For the common case of single lower layer, embed ovl_entry with a
single lower path in ovl_inode, so no stack allocation is needed.
For directory with more than single lower layer and for regular file
with lowerdata, the lower stack is stored in an external allocation.
Use accessor ovl_lowerstack() to get the embedded or external stack.
Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
---
fs/overlayfs/dir.c | 2 ++
fs/overlayfs/export.c | 18 +++++----------
fs/overlayfs/inode.c | 12 ++++------
fs/overlayfs/namei.c | 15 +++++--------
fs/overlayfs/overlayfs.h | 10 +++++----
fs/overlayfs/ovl_entry.h | 14 +++++++-----
fs/overlayfs/super.c | 41 +++++++++++++---------------------
fs/overlayfs/util.c | 48 +++++++++++++++++++++++++++++-----------
8 files changed, 81 insertions(+), 79 deletions(-)
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 92bdcedfaaec..aa0465c61064 100644
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -262,9 +262,11 @@ static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
struct dentry *newdentry, bool hardlink)
{
+ struct ovl_entry oe = {};
struct ovl_inode_params oip = {
.upperdentry = newdentry,
.newinode = inode,
+ .oe = &oe,
};
ovl_dir_modified(dentry->d_parent, false);
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index d4caf57c8e17..9951c504fb8d 100644
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -287,30 +287,22 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
struct dentry *upper = upper_alias ?: index;
struct dentry *dentry;
struct inode *inode = NULL;
- struct ovl_entry *oe;
+ struct ovl_entry oe;
struct ovl_inode_params oip = {
- .lowerpath = lowerpath,
+ .oe = &oe,
.index = index,
- .numlower = !!lower
};
/* We get overlay directory dentries with ovl_lookup_real() */
if (d_is_dir(upper ?: lower))
return ERR_PTR(-EIO);
- oe = ovl_alloc_entry(!!lower);
- if (!oe)
- goto nomem;
-
oip.upperdentry = dget(upper);
- if (lower) {
- ovl_lowerstack(oe)->dentry = dget(lower);
- ovl_lowerstack(oe)->layer = lowerpath->layer;
- }
- oip.oe = oe;
+ /* Should not fail because does not allocate lowerstack */
+ ovl_init_entry(&oe, lowerpath, !!lower);
inode = ovl_get_inode(sb, &oip);
if (IS_ERR(inode)) {
- ovl_free_entry(oe);
+ ovl_destroy_entry(&oe);
dput(upper);
return ERR_CAST(inode);
}
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index c296bd656858..9f29fc3e9fa5 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -1004,12 +1004,8 @@ void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
struct ovl_inode *oi = OVL_I(inode);
oi->__upperdentry = oip->upperdentry;
- oi->oe = oip->oe;
+ oi->oe = *oip->oe;
oi->redirect = oip->redirect;
- if (oip->lowerpath && oip->lowerpath->dentry) {
- oi->lowerpath.dentry = dget(oip->lowerpath->dentry);
- oi->lowerpath.layer = oip->lowerpath->layer;
- }
if (oip->lowerdata)
oi->lowerdata = igrab(d_inode(oip->lowerdata));
@@ -1326,7 +1322,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
{
struct ovl_fs *ofs = OVL_FS(sb);
struct dentry *upperdentry = oip->upperdentry;
- struct ovl_path *lowerpath = oip->lowerpath;
+ struct ovl_path *lowerpath = ovl_lowerstack(oip->oe);
struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
struct inode *inode;
struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
@@ -1370,7 +1366,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
}
dput(upperdentry);
- ovl_free_entry(oip->oe);
+ ovl_destroy_entry(oip->oe);
kfree(oip->redirect);
goto out;
}
