Now that copy up of regular file is done using O_TMPFILE,
we don't need to hold rename_lock throughout copy up.
Use the copy up waitqueue to synchronize concurrent copy up
of the same file. Different regular files can be copied up
concurrently.
The upper dir inode_lock is taken instead of rename_lock,
because it is needed for lookup and later for linking the
temp file, but it is released while copying up data.
Suggested-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/copy_up.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index d3b6c15..ddf5e2d 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -291,7 +291,14 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
BUG_ON(upperpath.dentry != NULL);
upperpath.dentry = temp;
+ if (tmpfile)
+ inode_unlock(udir);
+
err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
+
+ if (tmpfile)
+ inode_lock_nested(udir, I_MUTEX_PARENT);
+
if (err)
goto out_cleanup;
}
@@ -371,6 +378,19 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
return PTR_ERR(link);
}
+ if (tmpfile) {
+ err = ovl_copy_up_start(dentry);
+ /* err < 0: interrupted, err > 0: raced with another copy-up */
+ if (unlikely(err)) {
+ pr_debug("ovl_copy_up_start(%pd2) = %i\n", dentry, err);
+ if (err > 0)
+ err = 0;
+ goto out_done;
+ }
+ /* lock_rename/unlock_rename will lock/unlock only upperdir */
+ workdir = upperdir;
+ }
+
err = -EIO;
if (lock_rename(workdir, upperdir) != NULL) {
pr_err("overlayfs: failed to lock workdir+upperdir\n");
@@ -390,6 +410,9 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
}
out_unlock:
unlock_rename(workdir, upperdir);
+ if (tmpfile)
+ ovl_copy_up_end(dentry);
+out_done:
do_delayed_call(&done);
return err;
--
2.7.4
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