[PATCH 5.11 480/601] ovl: invalidate readdir cache on changes to dir with origin

Greg Kroah-Hartman
2021-05-12T17:56:08Z

From: Amir Goldstein <amir73il@gmail.com>

[ Upstream commit 65cd913ec9d9d71529665924c81015b7ab7d9381 ]

The test in ovl_dentry_version_inc() was out-dated and did not include
the case where readdir cache is used on a non-merge dir that has origin
xattr, indicating that it may contain leftover whiteouts.

To make the code more robust, use the same helper ovl_dir_is_real()
to determine if readdir cache should be used and if readdir cache should
be invalidated.

Fixes: b79e05aaa166 ("ovl: no direct iteration for dir with origin xattr")
Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxht70nODhNHNwGFMSqDyOKLXOKrY0H6g849os4BQ7cokA@mail.gmail.com/
Cc: Chris Murphy <lists@colorremedies.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/overlayfs/overlayfs.h | 30 +++++++++++++++++++++++++++---
fs/overlayfs/readdir.c | 12 ------------
fs/overlayfs/util.c | 31 +++++++++----------------------
3 files changed, 36 insertions(+), 37 deletions(-)

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index cb4e2d60ecf9..cf0c5ea2f2fc 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -310,9 +310,6 @@ int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
enum ovl_xattr ox, const void *value, size_t size,
int xerr);
int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
-void ovl_set_flag(unsigned long flag, struct inode *inode);
-void ovl_clear_flag(unsigned long flag, struct inode *inode);
-bool ovl_test_flag(unsigned long flag, struct inode *inode);
bool ovl_inuse_trylock(struct dentry *dentry);
void ovl_inuse_unlock(struct dentry *dentry);
bool ovl_is_inuse(struct dentry *dentry);
@@ -326,6 +323,21 @@ char *ovl_get_redirect_xattr(struct ovl_fs *ofs, struct dentry *dentry,
int padding);
int ovl_sync_status(struct ovl_fs *ofs);

+static inline void ovl_set_flag(unsigned long flag, struct inode *inode)
+{
+ set_bit(flag, &OVL_I(inode)->flags);
+}
+
+static inline void ovl_clear_flag(unsigned long flag, struct inode *inode)
+{
+ clear_bit(flag, &OVL_I(inode)->flags);
+}
+
+static inline bool ovl_test_flag(unsigned long flag, struct inode *inode)
+{
+ return test_bit(flag, &OVL_I(inode)->flags);
+}
+
static inline bool ovl_is_impuredir(struct super_block *sb,
struct dentry *dentry)
{
@@ -430,6 +442,18 @@ int ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
struct dentry *dentry, int level);
int ovl_indexdir_cleanup(struct ovl_fs *ofs);

+/*
+ * Can we iterate real dir directly?
+ *
+ * Non-merge dir may contain whiteouts from a time it was a merge upper, before
+ * lower dir was removed under it and possibly before it was rotated from upper
+ * to lower layer.
+ */
+static inline bool ovl_dir_is_real(struct dentry *dir)
+{
+ return !ovl_test_flag(OVL_WHITEOUTS, d_inode(dir));
+}
+
/* inode.c */
int ovl_set_nlink_upper(struct dentry *dentry);
int ovl_set_nlink_lower(struct dentry *dentry);
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index f404a78e6b60..cc1e80257064 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -319,18 +319,6 @@ static inline int ovl_dir_read(struct path *realpath,
return err;
}

-/*
- * Can we iterate real dir directly?
- *
- * Non-merge dir may contain whiteouts from a time it was a merge upper, before
- * lower dir was removed under it and possibly before it was rotated from upper
- * to lower layer.
- */
-static bool ovl_dir_is_real(struct dentry *dir)
-{
- return !ovl_test_flag(OVL_WHITEOUTS, d_inode(dir));
-}
-
static void ovl_dir_reset(struct file *file)
{
struct ovl_dir_file *od = file->private_data;
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 9826b003f1d2..47dab5a709db 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -422,18 +422,20 @@ void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
}
}

-static void ovl_dentry_version_inc(struct dentry *dentry, bool impurity)
+static void ovl_dir_version_inc(struct dentry *dentry, bool impurity)
{
struct inode *inode = d_inode(dentry);

WARN_ON(!inode_is_locked(inode));
+ WARN_ON(!d_is_dir(dentry));
/*
- * Version is used by readdir code to keep cache consistent. For merge
- * dirs all changes need to be noted. For non-merge dirs, cache only
- * contains impure (ones which have been copied up and have origins)
- * entries, so only need to note changes to impure entries.
+ * Version is used by readdir code to keep cache consistent.
+ * For merge dirs (or dirs with origin) all changes need to be noted.
+ * For non-merge dirs, cache contains only impure entries (i.e. ones
+ * which have been copied up and have origins), so only need to note
+ * changes to impure entries.
*/
- if (OVL_TYPE_MERGE(ovl_path_type(dentry)) || impurity)
+ if (!ovl_dir_is_real(dentry) || impurity)
OVL_I(inode)->version++;
}

@@ -442,7 +444,7 @@ void ovl_dir_modified(struct dentry *dentry, bool impurity)
/* Copy mtime/ctime */
ovl_copyattr(d_inode(ovl_dentry_upper(dentry)), d_inode(dentry));

- ovl_dentry_version_inc(dentry, impurity);
+ ovl_dir_version_inc(dentry, impurity);
}

u64 ovl_dentry_version_get(struct dentry *dentry)
@@ -638,21 +640,6 @@ int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
return err;
}

-void ovl_set_flag(unsigned long flag, struct inode *inode)
-{
- set_bit(flag, &OVL_I(inode)->flags);
-}
-
-void ovl_clear_flag(unsigned long flag, struct inode *inode)
-{
- clear_bit(flag, &OVL_I(inode)->flags);
-}
-
-bool ovl_test_flag(unsigned long flag, struct inode *inode)
-{
- return test_bit(flag, &OVL_I(inode)->flags);
-}
-
/**
* Caller must hold a reference to inode to prevent it from being freed while
* it is marked inuse.
--
2.30.2