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ovl: use vfs_clone_file_range() for copy up if possible 

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.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2016-09-23 11:38:12 +03:00 committed by Miklos Szeredi
parent 31c3a70695
commit 2ea9846649
1 changed files with 8 additions and 1 deletions
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9
fs/overlayfs/copy_up.c
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@ -153,6 +153,13 @@ 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;
@ -177,7 +184,7 @@ static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
len -= bytes;
}
out:
if (!error)
error = vfs_fsync(new_file, 0);
fput(new_file);