@@ -1405,7 +1401,7 @@ struct inode *ovl_get_inode(struct super_block *sb,
/* Check for non-merge dir that may have whiteouts */
if (is_dir) {
- if (((upperdentry && lowerdentry) || oip->numlower > 1) ||
+ if (((upperdentry && lowerdentry) || ovl_numlower(oip->oe) > 1) ||
ovl_path_check_origin_xattr(ofs, &realpath)) {
ovl_set_flag(OVL_WHITEOUTS, inode);
}
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index a0a1c498dbd1..cdcb2ac5d95c 100644
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -831,7 +831,7 @@ static int ovl_fix_origin(struct ovl_fs *ofs, struct dentry *dentry,
struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
- struct ovl_entry *oe;
+ struct ovl_entry oe;
const struct cred *old_cred;
struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
struct ovl_entry *poe = OVL_E(dentry->d_parent);
@@ -1067,13 +1067,10 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
}
}
- oe = ovl_alloc_entry(ctr);
- err = -ENOMEM;
- if (!oe)
+ err = ovl_init_entry(&oe, stack, ctr);
+ if (err)
goto out_put;
- ovl_stack_cpy(ovl_lowerstack(oe), stack, ctr);
-
if (upperopaque)
ovl_dentry_set_opaque(dentry);
@@ -1105,10 +1102,8 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (upperdentry || ctr) {
struct ovl_inode_params oip = {
.upperdentry = upperdentry,
- .lowerpath = stack,
- .oe = oe,
+ .oe = &oe,
.index = index,
- .numlower = ctr,
.redirect = upperredirect,
.lowerdata = (ctr > 1 && !d.is_dir) ?
stack[ctr - 1].dentry : NULL,
@@ -1135,7 +1130,7 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
return d_splice_alias(inode, dentry);
out_free_oe:
- ovl_free_entry(oe);
+ ovl_destroy_entry(&oe);
out_put:
dput(index);
ovl_stack_free(stack, ctr);
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index e14ca0fd1063..32532342e56a 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -377,8 +377,12 @@ struct ovl_path *ovl_stack_alloc(unsigned int n);
void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src, unsigned int n);
void ovl_stack_put(struct ovl_path *stack, unsigned int n);
void ovl_stack_free(struct ovl_path *stack, unsigned int n);
-struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
-void ovl_free_entry(struct ovl_entry *oe);
+struct ovl_path *ovl_alloc_stack(unsigned int n);
+void ovl_stack_cpy(struct ovl_path *dst, struct ovl_path *src, unsigned int n);
+void ovl_stack_put(struct ovl_path *stack, unsigned int n);
+int ovl_init_entry(struct ovl_entry *oe, struct ovl_path *stack,
+ unsigned int numlower);
+void ovl_destroy_entry(struct ovl_entry *oe);
bool ovl_dentry_remote(struct dentry *dentry);
void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *realdentry);
void ovl_dentry_init_reval(struct dentry *dentry, struct dentry *upperdentry,
@@ -653,10 +657,8 @@ bool ovl_is_private_xattr(struct super_block *sb, const char *name);
struct ovl_inode_params {
struct inode *newinode;
struct dentry *upperdentry;
- struct ovl_path *lowerpath;
struct ovl_entry *oe;
bool index;
- unsigned int numlower;
char *redirect;
struct dentry *lowerdata;
};
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
index 201de9da45d3..5d95e937f555 100644
--- a/fs/overlayfs/ovl_entry.h
+++ b/fs/overlayfs/ovl_entry.h
@@ -49,7 +49,12 @@ struct ovl_path {
struct ovl_entry {
unsigned int __numlower;
- struct ovl_path __lowerstack[];
+ union {
+ /* Embedded path for numlower == 1 */
+ struct ovl_path __lowerpath;
+ /* External stack for numlower > 1 */
+ struct ovl_path *__lowerstack;
