XATTR
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -1492,6 +1492,15 @@ static int ext3_fill_super (struct super
        sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
                ((sbi->s_mount_opt & EXT3_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
 
+       if ((sb->s_flags & MS_UNION) && !(sb->s_flags & MS_RDONLY)) {
+               if (!EXT3_HAS_INCOMPAT_FEATURE(sb,
+                               EXT3_FEATURE_INCOMPAT_WHITEOUT)) {
+                       sb->s_flags |= MS_RDONLY;
+                       ext3_warning(sb, __FUNCTION__,
+                       "no whiteout support, mounting filesystem read-only");
+               }
+       }
+
        if (le32_to_cpu(es->s_rev_level) == EXT3_GOOD_OLD_REV &&
            (EXT3_HAS_COMPAT_FEATURE(sb, ~0U) ||
             EXT3_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
@@ -2748,7 +2757,7 @@ static struct file_system_type ext3_fs_t
        .name           = "ext3",
        .get_sb         = ext3_get_sb,
        .kill_sb        = kill_block_super,
-       .fs_flags       = FS_REQUIRES_DEV,
+       .fs_flags       = FS_REQUIRES_DEV | FS_WHT,
 };
 
 static int __init init_ext3_fs(void)
--- a/include/linux/ext3_fs.h
+++ b/include/linux/ext3_fs.h
@@ -63,6 +63,7 @@
 #define EXT3_UNDEL_DIR_INO      6      /* Undelete directory inode */
 #define EXT3_RESIZE_INO                 7      /* Reserved group descriptors 
inode */
 #define EXT3_JOURNAL_INO        8      /* Journal inode */
+#define EXT3_WHT_INO            9      /* Whiteout inode */
 
 /* First non-reserved inode for old ext3 filesystems */
 #define EXT3_GOOD_OLD_FIRST_INO        11
@@ -582,6 +583,7 @@ static inline int ext3_valid_inum(struct
 #define EXT3_FEATURE_INCOMPAT_RECOVER          0x0004 /* Needs recovery */
 #define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV      0x0008 /* Journal device */
 #define EXT3_FEATURE_INCOMPAT_META_BG          0x0010
+#define EXT3_FEATURE_INCOMPAT_WHITEOUT         0x0020
 
 #define EXT3_FEATURE_COMPAT_SUPP       EXT2_FEATURE_COMPAT_EXT_ATTR
 #define EXT3_FEATURE_INCOMPAT_SUPP     (EXT3_FEATURE_INCOMPAT_FILETYPE| \
@@ -648,8 +650,9 @@ struct ext3_dir_entry_2 {
 #define EXT3_FT_FIFO           5
 #define EXT3_FT_SOCK           6
 #define EXT3_FT_SYMLINK                7
+#define EXT3_FT_WHT            8
 
-#define EXT3_FT_MAX            8
+#define EXT3_FT_MAX            9
 
 /*
  * EXT3_DIR_PAD defines the directory entries boundaries
-
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