ovl: whiteout index when union nlink drops to zero
With NFS export feature enabled, when overlay inode nlink drops to
zero, instead of removing the index entry, replace it with a whiteout
index entry.
This is needed for NFS export in order to prevent future open by handle
from opening the lower file directly.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index a1a7606..839709c 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -63,8 +63,7 @@ struct dentry *ovl_lookup_temp(struct dentry *workdir)
}
/* caller holds i_mutex on workdir */
-static struct dentry *ovl_whiteout(struct dentry *workdir,
- struct dentry *dentry)
+static struct dentry *ovl_whiteout(struct dentry *workdir)
{
int err;
struct dentry *whiteout;
@@ -83,6 +82,38 @@ static struct dentry *ovl_whiteout(struct dentry *workdir,
return whiteout;
}
+/* Caller must hold i_mutex on both workdir and dir */
+int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
+ struct dentry *dentry)
+{
+ struct inode *wdir = workdir->d_inode;
+ struct dentry *whiteout;
+ int err;
+ int flags = 0;
+
+ whiteout = ovl_whiteout(workdir);
+ err = PTR_ERR(whiteout);
+ if (IS_ERR(whiteout))
+ return err;
+
+ if (d_is_dir(dentry))
+ flags = RENAME_EXCHANGE;
+
+ err = ovl_do_rename(wdir, whiteout, dir, dentry, flags);
+ if (err)
+ goto kill_whiteout;
+ if (flags)
+ ovl_cleanup(wdir, dentry);
+
+out:
+ dput(whiteout);
+ return err;
+
+kill_whiteout:
+ ovl_cleanup(wdir, whiteout);
+ goto out;
+}
+
int ovl_create_real(struct inode *dir, struct dentry *newdentry,
struct cattr *attr, struct dentry *hardlink, bool debug)
{
@@ -591,14 +622,10 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
struct list_head *list)
{
struct dentry *workdir = ovl_workdir(dentry);
- struct inode *wdir = workdir->d_inode;
struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
- struct inode *udir = upperdir->d_inode;
- struct dentry *whiteout;
struct dentry *upper;
struct dentry *opaquedir = NULL;
int err;
- int flags = 0;
if (WARN_ON(!workdir))
return -EROFS;
@@ -627,24 +654,13 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
goto out_dput_upper;
}
- whiteout = ovl_whiteout(workdir, dentry);
- err = PTR_ERR(whiteout);
- if (IS_ERR(whiteout))
- goto out_dput_upper;
-
- if (d_is_dir(upper))
- flags = RENAME_EXCHANGE;
-
- err = ovl_do_rename(wdir, whiteout, udir, upper, flags);
+ err = ovl_cleanup_and_whiteout(workdir, d_inode(upperdir), upper);
if (err)
- goto kill_whiteout;
- if (flags)
- ovl_cleanup(wdir, upper);
+ goto out_d_drop;
ovl_dentry_version_inc(dentry->d_parent, true);
out_d_drop:
d_drop(dentry);
- dput(whiteout);
out_dput_upper:
dput(upper);
out_unlock:
@@ -653,10 +669,6 @@ static int ovl_remove_and_whiteout(struct dentry *dentry,
dput(opaquedir);
out:
return err;
-
-kill_whiteout:
- ovl_cleanup(wdir, whiteout);
- goto out_d_drop;
}
static int ovl_remove_upper(struct dentry *dentry, bool is_dir,
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index d7e6528..8f4313c 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -321,6 +321,8 @@ static inline void ovl_copyattr(struct inode *from, struct inode *to)
/* dir.c */
extern const struct inode_operations ovl_dir_inode_operations;
struct dentry *ovl_lookup_temp(struct dentry *workdir);
+int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
+ struct dentry *dentry);
struct cattr {
dev_t rdev;
umode_t mode;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 6b11e11..aa2234d 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -487,7 +487,8 @@ bool ovl_need_index(struct dentry *dentry)
/* Caller must hold OVL_I(inode)->lock */
static void ovl_cleanup_index(struct dentry *dentry)
{
- struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode;
+ struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
+ struct inode *dir = indexdir->d_inode;
struct dentry *lowerdentry = ovl_dentry_lower(dentry);
struct dentry *upperdentry = ovl_dentry_upper(dentry);
struct dentry *index = NULL;
@@ -518,13 +519,17 @@ static void ovl_cleanup_index(struct dentry *dentry)
}
inode_lock_nested(dir, I_MUTEX_PARENT);
- /* TODO: whiteout instead of cleanup to block future open by handle */
- index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len);
+ index = lookup_one_len(name.name, indexdir, name.len);
err = PTR_ERR(index);
- if (!IS_ERR(index))
- err = ovl_cleanup(dir, index);
- else
+ if (IS_ERR(index)) {
index = NULL;
+ } else if (ovl_index_all(dentry->d_sb)) {
+ /* Whiteout orphan index to block future open by handle */
+ err = ovl_cleanup_and_whiteout(indexdir, dir, index);
+ } else {
+ /* Cleanup orphan index entries */
+ err = ovl_cleanup(dir, index);
+ }
inode_unlock(dir);
if (err)