Date:	Fri, 04 Apr 2008 20:19:49 +0900
From:	Akira Fujita <a-fujita@...jp.nec.com>
To:	linux-ext4@...r.kernel.org, Theodore Tso <tytso@....edu>,
	Mingming Cao <cmm@...ibm.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
CC:	linux-fsdevel@...r.kernel.org,
	Akira Fujita <a-fujita@...jp.nec.com>
Subject: [RFC][PATCH 4/8] main function of defrag and ioctl implementation

ext4: online defrag-- Main function of defrag and ioctl implementation

From: Akira Fujita <a-fujita@...jp.nec.com>

Create the temporary inode and do defrag per
defrag_size (defalut 64MB).

Signed-off-by: Akira Fujita <a-fujita@...jp.nec.com>
Signed-off-by: Takashi Sato <t-sato@...jp.nec.com>
---
 fs/ext4/defrag.c |  289 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 fs/ext4/ext4.h   |   19 ++++-
 fs/ext4/ioctl.c  |    3 +
 3 files changed, 310 insertions(+), 1 deletions(-)

diff --git a/fs/ext4/defrag.c b/fs/ext4/defrag.c
index 09b2c56..baa04d9 100644
--- a/fs/ext4/defrag.c
+++ b/fs/ext4/defrag.c
@@ -1,3 +1,18 @@
+/*
+ * Copyright (c) 2008, NEC Software Tohoku, Ltd.
+ * Written by Takashi Sato <t-sato@...jp.nec.com>
+ *            Akira Fujita <a-fujita@...jp.nec.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
 /* Online defragmentation for EXT4 */

 #include <linux/quotaops.h>
@@ -74,6 +89,27 @@ ext4_defrag_next_extent(struct inode *inode,
 	return 1;
 }

