Commit 1939dd84 authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Theodore Ts'o
Browse files

ext4: cleanup ext4_ext_grow_indepth code 



Currently code make an impression what grow procedure is very complicated
and some mythical paths, blocks are involved. But in fact grow in depth
it relatively simple procedure:
 1) Just create new meta block and copy root data to that block.
 2) Convert root from extent to index if old depth == 0
 3) Update root block pointer

This patch does:
 - Reorganize code to make it more self explanatory
 - Do not pass path parameter to new_meta_block() in order to
   provoke allocation from inode's group because top-level block
   should site closer to it's inode, but not to leaf data block.

   [ This happens anyway, due to logic in mballoc; we should drop
     the path parameter from new_meta_block() entirely.  -- tytso ]

Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 45dc63e7

fs/ext4/extents.c

+15 −26
Original line number Diff line number Diff line
@@ -1050,16 +1050,14 @@ cleanup: 
 */

static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,

				 unsigned int flags,

				 struct ext4_ext_path *path,

				 struct ext4_extent *newext)

{

	struct ext4_ext_path *curp = path;

	struct ext4_extent_header *neh;

	struct buffer_head *bh;

	ext4_fsblk_t newblock;

	int err = 0;



	newblock = ext4_ext_new_meta_block(handle, inode, path,

	newblock = ext4_ext_new_meta_block(handle, inode, NULL,

		newext, &err, flags);

	if (newblock == 0)

		return err;
@@ -1079,7 +1077,8 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode, 
	}



	/* move top-level index/leaf into new block */

	memmove(bh->b_data, curp->p_hdr, sizeof(EXT4_I(inode)->i_data));

	memmove(bh->b_data, EXT4_I(inode)->i_data,

		sizeof(EXT4_I(inode)->i_data));



	/* set size of new block */

	neh = ext_block_hdr(bh);
@@ -1097,32 +1096,23 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode, 
	if (err)

		goto out;



	/* create index in new top-level index: num,max,pointer */

	err = ext4_ext_get_access(handle, inode, curp);

	if (err)

		goto out;



	curp->p_hdr->eh_magic = EXT4_EXT_MAGIC;

	curp->p_hdr->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));

	curp->p_hdr->eh_entries = cpu_to_le16(1);

	curp->p_idx = EXT_FIRST_INDEX(curp->p_hdr);



	if (path[0].p_hdr->eh_depth)

		curp->p_idx->ei_block =

			EXT_FIRST_INDEX(path[0].p_hdr)->ei_block;

	else

		curp->p_idx->ei_block =

			EXT_FIRST_EXTENT(path[0].p_hdr)->ee_block;

	ext4_idx_store_pblock(curp->p_idx, newblock);



	/* Update top-level index: num,max,pointer */

	neh = ext_inode_hdr(inode);

	neh->eh_entries = cpu_to_le16(1);

	ext4_idx_store_pblock(EXT_FIRST_INDEX(neh), newblock);

	if (neh->eh_depth == 0) {

		/* Root extent block becomes index block */

		neh->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));

		EXT_FIRST_INDEX(neh)->ei_block =

			EXT_FIRST_EXTENT(neh)->ee_block;

	}

	ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",

		  le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),

		  le32_to_cpu(EXT_FIRST_INDEX(neh)->ei_block),

		  ext4_idx_pblock(EXT_FIRST_INDEX(neh)));



	neh->eh_depth = cpu_to_le16(path->p_depth + 1);

	err = ext4_ext_dirty(handle, inode, curp);

	neh->eh_depth = cpu_to_le16(neh->eh_depth + 1);

	ext4_mark_inode_dirty(handle, inode);

out:

	brelse(bh);
@@ -1170,8 +1160,7 @@ repeat: 
			err = PTR_ERR(path);

	} else {

		/* tree is full, time to grow in depth */

		err = ext4_ext_grow_indepth(handle, inode, flags,

					    path, newext);

		err = ext4_ext_grow_indepth(handle, inode, flags, newext);

		if (err)

			goto out;

CRA Git | Maintained and supported by SUSTech CRA and CCSE