[PATCH 3/6] ovl: simplify ovl_same_sb() helper

Amir Goldstein
2019-11-17T15:43:46Z

No code uses the sb returned from this helper, so make it retrun
a boolean and rename it to ovl_same_fs().

The xino mode is irrelevant when all layers are on same fs, so
instead of describing samefs with mode OVL_XINO_OFF, use a new mode
OVL_XINO_SAME_FS, which is different than the case of non-samefs
with xino=off.

Create a new helper ovl_same_dev(), to use instead of the common check
for (ovl_same_fs() || xinobits).

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
fs/overlayfs/inode.c | 7 +++----
fs/overlayfs/overlayfs.h | 21 ++++++++++++++++++++-
fs/overlayfs/ovl_entry.h | 5 +++++
fs/overlayfs/readdir.c | 4 ++--
fs/overlayfs/super.c | 13 +++++--------
fs/overlayfs/util.c | 12 ------------
6 files changed, 35 insertions(+), 27 deletions(-)

diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index dab39933bbd4..717337f2b3fb 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -78,7 +78,7 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
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);
+ bool samefs = ovl_same_fs(dentry->d_sb);
unsigned int xinobits = ovl_xino_bits(dentry->d_sb);

if (samefs) {
@@ -146,7 +146,6 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
struct path realpath;
const struct cred *old_cred;
bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
- bool samefs = ovl_same_sb(dentry->d_sb);
struct ovl_layer *lower_layer = NULL;
int err;
bool metacopy_blocks = false;
@@ -168,7 +167,7 @@ int ovl_getattr(const struct path *path, struct kstat *stat,
* If lower filesystem supports NFS file handles, this also guaranties
* persistent st_ino across mount cycle.
*/
- if (!is_dir || samefs || ovl_xino_bits(dentry->d_sb)) {
+ if (!is_dir || ovl_same_dev(dentry->d_sb)) {
if (!OVL_TYPE_UPPER(type)) {
lower_layer = ovl_dentry_layer(dentry);
} else if (OVL_TYPE_ORIGIN(type)) {
@@ -565,7 +564,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
* ovl_new_inode(), ino arg is 0, so i_ino will be updated to real
* upper inode i_ino on ovl_inode_init() or ovl_inode_update().
*/
- if (ovl_same_sb(inode->i_sb) || xinobits) {
+ if (ovl_same_dev(inode->i_sb)) {
inode->i_ino = ino;
if (xinobits && fsid && !(ino >> (64 - xinobits)))
inode->i_ino |= (unsigned long)fsid << (64 - xinobits);
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 50d41a314308..f7d01c06cdaf 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -45,6 +45,14 @@ enum ovl_entry_flag {
OVL_E_CONNECTED,
};

+enum {
+ OVL_XINO_OFF,
+ OVL_XINO_AUTO,
+ OVL_XINO_ON,
+ /* With samefs, xino is irrelevant */
+ OVL_XINO_SAME_FS,
+};
+
/*
* The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
* where:
@@ -221,7 +229,6 @@ int ovl_want_write(struct dentry *dentry);
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);
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);
@@ -306,6 +313,18 @@ static inline unsigned int ovl_xino_bits(struct super_block *sb)
return ofs->xino_bits;
}

+/* All layers on same fs? */
+static inline bool ovl_same_fs(struct super_block *sb)
+{
+ return OVL_FS(sb)->config.xino == OVL_XINO_SAME_FS;
+}
+
+/* All overlay inodes have same st_dev? */
+static inline bool ovl_same_dev(struct super_block *sb)
+{
+ return OVL_FS(sb)->config.xino != OVL_XINO_OFF;
+}
+
static inline int ovl_inode_lock(struct inode *inode)
{
return mutex_lock_interruptible(&OVL_I(inode)->lock);
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index ffaf7376f4ab..ef05817d8d89 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -75,6 +75,11 @@ struct ovl_fs {
unsigned int xino_bits;
};

+static inline struct ovl_fs *OVL_FS(struct super_block *sb)
+{
+ return (struct ovl_fs *)sb->s_fs_info;
+}
+
/* private information held for every overlayfs dentry */
struct ovl_entry {
union {
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index 32a7f8a38091..56f13e9ccbe6 100644
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -469,7 +469,7 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
int xinobits = ovl_xino_bits(dir->d_sb);
int err = 0;

- if (!ovl_same_sb(dir->d_sb) && !xinobits)
+ if (!ovl_same_dev(dir->d_sb))
goto out;

if (p->name[0] == '.') {
@@ -737,7 +737,7 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
* entries.
*/
if (ovl_xino_bits(dentry->d_sb) ||
- (ovl_same_sb(dentry->d_sb) &&
+ (ovl_same_fs(dentry->d_sb) &&
(ovl_is_impure_dir(file) ||
OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
return ovl_iterate_real(file, ctx);
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index 4ff6eede5f90..ae22c3363c33 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -316,12 +316,6 @@ static const char *ovl_redirect_mode_def(void)
return ovl_redirect_dir_def ? "on" : "off";
}

-enum {
- OVL_XINO_OFF,
- OVL_XINO_AUTO,
- OVL_XINO_ON,
-};
-
static const char * const ovl_xino_str[] = {
"off",
"auto",
@@ -358,7 +352,8 @@ static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
if (ofs->config.nfs_export != ovl_nfs_export_def)
seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
"on" : "off");
- if (ofs->config.xino != ovl_xino_def())
+ if (ofs->config.xino != ovl_xino_def() &&
+ ofs->config.xino != OVL_XINO_SAME_FS)
seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
if (ofs->config.metacopy != ovl_metacopy_def)
seq_printf(m, ",metacopy=%s",
@@ -1393,8 +1388,10 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
* inode number.
*/
if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) {
+ if (ofs->config.xino == OVL_XINO_ON)
+ pr_info("overlayfs: \"xino=on\" is useless with all layers on same fs, ignore.\n");
ofs->xino_bits = 0;
- ofs->config.xino = OVL_XINO_OFF;
+ ofs->config.xino = OVL_XINO_SAME_FS;
} else if (ofs->config.xino == OVL_XINO_ON && !ofs->xino_bits) {
/*
* This is a roundup of number of bits needed for numlowerfs+1
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 3fa1ca8ddd48..256f166b4a17 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -40,18 +40,6 @@ const struct cred *ovl_override_creds(struct super_block *sb)
return override_creds(ofs->creator_cred);
}

-struct super_block *ovl_same_sb(struct super_block *sb)
-{
- struct ovl_fs *ofs = sb->s_fs_info;
-
- if (!ofs->numlowerfs)
- return ofs->upper_mnt->mnt_sb;
- else if (ofs->numlowerfs == 1 && !ofs->upper_mnt)
- return ofs->lower_fs[0].sb;
- else
- return NULL;
-}
-
/*
* Check if underlying fs supports file handles and try to determine encoding
* type, in order to deduce maximum inode number used by fs.
--
2.17.1