When copying up within the same fs, try to use vfs_clone_file_range().
This is very efficient when lower and upper are on the same fs
with file reflink support. If vfs_clone_file_range() fails for any
reason, copy up falls back to the regular data copy code.
Tested correct behavior when lower and upper are on:
1. same ext4 (copy)
2. same xfs + reflink patches + mkfs.xfs (copy)
3. same xfs + reflink patches + mkfs.xfs -m reflink=1 (reflink)
4. different xfs + reflink patches + mkfs.xfs -m reflink=1 (copy)
For comparison, on my laptop, xfstest overlay/001 (copy up of large
sparse files) takes less than 1 second in the xfs reflink setup vs.
25 seconds on the rest of the setups.
Acked-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/copy_up.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 43fdc27..93f0a34 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -136,6 +136,13 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
goto out_fput;
}
+ /* Try to use clone_file_range to clone up within the same fs */
+ error = vfs_clone_file_range(old_file, 0, new_file, 0, len);
+ if (!error)
+ goto out;
+ /* Couldn't clone, so now we try to copy the data */
+ error = 0;
+
/* FIXME: copy up sparse files efficiently */
while (len) {
size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
@@ -161,6 +168,7 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
len -= bytes;
}
+out:
fput(new_file);
out_fput:
fput(old_file);
--
2.7.4
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