+ };
};
/* private information held for overlayfs's superblock */
@@ -117,7 +122,7 @@ static inline unsigned int ovl_numlower(struct ovl_entry *oe)
static inline struct ovl_path *ovl_lowerstack(struct ovl_entry *oe)
{
- return oe ? oe->__lowerstack : NULL;
+ return oe && oe->__numlower > 1 ? oe->__lowerstack : &oe->__lowerpath;
}
/* private information held for every overlayfs dentry */
@@ -136,8 +141,7 @@ struct ovl_inode {
unsigned long flags;
struct inode vfs_inode;
struct dentry *__upperdentry;
- struct ovl_path lowerpath;
- struct ovl_entry *oe;
+ struct ovl_entry oe;
/* synchronize copy up and more */
struct mutex lock;
@@ -150,7 +154,7 @@ static inline struct ovl_inode *OVL_I(struct inode *inode)
static inline struct ovl_entry *OVL_I_E(struct inode *inode)
{
- return inode ? OVL_I(inode)->oe : NULL;
+ return inode ? &OVL_I(inode)->oe : NULL;
}
static inline struct ovl_entry *OVL_E(struct dentry *dentry)
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index b9e62ccd609f..e01a76de787c 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -171,9 +171,7 @@ static struct inode *ovl_alloc_inode(struct super_block *sb)
oi->version = 0;
oi->flags = 0;
oi->__upperdentry = NULL;
- oi->oe = NULL;
- oi->lowerpath.dentry = NULL;
- oi->lowerpath.layer = NULL;
+ ovl_init_entry(&oi->oe, NULL, 0);
oi->lowerdata = NULL;
mutex_init(&oi->lock);
@@ -194,8 +192,7 @@ static void ovl_destroy_inode(struct inode *inode)
struct ovl_inode *oi = OVL_I(inode);
dput(oi->__upperdentry);
- dput(oi->lowerpath.dentry);
- ovl_free_entry(oi->oe);
+ ovl_destroy_entry(&oi->oe);
if (S_ISDIR(inode->i_mode))
ovl_dir_cache_free(inode);
else
@@ -1702,7 +1699,7 @@ static int ovl_get_layers(struct super_block *sb, struct ovl_fs *ofs,
return err;
}
-static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
+static int ovl_get_lowerstack(struct super_block *sb, struct ovl_entry *oe,
const char *lower, unsigned int numlower,
struct ovl_fs *ofs, struct ovl_layer *layers)
{
@@ -1710,16 +1707,15 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
struct path *stack = NULL;
struct ovl_path *lowerstack;
unsigned int i;
- struct ovl_entry *oe;
if (!ofs->config.upperdir && numlower == 1) {
pr_err("at least 2 lowerdir are needed while upperdir nonexistent\n");
- return ERR_PTR(-EINVAL);
+ return -EINVAL;
}
stack = kcalloc(numlower, sizeof(struct path), GFP_KERNEL);
if (!stack)
- return ERR_PTR(-ENOMEM);
+ return -ENOMEM;
err = -EINVAL;
for (i = 0; i < numlower; i++) {
@@ -1741,9 +1737,8 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
if (err)
goto out_err;
- err = -ENOMEM;
- oe = ovl_alloc_entry(numlower);
- if (!oe)
+ err = ovl_init_entry(oe, NULL, numlower);
+ if (err)
goto out_err;
lowerstack = ovl_lowerstack(oe);
@@ -1752,16 +1747,12 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
lowerstack[i].layer = &ofs->layers[i+1];
}
-out:
+out_err:
for (i = 0; i < numlower; i++)
path_put(&stack[i]);
kfree(stack);
- return oe;
-
-out_err:
- oe = ERR_PTR(err);
- goto out;
+ return err;
}
/*
@@ -1847,7 +1838,6 @@ static struct dentry *ovl_get_root(struct super_block *sb,
int fsid = lowerpath->layer->fsid;
struct ovl_inode_params oip = {
.upperdentry = upperdentry,
- .lowerpath = lowerpath,
.oe = oe,
};
@@ -1878,7 +1868,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
{
struct path upperpath = { };
struct dentry *root_dentry;
- struct ovl_entry *oe;
+ struct ovl_entry oe;
struct ovl_fs *ofs;
struct ovl_layer *layers;
