From: Jan Blunck <[EMAIL PROTECTED]>
Subject: ext2 whiteout support

Introduce whiteout support to ext2.

Signed-off-by: Jan Blunck <[EMAIL PROTECTED]>
Signed-off-by: Bharata B Rao <[EMAIL PROTECTED]>
---
 fs/ext2/dir.c           |    2 ++
 fs/ext2/namei.c         |   17 +++++++++++++++++
 fs/ext2/super.c         |   11 ++++++++++-
 include/linux/ext2_fs.h |    4 ++++
 4 files changed, 33 insertions(+), 1 deletion(-)

--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -218,6 +218,7 @@ static unsigned char ext2_filetype_table
        [EXT2_FT_FIFO]          = DT_FIFO,
        [EXT2_FT_SOCK]          = DT_SOCK,
        [EXT2_FT_SYMLINK]       = DT_LNK,
+       [EXT2_FT_WHT]           = DT_WHT,
 };
 
 #define S_SHIFT 12
@@ -229,6 +230,7 @@ static unsigned char ext2_type_by_mode[S
        [S_IFIFO >> S_SHIFT]    = EXT2_FT_FIFO,
        [S_IFSOCK >> S_SHIFT]   = EXT2_FT_SOCK,
        [S_IFLNK >> S_SHIFT]    = EXT2_FT_SYMLINK,
+       [S_IFWHT >> S_SHIFT]    = EXT2_FT_WHT,
 };
 
 static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -288,6 +288,22 @@ static int ext2_rmdir (struct inode * di
        return err;
 }
 
+static int ext2_whiteout(struct inode *dir, struct dentry *dentry)
+{
+       struct inode *inode;
+       int err;
+
+       inode = ext2_new_inode (dir, S_IFWHT | S_IRUGO);
+       err = PTR_ERR(inode);
+       if (IS_ERR(inode))
+               goto out;
+
+       mark_inode_dirty(inode);
+       err = ext2_add_nondir(dentry, inode);
+out:
+       return err;
+}
+
 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
        struct inode * new_dir, struct dentry * new_dentry )
 {
@@ -382,6 +398,7 @@ const struct inode_operations ext2_dir_i
        .mkdir          = ext2_mkdir,
        .rmdir          = ext2_rmdir,
        .mknod          = ext2_mknod,
+       .whiteout       = ext2_whiteout,
        .rename         = ext2_rename,
 #ifdef CONFIG_EXT2_FS_XATTR
        .setxattr       = generic_setxattr,
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -754,6 +754,15 @@ static int ext2_fill_super(struct super_
        ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
                                    EXT2_MOUNT_XIP if not */
 
+       if ((sb->s_flags & MS_UNION) && !(sb->s_flags & MS_RDONLY)) {
+               if (!EXT2_HAS_INCOMPAT_FEATURE(sb,
+                               EXT2_FEATURE_INCOMPAT_WHITEOUT)) {
+                       sb->s_flags |= MS_RDONLY;
+                       ext2_warning(sb, __FUNCTION__,
+                       "no whiteout support, mounting filesystem read-only");
+               }
+       }
+
        if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
            (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
             EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
@@ -1292,7 +1301,7 @@ static struct file_system_type ext2_fs_t
        .name           = "ext2",
        .get_sb         = ext2_get_sb,
        .kill_sb        = kill_block_super,
-       .fs_flags       = FS_REQUIRES_DEV,
+       .fs_flags       = FS_REQUIRES_DEV | FS_WHT,
 };
 
 static int __init init_ext2_fs(void)
--- a/include/linux/ext2_fs.h
+++ b/include/linux/ext2_fs.h
@@ -61,6 +61,7 @@
 #define EXT2_ROOT_INO           2      /* Root inode */
 #define EXT2_BOOT_LOADER_INO    5      /* Boot loader inode */
 #define EXT2_UNDEL_DIR_INO      6      /* Undelete directory inode */
+#define EXT2_WHT_INO            7      /* Whiteout inode */
 
 /* First non-reserved inode for old ext2 filesystems */
 #define EXT2_GOOD_OLD_FIRST_INO        11
@@ -479,10 +480,12 @@ struct ext2_super_block {
 #define EXT3_FEATURE_INCOMPAT_RECOVER          0x0004
 #define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV      0x0008
 #define EXT2_FEATURE_INCOMPAT_META_BG          0x0010
+#define EXT2_FEATURE_INCOMPAT_WHITEOUT         0x0020
 #define EXT2_FEATURE_INCOMPAT_ANY              0xffffffff
 
 #define EXT2_FEATURE_COMPAT_SUPP       EXT2_FEATURE_COMPAT_EXT_ATTR
 #define EXT2_FEATURE_INCOMPAT_SUPP     (EXT2_FEATURE_INCOMPAT_FILETYPE| \
+                                        EXT2_FEATURE_INCOMPAT_WHITEOUT| \
                                         EXT2_FEATURE_INCOMPAT_META_BG)
 #define EXT2_FEATURE_RO_COMPAT_SUPP    (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
                                         EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
@@ -549,6 +552,7 @@ enum {
        EXT2_FT_FIFO,
        EXT2_FT_SOCK,
        EXT2_FT_SYMLINK,
+       EXT2_FT_WHT,
        EXT2_FT_MAX
 };
 
-
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