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Subject[PATCH 68/73] ext2: Add whiteout and opaque directory support [ver #2]
Date
Add support for whiteouts and opaque directories to ext2.

Original-author: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com> (Further development)
cc: linux-ext4@vger.kernel.org
---

fs/ext2/dir.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++-
fs/ext2/ext2.h | 2 ++
fs/ext2/inode.c | 11 ++++++--
fs/ext2/namei.c | 51 +++++++++++++++++++++++++++++++++++++--
fs/ext2/super.c | 4 +++
include/linux/ext2_fs.h | 4 +++
6 files changed, 128 insertions(+), 6 deletions(-)

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index dcb2d64..df4d6b1 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -220,7 +220,7 @@ fail:

static inline int ext2_dirent_in_use(struct ext2_dir_entry_2 *de)
{
- return de->inode != 0;
+ return de->inode != 0 || de->file_type == EXT2_FT_WHT;
}

/*
@@ -269,6 +269,7 @@ static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
[EXT2_FT_FIFO] = DT_FIFO,
[EXT2_FT_SOCK] = DT_SOCK,
[EXT2_FT_SYMLINK] = DT_LNK,
+ [EXT2_FT_WHT] = DT_WHT,
};

#define S_SHIFT 12
@@ -472,6 +473,26 @@ static int ext2_prepare_chunk(struct page *page, loff_t pos, unsigned len)
return __block_write_begin(page, pos, len, ext2_get_block);
}

+/* Special version for filetype based whiteout support */
+ino_t ext2_inode_by_dentry(struct inode *dir, struct dentry *dentry)
+{
+ ino_t res = 0;
+ struct ext2_dir_entry_2 *de;
+ struct page *page;
+
+ de = ext2_find_entry(dir, &dentry->d_name, &page);
+ if (de) {
+ res = le32_to_cpu(de->inode);
+ if (!res && de->file_type == EXT2_FT_WHT) {
+ spin_lock(&dentry->d_lock);
+ dentry->d_flags |= DCACHE_WHITEOUT;
+ spin_unlock(&dentry->d_lock);
+ }
+ ext2_put_page(page);
+ }
+ return res;
+}
+
/* Releases the page */
void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
struct page *page, struct inode *inode, int update_times)
@@ -580,6 +601,40 @@ int ext2_add_entry(struct dentry *dentry, ino_t ino, umode_t mode,
return -EINVAL;

got_it:
+ /* Pre-existing entries with the same name are allowable depending on
+ * the type of the entry being created, so we need to sanity check what
+ * we got.
+ *
+ * - Fallthru entries may be replaced by regular entries (copyup or
+ * rename) or whiteouts (unlink, rmdir or rename), but not by another
+ * fallthru.
+ * - Whiteout entries may be replaced by a regular entry (open, link,
+ * symlink, mkdir, mknod, socket or rename).
+ * - Regular entries may be replaced by a whiteout (unlink, rmdir or
+ * rename).
+ *
+ * Fallthru entries may only be created during directory copyup and
+ * should not already exist in the top directory at that time.
+ */
+ err = -EEXIST;
+ if (ext2_match(namelen, name, de)) {
+ switch (de->file_type) {
+ case EXT2_FT_WHT:
+ if (new_file_type == EXT2_FT_WHT) {
+ WARN(1, "Ext2: Can't turn whiteout into whiteout: %s\n",
+ dentry->d_name.name);
+ goto out_unlock;
+ }
+ break;
+ default:
+ if (new_file_type != EXT2_FT_WHT) {
+ WARN(1, "Ext2: Can't turn dirent into non-whiteout: %s\n",
+ dentry->d_name.name);
+ goto out_unlock;
+ }
+ break;
+ }
+ }
pos = page_offset(page) +
(char*)de - (char*)page_address(page);
err = ext2_prepare_chunk(page, pos, rec_len);
@@ -614,6 +669,11 @@ int ext2_add_link(struct dentry *dentry, struct inode *inode)
return ext2_add_entry(dentry, inode->i_ino, inode->i_mode, 0);
}

