132 lines
3.9 KiB
Diff
132 lines
3.9 KiB
Diff
From eea2fb4851e9dcbab6b991aaf47e2e024f1f55a0 Mon Sep 17 00:00:00 2001
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From: Miklos Szeredi <mszeredi@redhat.com>
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Date: Thu, 1 Sep 2016 11:11:59 +0200
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Subject: [PATCH] ovl: proper cleanup of workdir
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When mounting overlayfs it needs a clean "work" directory under the
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supplied workdir.
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Previously the mount code removed this directory if it already existed and
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created a new one. If the removal failed (e.g. directory was not empty)
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then it fell back to a read-only mount not using the workdir.
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While this has never been reported, it is possible to get a non-empty
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"work" dir from a previous mount of overlayfs in case of crash in the
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middle of an operation using the work directory.
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In this case the left over state should be discarded and the overlay
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filesystem will be consistent, guaranteed by the atomicity of operations on
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moving to/from the workdir to the upper layer.
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This patch implements cleaning out any files left in workdir. It is
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implemented using real recursion for simplicity, but the depth is limited
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to 2, because the worst case is that of a directory containing whiteouts
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under "work".
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Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Cc: <stable@vger.kernel.org>
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---
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fs/overlayfs/overlayfs.h | 2 ++
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fs/overlayfs/readdir.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++-
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fs/overlayfs/super.c | 2 +-
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3 files changed, 65 insertions(+), 2 deletions(-)
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--- a/fs/overlayfs/overlayfs.h
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+++ b/fs/overlayfs/overlayfs.h
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@@ -164,6 +164,8 @@ extern const struct file_operations ovl_
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int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
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void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list);
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void ovl_cache_free(struct list_head *list);
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+void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
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+ struct dentry *dentry, int level);
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/* inode.c */
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int ovl_setattr(struct dentry *dentry, struct iattr *attr);
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--- a/fs/overlayfs/readdir.c
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+++ b/fs/overlayfs/readdir.c
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@@ -247,7 +247,7 @@ static inline int ovl_dir_read(struct pa
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err = rdd->err;
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} while (!err && rdd->count);
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- if (!err && rdd->first_maybe_whiteout)
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+ if (!err && rdd->first_maybe_whiteout && rdd->dentry)
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err = ovl_check_whiteouts(realpath->dentry, rdd);
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fput(realfile);
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@@ -573,3 +573,64 @@ void ovl_cleanup_whiteouts(struct dentry
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}
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mutex_unlock(&upper->d_inode->i_mutex);
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}
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+
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+static void ovl_workdir_cleanup_recurse(struct path *path, int level)
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+{
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+ int err;
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+ struct inode *dir = path->dentry->d_inode;
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+ LIST_HEAD(list);
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+ struct ovl_cache_entry *p;
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+ struct ovl_readdir_data rdd = {
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+ .ctx.actor = ovl_fill_merge,
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+ .dentry = NULL,
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+ .list = &list,
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+ .root = RB_ROOT,
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+ .is_lowest = false,
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+ };
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+
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+ err = ovl_dir_read(path, &rdd);
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+ if (err)
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+ goto out;
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+
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+ mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
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+ list_for_each_entry(p, &list, l_node) {
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+ struct dentry *dentry;
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+
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+ if (p->name[0] == '.') {
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+ if (p->len == 1)
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+ continue;
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+ if (p->len == 2 && p->name[1] == '.')
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+ continue;
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+ }
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+ dentry = lookup_one_len(p->name, path->dentry, p->len);
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+ if (IS_ERR(dentry))
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+ continue;
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+ if (dentry->d_inode)
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+ ovl_workdir_cleanup(dir, path->mnt, dentry, level);
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+ dput(dentry);
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+ }
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+ mutex_unlock(&dir->i_mutex);
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+out:
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+ ovl_cache_free(&list);
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+}
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+
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+void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
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+ struct dentry *dentry, int level)
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+{
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+ int err;
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+
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+ if (!d_is_dir(dentry) || level > 1) {
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+ ovl_cleanup(dir, dentry);
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+ return;
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+ }
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+
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+ err = ovl_do_rmdir(dir, dentry);
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+ if (err) {
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+ struct path path = { .mnt = mnt, .dentry = dentry };
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+
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+ mutex_unlock(&dir->i_mutex);
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+ ovl_workdir_cleanup_recurse(&path, level + 1);
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+ mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
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+ ovl_cleanup(dir, dentry);
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+ }
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+}
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--- a/fs/overlayfs/super.c
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+++ b/fs/overlayfs/super.c
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@@ -784,7 +784,7 @@ retry:
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goto out_dput;
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retried = true;
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- ovl_cleanup(dir, work);
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+ ovl_workdir_cleanup(dir, mnt, work, 0);
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dput(work);
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goto retry;
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}
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