On 2017年09月11日 14:05, shally verma wrote:
I was going through BTRFS Deduplication page
(https://btrfs.wiki.kernel.org/index.php/Deduplication) and I read
"As such, xfs_io, is able to perform deduplication on a BTRFS file system," ..
following this, I followed on to xfs_io link https://linux.die.net/man/8/xfs_io
As I understand, these are set of commands allow us to do different
operations on "xfs" filesystem.
Nope, it's just a tool triggering different read/write or ioctls.
In fact most of its command is fs independent.
Only a limited number of operations are only supported by XFS.
It's just due to historical reasons it's still named as xfs_io.
I won't be surprised if one day it's split as an independent tool.
and command set mentioned here, couldn't see which is command to
invoke dedupe task.
"dedupe" and "reflink" command.
and how this works with BTRFS.
Fs support FIDEDUPERANGE or BTRFS_IOC_FILE_EXTENT_SAME ioctl can use it
to determine if two ranges are containing identical data.
And if they are identical, we use FICLONERANGE or BTRFS_IOC_CLONE_RANGE
ioctl to reflink one to another, freeing one of them.
BTW nowadays, such dedupe and reflink ioctl is genericized in VFS.
file_operations structure now includes both clone_file_range() and
dedupe_file_range() callbacks now.
Thanks,
Qu
So, can anyone help here and point me what am I missing here.
Thanks
Shally
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