ext4: lookup block mapping in extent status tree
After tracking all extent status, we already have a extent cache in memory. Every time we want to lookup a block mapping, we can first try to lookup it in extent status tree to avoid a potential disk I/O. A new function called ext4_es_lookup_extent is defined to finish this work. When we try to lookup a block mapping, we always call ext4_map_blocks and/or ext4_da_map_blocks. So in these functions we first try to lookup a block mapping in extent status tree. A new flag EXT4_GET_BLOCKS_NO_PUT_HOLE is used in ext4_da_map_blocks in order not to put a hole into extent status tree because this hole will be converted to delayed extent in the tree immediately. Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: Jan kara <jack@suse.cz>
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d100eef244
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@ -579,6 +579,8 @@ enum {
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#define EXT4_GET_BLOCKS_KEEP_SIZE 0x0080
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/* Do not take i_data_sem locking in ext4_map_blocks */
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#define EXT4_GET_BLOCKS_NO_LOCK 0x0100
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/* Do not put hole in extent cache */
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#define EXT4_GET_BLOCKS_NO_PUT_HOLE 0x0200
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/*
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* Flags used by ext4_free_blocks
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@ -2167,6 +2167,9 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
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block,
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le32_to_cpu(ex->ee_block),
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ext4_ext_get_actual_len(ex));
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if (!ext4_find_delalloc_range(inode, lblock, lblock + len - 1))
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ext4_es_insert_extent(inode, lblock, len, ~0,
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EXTENT_STATUS_HOLE);
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} else if (block >= le32_to_cpu(ex->ee_block)
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+ ext4_ext_get_actual_len(ex)) {
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ext4_lblk_t next;
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@ -2180,6 +2183,9 @@ ext4_ext_put_gap_in_cache(struct inode *inode, struct ext4_ext_path *path,
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block);
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BUG_ON(next == lblock);
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len = next - lblock;
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if (!ext4_find_delalloc_range(inode, lblock, lblock + len - 1))
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ext4_es_insert_extent(inode, lblock, len, ~0,
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EXTENT_STATUS_HOLE);
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} else {
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lblock = len = 0;
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BUG();
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@ -4018,7 +4024,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
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* put just found gap into cache to speed up
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* subsequent requests
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*/
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ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
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if ((flags & EXT4_GET_BLOCKS_NO_PUT_HOLE) == 0)
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ext4_ext_put_gap_in_cache(inode, path, map->m_lblk);
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goto out2;
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}
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@ -461,6 +461,66 @@ int ext4_es_insert_extent(struct inode *inode, ext4_lblk_t lblk,
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return err;
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}
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/*
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* ext4_es_lookup_extent() looks up an extent in extent status tree.
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*
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* ext4_es_lookup_extent is called by ext4_map_blocks/ext4_da_map_blocks.
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*
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* Return: 1 on found, 0 on not
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*/
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int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
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struct extent_status *es)
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{
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struct ext4_es_tree *tree;
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struct extent_status *es1 = NULL;
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struct rb_node *node;
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int found = 0;
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trace_ext4_es_lookup_extent_enter(inode, lblk);
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es_debug("lookup extent in block %u\n", lblk);
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tree = &EXT4_I(inode)->i_es_tree;
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read_lock(&EXT4_I(inode)->i_es_lock);
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/* find extent in cache firstly */
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es->es_lblk = es->es_len = es->es_pblk = 0;
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if (tree->cache_es) {
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es1 = tree->cache_es;
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if (in_range(lblk, es1->es_lblk, es1->es_len)) {
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es_debug("%u cached by [%u/%u)\n",
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lblk, es1->es_lblk, es1->es_len);
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found = 1;
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goto out;
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}
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}
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node = tree->root.rb_node;
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while (node) {
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es1 = rb_entry(node, struct extent_status, rb_node);
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if (lblk < es1->es_lblk)
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node = node->rb_left;
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else if (lblk > ext4_es_end(es1))
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node = node->rb_right;
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else {
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found = 1;
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break;
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}
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}
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out:
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if (found) {
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BUG_ON(!es1);
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es->es_lblk = es1->es_lblk;
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es->es_len = es1->es_len;
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es->es_pblk = es1->es_pblk;
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}
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read_unlock(&EXT4_I(inode)->i_es_lock);
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trace_ext4_es_lookup_extent_exit(inode, es, found);
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return found;
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}
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static int __es_remove_extent(struct ext4_es_tree *tree, ext4_lblk_t lblk,
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ext4_lblk_t end)
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{
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@ -53,6 +53,8 @@ extern int ext4_es_remove_extent(struct inode *inode, ext4_lblk_t lblk,
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ext4_lblk_t len);
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extern void ext4_es_find_delayed_extent(struct inode *inode, ext4_lblk_t lblk,
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struct extent_status *es);
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extern int ext4_es_lookup_extent(struct inode *inode, ext4_lblk_t lblk,
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struct extent_status *es);
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static inline int ext4_es_is_written(struct extent_status *es)
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{
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@ -507,12 +507,33 @@ static pgoff_t ext4_num_dirty_pages(struct inode *inode, pgoff_t idx,
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int ext4_map_blocks(handle_t *handle, struct inode *inode,
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struct ext4_map_blocks *map, int flags)
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{
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struct extent_status es;
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int retval;
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map->m_flags = 0;
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ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
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"logical block %lu\n", inode->i_ino, flags, map->m_len,
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(unsigned long) map->m_lblk);
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/* Lookup extent status tree firstly */
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if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
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if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
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map->m_pblk = ext4_es_pblock(&es) +
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map->m_lblk - es.es_lblk;
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map->m_flags |= ext4_es_is_written(&es) ?
