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Date: Fri, 30 May 2008 20:18:12 +0900
From: Akira Fujita <a-fujita@...jp.nec.com>
To: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Theodore Tso <tytso@....edu>, Mingming Cao <cmm@...ibm.com>
CC: Akira Fujita <a-fujita@...jp.nec.com>
Subject: [RFC][PATCH 4/8]ext4: exchange the blocks between two inodes
ext4: online defrag-- Exchange the blocks between two inodes
From: Akira Fujita <a-fujita@...jp.nec.com>
Exchange the data blocks between the temporary inode and
the original inode.
Signed-off-by: Akira Fujita <a-fujita@...jp.nec.com>
Signed-off-by: Takashi Sato <t-sato@...jp.nec.com>
---
fs/ext4/defrag.c | 240 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 240 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/defrag.c b/fs/ext4/defrag.c
index f5d75c2..8ae5a48 100644
--- a/fs/ext4/defrag.c
+++ b/fs/ext4/defrag.c
@@ -134,6 +134,188 @@ int ext4_defrag_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
}
/**
+ * ext4_defrag_merge_across_blocks - Merge extents across leaf block
+ *
+ * @handle: journal handle
+ * @org_inode: original inode
+ * @o_start: first original extent to be defraged
+ * @o_end: last original extent to be defraged
+ * @start_ext: first new extent to be merged
+ * @new_ext: middle of new extent to be merged
+ * @end_ext: last new extent to be merged
+ *
+ * This function returns 0 if succeed, otherwise returns error value.
+ */
+static int
+ext4_defrag_merge_across_blocks(handle_t *handle, struct inode *org_inode,
+ struct ext4_extent *o_start, struct ext4_extent *o_end,
+ struct ext4_extent *start_ext, struct ext4_extent *new_ext,
+ struct ext4_extent *end_ext)
+{
+ struct ext4_ext_path *org_path = NULL;
+ ext4_lblk_t eblock = 0;
+ int new_flag = 0;
+ int end_flag = 0;
+ int err;
+
+ if (le16_to_cpu(start_ext->ee_len) &&
+ le16_to_cpu(new_ext->ee_len) &&
+ le16_to_cpu(end_ext->ee_len)) {
+
+ if (o_start == o_end) {
+
+ /* start_ext new_ext end_ext
+ * dest |---------|-----------|--------|
+ * org |------------------------------|
+ */
+
+ end_flag = 1;
+ } else {
+
+ /* start_ext new_ext end_ext
+ * dest |---------|----------|---------|
+ * org |---------------|--------------|
+ */
+
+ o_end->ee_block = end_ext->ee_block;
+ o_end->ee_len = end_ext->ee_len;
+ ext4_ext_store_pblock(o_end, ext_pblock(end_ext));
+ }
+
+ o_start->ee_len = start_ext->ee_len;
+ new_flag = 1;
+
+ } else if (le16_to_cpu(start_ext->ee_len) &&
+ le16_to_cpu(new_ext->ee_len) &&
+ !le16_to_cpu(end_ext->ee_len) &&
+ o_start == o_end) {
+
+ /* start_ext new_ext
+ * dest |--------------|---------------|
+ * org |------------------------------|
+ */
+
+ o_start->ee_len = start_ext->ee_len;
+ new_flag = 1;
+
+ } else if (!le16_to_cpu(start_ext->ee_len) &&
+ le16_to_cpu(new_ext->ee_len) &&
+ le16_to_cpu(end_ext->ee_len) &&
+ o_start == o_end) {
+
+ /* new_ext end_ext
+ * dest |--------------|---------------|
+ * org |------------------------------|
+ */
+
+ o_end->ee_block = end_ext->ee_block;
+ o_end->ee_len = end_ext->ee_len;
+ ext4_ext_store_pblock(o_end, ext_pblock(end_ext));
+
+ /*
+ * Set 0 to the extent block if new_ext was
+ * the first block.