+int ext2_whiteout_entry(struct dentry *dentry)
+{
+ return ext2_add_entry(dentry, 0, 0, EXT2_FT_WHT);
+}
+
/*
* ext2_delete_entry deletes a directory entry by merging it with the
* previous entry. Page is up-to-date. Releases the page.
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 75ad433..b285d9a 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -102,9 +102,11 @@ extern void ext2_rsv_window_add(struct super_block *sb, struct ext2_reserve_wind
/* dir.c */
extern int ext2_add_link (struct dentry *, struct inode *);
extern ino_t ext2_inode_by_name(struct inode *, struct qstr *);
+extern ino_t ext2_inode_by_dentry(struct inode *, struct dentry *);
extern int ext2_make_empty(struct inode *, struct inode *);
extern struct ext2_dir_entry_2 * ext2_find_entry (struct inode *,struct qstr *, struct page **);
extern int ext2_delete_entry (struct ext2_dir_entry_2 *, struct page *);
+extern int ext2_whiteout_entry(struct dentry *);
extern int ext2_empty_dir (struct inode *);
extern struct ext2_dir_entry_2 * ext2_dotdot (struct inode *, struct page **);
extern void ext2_set_link(struct inode *, struct ext2_dir_entry_2 *, struct page *, struct inode *, int);
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 740cad8..2ffc91a 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1253,7 +1253,8 @@ void ext2_set_inode_flags(struct inode *inode)
{
unsigned int flags = EXT2_I(inode)->i_flags;

- inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
+ inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|
+ S_OPAQUE);
if (flags & EXT2_SYNC_FL)
inode->i_flags |= S_SYNC;
if (flags & EXT2_APPEND_FL)
@@ -1264,6 +1265,8 @@ void ext2_set_inode_flags(struct inode *inode)
inode->i_flags |= S_NOATIME;
if (flags & EXT2_DIRSYNC_FL)
inode->i_flags |= S_DIRSYNC;
+ if (flags & EXT2_OPAQUE_FL)
+ inode->i_flags |= S_OPAQUE;
}

/* Propagate flags from i_flags to EXT2_I(inode)->i_flags */
@@ -1271,8 +1274,8 @@ void ext2_get_inode_flags(struct ext2_inode_info *ei)
{
unsigned int flags = ei->vfs_inode.i_flags;

- ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|
- EXT2_IMMUTABLE_FL|EXT2_NOATIME_FL|EXT2_DIRSYNC_FL);
+ ei->i_flags &= ~(EXT2_SYNC_FL|EXT2_APPEND_FL|EXT2_IMMUTABLE_FL|
+ EXT2_NOATIME_FL|EXT2_DIRSYNC_FL|EXT2_OPAQUE_FL);
if (flags & S_SYNC)
ei->i_flags |= EXT2_SYNC_FL;
if (flags & S_APPEND)
@@ -1283,6 +1286,8 @@ void ext2_get_inode_flags(struct ext2_inode_info *ei)
ei->i_flags |= EXT2_NOATIME_FL;
if (flags & S_DIRSYNC)
ei->i_flags |= EXT2_DIRSYNC_FL;
+ if (flags & S_OPAQUE)
+ ei->i_flags |= EXT2_OPAQUE_FL;
}

struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
diff --git a/fs/ext2/namei.c b/fs/ext2/namei.c
index 0804198..8227267 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -55,7 +55,8 @@ static inline int ext2_add_nondir(struct dentry *dentry, struct inode *inode)
* Methods themselves.
*/

-static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
+static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry,
+ struct nameidata *nd)
{
struct inode * inode;
ino_t ino;
@@ -63,7 +64,7 @@ static struct dentry *ext2_lookup(struct inode * dir, struct dentry *dentry, str
if (dentry->d_name.len > EXT2_NAME_LEN)
return ERR_PTR(-ENAMETOOLONG);

