When overlay inode nlink drops to zero, instead of cleanup the index
entry, replace it with a whiteout index entry.
This is needed for NFS export in order to prevent future open by handle
to open the lower file directly.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/dir.c | 58 +++++++++++++++++++++++++++++-------------------
fs/overlayfs/overlayfs.h | 2 ++
fs/overlayfs/util.c | 20 +++++++++++------
3 files changed, 50 insertions(+), 30 deletions(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index d916fc19e724..060a1bfa0531 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 'lock_rename' on workdir+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)
{
@@ -629,14 +660,10 @@ static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper)
static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
{
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;
@@ -665,24 +692,13 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
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:
@@ -691,10 +707,6 @@ static int ovl_remove_and_whiteout(struct dentry *dentry, bool is_dir)
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 e4caad7bae19..17c039485dc9 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -327,6 +327,8 @@ int ovl_create_real(struct inode *dir, struct dentry *newdentry,
struct cattr *attr,
struct dentry *hardlink, bool debug);
int ovl_cleanup(struct inode *dir, struct dentry *dentry);
+int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
+ struct dentry *dentry);
/* copy_up.c */
int ovl_copy_up(struct dentry *dentry);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 22cdf9ecd7ec..515ae156939f 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -453,7 +453,8 @@ void ovl_inuse_unlock(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 *workdir = ovl_workdir(dentry);
+ struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
struct dentry *lowerdentry = ovl_dentry_lower(dentry);
struct dentry *upperdentry = ovl_dentry_upper(dentry);
struct dentry *index = NULL;
@@ -483,16 +484,21 @@ static void ovl_cleanup_index(struct dentry *dentry)
goto out;
}
- inode_lock_nested(dir, I_MUTEX_PARENT);
- /* TODO: whiteout instead of cleanup to block future open by handle */
+ err = -EIO;
+ if (lock_rename(workdir, indexdir) != NULL)
+ goto fail;
+
index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len);
err = PTR_ERR(index);
- if (!IS_ERR(index))
- err = ovl_cleanup(dir, index);
- else
+ if (!IS_ERR(index)) {
+ /* Whiteout index to block future open by handle */
+ err = ovl_cleanup_and_whiteout(workdir, d_inode(indexdir),
+ index);
+ } else {
index = NULL;
+ }
- inode_unlock(dir);
+ unlock_rename(workdir, indexdir);
if (err)
goto fail;
--
2.7.4
--
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