These changes are the raw update to linux-4.4.6-rt14. Kernel sources

[kvmfornfv.git] / kernel / fs / overlayfs / inode.c

diff --git a/kernel/fs/overlayfs/inode.c b/kernel/fs/overlayfs/inode.c
index 04f1248..05ac9a9 100644 (file)
--- a/kernel/fs/overlayfs/inode.c
+++ b/kernel/fs/overlayfs/inode.c
@@ -12,8 +12,7 @@
 #include <linux/xattr.h>
 #include "overlayfs.h"
 
-static int ovl_copy_up_last(struct dentry *dentry, struct iattr *attr,
-                           bool no_data)
+static int ovl_copy_up_truncate(struct dentry *dentry)
 {
        int err;
        struct dentry *parent;
@@ -30,10 +29,8 @@ static int ovl_copy_up_last(struct dentry *dentry, struct iattr *attr,
        if (err)
                goto out_dput_parent;
 
-       if (no_data)
-               stat.size = 0;
-
-       err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat, attr);
+       stat.size = 0;
+       err = ovl_copy_up_one(parent, dentry, &lowerpath, &stat);
 
 out_dput_parent:
        dput(parent);
@@ -45,17 +42,32 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
        int err;
        struct dentry *upperdentry;
 
+       /*
+        * Check for permissions before trying to copy-up.  This is redundant
+        * since it will be rechecked later by ->setattr() on upper dentry.  But
+        * without this, copy-up can be triggered by just about anybody.
+        *
+        * We don't initialize inode->size, which just means that
+        * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not
+        * check for a swapfile (which this won't be anyway).
+        */
+       err = inode_change_ok(dentry->d_inode, attr);
+       if (err)
+               return err;
+
        err = ovl_want_write(dentry);
        if (err)
                goto out;
 
-       upperdentry = ovl_dentry_upper(dentry);
-       if (upperdentry) {
+       err = ovl_copy_up(dentry);
+       if (!err) {
+               upperdentry = ovl_dentry_upper(dentry);
+
                mutex_lock(&upperdentry->d_inode->i_mutex);
                err = notify_change(upperdentry, attr, NULL);
+               if (!err)
+                       ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
                mutex_unlock(&upperdentry->d_inode->i_mutex);
-       } else {
-               err = ovl_copy_up_last(dentry, attr, false);
        }
        ovl_drop_write(dentry);
 out:
@@ -140,11 +152,12 @@ struct ovl_link_data {
        void *cookie;
 };
 
-static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
+static const char *ovl_follow_link(struct dentry *dentry, void **cookie)
 {
-       void *ret;
        struct dentry *realdentry;
        struct inode *realinode;
+       struct ovl_link_data *data = NULL;
+       const char *ret;
 
        realdentry = ovl_dentry_real(dentry);
        realinode = realdentry->d_inode;
@@ -152,28 +165,28 @@ static void *ovl_follow_link(struct dentry *dentry, struct nameidata *nd)
        if (WARN_ON(!realinode->i_op->follow_link))
                return ERR_PTR(-EPERM);
 
-       ret = realinode->i_op->follow_link(realdentry, nd);
-       if (IS_ERR(ret))
-               return ret;
-
        if (realinode->i_op->put_link) {
-               struct ovl_link_data *data;
-
                data = kmalloc(sizeof(struct ovl_link_data), GFP_KERNEL);
-               if (!data) {
-                       realinode->i_op->put_link(realdentry, nd, ret);
+               if (!data)
                        return ERR_PTR(-ENOMEM);
-               }
                data->realdentry = realdentry;
-               data->cookie = ret;
+       }
 
-               return data;
-       } else {
-               return NULL;
+       ret = realinode->i_op->follow_link(realdentry, cookie);
+       if (IS_ERR_OR_NULL(ret)) {
+               kfree(data);
+               return ret;
        }
+
+       if (data)
+               data->cookie = *cookie;
+
+       *cookie = data;
+
+       return ret;
 }
 
-static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
+static void ovl_put_link(struct inode *unused, void *c)
 {
        struct inode *realinode;
        struct ovl_link_data *data = c;
@@ -182,7 +195,7 @@ static void ovl_put_link(struct dentry *dentry, struct nameidata *nd, void *c)
                return;
 
        realinode = data->realdentry->d_inode;
-       realinode->i_op->put_link(data->realdentry, nd, data->cookie);
+       realinode->i_op->put_link(realinode, data->cookie);
        kfree(data);
 }
 
@@ -336,37 +349,36 @@ static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
        return true;
 }
 
-static int ovl_dentry_open(struct dentry *dentry, struct file *file,
-                   const struct cred *cred)
+struct inode *ovl_d_select_inode(struct dentry *dentry, unsigned file_flags)
 {
        int err;
        struct path realpath;
        enum ovl_path_type type;
-       bool want_write = false;
+
+       if (d_is_dir(dentry))
+               return d_backing_inode(dentry);
 
        type = ovl_path_real(dentry, &realpath);
-       if (ovl_open_need_copy_up(file->f_flags, type, realpath.dentry)) {
-               want_write = true;
+       if (ovl_open_need_copy_up(file_flags, type, realpath.dentry)) {
                err = ovl_want_write(dentry);
                if (err)
-                       goto out;
+                       return ERR_PTR(err);
 
-               if (file->f_flags & O_TRUNC)
-                       err = ovl_copy_up_last(dentry, NULL, true);
+               if (file_flags & O_TRUNC)
+                       err = ovl_copy_up_truncate(dentry);
                else
                        err = ovl_copy_up(dentry);
+               ovl_drop_write(dentry);
                if (err)
-                       goto out_drop_write;
+                       return ERR_PTR(err);
 
                ovl_path_upper(dentry, &realpath);
        }
 
-       err = vfs_open(&realpath, file, cred);
-out_drop_write:
-       if (want_write)
-               ovl_drop_write(dentry);
-out:
-       return err;
+       if (realpath.dentry->d_flags & DCACHE_OP_SELECT_INODE)
+               return realpath.dentry->d_op->d_select_inode(realpath.dentry, file_flags);
+
+       return d_backing_inode(realpath.dentry);
 }
 
 static const struct inode_operations ovl_file_inode_operations = {
@@ -377,7 +389,6 @@ static const struct inode_operations ovl_file_inode_operations = {
        .getxattr       = ovl_getxattr,
        .listxattr      = ovl_listxattr,
        .removexattr    = ovl_removexattr,
-       .dentry_open    = ovl_dentry_open,
 };
 
 static const struct inode_operations ovl_symlink_inode_operations = {