ovl: consistent d_ino for non-samefs with xino

[sfrench/cifs-2.6.git] / fs / overlayfs / readdir.c

diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
index c11f5c0906c39087978036892f2e11fa88af0299..ef1fe42ff7bb3a4e38e1d75714a1ef1bad4acf42 100644 (file)
--- a/fs/overlayfs/readdir.c
+++ b/fs/overlayfs/readdir.c
@@ -120,6 +120,10 @@ static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd,
        if (!rdd->dentry)
                return false;
 
+       /* Always recalc d_ino when remapping lower inode numbers */
+       if (ovl_xino_bits(rdd->dentry->d_sb))
+               return true;
+
        /* Always recalc d_ino for parent */
        if (strcmp(p->name, "..") == 0)
                return true;
@@ -435,6 +439,19 @@ static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
        return cache;
 }
 
+/* Map inode number to lower fs unique range */
+static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,
+                              const char *name, int namelen)
+{
+       if (ino >> (64 - xinobits)) {
+               pr_warn_ratelimited("overlayfs: d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
+                                   namelen, name, ino, xinobits);
+               return ino;
+       }
+
+       return ino | ((u64)fsid) << (64 - xinobits);
+}
+
 /*
  * Set d_ino for upper entries. Non-upper entries should always report
  * the uppermost real inode ino and should not call this function.
@@ -452,9 +469,10 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
        struct dentry *this = NULL;
        enum ovl_path_type type;
        u64 ino = p->real_ino;
+       int xinobits = ovl_xino_bits(dir->d_sb);
        int err = 0;
 
-       if (!ovl_same_sb(dir->d_sb))
+       if (!ovl_same_sb(dir->d_sb) && !xinobits)
                goto out;
 
        if (p->name[0] == '.') {
@@ -491,6 +509,10 @@ get:
 
                WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
                ino = stat.ino;
+       } else if (xinobits && !OVL_TYPE_UPPER(type)) {
+               ino = ovl_remap_lower_ino(ino, xinobits,
+                                         ovl_layer_lower(this)->fsid,
+                                         p->name, p->len);
        }
 
 out:
@@ -618,6 +640,8 @@ struct ovl_readdir_translate {
        struct ovl_dir_cache *cache;
        struct dir_context ctx;
        u64 parent_ino;
+       int fsid;
+       int xinobits;
 };
 
 static int ovl_fill_real(struct dir_context *ctx, const char *name,
@@ -628,14 +652,17 @@ static int ovl_fill_real(struct dir_context *ctx, const char *name,
                container_of(ctx, struct ovl_readdir_translate, ctx);
        struct dir_context *orig_ctx = rdt->orig_ctx;
 
-       if (rdt->parent_ino && strcmp(name, "..") == 0)
+       if (rdt->parent_ino && strcmp(name, "..") == 0) {
                ino = rdt->parent_ino;
-       else if (rdt->cache) {
+       } else if (rdt->cache) {
                struct ovl_cache_entry *p;
 
                p = ovl_cache_entry_find(&rdt->cache->root, name, namelen);
                if (p)
                        ino = p->ino;
+       } else if (rdt->xinobits) {
+               ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid,
+                                         name, namelen);
        }
 
        return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
@@ -646,11 +673,16 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
        int err;
        struct ovl_dir_file *od = file->private_data;
        struct dentry *dir = file->f_path.dentry;
+       struct ovl_layer *lower_layer = ovl_layer_lower(dir);
        struct ovl_readdir_translate rdt = {
                .ctx.actor = ovl_fill_real,
                .orig_ctx = ctx,
+               .xinobits = ovl_xino_bits(dir->d_sb),
        };
 
+       if (rdt.xinobits && lower_layer)
+               rdt.fsid = lower_layer->fsid;
+
        if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {
                struct kstat stat;
                struct path statpath = file->f_path;
@@ -693,9 +725,10 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx)
                 * dir is impure then need to adjust d_ino for copied up
                 * entries.
                 */
-               if (ovl_same_sb(dentry->d_sb) &&
-                   (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
-                    OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent)))) {
+               if (ovl_xino_bits(dentry->d_sb) ||
+                   (ovl_same_sb(dentry->d_sb) &&
+                    (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||
+                     OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
                        return ovl_iterate_real(file, ctx);
                }
                return iterate_dir(od->realfile, ctx);