[PATCH 13/35] fallthru: ext2 fallthru support

[Valerie Aurora]

Add support for fallthru directory entries to ext2.

XXX - Makes up inode number for fallthru entry
XXX - Might be better implemented as special symlinks

Cc: Theodore Tso <tytso@xxxxxxx>
Cc: linux-ext4@xxxxxxxxxxxxxxx
Signed-off-by: Valerie Aurora <vaurora@xxxxxxxxxx>
Signed-off-by: Jan Blunck <jblunck@xxxxxxx>
---
 fs/ext2/dir.c           |   92 ++++++++++++++++++++++++++++++++++++++++++++--
 fs/ext2/ext2.h          |    1 +
 fs/ext2/namei.c         |   22 +++++++++++
 include/linux/ext2_fs.h |    1 +
 4 files changed, 112 insertions(+), 4 deletions(-)

diff --git a/fs/ext2/dir.c b/fs/ext2/dir.c
index 030bd46..f3b4aff 100644
--- a/fs/ext2/dir.c
+++ b/fs/ext2/dir.c
@@ -219,7 +219,8 @@ static inline int ext2_match (int len, const char * const name,
 {
 	if (len != de->name_len)
 		return 0;
-	if (!de->inode && (de->file_type != EXT2_FT_WHT))
+	if (!de->inode && ((de->file_type != EXT2_FT_WHT) &&
+			   (de->file_type != EXT2_FT_FALLTHRU)))
 		return 0;
 	return !memcmp(name, de->name, len);
 }
@@ -256,6 +257,7 @@ static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
 	[EXT2_FT_SOCK]		= DT_SOCK,
 	[EXT2_FT_SYMLINK]	= DT_LNK,
 	[EXT2_FT_WHT]		= DT_WHT,
+	[EXT2_FT_FALLTHRU]	= DT_UNKNOWN,
 };
 
 #define S_SHIFT 12
@@ -342,6 +344,24 @@ ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
 					ext2_put_page(page);
 					return 0;
 				}
+			} else if (de->file_type == EXT2_FT_FALLTHRU) {
+				int over;
+				unsigned char d_type = DT_UNKNOWN;
+
+				offset = (char *)de - kaddr;
+				/* XXX We don't know the inode number
+				 * of the directory entry in the
+				 * underlying file system.  Should
+				 * look it up, either on fallthru
+				 * creation at first readdir or now at
+				 * filldir time. */
+				over = filldir(dirent, de->name, de->name_len,
+					       (n<<PAGE_CACHE_SHIFT) | offset,
+					       123 /* Made up ino */, d_type);
+				if (over) {
+					ext2_put_page(page);
+					return 0;
+				}
 			}
 			filp->f_pos += ext2_rec_len_from_disk(de->rec_len);
 		}
@@ -463,6 +483,10 @@ ino_t ext2_inode_by_dentry(struct inode *dir, struct dentry *dentry)
 			spin_lock(&dentry->d_lock);
 			dentry->d_flags |= DCACHE_WHITEOUT;
 			spin_unlock(&dentry->d_lock);
+		} else if(!res && de->file_type == EXT2_FT_FALLTHRU) {
+			spin_lock(&dentry->d_lock);
+			dentry->d_flags |= DCACHE_FALLTHRU;
+			spin_unlock(&dentry->d_lock);
 		}
 		ext2_put_page(page);
 	}
@@ -532,6 +556,7 @@ static ext2_dirent * ext2_append_entry(struct dentry * dentry,
 				de->name_len = 0;
 				de->rec_len = ext2_rec_len_to_disk(chunk_size);
 				de->inode = 0;
+				de->file_type = 0;
 				goto got_it;
 			}
 			if (de->rec_len == 0) {
@@ -545,6 +570,7 @@ static ext2_dirent * ext2_append_entry(struct dentry * dentry,
 			name_len = EXT2_DIR_REC_LEN(de->name_len);
 			rec_len = ext2_rec_len_from_disk(de->rec_len);
 			if (!de->inode && (de->file_type != EXT2_FT_WHT) &&
+			    (de->file_type != EXT2_FT_FALLTHRU) &&
 			    (rec_len >= reclen))
 				goto got_it;
 			if (rec_len >= name_len + reclen)
@@ -587,7 +613,8 @@ int ext2_add_link (struct dentry *dentry, struct inode *inode)
 
 	err = -EEXIST;
 	if (ext2_match (namelen, name, de)) {
-		if (de->file_type == EXT2_FT_WHT)
+		if ((de->file_type == EXT2_FT_WHT) ||
+		    (de->file_type == EXT2_FT_FALLTHRU))
 			goto got_it;
 		goto out_unlock;
 	}
@@ -602,7 +629,8 @@ got_it:
 							&page, NULL);
 	if (err)
 		goto out_unlock;
-	if (de->inode || ((de->file_type == EXT2_FT_WHT) &&
+	if (de->inode || (((de->file_type == EXT2_FT_WHT) ||
+			   (de->file_type == EXT2_FT_FALLTHRU)) &&
 			  !ext2_match (namelen, name, de))) {
 		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
 		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
@@ -627,6 +655,60 @@ out_unlock:
 }
 
