From 49c21e1cacd74a8c83407c70ad860c994e606e25 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Sat, 13 Dec 2014 00:59:42 +0100 Subject: [PATCH] ovl: check whiteout while reading directory Don't make a separate pass for checking whiteouts, since we can do it while reading the upper directory. This will make it easier to handle multiple layers. Signed-off-by: Miklos Szeredi --- fs/overlayfs/readdir.c | 77 ++++++++++++++++++-------------------------------- 1 file changed, 28 insertions(+), 49 deletions(-) diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index ab1e3dc..3efa44a 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -40,6 +40,7 @@ struct ovl_readdir_data { struct rb_root root; struct list_head *list; struct list_head middle; + struct dentry *dir; int count; int err; }; @@ -126,6 +127,32 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, if (p == NULL) return -ENOMEM; + if (d_type == DT_CHR) { + struct dentry *dentry; + const struct cred *old_cred; + struct cred *override_cred; + + override_cred = prepare_creds(); + if (!override_cred) { + kfree(p); + return -ENOMEM; + } + + /* + * CAP_DAC_OVERRIDE for lookup + */ + cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); + old_cred = override_creds(override_cred); + + dentry = lookup_one_len(name, rdd->dir, len); + if (!IS_ERR(dentry)) { + p->is_whiteout = ovl_is_whiteout(dentry); + dput(dentry); + } + revert_creds(old_cred); + put_cred(override_cred); + } + list_add_tail(&p->l_node, rdd->list); rb_link_node(&p->node, parent, newp); rb_insert_color(&p->node, &rdd->root); @@ -231,49 +258,6 @@ static void ovl_dir_reset(struct file *file) od->is_real = false; } -static int ovl_dir_mark_whiteouts(struct dentry *dir, - struct ovl_readdir_data *rdd) -{ - struct ovl_cache_entry *p; - struct dentry *dentry; - const struct cred *old_cred; - struct cred *override_cred; - - override_cred = prepare_creds(); - if (!override_cred) { - ovl_cache_free(rdd->list); - return -ENOMEM; - } - - /* - * CAP_DAC_OVERRIDE for lookup - */ - cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE); - old_cred = override_creds(override_cred); - - mutex_lock(&dir->d_inode->i_mutex); - list_for_each_entry(p, rdd->list, l_node) { - if (p->is_cursor) - continue; - - if (p->type != DT_CHR) - continue; - - dentry = lookup_one_len(p->name, dir, p->len); - if (IS_ERR(dentry)) - continue; - - p->is_whiteout = ovl_is_whiteout(dentry); - dput(dentry); - } - mutex_unlock(&dir->d_inode->i_mutex); - - revert_creds(old_cred); - put_cred(override_cred); - - return 0; -} - static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list) { int err; @@ -290,15 +274,10 @@ static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list) ovl_path_upper(dentry, &upperpath); if (upperpath.dentry) { + rdd.dir = upperpath.dentry; err = ovl_dir_read(&upperpath, &rdd); if (err) goto out; - - if (lowerpath.dentry) { - err = ovl_dir_mark_whiteouts(upperpath.dentry, &rdd); - if (err) - goto out; - } } if (lowerpath.dentry) { /* -- 2.7.4