diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index cfccd91c51e319e5cfe76d5a6bb7a04583d8e546..51d780898d891137384e4fc5b23a551fb759bfe6 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -63,6 +63,7 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
struct ovl_layer *lower_layer)
{
bool samefs = ovl_same_sb(dentry->d_sb);
+ unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
if (samefs) {
/*
@@ -71,7 +72,31 @@ static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
* which is friendly to du -x.
*/
stat->dev = dentry->d_sb->s_dev;
- } else if (S_ISDIR(dentry->d_inode->i_mode)) {
+ return 0;
+ } else if (xinobits) {
+ unsigned int shift = 64 - xinobits;
+ /*
+ * All inode numbers of underlying fs should not be using the
+ * high xinobits, so we use high xinobits to partition the
+ * overlay st_ino address space. The high bits holds the fsid
+ * (upper fsid is 0). This way overlay inode numbers are unique
+ * and all inodes use overlay st_dev. Inode numbers are also
+ * persistent for a given layer configuration.
+ */
+ if (stat->ino >> shift) {
+ pr_warn_ratelimited("overlayfs: inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
+ dentry, stat->ino, xinobits);
+ } else {
+ if (lower_layer)
+ stat->ino |= ((u64)lower_layer->fsid) << shift;
+
+ stat->dev = dentry->d_sb->s_dev;
+ return 0;
+ }
+ }
+
+ /* The inode could not be mapped to a unified st_ino address space */
+ if (S_ISDIR(dentry->d_inode->i_mode)) {
/*
* Always use the overlay st_dev for directories, so 'find
* -xdev' will scan the entire overlay mount and won't cross the
@@ -118,11 +143,13 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
/*
* For non-dir or same fs, we use st_ino of the copy up origin.
* This guaranties constant st_dev/st_ino across copy up.
+ * With xino feature and non-samefs, we use st_ino of the copy up
+ * origin masked with high bits that represent the layer id.
*
* If lower filesystem supports NFS file handles, this also guaranties
* persistent st_ino across mount cycle.
*/
- if (!is_dir || samefs) {
+ if (!is_dir || samefs || ovl_xino_bits(dentry->d_sb)) {
if (!OVL_TYPE_UPPER(type)) {
lower_layer = ovl_layer_lower(dentry);
} else if (OVL_TYPE_ORIGIN(type)) {
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 09779f9111a84fd7932bcec7b5123f1cb4fd5f9f..8eefc309aeb689df6421105623982dcd498dac20 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -202,7 +202,7 @@ void ovl_drop_write(struct dentry *dentry);
struct dentry *ovl_workdir(struct dentry *dentry);
const struct cred *ovl_override_creds(struct super_block *sb);
struct super_block *ovl_same_sb(struct super_block *sb);
-bool ovl_can_decode_fh(struct super_block *sb);
+int ovl_can_decode_fh(struct super_block *sb);
struct dentry *ovl_indexdir(struct super_block *sb);
bool ovl_index_all(struct super_block *sb);
bool ovl_verify_lower(struct super_block *sb);
@@ -264,6 +264,13 @@ static inline bool ovl_is_impuredir(struct dentry *dentry)
return ovl_check_dir_xattr(dentry, OVL_XATTR_IMPURE);
}
+static inline unsigned int ovl_xino_bits(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return ofs->xino_bits;
+}
+
/* namei.c */
int ovl_check_fh_len(struct ovl_fh *fh, int fh_len);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index e1c838c27a742bda334285e1b3e2887383b15328..620bd20f9a221d9c19662b4ece94d9fae08dcfb3 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -63,6 +63,8 @@ struct ovl_fs {
/* Did we take the inuse lock? */
bool upperdir_locked;
bool workdir_locked;
+ /* Inode numbers in all layers do not use the high xino_bits */
+ unsigned int xino_bits;
};
/* private information held for every overlayfs dentry */
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 7d97d30cad397eed320ee01e5a4dd3b5c921828d..d7284444f4041a8e29179219622e270940d99055 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -17,6 +17,7 @@
#include <linux/statfs.h>
#include <linux/seq_file.h>
#include <linux/posix_acl_xattr.h>
+#include <linux/exportfs.h>
#include "overlayfs.h"
MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
@@ -701,6 +702,7 @@ static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
static int ovl_lower_dir(const char *name, struct path *path,
struct ovl_fs *ofs, int *stack_depth, bool *remote)
{
+ int fh_type;
int err;
err = ovl_mount_dir_noesc(name, path);
@@ -720,15 +722,19 @@ static int ovl_lower_dir(const char *name, struct path *path,
* The inodes index feature and NFS export need to encode and decode
* file handles, so they require that all layers support them.