+int ext4_defrag_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
+			unsigned long arg)
+{
+	int err = 0;
+	if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
+			return -EINVAL;
+
+	if (cmd == EXT4_IOC_DEFRAG) {
+		struct ext4_ext_defrag_data defrag;
+
+		if (copy_from_user(&defrag,
+			(struct ext4_ext_defrag_data __user *)arg,
+			sizeof(defrag)))
+			return -EFAULT;
+		err = ext4_defrag(filp, defrag.start_offset,
+				defrag.defrag_size);
+	}
+
+	return err;
+}
+
 /**
  * ext4_defrag_merge_across_blocks - Merge extents across leaf block
  *
@@ -1022,3 +1058,256 @@ ext4_defrag_new_extent_tree(struct inode *inode, struct inode *tmp_inode,
 out:
 	return ret;
 }
+
+/**
+ * ext4_defrag - Defrag the specified range of a file
+ *
+ * @filp:		pointer to file
+ * @block_start:	starting offset to defrag in blocks
+ * @defrag_size:	size of defrag in blocks
+ *
+ * This function returns the number of blocks if succeeded, otherwise
+ * returns error value.
+ */
+int
+ext4_defrag(struct file *filp, ext4_lblk_t block_start,
+		ext4_lblk_t defrag_size)
+{
+	struct inode *inode = filp->f_dentry->d_inode, *tmp_inode = NULL;
+	struct ext4_ext_path *path = NULL, *holecheck_path = NULL;
+	struct ext4_extent *ext_prev = NULL, *ext_cur = NULL, *ext_dummy = NULL;
+	handle_t *handle;
+	ext4_lblk_t block_end = block_start + defrag_size - 1;
+	ext4_lblk_t seq_blocks = 0, seq_start = 0;
+	ext4_lblk_t add_blocks = 0;
+	ext4_lblk_t file_end = (inode->i_size - 1) >> inode->i_blkbits;
+	pgoff_t page_offset = 0, dest_offset = 0, seq_end_page = 0;
+	int ret = 0, depth = 0, last_extent = 0, seq_extents = 0;
+
+	/* ext4 online defrag supports only 4KB block size */
+	if (inode->i_sb->s_blocksize != DEFRAG_BLOCK_SIZE) {
+		printk(KERN_ERR "ext4 defrag: ext4 online defrag supports "
+				"only 4KB block size for the moment.\n");
+		return -EINVAL;
+	}
+
+	/* ext4 online defrag needs mballoc mount option. */
+	if (!test_opt(inode->i_sb, MBALLOC)) {
+		printk(KERN_ERR "ext4 defrag: multiblock allocation "
+				"is disabled\n");
+		return -EINVAL;
+	}
+
+	if (file_end < block_end)
+		defrag_size -= block_end - file_end;
+
+	mutex_lock(&inode->i_mutex);
+	down_write(&EXT4_I(inode)->i_data_sem);
+
+	path = ext4_ext_find_extent(inode, block_start, NULL);
+	if (IS_ERR(path)) {
+		ret = PTR_ERR(path);
+		path = NULL;
+		goto out;
+	}
+
+	/* Get path structure to check the hole */
+	holecheck_path = ext4_ext_find_extent(inode, block_start, NULL);
+	if (IS_ERR(holecheck_path)) {
+		ret = PTR_ERR(holecheck_path);
+		holecheck_path = NULL;
+		goto out;
+	}
+
+	depth = ext_depth(inode);
+	ext_cur = holecheck_path[depth].p_ext;
+	if (ext_cur == NULL)
+		goto out;
+
+	/*
+	 * Get proper extent whose ee_block is beyond block_start
+	 * if block_start was within the hole.
+	 */
+	if (le32_to_cpu(ext_cur->ee_block) +
+		le16_to_cpu(ext_cur->ee_len) - 1 < block_start) {
+		last_extent = ext4_defrag_next_extent(inode, holecheck_path,
+				&ext_cur);
+		if (last_extent < 0) {
+			ret = last_extent;
+			goto out;
+		}
+		last_extent = ext4_defrag_next_extent(inode, path, &ext_dummy);
+		if (last_extent < 0) {
+			ret = last_extent;
+			goto out;
+		}
+	}
+	seq_extents = 1;
+	seq_start = le32_to_cpu(ext_cur->ee_block);
+
+	/* No blocks within the specified range. */
+	if (le32_to_cpu(ext_cur->ee_block) > block_end) {
+		printk(KERN_INFO "ext4 defrag: The specified range of file"
+				" may be the hole\n");
+		goto out;
+	}
+
+	/* Adjust start blocks */
+	add_blocks = min(le32_to_cpu(ext_cur->ee_block) +
+			 le16_to_cpu(ext_cur->ee_len), block_end + 1) -
+		     max(le32_to_cpu(ext_cur->ee_block), block_start);
+
+	while (!last_extent && le32_to_cpu(ext_cur->ee_block) <= block_end) {
+		seq_blocks += add_blocks;
+
+		handle = ext4_journal_start(inode,
+			EXT4_DATA_TRANS_BLOCKS(inode->i_sb) +
+			EXT4_INDEX_EXTRA_TRANS_BLOCKS + 3 +
+			2 * EXT4_QUOTA_INIT_BLOCKS(inode->i_sb) + 1);
+		if (IS_ERR(handle)) {
+			ret = PTR_ERR(handle);
+			goto out;
+		}
+		tmp_inode = ext4_new_inode(handle,
+			inode->i_sb->s_root->d_inode, S_IFREG);
+		if (IS_ERR(tmp_inode)) {
+			ret = -ENOMEM;
+			ext4_journal_stop(handle);
+			tmp_inode = NULL;
+			goto out;
+		}
+
+		i_size_write(tmp_inode, i_size_read(inode));
+		tmp_inode->i_nlink = 0;
+		ext4_ext_tree_init(handle, tmp_inode);
+		ext4_orphan_add(handle, tmp_inode);
+		ext4_journal_stop(handle);
+
+		/* Adjust tail blocks */
+		if (seq_start + seq_blocks - 1 > block_end)
+			seq_blocks = block_end - seq_start + 1;
+
+		ext_prev = ext_cur;
+		last_extent = ext4_defrag_next_extent(inode, holecheck_path,
+				&ext_cur);
+		if (last_extent < 0) {
+			ret = last_extent;
+			break;
+		}
+		if (!last_extent)
+			seq_extents++;
+		add_blocks = le16_to_cpu(ext_cur->ee_len);
+
+		/*
+		 * Extend the length of contiguous block (seq_blocks)
+		 * if extents are contiguous.
+		 */
+		if ((le32_to_cpu(ext_prev->ee_block) +
+				le16_to_cpu(ext_prev->ee_len) ==
+				le32_to_cpu(ext_cur->ee_block) &&
+				block_end >= le32_to_cpu(ext_cur->ee_block) &&
+				!last_extent)) {
+			if (tmp_inode) {
+				iput(tmp_inode);
+				tmp_inode = NULL;
+			}
+			continue;
+		}
+
+		/* Found an isolated block */
+		if (seq_extents == 1) {
+			seq_start = le32_to_cpu(ext_cur->ee_block);
+			goto CLEANUP;
+		}
+
+		ret = ext4_defrag_new_extent_tree(inode, tmp_inode, path,
+			seq_start, seq_blocks, block_start);
+
+		if (ret < 0) {
+			break;
+		} else if (ret == 1) {
+			ret = 0;
+			seq_start = le32_to_cpu(ext_cur->ee_block);
+			goto CLEANUP;
+		}
+
+		page_offset = seq_start >>
+				(PAGE_CACHE_SHIFT - inode->i_blkbits);
+		seq_end_page = (seq_start + seq_blocks - 1) >>
+				(PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+		dest_offset = 0;
+		seq_start = le32_to_cpu(ext_cur->ee_block);
+
+		/*
+		 * Discard all preallocations.
+		 * This is provisional solution.
+		 * When true ext4_mb_return_to_preallocation() is
+		 * implemented, this will be removed.
+		 */
+		ext4_mb_discard_inode_preallocations(inode);
+
+		while (page_offset <= seq_end_page) {
+			/* Swap original branches with new branches */
+			ret = ext4_defrag_partial(tmp_inode, filp,
+					page_offset, dest_offset);
+			if (ret < 0)
+				goto out;
+
+			page_offset++;
+			dest_offset++;
+		}
+
+		/* Decrease buffer counter */
+		if (holecheck_path)
+			ext4_ext_drop_refs(holecheck_path);
+		holecheck_path =
+			ext4_ext_find_extent(inode, seq_start, holecheck_path);
+		if (IS_ERR(holecheck_path)) {
+			ret = PTR_ERR(holecheck_path);
+			holecheck_path = NULL;
+			break;
+		}
+		depth = holecheck_path->p_depth;
+
+CLEANUP:
+		/* Decrease buffer counter */
+		if (path)
+			ext4_ext_drop_refs(path);
+		path = ext4_ext_find_extent(inode, seq_start, path);
+		if (IS_ERR(path)) {
+			ret = PTR_ERR(path);
+			path = NULL;
+			break;
+		}
+
+		ext_cur = holecheck_path[depth].p_ext;
+		add_blocks = le16_to_cpu(ext_cur->ee_len);
+		seq_blocks = 0;
+		dest_offset = 0;
+		seq_extents = 1;
+
+		if (tmp_inode) {
+			iput(tmp_inode);
+			tmp_inode = NULL;
+		}
+	}
+
+out:
+	if (path) {
+		ext4_ext_drop_refs(path);
+		kfree(path);
+	}
+	if (holecheck_path) {
+		ext4_ext_drop_refs(holecheck_path);
+		kfree(holecheck_path);
+	}
+
+	up_write(&EXT4_I(inode)->i_data_sem);
+	mutex_unlock(&inode->i_mutex);
+
+	if (tmp_inode)
+		iput(tmp_inode);
+
+	return (ret ? ret : defrag_size);
+}
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 8dc174f..18c1fcf 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -298,6 +298,7 @@ struct ext4_new_group_data {
 #define EXT4_IOC_GETRSVSZ		_IOR('f', 5, long)
 #define EXT4_IOC_SETRSVSZ		_IOW('f', 6, long)
 #define EXT4_IOC_MIGRATE		_IO('f', 7)
+#define EXT4_IOC_DEFRAG		_IOW('f', 10, struct ext4_ext_defrag_data)

