ext4: let ext4_readdir handle inline data

For "." and "..", we just call filldir by ourselves
instead of iterating the real dir entry.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/dir.c

@@ -27,23 +27,11 @@
 #include <linux/slab.h>
 #include <linux/rbtree.h>
 #include "ext4.h"
-
+#include "xattr.h"
-static unsigned char ext4_filetype_table[] = {
-	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
-};
 
 static int ext4_dx_readdir(struct file *filp,
 			   void *dirent, filldir_t filldir);
 
-static unsigned char get_dtype(struct super_block *sb, int filetype)
-{
-	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
-	    (filetype >= EXT4_FT_MAX))
-		return DT_UNKNOWN;
-
-	return (ext4_filetype_table[filetype]);
-}
-
 /**
  * Check if the given dir-inode refers to an htree-indexed directory
  * (or a directory which chould potentially get coverted to use htree
@@ -68,6 +56,9 @@ static int is_dx_dir(struct inode *inode)
  * Return 0 if the directory entry is OK, and 1 if there is a problem
  *
  * Note: this is the opposite of what ext2 and ext3 historically returned...
+ *
+ * bh passed here can be an inode block or a dir data block, depending
+ * on the inode inline data flag.
  */
 int __ext4_check_dir_entry(const char *function, unsigned int line,
 			   struct inode *dir, struct file *filp,
@@ -124,6 +115,14 @@ static int ext4_readdir(struct file *filp,
 	int ret = 0;
 	int dir_has_error = 0;
 
+	if (ext4_has_inline_data(inode)) {
+		int has_inline_data = 1;
+		ret = ext4_read_inline_dir(filp, dirent, filldir,
+					   &has_inline_data);
+		if (has_inline_data)
+			return ret;
+	}
+
 	if (is_dx_dir(inode)) {
 		err = ext4_dx_readdir(filp, dirent, filldir);
 		if (err != ERR_BAD_DX_DIR) {

fs/ext4/ext4.h

@@ -1989,6 +1989,18 @@ static inline void ext4_update_dx_flag(struct inode *inode)
 				     EXT4_FEATURE_COMPAT_DIR_INDEX))
 		ext4_clear_inode_flag(inode, EXT4_INODE_INDEX);
 }
+static unsigned char ext4_filetype_table[] = {
+	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
+};
+
+static inline  unsigned char get_dtype(struct super_block *sb, int filetype)
+{
+	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_FILETYPE) ||
+	    (filetype >= EXT4_FT_MAX))
+		return DT_UNKNOWN;
+
+	return ext4_filetype_table[filetype];
+}
 
 /* fsync.c */
 extern int ext4_sync_file(struct file *, loff_t, loff_t, int);

