On 6.08.19 г. 13:09 ч., Filipe Manana wrote:
> On Mon, Aug 5, 2019 at 3:48 PM Nikolay Borisov <nbori...@suse.com> wrote:
<snip>
>> @@ -1371,23 +1376,39 @@ static noinline int run_delalloc_nocow(struct inode
>> *inode,
>>
>> btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
>>
>> + /* Didn't find anything for our INO */
>> if (found_key.objectid > ino)
>> break;
>> + /*
>> + * Found a different inode or no extents for our file,
>> + * goto next slot
>
> No. This does not mean that there are no extents for the file. If
> there weren't any, we would break instead of iterating to the next
> slot.
> One example described at
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1d512cb77bdbda80f0dd0620a3b260d697fd581d
I see, thanks for the pointer. How about the following :
/*
* Keep searching until we find an EXTENT ITEM or are
sure
* there are no more extents for this inode
*/
While it doesn't mention the race condition this check, coupled with the
next one (where we break if type > EXTENT_DATA_KEY), it reflects reality
close enough?
>
>> + */
>> if (WARN_ON_ONCE(found_key.objectid < ino) ||
>> found_key.type < BTRFS_EXTENT_DATA_KEY) {
>> path->slots[0]++;
>> goto next_slot;
>> }
>> +
>> + /* Found key is not EXTENT_DATA_KEY or starts after req
>> range */
>> if (found_key.type > BTRFS_EXTENT_DATA_KEY ||
>> found_key.offset > end)
>> break;
>>
>> + /*
>> + * If the found extent starts after requested offset, then
>> + * adjust extent_end to be right before this extent begins
>> + */
>> if (found_key.offset > cur_offset) {
>> extent_end = found_key.offset;
>> extent_type = 0;
>> goto out_check;
>> }
>>
>> +
>> + /*
>> + * Found extent which begins before our range and has the
>> + * potential to intersect it.
>> + */
>> fi = btrfs_item_ptr(leaf, path->slots[0],
>> struct btrfs_file_extent_item);
>> extent_type = btrfs_file_extent_type(leaf, fi);
<snip>
