Logical to Physical Address Mapping/Translation in Btrfs

[<saranyag@cdac.in>]

Hi,

May I know how the logical address is translated to the physical address in
Btrfs?

I have read the official documentation of Btrfs available here
(https://btrfs.readthedocs.io/en/latest/Introduction.html). It is not
covering the address translation part in detail.

I have also gone through the Btrfs source code
(https://github.com/torvalds/linux/tree/master/fs/btrfs). I could not figure
out the address translation from the code also.

After referring to the following functions, what I could understand is that
after getting the logical address of Chunk tree root from the superblock, we
need to convert it into the corresponding physical address for parsing into
the next level. 

int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices
*fs_devices, char *options)

int btrfs_read_chunk_tree(struct btrfs_fs_info *fs_info)

static int read_one_chunk(struct btrfs_key *key, struct extent_buffer
*leaf,  struct btrfs_chunk *chunk)

Any hints or pointers to the documentation on this is greatly appreciated.
I want to know the implementation part in btrfs-progs/source code.

Thanks in advance
Saranya G
CDAC



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