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ovl: check whiteout on lowest layer as well 

Not checking whiteouts on lowest layer was an optimization (there's nothing
to white out there), but it could result in inconsitent behavior when a
layer previously used as upper/middle is later used as lowest. 

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
This commit is contained in:
Miklos Szeredi 2014-12-13 00:59:45 +01:00
parent 3d3c6b8939
commit 3e01cee3b9
2 changed files with 51 additions and 57 deletions
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79
fs/overlayfs/readdir.c
View File

@ -80,23 +80,50 @@ static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
return NULL;
}
static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,
static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir,
const char *name, int len,
u64 ino, unsigned int d_type)
{
struct ovl_cache_entry *p;
size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
p = kmalloc(size, GFP_KERNEL);
if (p) {
memcpy(p->name, name, len);
p->name[len] = '\0';
p->len = len;
p->type = d_type;
p->ino = ino;
p->is_whiteout = false;
p->is_cursor = false;
}
if (!p)
return NULL;
memcpy(p->name, name, len);
p->name[len] = '\0';
p->len = len;
p->type = d_type;
p->ino = ino;
p->is_whiteout = false;
p->is_cursor = false;
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 NULL;
}
/*
* 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, dir, len);
if (!IS_ERR(dentry)) {
p->is_whiteout = ovl_is_whiteout(dentry);
dput(dentry);
}
revert_creds(old_cred);
put_cred(override_cred);
}
return p;
}
@ -123,36 +150,10 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
return 0;
}
p = ovl_cache_entry_new(name, len, ino, d_type);
p = ovl_cache_entry_new(rdd->dir, name, len, ino, d_type);
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);
@ -170,7 +171,7 @@ static int ovl_fill_lower(struct ovl_readdir_data *rdd,
if (p) {
list_move_tail(&p->l_node, &rdd->middle);
} else {
p = ovl_cache_entry_new(name, namelen, ino, d_type);
p = ovl_cache_entry_new(rdd->dir, name, namelen, ino, d_type);
if (p == NULL)
rdd->err = -ENOMEM;
else
@ -229,6 +230,7 @@ static inline int ovl_dir_read(struct path *realpath,
if (IS_ERR(realfile))
return PTR_ERR(realfile);
rdd->dir = realpath->dentry;
rdd->ctx.pos = 0;
do {
rdd->count = 0;
@ -274,7 +276,6 @@ static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list)
next = ovl_path_next(idx, dentry, &realpath);
if (next != -1) {
rdd.dir = realpath.dentry;
err = ovl_dir_read(&realpath, &rdd);
if (err)
break;

29
fs/overlayfs/super.c
View File

@ -350,16 +350,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
if (IS_ERR(this))
goto out;
/*
* If this is not the lowermost layer, check whiteout and opaque
* directory.
*/
if (poe->numlower && this) {
if (this) {
if (ovl_is_whiteout(this)) {
dput(this);
this = NULL;
upperopaque = true;
} else if (ovl_is_opaquedir(this)) {
} else if (poe->numlower && ovl_is_opaquedir(this)) {
upperopaque = true;
}
}
@ -384,19 +380,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
goto out_put;
if (!this)
continue;
/*
* If this is not the lowermost layer, check whiteout and opaque
* directory.
*/
if (i < poe->numlower - 1) {
if (ovl_is_whiteout(this)) {
dput(this);
break;
} else if (ovl_is_opaquedir(this)) {
opaque = true;
}
if (ovl_is_whiteout(this)) {
dput(this);
break;
}
/*
* Only makes sense to check opaque dir if this is not the
* lowermost layer.
*/
if (i < poe->numlower - 1 && ovl_is_opaquedir(this))
opaque = true;
/*
* If this is a non-directory then stop here.
*