*/
+ fh_type = ovl_can_decode_fh(path->dentry->d_sb);
if ((ofs->config.nfs_export ||
- (ofs->config.index && ofs->config.upperdir)) &&
- !ovl_can_decode_fh(path->dentry->d_sb)) {
+ (ofs->config.index && ofs->config.upperdir)) && !fh_type) {
ofs->config.index = false;
ofs->config.nfs_export = false;
pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
name);
}
+ /* Check if lower fs has 32bit inode numbers */
+ if (fh_type != FILEID_INO32_GEN)
+ ofs->xino_bits = 0;
+
return 0;
out_put:
@@ -952,6 +958,7 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
{
struct vfsmount *mnt = ofs->upper_mnt;
struct dentry *temp;
+ int fh_type;
int err;
err = mnt_want_write(mnt);
@@ -1001,12 +1008,16 @@ static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
}
/* Check if upper/work fs supports file handles */
- if (ofs->config.index &&
- !ovl_can_decode_fh(ofs->workdir->d_sb)) {
+ fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
+ if (ofs->config.index && !fh_type) {
ofs->config.index = false;
pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
}
+ /* Check if upper fs has 32bit inode numbers */
+ if (fh_type != FILEID_INO32_GEN)
+ ofs->xino_bits = 0;
+
/* NFS export of r/w mount depends on index */
if (ofs->config.nfs_export && !ofs->config.index) {
pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
@@ -1185,6 +1196,11 @@ static int ovl_get_lower_layers(struct ovl_fs *ofs, struct path *stack,
}
ofs->numlower++;
}
+
+ /* When all layers on same fs, overlay can use real inode numbers */
+ if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt))
+ ofs->xino_bits = 0;
+
err = 0;
out:
return err;
@@ -1308,6 +1324,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
sb->s_stack_depth = 0;
sb->s_maxbytes = MAX_LFS_FILESIZE;
+ /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
+ ofs->xino_bits = BITS_PER_LONG - 32;
if (ofs->config.upperdir) {
if (!ofs->config.workdir) {
pr_err("overlayfs: missing 'workdir'\n");
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 9dfec74ec77d466aac575438aecc1328f5907f81..6f1078028c66b4aced7c94f04959a754b293645c 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -55,10 +55,21 @@ struct super_block *ovl_same_sb(struct super_block *sb)
return NULL;
}
-bool ovl_can_decode_fh(struct super_block *sb)
+/*
+ * Check if underlying fs supports file handles and try to determine encoding
+ * type, in order to deduce maximum inode number used by fs.
+ *
+ * Return 0 if file handles are not supported.
+ * Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding.
+ * Return -1 if fs uses a non default encoding with unknown inode size.
+ */
+int ovl_can_decode_fh(struct super_block *sb)
{
- return (sb->s_export_op && sb->s_export_op->fh_to_dentry &&
- !uuid_is_null(&sb->s_uuid));
+ if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry ||
+ uuid_is_null(&sb->s_uuid))
+ return 0;
+
+ return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
}
struct dentry *ovl_indexdir(struct super_block *sb)