libext2fs-handle-inline-data-in-read-write-function-v2

From: Zheng Liu <wenqing.lz@taobao.com>

libext2fs: handle inline data in read/write function

Currently ext2fs_file_read/write are used to copy data from/to a file.
But they manipulate data by blocksize.  For supporting inline data, we
handle it in two new fucntions called ext2fs_file_read/write_inline_data.

In read path the implementation is straightforward.  But in write path
things get more complicated because if the size of data is greater than
the maximum size of inline data we will expand this file.  So now we
will check this in ext2fs_xattr_set().  If this inode doesn't have
enough space, it will return EXT2_ET_INLINE_DATA_NO_SPACE error.  Then
the caller will check this error and tries to expand the file.

The following commands in debugfs can handle inline_data feature after
applying this patch:
	- dump
	- cat
	- rdump
	- write

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
diff --git a/debugfs/debugfs.c b/debugfs/debugfs.c
index d1c81f1..0903c8e 100644
--- a/debugfs/debugfs.c
+++ b/debugfs/debugfs.c
@@ -1684,7 +1684,6 @@ fail:
 	return retval;
 }
 
-
 void do_write(int argc, char *argv[])
 {
 	int		fd;
@@ -1750,8 +1749,11 @@ void do_write(int argc, char *argv[])
 		current_fs->now ? current_fs->now : time(0);
 	inode.i_links_count = 1;
 	inode.i_size = statbuf.st_size;
-	if (current_fs->super->s_feature_incompat &
-	    EXT3_FEATURE_INCOMPAT_EXTENTS) {
+	if (EXT2_HAS_INCOMPAT_FEATURE(current_fs->super,
+				      EXT4_FEATURE_INCOMPAT_INLINE_DATA)) {
+		inode.i_flags |= EXT4_INLINE_DATA_FL;
+	} else if (current_fs->super->s_feature_incompat &
+		   EXT3_FEATURE_INCOMPAT_EXTENTS) {
 		int i;
 		struct ext3_extent_header *eh;
 
@@ -1768,6 +1770,11 @@ void do_write(int argc, char *argv[])
 		close(fd);
 		return;
 	}
+	if (inode.i_flags & EXT4_INLINE_DATA_FL) {
+		retval = ext2fs_inline_data_init(current_fs, newfile);
+		if (retval)
+			return;
+	}
 	if (LINUX_S_ISREG(inode.i_mode)) {
 		if (statbuf.st_blocks < statbuf.st_size / S_BLKSIZE) {
 			make_holes = 1;
diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
index 0781145..68aa3e0 100644
--- a/lib/ext2fs/ext2_err.et.in
+++ b/lib/ext2fs/ext2_err.et.in
@@ -503,4 +503,7 @@ ec	EXT2_ET_EA_NO_SPACE,
 ec	EXT2_ET_NO_INLINE_DATA,
 	"Inode doesn't have inline data"
 
+ec	EXT2_ET_INLINE_DATA_NO_SPACE,
+	"No free space in inline data"
+
 	end
diff --git a/lib/ext2fs/ext2fsP.h b/lib/ext2fs/ext2fsP.h
index bfc321c..e159128 100644
--- a/lib/ext2fs/ext2fsP.h
+++ b/lib/ext2fs/ext2fsP.h
@@ -102,6 +102,12 @@ extern errcode_t ext2fs_inline_data_dir_iterate(ext2_filsys fs,
 						  int	      ref_offset,
 						  void	      *priv_data),
 				      void *priv_data);
+extern errcode_t ext2fs_inline_data_get(ext2_filsys fs, ext2_ino_t ino,
+					struct ext2_inode *inode,
+					void *buf, size_t *size);
+extern errcode_t ext2fs_inline_data_set(ext2_filsys fs, ext2_ino_t ino,
+					struct ext2_inode *inode,
+					void *buf, size_t size);
 
 /* Generic numeric progress meter */
 
diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
index 0e9a9ab..98f0fbb 100644
--- a/lib/ext2fs/ext_attr.c
+++ b/lib/ext2fs/ext_attr.c
@@ -818,6 +818,71 @@ errcode_t ext2fs_xattr_get(struct ext2_xattr_handle *h, const char *key,
 	return EXT2_ET_EA_KEY_NOT_FOUND;
 }
 
