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Commit 35075bb0 authored by Alexander Block's avatar Alexander Block Committed by Chris Mason
Browse files

Btrfs: use kmalloc instead of stack for backref_ctx 



Make sure to never get in trouble due to the backref_ctx
which was on the stack before.

Commit is a result of Arne's review.

Signed-off-by: default avatarAlexander Block <ablock84@googlemail.com>
parent ee849c04

fs/btrfs/send.c

+18 −11
Original line number Diff line number Diff line
@@ -1149,7 +1149,7 @@ static int find_extent_clone(struct send_ctx *sctx, 
	u64 extent_item_pos;

	struct btrfs_file_extent_item *fi;

	struct extent_buffer *eb = path->nodes[0];

	struct backref_ctx backref_ctx;

	struct backref_ctx *backref_ctx = NULL;

	struct clone_root *cur_clone_root;

	struct btrfs_key found_key;

	struct btrfs_path *tmp_path;
@@ -1159,6 +1159,12 @@ static int find_extent_clone(struct send_ctx *sctx, 
	if (!tmp_path)

		return -ENOMEM;



	backref_ctx = kmalloc(sizeof(*backref_ctx), GFP_NOFS);

	if (!backref_ctx) {

		ret = -ENOMEM;

		goto out;

	}



	if (data_offset >= ino_size) {

		/*

		 * There may be extents that lie behind the file's size.
@@ -1206,12 +1212,12 @@ static int find_extent_clone(struct send_ctx *sctx, 
		cur_clone_root->found_refs = 0;

	}



	backref_ctx.sctx = sctx;

	backref_ctx.found = 0;

	backref_ctx.cur_objectid = ino;

	backref_ctx.cur_offset = data_offset;

	backref_ctx.found_itself = 0;

	backref_ctx.extent_len = num_bytes;

	backref_ctx->sctx = sctx;

	backref_ctx->found = 0;

	backref_ctx->cur_objectid = ino;

	backref_ctx->cur_offset = data_offset;

	backref_ctx->found_itself = 0;

	backref_ctx->extent_len = num_bytes;



	/*

	 * The last extent of a file may be too large due to page alignment.
@@ -1219,7 +1225,7 @@ static int find_extent_clone(struct send_ctx *sctx, 
	 * __iterate_backrefs work.

	 */

	if (data_offset + num_bytes >= ino_size)

		backref_ctx.extent_len = ino_size - data_offset;

		backref_ctx->extent_len = ino_size - data_offset;



	/*

	 * Now collect all backrefs.
@@ -1227,11 +1233,11 @@ static int find_extent_clone(struct send_ctx *sctx, 
	extent_item_pos = logical - found_key.objectid;

	ret = iterate_extent_inodes(sctx->send_root->fs_info,

					found_key.objectid, extent_item_pos, 1,

					__iterate_backrefs, &backref_ctx);

					__iterate_backrefs, backref_ctx);

	if (ret < 0)

		goto out;



	if (!backref_ctx.found_itself) {

	if (!backref_ctx->found_itself) {

		/* found a bug in backref code? */

		ret = -EIO;

		printk(KERN_ERR "btrfs: ERROR did not find backref in "
@@ -1246,7 +1252,7 @@ verbose_printk(KERN_DEBUG "btrfs: find_extent_clone: data_offset=%llu, " 
		"num_bytes=%llu, logical=%llu\n",

		data_offset, ino, num_bytes, logical);



	if (!backref_ctx.found)

	if (!backref_ctx->found)

		verbose_printk("btrfs:    no clones found\n");



	cur_clone_root = NULL;
@@ -1271,6 +1277,7 @@ verbose_printk(KERN_DEBUG "btrfs: find_extent_clone: data_offset=%llu, " 


out:

	btrfs_free_path(tmp_path);

	kfree(backref_ctx);

	return ret;

}