fs/ext4/inline.c

@@ -1288,6 +1288,142 @@ out:
 	return ret;
 }
 
+int ext4_read_inline_dir(struct file *filp,
+			 void *dirent, filldir_t filldir,
+			 int *has_inline_data)
+{
+	int error = 0;
+	unsigned int offset, parent_ino;
+	int i, stored;
+	struct ext4_dir_entry_2 *de;
+	struct super_block *sb;
+	struct inode *inode = filp->f_path.dentry->d_inode;
+	int ret, inline_size = 0;
+	struct ext4_iloc iloc;
+	void *dir_buf = NULL;
+
+	ret = ext4_get_inode_loc(inode, &iloc);
+	if (ret)
+		return ret;
+
+	down_read(&EXT4_I(inode)->xattr_sem);
+	if (!ext4_has_inline_data(inode)) {
+		up_read(&EXT4_I(inode)->xattr_sem);
+		*has_inline_data = 0;
+		goto out;
+	}
+
+	inline_size = ext4_get_inline_size(inode);
+	dir_buf = kmalloc(inline_size, GFP_NOFS);
+	if (!dir_buf) {
+		ret = -ENOMEM;
+		up_read(&EXT4_I(inode)->xattr_sem);
+		goto out;
+	}
+
+	ret = ext4_read_inline_data(inode, dir_buf, inline_size, &iloc);
+	up_read(&EXT4_I(inode)->xattr_sem);
+	if (ret < 0)
+		goto out;
+
+	sb = inode->i_sb;
+	stored = 0;
+	parent_ino = le32_to_cpu(((struct ext4_dir_entry_2 *)dir_buf)->inode);
+
+	while (!error && !stored && filp->f_pos < inode->i_size) {
+revalidate:
+		/*
+		 * If the version has changed since the last call to
+		 * readdir(2), then we might be pointing to an invalid
+		 * dirent right now.  Scan from the start of the inline
+		 * dir to make sure.
+		 */
+		if (filp->f_version != inode->i_version) {
+			for (i = 0;
+			     i < inode->i_size && i < offset;) {
+				if (!i) {
+					/* skip "." and ".." if needed. */
+					i += EXT4_INLINE_DOTDOT_SIZE;
+					continue;
+				}
+				de = (struct ext4_dir_entry_2 *)
+					(dir_buf + i);
+				/* It's too expensive to do a full
+				 * dirent test each time round this
+				 * loop, but we do have to test at
+				 * least that it is non-zero.  A
+				 * failure will be detected in the
+				 * dirent test below. */
+				if (ext4_rec_len_from_disk(de->rec_len,
+					inline_size) < EXT4_DIR_REC_LEN(1))
+					break;
+				i += ext4_rec_len_from_disk(de->rec_len,
+							    inline_size);
+			}
+			offset = i;
+			filp->f_pos = offset;
+			filp->f_version = inode->i_version;
+		}
+
+		while (!error && filp->f_pos < inode->i_size) {
+			if (filp->f_pos == 0) {
+				error = filldir(dirent, ".", 1, 0, inode->i_ino,
+						DT_DIR);
+				if (error)
+					break;
+				stored++;
+
+				error = filldir(dirent, "..", 2, 0, parent_ino,
+						DT_DIR);
+				if (error)
+					break;
+				stored++;
+
+				filp->f_pos = offset = EXT4_INLINE_DOTDOT_SIZE;
+				continue;
+			}
+
+			de = (struct ext4_dir_entry_2 *)(dir_buf + offset);
+			if (ext4_check_dir_entry(inode, filp, de,
+						 iloc.bh, dir_buf,
+						 inline_size, offset)) {
+				ret = stored;
+				goto out;
+			}
+			offset += ext4_rec_len_from_disk(de->rec_len,
+							 inline_size);
+			if (le32_to_cpu(de->inode)) {
+				/* We might block in the next section
+				 * if the data destination is
+				 * currently swapped out.  So, use a
+				 * version stamp to detect whether or
+				 * not the directory has been modified
+				 * during the copy operation.
+				 */
+				u64 version = filp->f_version;
+
+				error = filldir(dirent, de->name,
+						de->name_len,
+						filp->f_pos,
+						le32_to_cpu(de->inode),
+						get_dtype(sb, de->file_type));
+				if (error)
+					break;
+				if (version != filp->f_version)
+					goto revalidate;
+				stored++;
+			}
+			filp->f_pos += ext4_rec_len_from_disk(de->rec_len,
+							      inline_size);
+		}
+		offset = 0;
+	}
+out:
+	kfree(dir_buf);
+	brelse(iloc.bh);
+	return ret;
+}
+
 /*
  * Try to create the inline data for the new dir.
  * If it succeeds, return 0, otherwise return the error.

fs/ext4/xattr.h

@@ -168,6 +168,9 @@ extern int ext4_try_add_inline_entry(handle_t *handle, struct dentry *dentry,
 extern int ext4_try_create_inline_dir(handle_t *handle,
 				      struct inode *parent,
 				      struct inode *inode);
+extern int ext4_read_inline_dir(struct file *filp,
+				void *dirent, filldir_t filldir,
+				int *has_inline_data);
 # else  /* CONFIG_EXT4_FS_XATTR */
 
 static inline int
@@ -346,6 +349,12 @@ static inline int ext4_try_create_inline_dir(handle_t *handle,
 {
 	return 0;
 }
+static inline int ext4_read_inline_dir(struct file *filp,
+				       void *dirent, filldir_t filldir,
+				       int *has_inline_data)
+{
+	return 0;
+}
 # endif  /* CONFIG_EXT4_FS_XATTR */
 
 #ifdef CONFIG_EXT4_FS_SECURITY