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Subject[RFC 12/26] ext2 white-out support
Introduce white-out support to ext2.

Known Bugs:
- Needs a reserved inode number for white-outs
- S_OPAQUE isn't persistently stored

Signed-off-by: Jan Blunck <j.blunck@tu-harburg.de>
---
fs/ext2/dir.c | 2 ++
fs/ext2/namei.c | 18 ++++++++++++++++++
fs/ext2/super.c | 5 ++++-
include/linux/ext2_fs.h | 4 ++++
4 files changed, 28 insertions(+), 1 deletion(-)
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -230,6 +230,7 @@ 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
@@ -241,6 +242,7 @@ 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 +288,23 @@ 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;
+
+ init_special_inode(inode, inode->i_mode, 0);
+ 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 +399,7 @@ 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
@@ -752,6 +752,9 @@ static int ext2_fill_super(struct super_
ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
EXT2_MOUNT_XIP if not */

+ if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_WHITEOUT))
+ sb->s_flags |= MS_WHITEOUT;
+
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) ||
@@ -1299,7 +1302,7 @@ 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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