ovl: decide if revalidate needed on a per-dentry basis

Allow completely skipping ->revalidate() on a per-dentry basis, in case the
underlying layers used for a dentry do not themselves have ->revalidate().

E.g. negative overlay dentry has no underlying layers, hence revalidate is
unnecessary.  Or if lower layer is remote but overlay dentry is pure-upper,
then can skip revalidate.

The following places need to update whether the dentry needs revalidate or
not:

 - fill-super (root dentry)
 - lookup
 - create
 - fh_to_dentry

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
index 8e57d53..b3471ef 100644 (file)
--- a/fs/overlayfs/dir.c
+++ b/fs/overlayfs/dir.c
@@ -243,6 +243,9 @@ static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
 
        ovl_dir_modified(dentry->d_parent, false);
        ovl_dentry_set_upper_alias(dentry);
+       ovl_dentry_update_reval(dentry, newdentry,
+                       DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+
        if (!hardlink) {
                /*
                 * ovl_obtain_alias() can be called after ovl_create_real()

diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
index 6f54d70..a58b3d9 100644 (file)
--- a/fs/overlayfs/export.c
+++ b/fs/overlayfs/export.c
@@ -324,6 +324,8 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
                if (upper_alias)
                        ovl_dentry_set_upper_alias(dentry);
        }
+       ovl_dentry_update_reval(dentry, upper,
+                       DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
 
        return d_instantiate_anon(dentry, inode);
 

diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
index a5b998a..76e61cc 100644 (file)
--- a/fs/overlayfs/namei.c
+++ b/fs/overlayfs/namei.c
@@ -1077,6 +1077,9 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
                        goto out_free_oe;
        }
 
+       ovl_dentry_update_reval(dentry, upperdentry,
+                       DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
+
        revert_creds(old_cred);
        if (origin_path) {
                dput(origin_path->dentry);

diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 442fbff..70d1704 100644 (file)
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -230,6 +230,8 @@ bool ovl_index_all(struct super_block *sb);
 bool ovl_verify_lower(struct super_block *sb);
 struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
 bool ovl_dentry_remote(struct dentry *dentry);
+void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
+                            unsigned int mask);
 bool ovl_dentry_weird(struct dentry *dentry);
 enum ovl_path_type ovl_path_type(struct dentry *dentry);
 void ovl_path_upper(struct dentry *dentry, struct path *path);

diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index bc35cd6..d944ab4 100644 (file)
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -158,11 +158,6 @@ static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
 static const struct dentry_operations ovl_dentry_operations = {
        .d_release = ovl_dentry_release,
        .d_real = ovl_d_real,
-};
-
-static const struct dentry_operations ovl_reval_dentry_operations = {
-       .d_release = ovl_dentry_release,
-       .d_real = ovl_d_real,
        .d_revalidate = ovl_dentry_revalidate,
        .d_weak_revalidate = ovl_dentry_weak_revalidate,
 };
@@ -779,7 +774,7 @@ 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)
+                        struct ovl_fs *ofs, int *stack_depth)
 {
        int fh_type;
        int err;
@@ -794,9 +789,6 @@ static int ovl_lower_dir(const char *name, struct path *path,
 
        *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
 
-       if (ovl_dentry_remote(path->dentry))
-               *remote = true;
-
        /*
         * The inodes index feature and NFS export need to encode and decode
         * file handles, so they require that all layers support them.
@@ -1441,7 +1433,6 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
        char *lowertmp, *lower;
        struct path *stack = NULL;
        unsigned int stacklen, numlower = 0, i;
-       bool remote = false;
        struct ovl_entry *oe;
 
        err = -ENOMEM;
@@ -1473,7 +1464,7 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
        lower = lowertmp;
        for (numlower = 0; numlower < stacklen; numlower++) {
                err = ovl_lower_dir(lower, &stack[numlower], ofs,
-                                   &sb->s_stack_depth, &remote);
+                                   &sb->s_stack_depth);
                if (err)
                        goto out_err;
 
@@ -1501,11 +1492,6 @@ static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
                oe->lowerstack[i].layer = &ofs->layers[i+1];
        }
 
-       if (remote)
-               sb->s_d_op = &ovl_reval_dentry_operations;
-       else
-               sb->s_d_op = &ovl_dentry_operations;
-
 out:
        for (i = 0; i < numlower; i++)
                path_put(&stack[i]);
@@ -1623,6 +1609,7 @@ static struct dentry *ovl_get_root(struct super_block *sb,
        ovl_dentry_set_flag(OVL_E_CONNECTED, root);
        ovl_set_upperdata(d_inode(root));
        ovl_inode_init(d_inode(root), &oip, ino, fsid);
+       ovl_dentry_update_reval(root, upperdentry, DCACHE_OP_WEAK_REVALIDATE);
 
        return root;
 }
@@ -1636,6 +1623,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent)
        struct cred *cred;
        int err;
 
+       sb->s_d_op = &ovl_dentry_operations;
+
        err = -ENOMEM;
        ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
        if (!ofs)

diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
index 997c315..1cd805b 100644 (file)
--- a/fs/overlayfs/util.c
+++ b/fs/overlayfs/util.c
@@ -96,6 +96,21 @@ bool ovl_dentry_remote(struct dentry *dentry)
                (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);
 }
 
+void ovl_dentry_update_reval(struct dentry *dentry, struct dentry *upperdentry,
+                            unsigned int mask)
+{
+       struct ovl_entry *oe = OVL_E(dentry);
+       unsigned int i, flags = 0;
+
+       for (i = 0; i < oe->numlower; i++)
+               flags |= oe->lowerstack[i].dentry->d_flags;
+
+       spin_lock(&dentry->d_lock);
+       dentry->d_flags &= ~mask;
+       dentry->d_flags |= flags & mask;
+       spin_unlock(&dentry->d_lock);
+}
+
 bool ovl_dentry_weird(struct dentry *dentry)
 {
        return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |