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authorMiklos Szeredi <mszeredi@suse.cz>2014-12-13 00:59:44 +0100
committerMiklos Szeredi <mszeredi@suse.cz>2014-12-13 00:59:44 +0100
commit3d3c6b89399a1b5e8a59ffbb8cb2a7797a9ef154 (patch)
tree81ec06b0edc6cff0d809d06228e5b2604119b33f
parent9d7459d834c28f55c82f1737f638a6c90e0c0e0f (diff)
downloadlinux-3d3c6b89399a1b5e8a59ffbb8cb2a7797a9ef154.tar.gz
ovl: multi-layer lookup
Look up dentry in all relevant layers. Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
-rw-r--r--fs/overlayfs/super.c143
1 files changed, 94 insertions, 49 deletions
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
index c245043..f72b82f 100644
--- a/fs/overlayfs/super.c
+++ b/fs/overlayfs/super.c
@@ -333,82 +333,127 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct ovl_entry *oe;
- struct dentry *upperdir;
- struct path lowerdir;
- struct dentry *upperdentry = NULL;
- struct dentry *lowerdentry = NULL;
+ struct ovl_entry *poe = dentry->d_parent->d_fsdata;
+ struct path *stack = NULL;
+ struct dentry *upperdir, *upperdentry = NULL;
+ unsigned int ctr = 0;
struct inode *inode = NULL;
+ bool upperopaque = false;
+ struct dentry *this, *prev = NULL;
+ unsigned int i;
int err;
- err = -ENOMEM;
- oe = ovl_alloc_entry(1);
- if (!oe)
- goto out;
-
- upperdir = ovl_dentry_upper(dentry->d_parent);
- ovl_path_lower(dentry->d_parent, &lowerdir);
-
+ upperdir = ovl_upperdentry_dereference(poe);
if (upperdir) {
- upperdentry = ovl_lookup_real(upperdir, &dentry->d_name);
- err = PTR_ERR(upperdentry);
- if (IS_ERR(upperdentry))
- goto out_put_dir;
-
- if (lowerdir.dentry && upperdentry) {
- if (ovl_is_whiteout(upperdentry)) {
- dput(upperdentry);
- upperdentry = NULL;
- oe->opaque = true;
- } else if (ovl_is_opaquedir(upperdentry)) {
- oe->opaque = true;
+ this = ovl_lookup_real(upperdir, &dentry->d_name);
+ err = PTR_ERR(this);
+ if (IS_ERR(this))
+ goto out;
+
+ /*
+ * If this is not the lowermost layer, check whiteout and opaque
+ * directory.
+ */
+ if (poe->numlower && this) {
+ if (ovl_is_whiteout(this)) {
+ dput(this);
+ this = NULL;
+ upperopaque = true;
+ } else if (ovl_is_opaquedir(this)) {
+ upperopaque = true;
}
}
+ upperdentry = prev = this;
}
- if (lowerdir.dentry && !oe->opaque) {
- lowerdentry = ovl_lookup_real(lowerdir.dentry, &dentry->d_name);
- err = PTR_ERR(lowerdentry);
- if (IS_ERR(lowerdentry))
- goto out_dput_upper;
+
+ if (!upperopaque && poe->numlower) {
+ err = -ENOMEM;
+ stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL);
+ if (!stack)
+ goto out_put_upper;
}
- if (lowerdentry && upperdentry &&
- (!S_ISDIR(upperdentry->d_inode->i_mode) ||
- !S_ISDIR(lowerdentry->d_inode->i_mode))) {
- dput(lowerdentry);
- lowerdentry = NULL;
- oe->opaque = true;
+ for (i = 0; !upperopaque && i < poe->numlower; i++) {
+ bool opaque = false;
+ struct path lowerpath = poe->lowerstack[i];
+
+ opaque = false;
+ this = ovl_lookup_real(lowerpath.dentry, &dentry->d_name);
+ err = PTR_ERR(this);
+ if (IS_ERR(this))
+ 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 this is a non-directory then stop here.
+ *
+ * FIXME: check for opaqueness maybe better done in remove code.
+ */
+ if (!S_ISDIR(this->d_inode->i_mode)) {
+ opaque = true;
+ } else if (prev && (!S_ISDIR(prev->d_inode->i_mode) ||
+ !S_ISDIR(this->d_inode->i_mode))) {
+ if (prev == upperdentry)
+ upperopaque = true;
+ dput(this);
+ break;
+ }
+ stack[ctr].dentry = this;
+ stack[ctr].mnt = lowerpath.mnt;
+ ctr++;
+ prev = this;
+ if (opaque)
+ break;
}
- if (lowerdentry || upperdentry) {
+ oe = ovl_alloc_entry(ctr);
+ err = -ENOMEM;
+ if (!oe)
+ goto out_put;
+
+ if (upperdentry || ctr) {
struct dentry *realdentry;
- realdentry = upperdentry ? upperdentry : lowerdentry;
+ realdentry = upperdentry ? upperdentry : stack[0].dentry;
+
err = -ENOMEM;
inode = ovl_new_inode(dentry->d_sb, realdentry->d_inode->i_mode,
oe);
if (!inode)
- goto out_dput;
+ goto out_free_oe;
ovl_copyattr(realdentry->d_inode, inode);
}
+ oe->opaque = upperopaque;
oe->__upperdentry = upperdentry;
- if (lowerdentry) {
- oe->lowerstack[0].dentry = lowerdentry;
- oe->lowerstack[0].mnt = lowerdir.mnt;
- } else {
- oe->numlower = 0;
- }
+ memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr);
+ kfree(stack);
dentry->d_fsdata = oe;
d_add(dentry, inode);
return NULL;
-out_dput:
- dput(lowerdentry);
-out_dput_upper:
- dput(upperdentry);
-out_put_dir:
+out_free_oe:
kfree(oe);
+out_put:
+ for (i = 0; i < ctr; i++)
+ dput(stack[i].dentry);
+ kfree(stack);
+out_put_upper:
+ dput(upperdentry);
out:
return ERR_PTR(err);
}