Commit 10809df8 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: teach ext4_ext_find_extent() to realloc path if necessary 



This adds additional safety in case for some reason we end reusing a
path structure which isn't big enough for current depth of the inode.

Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent b7ea89ad

fs/ext4/ext4_extents.h

+1 −0
Original line number Diff line number Diff line
@@ -123,6 +123,7 @@ find_ext4_extent_tail(struct ext4_extent_header *eh) 
struct ext4_ext_path {

	ext4_fsblk_t			p_block;

	__u16				p_depth;

	__u16				p_maxdepth;

	struct ext4_extent		*p_ext;

	struct ext4_extent_idx		*p_idx;

	struct ext4_extent_header	*p_hdr;

fs/ext4/extents.c

+10 −10
Original line number Diff line number Diff line
@@ -869,14 +869,20 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block, 
	eh = ext_inode_hdr(inode);

	depth = ext_depth(inode);



	if (path)

	if (path) {

		ext4_ext_drop_refs(path);

	else {

		if (depth > path[0].p_maxdepth) {

			kfree(path);

			*orig_path = path = NULL;

		}

	}

	if (!path) {

		/* account possible depth increase */

		path = kzalloc(sizeof(struct ext4_ext_path) * (depth + 2),

				GFP_NOFS);

		if (unlikely(!path))

			return ERR_PTR(-ENOMEM);

		path[0].p_maxdepth = depth + 1;

	}

	path[0].p_hdr = eh;

	path[0].p_bh = NULL;
@@ -1820,6 +1826,7 @@ static void ext4_ext_try_to_merge_up(handle_t *handle, 
		sizeof(struct ext4_extent_idx);

	s += sizeof(struct ext4_extent_header);



	path[1].p_maxdepth = path[0].p_maxdepth;

	memcpy(path[0].p_hdr, path[1].p_hdr, s);

	path[0].p_depth = 0;

	path[0].p_ext = EXT_FIRST_EXTENT(path[0].p_hdr) +
@@ -2150,12 +2157,6 @@ static int ext4_fill_fiemap_extents(struct inode *inode, 
		/* find extent for this block */

		down_read(&EXT4_I(inode)->i_data_sem);



		if (path && ext_depth(inode) != depth) {

			/* depth was changed. we have to realloc path */

			kfree(path);

			path = NULL;

		}



		path = ext4_ext_find_extent(inode, block, &path, 0);

		if (IS_ERR(path)) {

			up_read(&EXT4_I(inode)->i_data_sem);
@@ -2173,7 +2174,6 @@ static int ext4_fill_fiemap_extents(struct inode *inode, 
		}

		ex = path[depth].p_ext;

		next = ext4_ext_next_allocated_block(path);

		ext4_ext_drop_refs(path);



		flags = 0;

		exists = 0;
@@ -2897,7 +2897,7 @@ int ext4_ext_remove_space(struct inode *inode, ext4_lblk_t start, 
			ext4_journal_stop(handle);

			return -ENOMEM;

		}

		path[0].p_depth = depth;

		path[0].p_maxdepth = path[0].p_depth = depth;

		path[0].p_hdr = ext_inode_hdr(inode);

		i = 0;