- ino = ext2_inode_by_name(dir, &dentry->d_name);
+ ino = ext2_inode_by_dentry(dir, dentry);
inode = NULL;
if (ino) {
inode = ext2_iget(dir->i_sb, ino);
@@ -303,6 +304,51 @@ static int ext2_rmdir (struct inode * dir, struct dentry *dentry)
return err;
}

+/*
+ * Create a whiteout for the dentry
+ */
+static int ext2_whiteout(struct inode *dir, struct dentry *dentry,
+ struct dentry *new_dentry)
+{
+ struct inode *inode = dentry->d_inode;
+ int err = -ENOTEMPTY;
+
+ if (!EXT2_HAS_INCOMPAT_FEATURE(dir->i_sb,
+ EXT2_FEATURE_INCOMPAT_FILETYPE)) {
+ ext2_error(dir->i_sb, "ext2_whiteout",
+ "can't set whiteout filetype");
+ err = -EPERM;
+ goto out;
+ }
+
+ dquot_initialize(dir);
+
+ if (inode && S_ISDIR(inode->i_mode) && !ext2_empty_dir(inode))
+ goto out;
+
+ err = ext2_whiteout_entry(dentry);
+ if (err)
+ goto out;
+
+ spin_lock(&new_dentry->d_lock);
+ new_dentry->d_flags |= DCACHE_WHITEOUT;
+ spin_unlock(&new_dentry->d_lock);
+ d_add(new_dentry, NULL);
+
+ if (inode) {
+ inode->i_ctime = dir->i_ctime;
+ inode_dec_link_count(inode);
+ if (S_ISDIR(inode->i_mode)) {
+ inode->i_size = 0;
+ inode_dec_link_count(inode);
+ inode_dec_link_count(dir);
+ }
+ }
+ err = 0;
+out:
+ return err;
+}
+
static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
struct inode * new_dir, struct dentry * new_dentry )
{
@@ -400,6 +446,7 @@ const struct inode_operations ext2_dir_inode_operations = {
.mkdir = ext2_mkdir,
.rmdir = ext2_rmdir,
.mknod = ext2_mknod,
+ .whiteout = ext2_whiteout,
.rename = ext2_rename,
#ifdef CONFIG_EXT2_FS_XATTR
.setxattr = generic_setxattr,
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index 0090595..8869794 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -1097,6 +1097,10 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
ext2_msg(sb, KERN_WARNING,
"warning: mounting ext3 filesystem as ext2");
+
+ if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_WHITEOUT))
+ sb->s_flags |= MS_WHITEOUT;
+
if (ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY))
sb->s_flags |= MS_RDONLY;
ext2_write_super(sb);
diff --git a/include/linux/ext2_fs.h b/include/linux/ext2_fs.h
index ce1b719..2202faa 100644
--- a/include/linux/ext2_fs.h
+++ b/include/linux/ext2_fs.h
@@ -190,6 +190,7 @@ struct ext2_group_desc
#define EXT2_NOTAIL_FL FS_NOTAIL_FL /* file tail should not be merged */
#define EXT2_DIRSYNC_FL FS_DIRSYNC_FL /* dirsync behaviour (directories only) */
#define EXT2_TOPDIR_FL FS_TOPDIR_FL /* Top of directory hierarchies*/
+#define EXT2_OPAQUE_FL FS_OPAQUE_FL /* Dir is opaque */
#define EXT2_RESERVED_FL FS_RESERVED_FL /* reserved for ext2 lib */

#define EXT2_FL_USER_VISIBLE FS_FL_USER_VISIBLE /* User visible flags */
@@ -504,10 +505,12 @@ 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| \
@@ -574,6 +577,7 @@ enum {
EXT2_FT_FIFO = 5,
EXT2_FT_SOCK = 6,
EXT2_FT_SYMLINK = 7,
+ EXT2_FT_WHT = 8,
EXT2_FT_MAX
};



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