+static errcode_t ext2fs_xattr_max_size(struct ext2_xattr_handle *handle, size_t *size)
+{
+	struct ext2_ext_attr_header *header;
+	struct ext2_ext_attr_entry *entry;
+	struct ext2_inode_large *inode;
+	__u32 ea_inode_magic;
+	unsigned int storage_size, freesize, minoff;
+	void *start;
+	int i;
+	errcode_t err;
+
+	i = EXT2_INODE_SIZE(handle->fs->super);
+	if (i < sizeof(*inode))
+		i = sizeof(*inode);
+	err = ext2fs_get_memzero(i, &inode);
+	if (err)
+		return err;
+
+	err = ext2fs_read_inode_full(handle->fs, handle->ino,
+				     (struct ext2_inode *)inode,
+				     EXT2_INODE_SIZE(handle->fs->super));
+	if (err)
+		goto out;
+
+	/* Does the inode have size for EA? */
+	if (EXT2_INODE_SIZE(handle->fs->super) <= EXT2_GOOD_OLD_INODE_SIZE +
+						  inode->i_extra_isize +
+						  sizeof(__u32)) {
+		err = EXT2_ET_INLINE_DATA_NO_SPACE;
+		goto out;
+	}
+
+	minoff = EXT2_INODE_SIZE(handle->fs->super) -
+		 sizeof(*inode) - sizeof(__u32);
+	memcpy(&ea_inode_magic, ((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
+	       inode->i_extra_isize, sizeof(__u32));
+	if (ea_inode_magic == EXT2_EXT_ATTR_MAGIC) {
+		/* has xattrs.  calculate the size */
+		storage_size = EXT2_INODE_SIZE(handle->fs->super) -
+			EXT2_GOOD_OLD_INODE_SIZE - inode->i_extra_isize -
+			sizeof(__u32);
+		start= ((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
+			inode->i_extra_isize + sizeof(__u32);
+		entry = start;
+		while (!EXT2_EXT_IS_LAST_ENTRY(entry)) {
+			if (!entry->e_value_block && entry->e_value_size) {
+				unsigned int offs = entry->e_value_offs;
+				if (offs < minoff)
+					minoff = offs;
+			}
+			entry = EXT2_EXT_ATTR_NEXT(entry);
+		}
+		*size = minoff - ((char *)entry - (char *)start) - sizeof(__u32);
+	} else {
+		/* no xattr.  return a maximum size */
+		*size = EXT2_EXT_ATTR_SIZE(minoff -
+					   EXT2_EXT_ATTR_LEN(strlen("data")) -
+					   EXT2_EXT_ATTR_ROUND - sizeof(__u32));
+	}
+
+out:
+	ext2fs_free_mem(&inode);
+	return err;
+}
+
 errcode_t ext2fs_xattr_set(struct ext2_xattr_handle *handle,
 			   const char *key,
 			   const void *value,
@@ -827,6 +892,17 @@ errcode_t ext2fs_xattr_set(struct ext2_xattr_handle *handle,
 	char *new_value;
 	errcode_t err;
 
+	/* we need to check inline data space */
+	if (strcmp(key, "system.data") == 0) {
+		size_t max_size;
+
+		err = ext2fs_xattr_max_size(handle, &max_size);
+		if (err)
+			return err;
+		if (value_len > max_size)
+			return EXT2_ET_INLINE_DATA_NO_SPACE;
+	}
+
 	last_empty = NULL;
 	for (x = handle->attrs; x < handle->attrs + handle->length; x++) {
 		if (!x->name) {
diff --git a/lib/ext2fs/fileio.c b/lib/ext2fs/fileio.c
index 02e6263..acb705d 100644
--- a/lib/ext2fs/fileio.c
+++ b/lib/ext2fs/fileio.c
@@ -224,6 +224,39 @@ errcode_t ext2fs_file_close(ext2_file_t file)
 }
 