 /*
  * ioctl commands in 32 bit emulation
@@ -315,8 +316,19 @@ struct ext4_new_group_data {
 #define EXT4_IOC32_GETVERSION_OLD	FS_IOC32_GETVERSION
 #define EXT4_IOC32_SETVERSION_OLD	FS_IOC32_SETVERSION

-#define EXT4_TRANS_META_BLOCKS 4 /* bitmap + group desc + sb + inode */
+/*
+ * Will go away.
+ * ext4 online defrag supports only 4KB block size.
+ */
+#define DEFRAG_BLOCK_SIZE	4096

+struct ext4_ext_defrag_data {
+	ext4_lblk_t start_offset;	/* start offset to defrag in blocks */
+	ext4_lblk_t defrag_size;	/* size of defrag in blocks */
+	ext4_fsblk_t goal;		/* block offset for allocation */
+};
+
+#define EXT4_TRANS_META_BLOCKS 4 /* bitmap + group desc + sb + inode */

 /*
  *  Mount options
@@ -1114,6 +1126,11 @@ extern void ext4_inode_table_set(struct super_block *sb,
 				 struct ext4_group_desc *bg, ext4_fsblk_t blk);
 /* extents.c */
 extern handle_t *ext4_ext_journal_restart(handle_t *handle, int needed);
+/* defrag.c */
+extern int ext4_defrag(struct file *filp, ext4_lblk_t block_start,
+			ext4_lblk_t defrag_size);
+extern int ext4_defrag_ioctl(struct inode *, struct file *, unsigned int,
+				unsigned long);

 static inline ext4_fsblk_t ext4_blocks_count(struct ext4_super_block *es)
 {
diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index 0d7430a..98b6f4a 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -231,6 +231,9 @@ flags_err:

 		return err;
 	}
+	case EXT4_IOC_DEFRAG: {
+		return ext4_defrag_ioctl(inode, filp, cmd, arg);
+	}
 	case EXT4_IOC_GROUP_ADD: {
 		struct ext4_new_group_data input;
 		struct super_block *sb = inode->i_sb;

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