Btrfs: fix file extent corruption (62fe51c1) · Commits · 戴 / test

In order to do hole punching we have a block reserve to hold the reservation we need to drop the extents in our range. Since we could end up dropping a lot of extents we set rsv->failfast so we can just loop around again and drop the remaining of the range. Unfortunately we unconditionally fill the hole extents in and start from the last extent we encountered, which we may or may not have dropped. So this can result in overlapping file extent entries, which can be tripped over in a variety of ways, either by hitting BUG_ON(!ret) in fill_holes() after the search, or in btrfs_set_item_key_safe() in btrfs_drop_extent() at a later time by an unrelated task. Fix this by only setting drop_end to the last extent we did actually drop. This way our holes are filled in properly for the range that we did drop, and the rest of the range that remains to be dropped is actually dropped. Thanks, Signed-off-by:

Josef Bacik <jbacik@fb.com> Signed-off-by:

David Sterba <dsterba@suse.com>

fs/btrfs/file.c

+12 −3

Original line number	Diff line number	Diff line
		@@ -705,6 +705,7 @@ int __btrfs_drop_extents(struct btrfs_trans_handle *trans,
		u64 num_bytes = 0;
		u64 extent_offset = 0;
		u64 extent_end = 0;
		u64 last_end = start;
		int del_nr = 0;
		int del_slot = 0;
		int extent_type;
		@@ -796,8 +797,10 @@ next_slot:
		* extent item in the call to setup_items_for_insert() later
		* in this function.
		*/
		if (extent_end == key.offset && extent_end >= search_start)
		if (extent_end == key.offset && extent_end >= search_start) {
		last_end = extent_end;
		goto delete_extent_item;
		}

		if (extent_end <= search_start) {
		path->slots[0]++;
		@@ -859,6 +862,12 @@ next_slot:
		}
		key.offset = start;
		}
		/*
		* From here on out we will have actually dropped something, so
		* last_end can be updated.
		*/
		last_end = extent_end;

		/*
		* \| ---- range to drop ----- \|
		* \| -------- extent -------- \|
		@@ -1009,7 +1018,7 @@ delete_extent_item:
		if (!replace_extent \|\| !(*key_inserted))
		btrfs_release_path(path);
		if (drop_end)
		*drop_end = found ? min(end, extent_end) : end;
		*drop_end = found ? min(end, last_end) : end;
		return ret;
		}

		@@ -2524,7 +2533,7 @@ static int btrfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)

		trans->block_rsv = &root->fs_info->trans_block_rsv;

		if (cur_offset < ino_size) {
		if (cur_offset < drop_end && cur_offset < ino_size) {
		ret = fill_holes(trans, inode, path, cur_offset,
		drop_end);
		if (ret) {

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