+ */
+ if (!new_ext->ee_block)
+ eblock = 0;
+ else
+ eblock = le32_to_cpu(new_ext->ee_block);
+
+ new_flag = 1;
+ } else {
+ printk(KERN_ERR "ext4 defrag: Unexpected merge case\n");
+ return -EIO;
+ }
+
+ if (new_flag) {
+ org_path = ext4_ext_find_extent(org_inode, eblock, NULL);
+ if (IS_ERR(org_path)) {
+ err = PTR_ERR(org_path);
+ org_path = NULL;
+ goto out;
+ }
+ err = ext4_ext_insert_extent(handle, org_inode,
+ org_path, new_ext);
+ if (err)
+ goto out;
+ }
+
+ if (end_flag) {
+ org_path = ext4_ext_find_extent(org_inode,
+ le32_to_cpu(end_ext->ee_block) - 1, org_path);
+ if (IS_ERR(org_path)) {
+ err = PTR_ERR(org_path);
+ org_path = NULL;
+ goto out;
+ }
+ err = ext4_ext_insert_extent(handle, org_inode,
+ org_path, end_ext);
+ if (err)
+ goto out;
+ }
+out:
+ if (org_path) {
+ ext4_ext_drop_refs(org_path);
+ kfree(org_path);
+ }
+
+ return err;
+
+}
+
+/**
+ * ext4_defrag_merge_inside_block - Merge new extent to the extent block
+ *
+ * @o_start: first original extent to be merged
+ * @o_end: last original extent to be merged
+ * @start_ext: first new extent to be merged
+ * @new_ext: middle of new extent to be merged
+ * @end_ext: last new extent to be merged
+ * @eh: extent header of target leaf block
+ * @replaced: the number of blocks which will be replaced with new_ext
+ * @range_to_move: used to decide how to merge
+ *
+ * This function always returns 0.
+ */
+static int
+ext4_defrag_merge_inside_block(struct ext4_extent *o_start,
+ struct ext4_extent *o_end, struct ext4_extent *start_ext,
+ struct ext4_extent *new_ext, struct ext4_extent *end_ext,
+ struct ext4_extent_header *eh, ext4_fsblk_t replaced,
+ int range_to_move)
+{
+ int i = 0;
+ unsigned len;
+
+ /* Move the existing extents */
+ if (range_to_move && o_end < EXT_LAST_EXTENT(eh)) {
+ len = (unsigned long)(EXT_LAST_EXTENT(eh) + 1) -
+ (unsigned long)(o_end + 1);
+ memmove(o_end + 1 + range_to_move, o_end + 1, len);
+ }
+
+ /* Insert start entry */
+ if (le16_to_cpu(start_ext->ee_len))
+ o_start[i++].ee_len = start_ext->ee_len;
+
+ /* Insert new entry */
+ if (le16_to_cpu(new_ext->ee_len)) {
+ o_start[i].ee_block = new_ext->ee_block;
+ o_start[i].ee_len = cpu_to_le16(replaced);
+ ext4_ext_store_pblock(&o_start[i++], ext_pblock(new_ext));
+ }
+
+ /* Insert end entry */
+ if (end_ext->ee_len)
+ o_start[i] = *end_ext;
+
+ /* Increment the total entries counter on the extent block */
+ le16_add_cpu(&eh->eh_entries, range_to_move);
+
+ return 0;
+}
+
+/**
* ext4_defrag_merge_extents - Merge new extent
*
* @handle: journal handle
@@ -155,7 +337,65 @@ ext4_defrag_merge_extents(handle_t *handle, struct inode *org_inode,
struct ext4_extent *start_ext, struct ext4_extent *new_ext,
struct ext4_extent *end_ext, ext4_fsblk_t replaced)
{
+ struct ext4_extent_header *eh;
+ unsigned need_slots, slots_range;
+ int range_to_move, depth, ret;
+
+ /*
+ * The extents need to be inserted
+ * start_extent + new_extent + end_extent.
+ */
+ need_slots = (le16_to_cpu(start_ext->ee_len) ? 1 : 0) +
+ (le16_to_cpu(end_ext->ee_len) ? 1 : 0) +
+ (le16_to_cpu(new_ext->ee_len) ? 1 : 0);
+
+ /* The number of slots between start and end */
+ slots_range = ((unsigned long)(o_end + 1) - (unsigned long)o_start + 1)
+ / sizeof(struct ext4_extent);
+
+ /* Range to move the end of extent */
+ range_to_move = need_slots - slots_range;
+ depth = org_path->p_depth;
+ org_path += depth;
+ eh = org_path->p_hdr;
+
+ if (depth) {
+ /* Register to journal */
+ ret = ext4_journal_get_write_access(handle, org_path->p_bh);
+ if (ret)
+ return ret;
+ }
+
+ /* Expansion */
+ if (range_to_move > 0 &&
+ (range_to_move > le16_to_cpu(eh->eh_max)
+ - le16_to_cpu(eh->eh_entries))) {
+
+ ret = ext4_defrag_merge_across_blocks(handle, org_inode,
+ o_start, o_end, start_ext, new_ext,
+ end_ext);
+ if (ret < 0)
+ return ret;
+ } else {
+ ret = ext4_defrag_merge_inside_block(o_start, o_end,
+ start_ext, new_ext, end_ext, eh,
+ replaced, range_to_move);
+ if (ret < 0)
+ return ret;
+ }
+
+ if (depth) {
+ ret = ext4_journal_dirty_metadata(handle, org_path->p_bh);
+ if (ret)
+ return ret;
+ } else {
+ ret = ext4_mark_inode_dirty(handle, org_inode);
+ if (ret < 0)
+ return ret;
+ }
+
return 0;
+
}
/**
--
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