Thread (7 messages) 7 messages, 2 authors, 2016-03-15

Re: [PATCH 1/2] man2: document FICLONE and FICLONERANGE

From: Darrick J. Wong <hidden>
Date: 2016-01-28 19:18:46
Also in: linux-fsdevel, linux-man

On Thu, Jan 28, 2016 at 05:33:29AM -0800, Christoph Hellwig wrote:
Now that we have this in 4.5-rc1 let's get this into man-pages as well.
quoted
--- /dev/null
+++ b/man2/ioctl_ficlone.2
think this should be a link to the clone range man page, and the
both ioctls should be documented together.  Basically just document
FICLONERANGE and then mentiond that FICLONE does a whole file clone.
Ok, that's an easy switch to make.
quoted
+.B #include <sys/ioctl.h>
Don't we need uapi/linux/fs.h as well?
Err... yes. :)
quoted
Not all filesystems support
+overlapping reflink ranges in the same file.
Which one doesn't?
At the moment, neither btrfs nor XFS support it.

I don't think it'd be difficult for XFS (make a copy of the extent mappings in
the source area, increase the refcounts of those blocks, do the usual
punch-and-remap, then delete & decrement that copy of the mappings) but that
can come later.
Also there should be a sentence that the clones are atomic vs
concurrent writes, so no locks need to be taken for a consistent
snapshot.
<nod>

I've updated the manpages and will repush the patchset ... optimistically,
when XFS reflink RFCv5 comes out, but sooner if anyone requests it. :)

Thank you for the review!

--D
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