Hi, Thanks for responses. I actually need the physical addresses. FIEMAP I believe (and I tested) gives logical address which as Andrei mentioned is useless. I'm assuming btfs-debug-tree gives the physical addresses right? I also need to know the compression method used on each extent and I don't think I can get that with the fiemap stuff. It seems that fiemap capability is not implemented in Btrfs as I'm looking at the Btrfs implementation and based on documentation of fiemap:
"File systems wishing to support fiemap must implement a ->fiemap callback on their inode_operations structure. The fs ->fiemap call is responsible for defining its set of supported fiemap flags, and calling a helper function on each discovered extent:" Thanks, Amin. On Wed, Apr 12, 2017 at 9:44 AM, Andrei Borzenkov <arvidj...@gmail.com> wrote: > 12.04.2017 14:20, Austin S. Hemmelgarn пишет: >> On 2017-04-12 00:18, Chris Murphy wrote: >>> On Tue, Apr 11, 2017 at 3:00 PM, Adam Borowski <kilob...@angband.pl> >>> wrote: >>>> On Tue, Apr 11, 2017 at 12:15:32PM -0700, Amin Hassani wrote: >>>>> I am working on a project with Btrfs and I was wondering if there is >>>>> any way to see the disk layout of the btrfs image. Let's assume I have >>>>> a read-only btrfs image with compression on and only using one disk >>>>> (no raid or anything). Is it possible to get a set of offset-lengths >>>>> for each file >>>> >>>> While btrfs-specific ioctls give more information, you might want to >>>> look at >>>> FIEMAP (Documentation/filesystems/fiemap.txt) as it works on most >>>> filesystems, not just btrfs. One interface to FIEMAP is provided in >>>> "/usr/sbin/filefrag -v". >>> >>> Good idea. Although, on Btrfs I'm pretty sure it reports the Btrfs >>> (internal) logical addressing; not the actual physical sector address >>> on the drive. So it depends on what the original poster is trying to >>> discover. >>> >> That said, there is a tool to translate that back, and depending on how >> detailed you want to get, that may be more efficient than debug tree. > > Could you give pointer to this tool? I use filefrag on bootinfoscript to > display physical disk offset of files of interest to bootloader. I was > not aware it shows logical offset which makes it kinda pointless. -- Amin Hassani. -- 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