 
+static errcode_t
+ext2fs_file_read_inline_data(ext2_file_t file, void *buf,
+			     unsigned int wanted, unsigned int *got)
+{
+	ext2_filsys fs;
+	errcode_t retval;
+	unsigned int start, count = 0;
+	size_t size;
+
+	fs = file->fs;
+	retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
+					file->buf, &size);
+	if (retval)
+		return retval;
+
+	if (file->pos >= size)
+		goto out;
+
+	start = file->pos % size;
+	count = size - start;
+	if (count > wanted)
+		count = wanted;
+	memcpy(buf, file->buf + start, count);
+	file->pos += count;
+	buf += count;
+
+out:
+	if (got)
+		*got = count;
+	return retval;
+}
+
+
 errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
 			   unsigned int wanted, unsigned int *got)
 {
@@ -236,6 +269,10 @@ errcode_t ext2fs_file_read(ext2_file_t file, void *buf,
 	EXT2_CHECK_MAGIC(file, EXT2_ET_MAGIC_EXT2_FILE);
 	fs = file->fs;
 
+	/* If an inode has inline data, things get complicated. */
+	if (file->inode.i_flags & EXT4_INLINE_DATA_FL)
+		return ext2fs_file_read_inline_data(file, buf, wanted, got);
+
 	while ((file->pos < EXT2_I_SIZE(&file->inode)) && (wanted > 0)) {
 		retval = sync_buffer_position(file);
 		if (retval)
@@ -266,6 +303,67 @@ fail:
 }
 
 
+static errcode_t
+ext2fs_file_write_inline_data(ext2_file_t file, const void *buf,
+			      unsigned int nbytes, unsigned int *written)
+{
+	ext2_filsys fs;
+	errcode_t retval;
+	unsigned int start, count = 0;
+	size_t size;
+
+	fs = file->fs;
+	retval = ext2fs_inline_data_get(fs, file->ino, &file->inode,
+					file->buf, &size);
+	if (retval)
+		return retval;
+
+	if (file->pos < size) {
+		start = file->pos % fs->blocksize;
+		count = nbytes - start;
+		memcpy(file->buf + start, buf, count);
+
+		retval = ext2fs_inline_data_set(fs, file->ino, &file->inode,
+						file->buf, count);
+		if (retval == EXT2_ET_INLINE_DATA_NO_SPACE)
+			goto expand;
+		if (retval)
+			return retval;
+
+		file->pos += count;
+
+		/* Update inode size */
+		if (count != 0 && EXT2_I_SIZE(&file->inode) < file->pos) {
+			errcode_t	rc;
+
+			rc = ext2fs_file_set_size2(file, file->pos);
+			if (retval == 0)
+				retval = rc;
+		}
+
+		if (written)
+			*written = count;
+		return 0;
+	}
+
+expand:
+	retval = ext2fs_inline_data_expand(fs, file->ino);
+	if (retval)
+		return retval;
+	/*
+	 * reload inode and return no space error
+	 *
+	 * XXX: file->inode could be copied from the outside
+	 * in ext2fs_file_open2().  We have no way to modify
+	 * the outside inode.
+	 */
+	retval = ext2fs_read_inode(fs, file->ino, &file->inode);
+	if (retval)
+		return retval;
+	return EXT2_ET_INLINE_DATA_NO_SPACE;
+}
+
+
 errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
 			    unsigned int nbytes, unsigned int *written)
 {
@@ -280,6 +378,16 @@ errcode_t ext2fs_file_write(ext2_file_t file, const void *buf,
 	if (!(file->flags & EXT2_FILE_WRITE))
 		return EXT2_ET_FILE_RO;
 
+	/* If an inode has inline data, things get complicated. */
+	if (file->inode.i_flags & EXT4_INLINE_DATA_FL) {
+		retval = ext2fs_file_write_inline_data(file, buf, nbytes,
+						       written);
+		if (retval != EXT2_ET_INLINE_DATA_NO_SPACE)
+			return retval;
+		/* fall through to read data from the block */
+		retval = 0;
+	}
+
 	while (nbytes > 0) {
 		retval = sync_buffer_position(file);
 		if (retval)
diff --git a/lib/ext2fs/inline_data.c b/lib/ext2fs/inline_data.c
index 16af814..4a35209 100644
--- a/lib/ext2fs/inline_data.c
+++ b/lib/ext2fs/inline_data.c
@@ -309,6 +309,7 @@ errcode_t ext2fs_inline_data_expand(ext2_filsys fs, ext2_ino_t ino)
 	struct ext2_inline_data data;
 	errcode_t retval;
 	blk64_t blk;
+	size_t inline_size;
 	char *inline_buf = 0;
 	char *blk_buf = 0;
 