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EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
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retval = es.es_len - (map->m_lblk - es.es_lblk);
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if (retval > map->m_len)
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retval = map->m_len;
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map->m_len = retval;
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} else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
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retval = 0;
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} else {
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BUG_ON(1);
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}
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goto found;
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}
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/*
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* Try to see if we can get the block without requesting a new
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* file system block.
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@ -544,6 +565,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
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if (!(flags & EXT4_GET_BLOCKS_NO_LOCK))
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up_read((&EXT4_I(inode)->i_data_sem));
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found:
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if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
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int ret = check_block_validity(inode, map);
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if (ret != 0)
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@ -1743,6 +1765,7 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
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struct ext4_map_blocks *map,
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struct buffer_head *bh)
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{
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struct extent_status es;
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int retval;
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sector_t invalid_block = ~((sector_t) 0xffff);
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ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
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"logical block %lu\n", inode->i_ino, map->m_len,
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(unsigned long) map->m_lblk);
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/* Lookup extent status tree firstly */
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if (ext4_es_lookup_extent(inode, iblock, &es)) {
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if (ext4_es_is_hole(&es)) {
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retval = 0;
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down_read((&EXT4_I(inode)->i_data_sem));
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goto add_delayed;
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}
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/*
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* Delayed extent could be allocated by fallocate.
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* So we need to check it.
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*/
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if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
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map_bh(bh, inode->i_sb, invalid_block);
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set_buffer_new(bh);
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set_buffer_delay(bh);
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return 0;
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}
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map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
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retval = es.es_len - (iblock - es.es_lblk);
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if (retval > map->m_len)
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retval = map->m_len;
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map->m_len = retval;
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if (ext4_es_is_written(&es))
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map->m_flags |= EXT4_MAP_MAPPED;
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else if (ext4_es_is_unwritten(&es))
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map->m_flags |= EXT4_MAP_UNWRITTEN;
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else
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BUG_ON(1);
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return retval;
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}
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/*
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* Try to see if we can get the block without requesting a new
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* file system block.
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map->m_flags |= EXT4_MAP_FROM_CLUSTER;
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retval = 0;
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} else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
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retval = ext4_ext_map_blocks(NULL, inode, map, 0);
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retval = ext4_ext_map_blocks(NULL, inode, map,
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EXT4_GET_BLOCKS_NO_PUT_HOLE);
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else
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retval = ext4_ind_map_blocks(NULL, inode, map, 0);
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retval = ext4_ind_map_blocks(NULL, inode, map,
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EXT4_GET_BLOCKS_NO_PUT_HOLE);
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add_delayed:
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if (retval == 0) {
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int ret;
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/*
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@ -2199,6 +2199,62 @@ TRACE_EVENT(ext4_es_find_delayed_extent_exit,
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__entry->pblk, __entry->status)
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);
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TRACE_EVENT(ext4_es_lookup_extent_enter,
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TP_PROTO(struct inode *inode, ext4_lblk_t lblk),
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TP_ARGS(inode, lblk),
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TP_STRUCT__entry(
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__field( dev_t, dev )
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__field( ino_t, ino )
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__field( ext4_lblk_t, lblk )
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),
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TP_fast_assign(
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__entry->dev = inode->i_sb->s_dev;
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__entry->ino = inode->i_ino;
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__entry->lblk = lblk;
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),
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TP_printk("dev %d,%d ino %lu lblk %u",
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MAJOR(__entry->dev), MINOR(__entry->dev),
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(unsigned long) __entry->ino, __entry->lblk)
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);
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TRACE_EVENT(ext4_es_lookup_extent_exit,
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TP_PROTO(struct inode *inode, struct extent_status *es,
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int found),
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TP_ARGS(inode, es, found),
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TP_STRUCT__entry(
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__field( dev_t, dev )
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__field( ino_t, ino )
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__field( ext4_lblk_t, lblk )
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__field( ext4_lblk_t, len )
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__field( ext4_fsblk_t, pblk )
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__field( unsigned long long, status )
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__field( int, found )
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),
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TP_fast_assign(
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__entry->dev = inode->i_sb->s_dev;
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__entry->ino = inode->i_ino;
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__entry->lblk = es->es_lblk;
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__entry->len = es->es_len;
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__entry->pblk = ext4_es_pblock(es);
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__entry->status = ext4_es_status(es);
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__entry->found = found;
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),
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TP_printk("dev %d,%d ino %lu found %d [%u/%u) %llu %llx",
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MAJOR(__entry->dev), MINOR(__entry->dev),
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(unsigned long) __entry->ino, __entry->found,
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__entry->lblk, __entry->len,
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__entry->found ? __entry->pblk : 0,
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__entry->found ? __entry->status : 0)
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);
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#endif /* _TRACE_EXT4_H */
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/* This part must be outside protection */
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