struct cred *cred;
@@ -1991,9 +1981,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
sb->s_stack_depth = upper_sb->s_stack_depth;
sb->s_time_gran = upper_sb->s_time_gran;
}
- oe = ovl_get_lowerstack(sb, splitlower, numlower, ofs, layers);
- err = PTR_ERR(oe);
- if (IS_ERR(oe))
+ err = ovl_get_lowerstack(sb, &oe, splitlower, numlower, ofs, layers);
+ if (err)
goto out_err;
/* If the upper fs is nonexistent, we mark overlayfs r/o too */
@@ -2006,7 +1995,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
}
if (!ovl_force_readonly(ofs) && ofs->config.index) {
- err = ovl_get_indexdir(sb, ofs, oe, &upperpath);
+ err = ovl_get_indexdir(sb, ofs, &oe, &upperpath);
if (err)
goto out_free_oe;
@@ -2047,7 +2036,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
sb->s_iflags |= SB_I_SKIP_SYNC;
err = -ENOMEM;
- root_dentry = ovl_get_root(sb, upperpath.dentry, oe);
+ root_dentry = ovl_get_root(sb, upperpath.dentry, &oe);
if (!root_dentry)
goto out_free_oe;
@@ -2059,7 +2048,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
return 0;
out_free_oe:
- ovl_free_entry(oe);
+ ovl_destroy_entry(&oe);
out_err:
kfree(splitlower);
path_put(&upperpath);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index f5e2c70a57f8..540819ac9b9c 100644
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -111,21 +111,41 @@ void ovl_stack_free(struct ovl_path *stack, unsigned int n)
kfree(stack);
}
-struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
-{
- size_t size = offsetof(struct ovl_entry, __lowerstack[numlower]);
- struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
+/* On success, takes references on @stack dentries */
+int ovl_init_entry(struct ovl_entry *oe, struct ovl_path *stack,
+ unsigned int numlower)
+{
+ oe->__numlower = numlower;
+ oe->__lowerpath = (struct ovl_path) {};
+
+ /* No allocated stack for numlower <= 1 */
+ if (numlower <= 1) {
+ if (numlower && stack)
+ oe->__lowerpath = *stack;
+ dget(oe->__lowerpath.dentry);
+ return 0;
+ }
+
+ oe->__lowerstack = ovl_stack_alloc(numlower);
+ if (!oe->__lowerstack)
+ return -ENOMEM;
+
+ if (!stack)
+ return 0;
- if (oe)
- oe->__numlower = numlower;
+ ovl_stack_cpy(oe->__lowerstack, stack, numlower);
- return oe;
+ return 0;
}
-void ovl_free_entry(struct ovl_entry *oe)
+void ovl_destroy_entry(struct ovl_entry *oe)
{
- ovl_stack_put(ovl_lowerstack(oe), ovl_numlower(oe));
- kfree(oe);
+ if (oe->__numlower > 1) {
+ ovl_stack_put(oe->__lowerstack, oe->__numlower);
+ kfree(oe->__lowerstack);
+ } else {
+ dput(oe->__lowerpath.dentry);
+ }
}
#define OVL_D_REVALIDATE (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE)
@@ -306,10 +326,12 @@ struct dentry *ovl_i_dentry_upper(struct inode *inode)
void ovl_i_path_real(struct inode *inode, struct path *path)
{
+ struct ovl_path *lowerstack = ovl_lowerstack(OVL_I_E(inode));
+
path->dentry = ovl_i_dentry_upper(inode);
if (!path->dentry) {
- path->dentry = OVL_I(inode)->lowerpath.dentry;
- path->mnt = OVL_I(inode)->lowerpath.layer->mnt;
+ path->dentry = lowerstack->dentry;
+ path->mnt = lowerstack->layer->mnt;
} else {
path->mnt = ovl_upper_mnt(OVL_FS(inode->i_sb));
}
@@ -324,7 +346,7 @@ struct inode *ovl_inode_upper(struct inode *inode)
struct inode *ovl_inode_lower(struct inode *inode)
{
- struct dentry *lowerdentry = OVL_I(inode)->lowerpath.dentry;
+ struct dentry *lowerdentry = ovl_lowerstack(OVL_I_E(inode))->dentry;
return lowerdentry ? d_inode(lowerdentry) : NULL;
}
--
2.34.1
