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Commit 01ad3eb8 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
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ovl: concurrent copy up of regular files 



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: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 39d3d60a

fs/overlayfs/copy_up.c

+31 −4
Original line number Diff line number Diff line
@@ -291,7 +291,16 @@ static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir, 
		BUG_ON(upperpath.dentry != NULL);

		upperpath.dentry = temp;



		err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);

		if (tmpfile) {

			inode_unlock(udir);

			err = ovl_copy_up_data(lowerpath, &upperpath,

					       stat->size);

			inode_lock_nested(udir, I_MUTEX_PARENT);

		} else {

			err = ovl_copy_up_data(lowerpath, &upperpath,

					       stat->size);

		}



		if (err)

			goto out_cleanup;

	}
@@ -353,8 +362,6 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
	struct dentry *upperdir;

	const char *link = NULL;

	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;

	/* Should we copyup with O_TMPFILE or with workdir? */

	bool tmpfile = S_ISREG(stat->mode) && ofs->tmpfile;



	if (WARN_ON(!workdir))

		return -EROFS;
@@ -374,6 +381,25 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
			return PTR_ERR(link);

	}



	/* Should we copyup with O_TMPFILE or with workdir? */

	if (S_ISREG(stat->mode) && ofs->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;

		}



		inode_lock_nested(upperdir->d_inode, I_MUTEX_PARENT);

		err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,

					 stat, link, &pstat, true);

		inode_unlock(upperdir->d_inode);

		ovl_copy_up_end(dentry);

		goto out_done;

	}



	err = -EIO;

	if (lock_rename(workdir, upperdir) != NULL) {

		pr_err("overlayfs: failed to lock workdir+upperdir\n");
@@ -386,9 +412,10 @@ static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry, 
	}



	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,

				 stat, link, &pstat, tmpfile);

				 stat, link, &pstat, false);

out_unlock:

	unlock_rename(workdir, upperdir);

out_done:

	do_delayed_call(&done);



	return err;