The following sequence of commands causes a lowerdir file and an
overlay file to have the same values for st_ino/st_dev,
$ xfs_io -f -c "pwrite 0 4k" /mnt/lowerdir/testfile -c sync
$ xfs_io -a -c "pwrite 4k 4k" /mnt/ovl/testfile # Copy-up occurs here
This commit solves the bug by reporting pseudo device numbers for files
on lowerdir.
Signed-off-by: Chandan Rajendra <chandan@xxxxxxxxxxxxxxxxxx>
---
fs/overlayfs/inode.c | 23 ++++++++++++++++++++---
fs/overlayfs/ovl_entry.h | 8 +++++++-
fs/overlayfs/super.c | 33 +++++++++++++++++++++++++--------
3 files changed, 52 insertions(+), 12 deletions(-)
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 5f285c1..154c87892 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -13,6 +13,19 @@
#include <linux/xattr.h>
#include <linux/posix_acl.h>
#include "overlayfs.h"
+#include "ovl_entry.h"
+
+static dev_t get_lowerdir_pseudo_dev(struct ovl_fs *ufs, dev_t dev)
+{
+ int i;
+
+ for (i = 0; i < ufs->numlower; i++) {
+ if (ufs->lower_mnt[i].real_dev == dev)
+ return ufs->lower_mnt[i].pseudo_dev;
+ }
+
+ BUG();
+}
int ovl_setattr(struct dentry *dentry, struct iattr *attr)
{
@@ -61,6 +74,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
struct dentry *dentry = path->dentry;
+ struct ovl_fs *ufs;
enum ovl_path_type type;
struct path realpath;
const struct cred *old_cred;
@@ -103,10 +117,13 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
if (is_dir || lowerstat.nlink == 1)
stat->ino = lowerstat.ino;
- if (samefs)
+ if (samefs) {
WARN_ON_ONCE(stat->dev != lowerstat.dev);
- else
- stat->dev = lowerstat.dev;
+ } else {
+ ufs = dentry->d_sb->s_fs_info;
+ stat->dev = get_lowerdir_pseudo_dev(ufs,
+ lowerstat.dev);
+ }
}
if (samefs)
stat->dev = dentry->d_sb->s_dev;
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 34bc4a9..92aebe9 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -16,11 +16,17 @@ struct ovl_config {
bool redirect_dir;
};
+struct ovl_lower_mnt {
+ struct vfsmount *mnt;
+ dev_t real_dev;
+ dev_t pseudo_dev;
+};
+
/* private information held for overlayfs's superblock */
struct ovl_fs {
struct vfsmount *upper_mnt;
unsigned numlower;
- struct vfsmount **lower_mnt;
+ struct ovl_lower_mnt *lower_mnt;
struct dentry *workdir;
long namelen;
/* pathnames of lower and upper dirs, for show_options */
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 4882ffb..c922a92 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -172,8 +172,10 @@ static void ovl_put_super(struct super_block *sb)
dput(ufs->workdir);
mntput(ufs->upper_mnt);
- for (i = 0; i < ufs->numlower; i++)
- mntput(ufs->lower_mnt[i]);
+ for (i = 0; i < ufs->numlower; i++) {
+ mntput(ufs->lower_mnt[i].mnt);
+ free_anon_bdev(ufs->lower_mnt[i].pseudo_dev);
+ }
kfree(ufs->lower_mnt);
kfree(ufs->config.lowerdir);
@@ -908,15 +910,25 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
err = -ENOMEM;
- ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL);
+ ufs->lower_mnt = kcalloc(numlower, sizeof(struct ovl_lower_mnt),
+ GFP_KERNEL);
if (ufs->lower_mnt == NULL)
goto out_put_workdir;
for (i = 0; i < numlower; i++) {
- struct vfsmount *mnt = clone_private_mount(&stack[i]);
+ struct vfsmount *mnt;
+ dev_t dev;
+ err = get_anon_bdev(&dev);
+ if (err) {
+ pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
+ goto out_put_lower_mnt;
+ }
+
+ mnt = clone_private_mount(&stack[i]);
err = PTR_ERR(mnt);
if (IS_ERR(mnt)) {
pr_err("overlayfs: failed to clone lowerpath\n");
+ free_anon_bdev(dev);
goto out_put_lower_mnt;
}
/*
@@ -925,7 +937,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
*/
mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
- ufs->lower_mnt[ufs->numlower] = mnt;
+ ufs->lower_mnt[ufs->numlower].mnt = mnt;
+ ufs->lower_mnt[ufs->numlower].real_dev = mnt->mnt_sb->s_dev;
+ ufs->lower_mnt[ufs->numlower].pseudo_dev = dev;
ufs->numlower++;
/* Check if all lower layers are on same sb */
@@ -980,7 +994,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
for (i = 0; i < numlower; i++) {
oe->lowerstack[i].dentry = stack[i].dentry;
- oe->lowerstack[i].mnt = ufs->lower_mnt[i];
+ oe->lowerstack[i].mnt = ufs->lower_mnt[i].mnt;
}
kfree(stack);
@@ -999,8 +1013,11 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
out_put_cred:
put_cred(ufs->creator_cred);
out_put_lower_mnt:
- for (i = 0; i < ufs->numlower; i++)
- mntput(ufs->lower_mnt[i]);
+ for (i = 0; i < ufs->numlower; i++) {
+ if (ufs->lower_mnt[i].mnt)
+ free_anon_bdev(ufs->lower_mnt[i].pseudo_dev);
+ mntput(ufs->lower_mnt[i].mnt);
+ }
kfree(ufs->lower_mnt);
out_put_workdir:
dput(ufs->workdir);
--
2.9.4
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