 /*
+ * Create a fallthru entry.
+ */
+int ext2_fallthru_entry (struct inode *dir, struct dentry *dentry)
+{
+	const char *name = dentry->d_name.name;
+	int namelen = dentry->d_name.len;
+	unsigned short rec_len, name_len;
+	ext2_dirent * de;
+	struct page *page;
+	loff_t pos;
+	int err;
+
+	de = ext2_append_entry(dentry, &page);
+	if (IS_ERR(de))
+		return PTR_ERR(de);
+
+	err = -EEXIST;
+	if (ext2_match (namelen, name, de))
+		goto out_unlock;
+
+	name_len = EXT2_DIR_REC_LEN(de->name_len);
+	rec_len = ext2_rec_len_from_disk(de->rec_len);
+
+	pos = page_offset(page) +
+		(char*)de - (char*)page_address(page);
+	err = __ext2_write_begin(NULL, page->mapping, pos, rec_len, 0,
+							&page, NULL);
+	if (err)
+		goto out_unlock;
+	if (de->inode || (de->file_type == EXT2_FT_WHT) ||
+	    (de->file_type == EXT2_FT_FALLTHRU)) {
+		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
+		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
+		de->rec_len = ext2_rec_len_to_disk(name_len);
+		de = de1;
+	}
+	de->name_len = namelen;
+	memcpy(de->name, name, namelen);
+	de->inode = 0;
+	de->file_type = EXT2_FT_FALLTHRU;
+	err = ext2_commit_chunk(page, pos, rec_len);
+	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
+	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
+	mark_inode_dirty(dir);
+	/* OFFSET_CACHE */
+out_put:
+	ext2_put_page(page);
+	return err;
+out_unlock:
+	unlock_page(page);
+	goto out_put;
+}
+
+/*
  * ext2_delete_entry deletes a directory entry by merging it with the
  * previous entry. Page is up-to-date. Releases the page.
  */
@@ -711,7 +793,9 @@ int ext2_whiteout_entry (struct inode * dir, struct dentry * dentry,
 	 */
 	if (ext2_match (namelen, name, de))
 		de->inode = 0;
-	if (de->inode || (de->file_type == EXT2_FT_WHT)) {
+	if (de->inode || (((de->file_type == EXT2_FT_WHT) ||
+			   (de->file_type == EXT2_FT_FALLTHRU)) &&
+			  !ext2_match (namelen, name, de))) {
 		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
 		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
 		de->rec_len = ext2_rec_len_to_disk(name_len);
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 44d190c..2fa32b3 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -108,6 +108,7 @@ extern struct ext2_dir_entry_2 * ext2_find_entry (struct inode *,struct qstr *,
 extern int ext2_delete_entry (struct ext2_dir_entry_2 *, struct page *);
 extern int ext2_whiteout_entry (struct inode *, struct dentry *,
 				struct ext2_dir_entry_2 *, struct page *);
+extern int ext2_fallthru_entry (struct inode *, 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/namei.c b/fs/ext2/namei.c
index 12195a5..f28154c 100644
--- a/fs/ext2/namei.c
+++ b/fs/ext2/namei.c
@@ -349,6 +349,7 @@ static int ext2_whiteout(struct inode *dir, struct dentry *dentry,
 		goto out;
 
 	spin_lock(&new_dentry->d_lock);
+	new_dentry->d_flags &= ~DCACHE_FALLTHRU;
 	new_dentry->d_flags |= DCACHE_WHITEOUT;
 	spin_unlock(&new_dentry->d_lock);
 	d_add(new_dentry, NULL);
@@ -367,6 +368,26 @@ out:
 	return err;
 }
 
+/*
+ * Create a fallthru entry.
+ */
+static int ext2_fallthru (struct inode *dir, struct dentry *dentry)
+{
+	int err;
+
+	dquot_initialize(dir);
+
+	err = ext2_fallthru_entry(dir, dentry);
+	if (err)
+		return err;
+
+	d_instantiate(dentry, NULL);
+	spin_lock(&dentry->d_lock);
+	dentry->d_flags |= DCACHE_FALLTHRU;
+	spin_unlock(&dentry->d_lock);
+	return 0;
+}
+
 static int ext2_rename (struct inode * old_dir, struct dentry * old_dentry,
 	struct inode * new_dir,	struct dentry * new_dentry )
 {
@@ -470,6 +491,7 @@ const struct inode_operations ext2_dir_inode_operations = {
 	.rmdir		= ext2_rmdir,
 	.mknod		= ext2_mknod,
 	.whiteout	= ext2_whiteout,
+	.fallthru	= ext2_fallthru,
 	.rename		= ext2_rename,
 #ifdef CONFIG_EXT2_FS_XATTR
 	.setxattr	= generic_setxattr,
diff --git a/include/linux/ext2_fs.h b/include/linux/ext2_fs.h
index 20468bd..cb3d400 100644
--- a/include/linux/ext2_fs.h
+++ b/include/linux/ext2_fs.h
@@ -577,6 +577,7 @@ enum {
 	EXT2_FT_SOCK		= 6,
 	EXT2_FT_SYMLINK		= 7,
 	EXT2_FT_WHT		= 8,
+	EXT2_FT_FALLTHRU	= 9,
 	EXT2_FT_MAX
 };
 
-- 
1.6.3.3

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