On Thu, Apr 20, 2017 at 10:09:39AM +0800, Qu Wenruo wrote: > >>> If I understand it correctly, what it's missing currently is 'merge', a > >>> straightfoward idea is to make use of the 'merge' ability of > >>> btrfs_get_extent. > > >>> Since btrfs_get_extent_fiemap is a wrapper of btrfs_get_extent, does it > >>> make > >>> sense if we make btrfs_get_extent_fiemap iterate all extent maps within > >>> the > >>> range passing to it or just one more extent map to check if > >>> btrfs_get_extent > >>> could return a merged extent map before returning? > >> > >> So your idea to to do the merging inside btrfs_get_extent(), instead of > >> merging it in extent_fiemap()? > >> > > > > No, merge ems inside the wrapper, ie. btrfs_get_extent_fiemap(). > > Then llseek() with SEEK_HOLE/SEEK_DATA also get affected.
Agreed, unconditionally reading all extents inside seek would need to be evaluated first. Limiting the scope to the fiemap ioctl is safer. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