@@ -327,8 +328,8 @@ errcode_t ext2fs_inline_data_expand(ext2_filsys fs, ext2_ino_t ino)
 	retval = ext2fs_inline_data_ea_get(&data);
 	if (retval)
 		return retval;
-	retval = ext2fs_get_mem(EXT4_MIN_INLINE_DATA_SIZE + data.ea_size,
-				&inline_buf);
+	inline_size = data.ea_size + EXT4_MIN_INLINE_DATA_SIZE;
+	retval = ext2fs_get_mem(inline_size, &inline_buf);
 	if (retval)
 		goto errout;
 
@@ -347,10 +348,14 @@ errcode_t ext2fs_inline_data_expand(ext2_filsys fs, ext2_ino_t ino)
 	if (retval)
 		goto errout;
 
-	/* Adjust the rec_len */
-	retval = ext2fs_inline_data_convert_dir(fs, ino, blk_buf, inline_buf,
-						EXT4_MIN_INLINE_DATA_SIZE +
-							data.ea_size);
+	if (LINUX_S_ISDIR(inode.i_mode)) {
+		/* Adjust the rec_len */
+		retval = ext2fs_inline_data_convert_dir(fs, ino, blk_buf,
+							inline_buf, inline_size);
+	} else {
+		/* Copy data for a regular inode */
+		memcpy(blk_buf, inline_buf, inline_size);
+	}
 	if (retval)
 		goto errout;
 
@@ -389,3 +394,76 @@ errout:
 	ext2fs_free_mem(&data.ea_data);
 	return retval;
 }
+
+/*
+ * When caller uses this function to retrieve the inline data, it must
+ * allocate a buffer which has the size of inline data.  The size of
+ * inline data can be know by ext2fs_inline_data_get_size().
+ */
+errcode_t ext2fs_inline_data_get(ext2_filsys fs, ext2_ino_t ino,
+				 struct ext2_inode *inode,
+				 void *buf, size_t *size)
+{
+	struct ext2_inode inode_buf;
+	struct ext2_inline_data data;
+	errcode_t retval;
+
+	if (!inode) {
+		retval = ext2fs_read_inode(fs, ino, &inode_buf);
+		if (retval)
+			return retval;
+		inode = &inode_buf;
+	}
+
+	data.fs = fs;
+	data.ino = ino;
+	retval = ext2fs_inline_data_ea_get(&data);
+	if (retval)
+		return retval;
+
+	memcpy(buf, (void *)inode->i_block, EXT4_MIN_INLINE_DATA_SIZE);
+	if (data.ea_size > 0)
+		memcpy(buf + EXT4_MIN_INLINE_DATA_SIZE,
+		       data.ea_data, data.ea_size);
+
+	if (size)
+		*size = EXT4_MIN_INLINE_DATA_SIZE + data.ea_size;
+	ext2fs_free_mem(&data.ea_data);
+	return 0;
+}
+
+errcode_t ext2fs_inline_data_set(ext2_filsys fs, ext2_ino_t ino,
+				 struct ext2_inode *inode,
+				 void *buf, size_t size)
+{
+	struct ext2_inode inode_buf;
+	struct ext2_inline_data data;
+	unsigned int max_size = 0;
+	errcode_t retval;
+
+	if (!inode) {
+		retval = ext2fs_read_inode(fs, ino, &inode_buf);
+		if (retval)
+			return retval;
+		inode = &inode_buf;
+	}
+
+	/* simple case */
+	if (size <= EXT4_MIN_INLINE_DATA_SIZE) {
+		memcpy((void *)inode->i_block, buf, size);
+		return ext2fs_write_inode(fs, ino, inode);
+	}
+
+	/*
+	 * complicated case
+	 */
+	memcpy((void *)inode->i_block, buf, EXT4_MIN_INLINE_DATA_SIZE);
+	retval = ext2fs_write_inode(fs, ino, inode);
+	if (retval)
+		return retval;
+	data.fs = fs;
+	data.ino = ino;
+	data.ea_size = size - EXT4_MIN_INLINE_DATA_SIZE;
+	data.ea_data = buf + EXT4_MIN_INLINE_DATA_SIZE;
+	return ext2fs_inline_data_ea_set(&data);
+}